-
AAS :
-
abbreviation for Alternate Air Source, such as a pony bottle.
-
AAUS :
-
American Academy of Underwater Sciences.
-
aback :
-
toward the back, to the rear. Also, when the wind presses against
the front or forward part of the sail or sails. Also, to surprise
or disconcert; as to be taken aback.
-
abaft :
-
behind or to the rear; toward the stern; astern or aft.
-
abeam :
-
on a line at right angles to a ship's keel; at right angles to
the fore-and-aft line.
-
ABJ :
-
abbreviation for Adjustable Buoyancy Jacket.
-
ABLJ :
-
abbreviation for Adjustable Buoyancy LifeJacket, the old
horsecollar style.
-
ABS :
-
a strong lightweight plastic that's a copolymer of acrylonitrile,
butadiene, and styrene, hence its designation by UniRoyal; this
plastic core is often sandwiched between vinyl layers to protect
it from being degraded by ultraviolet light.
-
absolute pressure :
-
the total pressure at any depth, which is a sum of atmospheric
pressure and hydrostatic pressure; calculated from a vacuum being
rated as the zero point.
-
absolute temperature scale :
-
temperature measured on a scale in which the hypothetical lowest
limit of physical temperatures is assigned the value of zero
(abÆsolute zeÆro), as in the kelvin and rankine scales; also
called absolute temperature or absolute scale. [nb: the degree
intervals of the kelvin scale are the same as celsius, as the
rankine are the same as fahrenheit]
-
absolute zero :
-
the hypothetical temperature at which all molecular activity and
kinetic energy ceases; computed at -273.16°C or
-459.69°F, and represented as 0°K and 0°R. [nb: the
degree intervals of the kelvin scale are the same as celsius, as
the rankine are the same as fahrenheit]
-
ABT :
-
abbreviation for Actual Bottom Time; also called bottom time.
-
abyssal :
-
pertaining to the biogeographic zone of the ocean bottom between
the bathyal and hadal zones; from depths of approximately 13,000
to 21,000 feet. Also, like an abyss, being immeasurable or
unfathomable.
-
accommodation ladder :
-
a portable flight of steps suspended from the side of a vessel to
give crew and/or passenger ingress and egress access from smaller
boats alongside; also known as boarding ladder.
-
acetal resin :
-
a lightweight polymer (ie: polyoxymethylene) engineered for use
as a high-performance metal replacement, exhibiting both high
strength and impact resistance; commercially marketed as Delrin,
Celcon, Hostaform, Duracon, Kepital, Iupital, and Ultraform.
-
acre-foot :
-
a unit of measure for the volume of liquid covered by a surface
area sized one acre to a depth of one foot, or equal to 43,56
cubic feet or 325,850 US gallons; it's used in the United States
as a reference for large-scale water resources, such as
reservoirs, aqueducts, canals, river flows, and the like.
-
actual bottom time :
-
the total amount of time a diver spends descending or at depth;
calculated to begin upon descent and ends upon starting the
ascent; also called bottom time.
-
ACUC :
-
abbreviation for American Canadian Underwater Certifications,
being Canada's scuba certification body.
-
ACV :
-
abbreviation for an Air-Cushion Vehicle or Air-Cushioned Vehicle;
also known as a hovercraft.
-
adjusted no-decompression limit :
-
the maximum bottom time for repetitive dives, being equal to the
no-decompression limit plus residual nitrogen time.
-
admeasure :
-
to measure the dimensions and capacity of a vessel, as for
official registration; as derived from apportion.
-
adrift :
-
anything unsecured, or that has slipped its mooring or fast, as
being out of control, including items improperly stowed, or
things lost overboard.
-
ADS :
-
abbreviation for the Atmospheric Diving Suit, being an
articulated self-contained hard-shell protective body covering
for deep underwater explorations (2000ft at a max 6-8hrs) without
obligatory decompression stops during ascent.
-
ADT :
-
abbreviation for Actual Dive Time.
-
advection :
-
the horizontal flow of air, water, or the like, which often
entails a change of temperature or humidity; as distinct from
convection.
-
AEDU :
-
abbreviation for Admiralty Experimental Diving Unit.
-
aeroembolism :
-
an obstruction of the circulatory system caused by one or more
air bubbles; a condition of decompression sickness.
-
afoul :
-
to be or become entangled, or in a state of collision; as to run,
come, or fall afoul.
-
aft :
-
at the rear or stern, or toward the back of a vessel or craft.
-
AGE :
-
acronym for Arterial Gas Embolism; also called air embolism.
-
ahoy :
-
call used by seafarers to hail or alert others; derived "hoy", as
to hoist.
-
AI :
-
abbreviation for Assistant Instructor.
-
air :
-
a gas mixture present in the earth's atmosphere that's necessary
for human respiration, containing 21% oxygen, 78% nitrogen, and
1% other gases (mainly argon) which is compressed into air tanks
for recreational scuba diving.
-
air bladder / bladder :
-
the inner air cell of a buoyancy compensator (BC), which holds
the necessary amount of air used to provide proper neutral
buoyancy at depth.
-
air cell :
-
a term used to describe a wing-style buoyancy compensator.
-
air compressor :
-
a machine that's used to transfer pressurized air into tanks for
scuba diving; the air is compressed from the atmospheric level
(14.7 psi at sea level) to the capacity of the tank, usually
between 2500-3000 psi. [nb: according to the first law of
thermodynamics, the internal energy of a gas increases when the
gas is compressed]
-
air-cushioned vehicle :
-
a craft that rides on a cushion of air, is kept aloft by fans and
driven forward by propellers; abbreviated ACV.
-
air embolism :
-
an obstruction (gas bubble, or other embolus) that has the
potential to rupture a vessel or organ as a result of the
increase in pressure when blood gases begin to expand or cease to
circulate; a characteristic injury from breath holding during the
ascent after a dive. Also called arterial gas embolism (AGE) or
venous gas embolism (VGE).
-
air pressure :
-
the weight of air, calculated by the force exerted per unit area;
measured at sea level the air pressure is 14.7 pounds per square
inch (psi), decreasing with altitude and increasing with depth.
-
alaia :
-
a traditional wooden type of surfboard, usually more than six
feet in length, that was used by ordinary Hawaiians for surfing
the waves before the overthrow of the Hawaiian monarchy in the
late 19th century.
-
Aldis lamp :
-
a hand-held or portable signal lamp that's used to flash messages
in Morse code; eponymously after the British inventor, A.C.W.
Aldis.
-
alfa :
-
the phonetic representation of the letter 'A'; which is also
represented by a maritime signal flag in the international code.
When hoisted alone, the alfa burgee warns that there is a diver
down (underwater), and other vessels should steer clear at slow
speed; when accompanied by three numeral flags, this signal also
includes the radius within which divers are working. [nb: "alfa"
denotes the phonetic letter, "alpha" denotes the first in a
series]
-
algorithm :
-
a set of rules for solving a problem in a finite number of steps;
as the set of equations used in dive profiles and decompression
tables to compute air supply, air mixture, underwater duration,
and dive intervals.
-
Alluvium :
-
a deposit of sand, mud, and other sedimentary matter that's
formed by the wash of flowing water, which has been deposited
within recent times, especially in the valleys or outlets of
large rivers.
-
alternate air source :
-
any device a diver can use in place of the primary regulator, in
order to make an ascent while still breathing normally.
-
altitude diving :
-
underwater diving while at heights significantly above sea level,
as when quarry or cave diving in uplands; the decompression stops
used for dives at higher altitude are different from those used
for the same dive profile at sea level.
-
aluminum :
-
a silver-white metallic element, lightweight and non-magnetic,
ductile and malleable, and not readily corroded or tarnished, as
used in alloys. [nb: one of the higher strength aluminum alloys
is 5052, which has excellent forming characteristics and good
corrosion resistance, including resistance to salt water; 6351-T6
is an aluminum alloy that's experienced air tank ruptures]
-
alveolus / alveoli :
-
the tiny bunched air sacs at the end of the bronchioles in the
lungs where gas exchange occurs with the circulatory system.
-
ambient light :
-
the sunshine penetrating underwater, diminishing with depth and
turbidity, that's used as natural illumination.
-
ambient pressure :
-
the surrounding pressure; being the effective pressure from the
weight of the water and atmosphere around the diver at any
particular depth. [nb: one atmosphere is approximately 14.7
pounds of pressure per square inch (psi)]
-
AMBU bag :
-
Artificial Manual Breathing Unit is the proprietary name for a
manual resuscitator, a self-inflating bag, or a bag valve mask
(BVM), which is a hand-held device used to provide positive
pressure ventilation to persons who are not breathing or not
breathing adequately; invented in 1953 by Holger Hesse and
Henning Ruben for use by rescuers and medicos.
-
AMDT :
-
abbreviation for Adjusted Maximum Dive Time.
-
amidship / amidships :
-
in, at, or toward the middle part of a vessel or craft.
-
amphibian :
-
an airplane designed for taking-off from and landing on either
land or water.
-
anadromous :
-
pertaining to fish that migrate from saltwater to spawn in
freshwater; as distinguished from catadromous.
-
analog :
-
a mechanism that represents data by measurement to a continuous
physical variable (eg: voltage, pressure, etc) and displayed on a
readout by a pointer or hands on a dial.
-
anchor :
-
any heavy device or similar item that's dropped by a tethering
chain or cable to the bottom of a body of water that's used for
restraining the motion of a vessel or some other floating object;
to be "at anchor" by holding fast or controlling motion.
-
anchorage :
-
a seaport or harbor with secure docking facilities for a ship.
-
anchor deck :
-
a small forecastle that houses the machinery for operating the
anchors of a ship.
-
ANDI :
-
abbreviation for Association of Nitrox Divers International; also
American Nitrox Divers Incorporated.
-
ANDL :
-
abbreviation for Adjusted No-Decompression Limit.
-
angling :
-
moving across the main current or primary flow of water so as to
enhance one's control or improve one's relative position.
-
anoxia :
-
the mental and physical disturbances that result from hypoxia, a
lack of oxygen or suffocation.
-
Antarctic Circle :
-
a parallel of latitude that marks the farthest point (66.5°S)
south of the equator where the sun appears above the horizon each
day of the year.
-
anticoagulant :
-
an agent that inhibits coagulation, especially something that
prevents blood from clotting or congealing; the use of such
medications (including aspirin) is particularly dangerous to
divers due to the barotrauma of air-filled body cavities.
-
AODC :
-
abbreviation for Association of Offshore Diving Contractors.
-
AOW :
-
abbreviation for Advanced Open Water, the second level of PADI
scuba certification.
-
AP :
-
abbreviation for Absolute Pressure.
-
apparatus :
-
a combination of parts or mechanisms, instruments or machineries
having a particular function; a complex device or group of
devices that function together for a particular purpose.
-
aquaclude :
-
an earth layer that inhibits or precludes the passage of water,
such as shale, or unfractured igneous and metamorphic rocks.
-
aqua-lung :
-
the name of the original open-circuit, self-contained, underwater
breathing equipment, developed by Emile Gagnan and Jacques Y.
Cousteau in 1942 during World War Two; consisting of a regulator
and a high pressure air cylinder that supplied the required
breathing gas at ambient pressure through a double-hosed demand
valve. This system superseded the earlier attempts at
constant-flow compressed-air breathing setups. [nb: "Aqualung"
and "Aqua Lung" are registered trademarks of commercial products]
[nb: the single-hosed scuba regulator was invented by Ted Eldred,
an Australian, in 1953]
-
aquanaut :
-
a specially trained scuba diver who works for an extended period
of time from, and in the vicinity of, a submerged dwelling.
-
aqua sled / aqua-sled :
-
a surface or subsurface water glider that's made of transparent
materials, of various widths and lengths, with or without keels
or skegs, with floats embedded along the outside edges (also
serving as bumpers) forming a cupped or depressed central area
where the operator lays prone so as to control the attitude
adjustments (ie: pitch, roll, yaw, and heave) of the craft with
two primitive steering levers, such that this towable sled may
ride the currents, afloat or submerged, as desired by its
operator; first introduced (1956) as an improvement on the full
body surfboard, and a replacement for cargo-carrying paired water
skis, this sled has since been motorized for greater autonomy.
-
aqueduct :
-
a conduit, canal, or artificial channel serving to conduct water
from a distance.
-
aquifer :
-
a geological formation of permeable rock, gravel, or sand
containing or conducting groundwater, especially one that
supplies the fresh water for wells, springs, and the like.
-
arbalest / arbalist :
-
a powerful crossbow with a spring-steel bow that's capable of
shooting stones and metal balls, bolts and fletched arrows;
originating in the medieval era.
-
Archimedes' principle :
-
a mechanistic theorem on relative displacement that states a body
immersed in a fluid is buoyed up by a force equal to the weight
of the displaced fluid, or a floating object displaces an amount
of water that is equal in weight to the floating object; which is
used by divers to calculate the buoyancy of an object.
-
Arctic Circle :
-
a parallel of latitude that marks the farthest point (66.5°N)
north of the equator where the sun appears above the horizon each
day of the year.
-
argon :
-
a colorless, odorless, chemically inactive, monatomic, gaseous
element that makes up less than 1% of air; this inert element is
often used as dry suit inflation in cold water due to its
insulating properties.
-
arm :
-
an inlet or cove, as "an arm of the sea". Also, a curved piece on
an anchor that terminates in a fluke.
-
artesian well :
-
a well in which water rises under pressure from a permeable
stratum overlaid by impermeable rock.
-
arterial gas embolism :
-
a condition in which gas bubbles enter the arterial system and
cause damage by blocking blood flow to vital organs, most
commonly the brain, which most often occurs when air passes
through the walls of capillaries and alveoli into the
bloodstream; abbreviated AGE, and also called "air embolism".
-
articles of agreement :
-
a contract, between the captain of a ship and a crewmember,
regarding stipulations of a voyage that's signed prior to and
upon termination of a voyage; also called "shipping articles".
-
artificial reef :
-
a man-made underwater structure that's been emplaced so as to
reduce beach erosion by lessening the impact of swells, and to
provide a suitable ecology for aquafauna.
-
artificial respiration :
-
the stimulation of natural respiratory functions in a person
whose breathing has failed by forcing air into and out of the
lungs; to simulate, by various means, pulmonary ventilation.
-
artificial spit :
-
a commercial product that imitates the properties of a natural
secretion; being small bottles of specially compounded liquid
that's used by divers to keep the window of their masks defogged.
-
ascent bottle :
-
an extra or reserve gas cylinder that has been prepositioned to
accommodate the mandatory in-water decompression stops on deep
dives; also called stage bottle.
-
ascent / descent line :
-
an anchored line, suspended from a boat or buoy, that's used to
control a diver's rate of ascent or descent, to provide
orientation in strong currents and low light on deep dives, and
to secure reserve gas cylinders for decompression stops; a type
of safety line that's also called "drop line".
-
ascent rate :
-
the prescribed safe rate of ascent for off-gassing a diver is 30
feet per minute while rising to the surface.
-
ASD :
-
Atrial Septal Defect, being a disqualifying congenital cardiac
condition.
-
ASF :
-
abbreviation for Australian Speleological Federation.
-
ASL :
-
abbreviation for American Sign Language, being hand and arm
signals representing whole words and phrases.
-
asphyxiation :
-
the extreme condition (suffocation) caused by lack of oxygen and
excess of carbon dioxide in the blood, produced by interference
with respiration or insufficient oxygenated air; as derived from
"stopping of the pulse". Also, to lose consciousness by impairing
normal breathing; to cause to choke or smother, as by gas or
other noxious agents.
-
astern :
-
situated behind something else, as being to the rear of a
specified craft. Also, a backward direction.
-
ASTM :
-
abbreviation for American Society for Testing and Materials,
being a standards organization that sets industrial measurements;
for example, the ASTM 568A schedule identifies O-rings by a three
digit suffix denoting their diameter and hardness.
-
asymmetrical zipper :
-
a zipper closure with staggered or offset teeth that's used on
wet suits to maintain a tighter seal and prevent leakage.
-
ATA :
-
abbreviation for Atmosphere Absolute, a measure of absolute
atmospheric pressure.
-
ATEA :
-
abbreviation for Amphibian Tank Escape Apparatus.
-
athwart :
-
from side to side, across, crosswise; not aligned or
adjacent.
-
ATM :
-
abbreviation for a standard atmosphere; this established constant
is approximately equal to the typical air pressure at earth mean
sea level, and is defined as: 1 atm = 101325 Pa / 101.325 kPa, or
760 mm Hg, or 14.7 psi.
[nb: a rule of thumb used by divers states that the pressure
exerted by ten metres (33 feet, depending upon salinity) depth
of water is approximately equal to one atmosphere]
-
atmosphere absolute :
-
the ambient pressure, including the barometric pressure of the
air above the water; abbreviated ATA.
-
atmospheric pressure :
-
the normal amount of pressure exerted by the earth's atmosphere,
being 14.7 pounds per square inch (called "one atmosphere") at
sea level; also known as "barometric pressure". [nb: atmospheric
pressure typically doubles at 33ft below sea level, and is
halved at 18,000ft above sea level]
-
atoll :
-
a ring-shaped coral reef, or a string of closely spaced small
coral islands, enclosing or nearly enclosing a shallow lagoon;
previously called atollon.
-
At-Pak :
-
brand name of an early ScubaPro backpack-style buoyancy
compensator that used lead shot for ballast, which was considered
to be a more comfortable alternative to a lead weight belt; in an
emergency, the shot could be unloaded by pulling a release pin.
-
ATS :
-
abbreviation for Atmospheres Absolute Over Sea Level (ie: gauge
pressure).
-
AUF :
-
abbreviation for the Australian Underwater Federation.
-
auxiliary bridge :
-
on large ships and ocean liners, a secondary room setup with
duplicate controls that may be used as a substitute or reserve in
case of need.
-
AV :
-
abbreviation for Artificial Ventilation.
-
avast :
-
an imperative directive or command to stop or cease; perhaps
derived from "hold fast".
-
avocational :
-
a certified volunteer who assists on a research or exploration
project, such as marine archaeology or aquatic biology, as
undertaken by students or professionals in other fields during
their vacations so as to gain experience and advance knowledge.
-
Avogadro's law :
-
the principle that equal volumes of all gases at the same
temperature and pressure contain the same number of molecules;
thus the molar volume of all ideal gases at 0°C and a
pressure of 1atm is 22.4 liters; named after Amadeo Avogadro.
[nb: when the temperature of a gas is absolute zero, its volume
is also zero]
-
Avogadro's number :
-
the constant (6.022 x 1023) representing the number of
atoms in a gram atom, or the number of molecules in a gram
molecule of a given substance; also called "Avogadro's constant".
-
AWARE :
-
abbreviation for Aquatic World Awareness Responsibility and
Education, being a PADI nonprofit environmental foundation.
-
axial flow scrubber :
-
a type of treatment canister used in re-breathers where exhaust
gas enters at one end and, after filtering, exits the other end.
-
A-yoke :
-
a tank valve that provides a high pressure seal between the tank
valve and the regulator first stage, and works by compressing an
O-ring between two metal seats; also known as a compressed O-ring
valve, this yoke assembly holds the seal in place.
-
azimuth :
-
the horizontal deviation of a bearing (usually in "degrees") as
measured from a standard reference (usually "magnetic north"); a
compass heading or angle.
-
backing off / backing-off :
-
the diminution of a wave as it passes from shallow water into
deeper water that's closer to shore, tending to occur shoreward
of offshore reefs or sand bars, with the wave becoming less
steep, or the broken whitewater fading away; the wave may reform
and break again in even shallower water closer to shore.
-
back-mount :
-
an equipment configuration wherein the air tanks are attached
onto the divers back by a harness and backplate; as opposed to
side-mount.
-
back paddle :
-
to work an oar or paddle in reverse (backwater), often against
the prevailing current, so as to slow the forward movement of a
paddleboard or small watercraft, or to hold it in relative
position so that it doesn't continue to move with the flow from
earlier strokes or to proceed farther downstream.
-
backplate :
-
a mounting plate, made of aluminum, steel, molded plastic, or
ballistic nylon, through which the diving harness is threaded,
and to which the air tanks and buoyancy compensator (BC) are
mounted; the original design was by Greg Flannigan in 1979.
-
back roll entry :
-
see backward roll entry.
-
backscatter :
-
(forthcoming) [v: nephelometer]
-
backstroke :
-
a swimming stroke, performed in the supine position, wherein both
arms are alternately brought out of the water in an overhead
circular motion, which movements are combined with the flutter
kick.
-
backup light :
-
an alternate or substitute source of illumination that's kept in
reserve for an emergency, being a redundancy precaution.
-
backward roll entry :
-
a self-protective water entry method in which the fully equipped
seated diver rolls off the side or stern of the boat, allowing
the back-mounted air tanks to strike the surface first, while the
diver's body is in a tuck, face mask held in place, and then
continues the roll underwater into a prone swimming position; any
extra gear or bottles ride in the diver's protected "breadbasket"
for a safe and secure entry; also called "back roll entry" or
"flip-flop entry".
-
backwash :
-
a wave reflected by an obstacle or a steep onshore grade that
rebounds against the incoming main flow or current, which can
create spectacularly explosive collisions of rushing water. Also,
water thrown backward by the motion of oars, propellers, paddle
wheels, or any other means of propulsion. Also, to clean
something out, such as a clogged filter, by reversing the flow of
fluid passing through it. Also, a condition, or the effects of a
condition, usually undesirable, that continues long after the
event which caused it; aftermath, consequence, result, upshot.
-
backwater :
-
water held or forced back, as by a dam, flood, or tide. Also, to
halt or reverse the forward movement of a vessel by applying
opposite or reverse propulsion; backwash. Also, to literally back
up, as to retreat, or to figuratively back down, as to
back-pedal. Also, an isolated or stagnant place that has been
literally or figuratively bypassed; undeveloped, regressive, or
backward.
-
baggywrinkle :
-
chafing gear made from old ropes.
-
bail :
-
a dipper, bucket, or other container used for emptying excess
water out of a boat; to remove said water by use of a dipping
container; as derived from 'carrier' [baiulus (Latin)]. Also, to
escape, abandon, or give up on a difficult situation or
predicament; also represented as 'bail-out'. Also, a semicircular
hoop, such as a handle for a kettle or pail, or a support for a
canopy or cover (eg: spray deck).
-
bail-out bottle / bailout bottle :
-
an air cylinder containing an emergency supply of breathing gas
that's used to escape from trouble with the primary air supply.
-
ballast :
-
a heavy material (including sea water) carried on a vessel to
control draft and stability. Also, a heavy material (eg: lead
weights) carried by an underwater swimmer to control depth and
trim.
-
ballistic nylon :
-
a high-performance synthetic thermoplastic material that's
characterized by strength and elasticity, resistance to abrasion
and chemicals, low moisture absorbency and a capacity to be
permanently set by heat; this tough polyamide fabric is tear
resistant and was introduced during WWII as protection against
flying debris.
-
balsa :
-
a tropical MesoAmerican tree yielding a lightweight porous wood
[ety: boat (Spanish)] that's useful for making life rafts and
marker floats, among other items; the core material for early
surfboards and paddleboards (later replaced by polyurethane foam)
when laminating techniques enabled the structural body to be
sealed against waterlogging.
-
bamboo :
-
an alternative to fiberglass when making thin strong laminar
sheets that're used in the construction of watercraft.
-
bank :
-
a broad seafloor elevation (eg: sandbank) around which the water
is relatively shallow, but not a hazard to surface navigation.
-
bang stick :
-
a hollow tube containing a sealed pistol, rifle, or shotgun
cartridge that can only be triggered by direct contact with its
target, as used for hunting or self-defense while swimming
underwater.
-
bar :
-
a centimeter-gram-second unit of pressure (term derives from
"weight") that's equal to one million dynes per square centimeter
(15 psi, 101 kPa); used by divers to represent the force exerted
upon a given area, and equivalent to the force of one atmosphere
(1 ATA = 1.0132 bar). Also, a long ridge of sand (ie: sand bar),
gravel, or other material near or slightly above the surface of a
body of water, often an obstruction to navigation.
-
Barisal guns :
-
the name given to mysterious booming sounds that seemingly come
from nearby occurrences at sea, being situated offshore from
Barisal (Eastern Bengal), Bangladesh.
-
barometric pressure :
-
atmospheric pressure affected by weather, as measured by an
aneroid barometer, wherein standard atmospheric pressure has a
value that's equivalent to the pressure exerted by a column of
mercury 29.92 inches (760 mm) high, or 1013 millibars (101.3
kilopascals).
-
barotrauma :
-
injury, generally to the middle ear or paranasal sinuses,
resulting from imbalance between ambient pressure and that within
the affected cavity.
-
barrel / tube :
-
the space inside a tubular breaking wave between the lip and
face; a curling hollow opening in a comber.
-
barrier island :
-
a broadened barrier beach, which may be habitable in places, that
provides a measure of protection for the mainland, as during
hurricanes and tidal waves.
-
basin :
-
a partially enclosed, sheltered area along a shore where boats
may be moored. Also, a natural or artificial hollow place
containing water.
-
bateau / batteau :
-
a small flat-bottomed rowboat that's designed for use on rivers
and other constricted waterways.
-
bathing suit :
-
a garment worn for swimming or for recreational activities in and
around water; also called swimsuit or swimming suit.
-
bathyal :
-
pertaining to the biogeographic region of the ocean bottom
between the sublittoral and abyssal zones; from depths of
approximately 660 to 13,000 feet.
-
bathymetry :
-
the measurement of the depth of water in oceans, seas, lakes, or
other large bodies of water, so as to determine the topography of
the seafloor or underwater bottom.
-
bathyscaphe :
-
a navigable submersible vessel, with an observation chamber in
its hull, that's used for exploring the ocean's depths; coined by
Auguste Piccard.
-
batten :
-
a thin or narrow strip of lumber attached to sailcloth to keep it
flat or taut. Also, to cover a hatch or other opening so as to
make it watertight.
-
bay :
-
a body of water that forms an indentation in the shoreline, which
is larger than a cove but smaller than a gulf. Also, in the south
Atlantic statesregion, an arm of a swamp.
-
BC :
-
abbreviation for Buoyancy Compensator.
-
BCD :
-
abbreviation for Buoyancy Control Device; enables the diver to
regulate buoyancy to control depth, and acts as a flotation
device on the surface.
-
BCRA :
-
abbreviation for British Cave Research Association.
-
beach :
-
an expanse of sand or pebbles along a shore, often washed by the
tide or waves. Also, to haul something or run a boat onto the
shore. Also, to cause to be unemployed or idle; as "on the
beach".
-
beach break :
-
waves that break over a sand or pebble shore.
-
beach drift :
-
the drifting of marine sediments in patterns parallel to the
contours of a beach, due to the action of waves and currents;
also called "littoral drift" or "longshore drift".
-
beachmaster / beach master :
-
the person responsible for the accountability of persons and
equipment on shore, and in charge of the on shore work party;
more commonly called a 'dive marshal'.
-
beam :
-
the maximum width (breadth) of a ship at its widest part.
-
bearing :
-
a horizontal direction, expressed in degrees, east or west of the
true or magnetic north (or south) direction. Also, one's relative
position or direction, often expressed as "bearings".
-
Beaufort scale :
-
a scale indicating the speed or force of wind, enumerated 0-12 or
0-17, commonly expressed as "Force #"; devised by British Admiral
Francis Beaufort around 1855.
-
beaver / beaver tail / butt flap :
-
a piece of neoprene fabric that hangs down in the back on a
wet suit jacket and is drawn forward between the legs to attach
to the front, covering the diver's crotch.
-
belay :
-
to fasten by connection or attachment so as to make secure,
especially a rope or line used by someone for descent or ascent.
Also, an imperative directive to stop or cease, desist or quit.
Also, a secure object or other safe projection that's sturdy
enough to anchor a rope or line under a full load.
-
bends :
-
common term for decompression sickness (DCS) or aeroembolism.
Also, the wales of a vessel; thick planking immediately below the
waterways of a wooden vessel.
-
benthos :
-
the biogeographic region that includes the bottom of a lake, sea,
or ocean, and the littoral and supralittoral zones of the shore;
also known as benthic division or benthonic zone.
-
bergy bit :
-
a small iceberg, somewhat larger than a growler.
-
berth :
-
a shelflike sleeping space aboard ship. Also, the space, at a
safe distance from shore, that's been allotted for a vessel to
dock or lie at anchor; a water surface mooring area that's
delineated by either floating or fixed dock structures, for the
purposes of embarking, disembarking, and the wet storage of a
recreational boat. Also, a job or position; a place or situation
of employment.
-
bezel :
-
the angled rim surrounding the face of a watch or compass,
especially a rotating ring that can serve to mark time or
indicate position; as derived from 'bevel' or 'chamfer'.
-
bibb :
-
any of several timbers bolted to a ship's mast to support the
trestletrees.
-
BIBS :
-
abbreviation for Built-In Breathing System on a pressure sealed
device (eg: hyperbaric chamber).
-
bight :
-
a looped or slack part of a rope. Also, a bend or curve in the
shoreline of a sea or river. Also, a body of water bounded by
such a bend, as a bay or gulf.
-
bilge :
-
either of the rounded areas that form the transition between the
bottom and the sides on the exterior of a hull; derived by
alteration of "bulge". Also, an enclosed area at the bottom of a
vessel where seepage collects; usually called "bilges". Also, the
seepage collected in this space; also called "bilge water". Also,
slang for foolish talk or worthless ideas; nonsense, claptrap,
malarkey, confetti, snow, blow smoke.
-
bilge keel :
-
a keellike projection along a ship's bilge to retard rolling;
also called "baby keel".
-
billethead :
-
a carved ornamental scroll or volute, terminating a stem or
cutwater at its upper end, in place of a figurehead; also called
scrollhead.
-
billow :
-
a great wave or surge of the sea; as derived from 'bulge'. Also,
to swell or rise, wax or expand, heave or undulate, as when blown
by the wind.
-
bimini / bimini top :
-
a protective canopy without side panels or drapes that's
supported by scantling over the cockpit of a boat.
-
bitt :
-
a strong post, which usually projects in pairs, that's set above
the deck of a ship for securing cables, hawsers, towing lines,
and the like; as derived from "wooden peg".
-
black water :
-
the dark depths of sea water that's below the level of
penetration of sunlight; being at or below a depth of 90ft or two
atmospheres of pressure. Also, clear or frothy water running
underground in a stream where navigation thereupon cannot be
aided by natural illumination.
-
black-water rafting / blackwater rafting :
-
quickly moving over or through frothy rapids along an underground
passage where natural illumination cannot aid in navigation; also
called "cave tubing", the participants are usually outfitted in
wet suits and life jackets while riding in an inflated dinghy.
-
bladder / air bladder :
-
the inner air cell of a buoyancy compensator (BC), which holds
the necessary amount of air used to provide proper neutral
buoyancy at depth.
-
blank :
-
a block of polyurethane foam, often from a pre-shaped mold in a
basic outline, suitable for sizing, shaping, laminating, and
finishing into a paddleboard or surfboard.
-
blind roller :
-
a long oceanic swell that almost rises to breaking as it passes
over shoals.
-
blindstitched / blind-stitched :
-
a wet suit seam that's glued together before being sewn halfway
through the material so that the partial penetration helps to
preserve watertightness while making the garment more durable and
flexible ... generally used on higher-end suits.
-
blink :
-
a brightening of the base of a cloud layer caused by the
reflection of light by snow or ice, as derived from gleam,
twinkle, glitter, or shine.
-
block :
-
a housing or part enclosing one or more freely rotating, grooved
pulleys, about which ropes or chains pass to form a hoisting or
hauling tackle; also known as "tackle block" or "block 'n'
tackle". Also, an obstruction, obstacle, hindrance, or stoppage.
-
blown out / blown-out :
-
a surf condition caused by strong onshore winds, which creates
chop on the wave faces, extending into the wave lineup.
-
blue hole :
-
a sinkhole in a lake or the sea, which is subject to tides,
causing its flow to reverse; such sinkholes are often the
entrance to a cave.
-
blue jacket :
-
informal designation for a seaman or sailor, by reference to his
blue duffel or pea jacket.
-
blue nose :
-
a ship that has crossed the Arctic Circle (between the North
Frigid Zone and the North Temperate Zone) or Antarctic Circle
(between the South Frigid Zone and the South Temperate Zone), so
called from painting the hawsepipes blue, as being representative
of the cold; the ship's company of such a voyage may be called
"blue noses". [nb: alternatively, the "Order of the Blue Nose" is
reserved exclusively for the Arctic Circle, and the "Order of the
Red Nose" exists as an exclusive distinction for the Antarctic
Circle]
-
blue water :
-
nautical reference to the open sea, or oceangoing; also
represented as "deep water", and sometimes spelled "blue-water".
-
bluff :
-
a bold coastline or precipitous headland. Also, a full blunt bow
on a vessel. Also, a cliff or headland with a broad steep face.
-
board :
-
the side of a ship; or the windward tack of a ship's course.
-
boarding float :
-
a platform-type structure, either floating or fixed, stationary
or adjustable that's designed for short-term moorage of boats,
and to facilitate pedestrian access to and from boats in the
water; it's located on, along side of, or near a boat launch
ramp; also known as a boarding pier (qv).
-
boarding ladder :
-
any stairway, ladder, net, or similar construction used to
accommodate the ingress or egress of people over the side of a
ship.
-
boarding party :
-
a group of persons who board a vessel, especially to attack,
seize, or search it.
-
boarding pier :
-
the portion of a pier where a boat is temporarily secured for the
purpose of embarkation or disembarkation.
-
boat deck :
-
a superstructure deck on which most of the lifeboats of a ship
are stowed.
-
boat dock :
-
a boat slip or berth (qv).
-
boating party :
-
a group of persons who board a vessel for transport or
recreation, especially when paying for the privilege.
-
boat launch ramp :
-
a sloped surface at the edge of a body of water that's designed
and constructed (usually paved) for the launching and retrieval
of trailered boats and other watercraft.
-
boat ramp :
-
a boat launch ramp (qv).
-
boat slip :
-
a boat dock or berth (qv).
-
boatswain's chair :
-
a wooden plank or canvas seat that's hung by ropes over the side
of a ship's rail, deck, bridge, and the like for stable access
while performing construction, maintenance, or rescue work.
-
boatswain's locker :
-
a storage compartment, usually located forward, where tools,
line, and other small equipment for working on deck is stowed.
-
boatswain's pipe / boatswain's whistle :
-
a simple musical device used by the boatswain to make shipboard
announcements over the public address (PA) or loudspeaker system.
-
bodyboard / bodyboarding :
-
a relatively small polyethylene foam board that's ridden prone
(occasionally drop knee) on the surface of the water, often with
swim fins, being intended for use by beginners and by those
persons using it for exercise or in sporting competitions;
inspired by the "Morey Boogie board" during the 1970s.
-
body suit :
-
a lightweight wet suit made of thin rubber or neoprene so as to
maximize flexibility and mobility in warm waters while still
providing environmental protection, as from fish stings, coral
scrapes, sun and wind burns.
-
body-surf / body-surfing :
-
to ride the crest of a wave without a surfboard, being the
original form of surfing; in shallow water, a body-surfer can
work the dynamics of a wave as it responds to the seafloor, but
in deep water, the use of swim fins will be necessary to catch
the current.
-
bollard :
-
a substantial post on a wharf or deck ("bitt") made of wood,
metal, or concrete that's used for mooring vessels.
-
BOLT :
-
a mnemonic acronym for the in water check performed prior to
diving: Bubbles (manifold and valve check), Out of air (S-drill),
Lights, Turn Time (Thirds).
-
boltrope :
-
cordage sewn to the edge of canvas yardage or sheeting (ie: tarp,
tentage, sail) that's used to reinforce and strengthen it.
-
bolt snap :
-
a hardware device, made of brass or stainless steel, that has a
spring-loaded thumb-gate, can be double ended or have a swivel on
one end, that's used to clip items to the diver's harness; also
known as a piston bolt.
-
bombiti / baturlio marina :
-
the name given to mysterious booming sounds that seemingly come
from nearby occurrences at sea, being situated off certain
coastal sites in Italy.
-
bonzer :
-
a surfboard featuring a single or double concave-shaped (channel)
underside; originated by Duncan and Malcolm Campbell (1971), and
so-called after the Australian exclamation for great or
fantastic, remarkable or exceptional, wonderful or terrific.
-
boogie board / boogie-boarding :
-
a small polyethylene foam surfboard (cut down from a larger blank
to be about 45inches long by 25inches wide by 2.25inches thick)
that was developed by Tom Morey in July 1971 for its sport and
recreational applications, especially among novices; the "Morey
Boogie board" (initially trademarked but since genericized)
inspired the bodyboarding craze (similar to the shorty skiing
fad) because these short flexible boards were so manageable and
fun ... the name probably derives from the slang of the era for
scoot, spurt, move out or move along.
-
boom :
-
any of various spars, beams, or poles projecting from a mast, as
used to extend a ship's sails, to handle cargo, to guide objects,
or to hold devices; also called a derrick or crane, an arm or
stick. Also, a chain, cable, or the like serving to obstruct
navigation.
-
boot :
-
a plastic footing that fits on the rounded bottom of a scuba tank
that allows it to be stood upright without support; not used in
cave diving due to being an entanglement hazard.
-
bootie / bootee :
-
a waterproof (neoprene) sock-like foot covering, serving to
insulate and protect the diver's foot and ankle, that's worn
inside open-heeled flippers or fins; also called "footie".
-
boottop / boottopping :
-
a distinctive band of paint covering the area between the water
lines of a ship when fully loaded and when unloaded; also called
load-line mark or plimsoll mark.
-
booty :
-
slang for an unexplored ("virgin") cave.
-
bottle :
-
slang for the cylinder, usually steel or aluminum, of pressurized
breathing gas that's used in scuba diving; a portable tank
containing compressed air for breathing underwater.
-
bottom mix :
-
the breathing gas specified for the deepest depth of a dive, such
as air, nitrox, or helium, usually when other decompression gases
are present.
-
bottom time :
-
the elapsed time between a diver descending below the surface to
the beginning of the return ascent; also called actual bottom
time (ABT).
-
bottom timer :
-
a pressure activated timing device, mechanical or electronic,
that automatically starts measuring bottom time when a diver
descends underwater.
-
bounce dive :
-
in recreational diving, a descent to a specific depth, often the
seafloor maximum, that's immediately followed by a return ascent
back to the surface with the least delay, which is represented in
a dive profile resembling a spike; also called a "yo-yo dive". In
commercial diving, the alternative to saturation diving.
-
bourdon tube :
-
a spiral or c-shaped tube that changes its shape when pressure
increases at depth; used in depth gauges to alter the position of
the denotative indicator as the tube changes shape; derived from
the drone or low-pitched tone emitted by musical instruments.
-
bow :
-
the front of a craft or vessel; designated by the color white;
also called prow or stem. Also, the abbreviation for Basic Open
Water, a scuba certification. Also, the foremost oar, situated at
the forward end, when rowing a boat.
-
bower :
-
an anchor carried at the bow of a vessel.
-
bowl :
-
the concave face of a swelling wave; this curling bend adds
intensity, causing the wave to grow hollower or steeper.
-
bowline :
-
a non-slipping knot forming a fixed loop, especially at the end
of a rope. Also, a rope fastened to either of the lateral leeches
of a square sail so as to keep the sail as flat as possible
whenever sailing close-hauled.
-
bow line :
-
see painter.
-
bowsprit :
-
a spar projecting from the upper end of the bow of a sailing
vessel, for holding the tacks of various jibs or stays, and often
supporting a jib boom; as derived from bow pole.
-
boy :
-
an apprentice seaman or fisherman, especially one who has not
before gone to sea (eg: cabin boy).
-
Boyle's law :
-
the principle that, for relatively low pressures, the pressure of
an ideal gas kept at constant temperature varies inversely with
the volume of the gas; named after Robert Boyle, it's also called
Mariotte's law; also expressed as PV=k (Pressure)(Volume) =
(constant of proportionality), or PV=nRT.
-
BPR :
-
abbreviation for Back Pressure Regulator, wherein air flow
through a one-way valve is adjusted to sustain a constant level
of upstream (or downstream) pressure, if possible.
-
braided line :
-
woven nylon line that has better abrasion resistance than twisted
line.
-
brash / brash ice :
-
small, brittle fragments of suspended sea ice or floating river
ice.
-
breaker :
-
a wave that breaks into foam, either at an offshore surfline or
upon shoals or the shore.
-
breaking :
-
when an advancing wave passes from deep to shallow water, it
steepens as its energy is forced upward (shoaling) until the wave
becomes unstable, resulting in the crest tumbling down its face.
-
breaking strength :
-
the load that will cause a line or rope to fail.
-
breakline / break line :
-
the line where advancing waves begin to break; with all things
being equal, waves will begin to break when they reach water at a
depth of about 1.3 times the height of the wave face.
-
breakthrough :
-
indicates the entry of carbon dioxide into the inhalation side of
the breathing loop from the absorbent canister on a re-breather.
-
breakwater :
-
a barrier that breaks the force of incoming waves, as before a
harbor or bay. [nb: this term has been mistakenly used to mean
"where waves break" before a shore or upon shoals; which is
properly known as 'surf' or 'surfline']
-
breaststroke :
-
a swimming stroke, performed in a prone position, wherein the two
hands are simultaneously extended forward, outward, and rearward
from in front of the chest while the legs move simultaneously in
a frog kick.
-
breath-hold diving :
-
underwater diving without supplemental air or breathing
equipment; also called free diving or skin diving.
-
breathing loop :
-
the part of a re-breather system that includes the mouthpiece,
hoses, inhalation bag, exhalation bag, and absorbent canister.
-
breech :
-
the end of a block or pulley farthest from the supporting hook or
eye.
-
breeches buoy :
-
a life preserver with a pants-like canvas seat for hauling a
shipwrecked or disabled person on or off a vessel; also called
"britches buoy".
-
bridge :
-
a structure spanning and providing passage over an opening or
past an obstacle. Also, the platform from which a vessel is
controlled and navigated.
-
bridge deck :
-
a deck on top of a bridge house; also called a flying bridge.
Also, the deck from which a vessel is usually operated; the
location of the pilothouse. Also, the first deck in a bridge
house.
-
brightwork :
-
the polished metal parts on a ship. Also, all plain or varnished
woodwork that is kept scoured on a vessel.
-
brine :
-
the sea or ocean; the water of the sea. Also, water saturated or
strongly impregnated with salt; any saline solution. [v:
brackish]
-
broach :
-
to veer to windward. Also, to break the surface of water from
below, such that the rudder cannot be used to steer.
-
brow :
-
a gangplank, gangway, or passageway. Also, the edge of a steep
place or drop-off, as a brink or brim, by analogy with the brow
of the head.
-
brown water :
-
nautical reference to shallows, shoals, littoral or estuarial
waters.
-
BSAC :
-
abbreviation for British Sub-Aqua Club, a club-based organization
that has served, since 1953, as the governing body for the
instruction and practice of recreational scuba diving in the
United Kingdom.
-
BT :
-
abbreviation for Bottom Time, which definition is agency
dependent.
-
bubblehead :
-
slang for a submariner; also known as a dipper, boomer, or
dolphin.
-
buckle / ding :
-
a crease or crack (fracture line) in the fiberglass and resin of
certain boards or watercraft as a result of impact; such damage
often renders the object unusable ... strips of carbon fiber are
sometimes embedded into the polyester resin or laminated into the
fiberglass as reinforcement to forestall creases and cracks.
Delamination can occur if the fiberglass leaks and soaks the
core, or if an excess of heat causes the core to shrink enough to
break its laminar bond; in either case, the fiberglass weakens
enough to dramatically fracture or deform.
-
buddy :
-
a diving partner, or the member of a team or group who's
designated to be a safety companion.
-
buddy bottle :
-
an independent stage bottle that's carried for emergency
breathing gas on solo dives instead of a dive partner.
-
buddy breathing :
-
the sharing of the same demand valve by two or more divers,
generally after an out-of-gas emergency.
-
buddy check :
-
the inspection by one diver of another's diving equipment to
ensure that it's properly configured and functioning correctly;
this procedure is conducted before the start of the dive.
-
buddy diving :
-
underwater diving with a designated partner (not just swimming in
a group) so as to improve each diver's chance of surviving an
accident by the shared observance of proper procedures and safety
precautions; also called "backup" or buddy system.
-
bugeye :
-
a ketch-rigged (ie: two masted with the larger mainmast forward)
sailing vessel; so called after the former practice of painting a
large eye on each side of the ship's bow.
-
bulkhead :
-
a reinforced wall-like vertical partition inside ships and
aircraft that separates compartments, often air- or water-tight.
-
bull rail :
-
a low continuous safety rail, slightly raised and blocked,
running along the edge of a boat deck, berth, dock or pier; as
used for tying on mooring lines to prevent drifting, or for
bracing carts and carriers, objects or people to prevent them
from falling overboard; sometimes called a "curb" or "curbing".
-
bull's-eye :
-
a small circular opening or window set into a roof, ship's deck
or overhead, to admit light; sometimes called "deadlight".
-
bull's-eye squall :
-
a squall forming in fair weather that's characterized by the
peculiar appearance of the small isolated cloud marking the top
of the invisible vortex of the storm.
-
bulwarks :
-
a protective wall enclosing the perimeter of a deck, especially
the main or weather deck.
-
bum boat / bumboat :
-
an unofficial supply boat, such as a commercial one hired locally
for deliveries, but often one that purveys curios and souvenirs
to visiting ships.
-
bumpy :
-
separate swells, nodes or nodules that're distributed across the
surface of the sea, as caused by wind (at 6-10 knots velocity),
but not as severe as chop or whitecaps.
-
buntline :
-
one of the ropes attached to the foot of a square sail for
hauling it up to the yard so it can be furled.
-
buoy :
-
an anchored float used as a marker (eg: clear channel, hazard,
etc) or as a mooring (eg: anchorage, tether, etc), as derived
from "boye a float"; such a beacon [v: cresset] can collect
measurements of weather, wind, and waves to facilitate
meteorological and oceanographic forecasting. Also, any of
various buoyant devices for supporting a person in the water, as
a "life buoy" or "life preserver".
-
buoyancy :
-
upward pressure exerted by the fluid in which a body is immersed,
or the amount of lift acting on a submerged object, being that
force equal to the weight of the water displaced by the object;
submerged objects that float are positively buoyant, those that
sink are negatively buoyant, and those that remain at a level are
neutrally buoyant.
-
buoyancy compensator :
-
a vest, jacket, or backpack containing a distensible air bladder
that can be inflated and deflated to regulate a diver's buoyancy
underwater; also called buoyancy control device (BCD).
-
buoyancy control :
-
the ability to maintain neutral buoyancy while swimming at any of
various depths determined by the diver; problems include:
fluctuating currents, changing temperature, altered weight or
load, defective BCD bladder or valve, mis- or maladjusted BCD,
inexperience. An essential skill of practical diving technique.
-
burgee :
-
a small nautical flag or pennant that's used for identification
or as a signal; derived from a mark of the owner.
-
burst disk :
-
a safety release fixture located on the valve of a scuba tank
that prevents over-pressurization of the tank, and provides
visual confirmation of the breach by its deformation; a thin
copper disk that's held in place by a venting plug, which is
designed to rupture if the tank's pressure is greatly exceeded.
[nb: according to the first law of thermodynamics, the internal
energy of a gas increases when the gas is compressed]
-
burton :
-
any of various small tackles rove in a particular way for use on
shipboard; a metathetic variant of breton or briton (tackle).
-
bushwhack :
-
to pull a small boat upstream from on-board by grasping bushes,
branches, rocks, and the like on the shore.
-
butterfly :
-
an undulating swimming stroke wherein the swimmer brings both
arms forward out of the water in a simultaneously circular motion
while kicking both legs up and down together; this racing
breaststroke somewhat resembles the act of flying. Also, slang
for a squeamish, queasy, or otherwise uncomfortable feeling, as
caused by nervousness or excitement.
-
butt-mount :
-
secure placement of the canister battery pack for the large
primary dive light onto the bottom of a back-mount or side-mount
air cylinder, instead of attaching it to the equipment belt or
harness.
-
BVM :
-
Bag Valve Mask; see AMBU bag.
-
BWRAF :
-
a mnemonic for "Begin With Review And Friend" that's used in PADI
training for: BCD, Weights, Releases, Air, Final; mnemonic has
also been represented as "Big White Rabbits Are Fluffy", and
"Blonde Women Really Are Fun".
-
bypass valve :
-
a manual inlet control mechanism that permits the diver to add
gas into the breathing loop on a re-breather.
-
cable :
-
any strong heavy rope or cord made of twisted strands, especially
one made with metallic wire. Also, a thick hawser made of rope,
wire, or chain. Also, a strong heavy rope or cord that operates a
mechanism. Also, a unit of length equal to 720 feet on land, or
606 feet at sea.
[nb: 12 inches = 1 foot, 3 feet = 1 yard, 6 feet / 2 yards = 1
fathom, 16.5 feet = 1 rod (aka: pole or perch), 66 feet / 4 rods
= 1 chain (90 feet / 15 fathoms = 1 anchor chain), 10 chains /
660 feet (1/8 statute mile) = 1 furlong, 120 fathoms / 720 feet =
1 land cable, 101 fathoms / 606 feet (1/10 nautical mile) = 1
cable, 3 statute miles = 1 land league, 3 nautical miles = 1 sea
league / shot]
-
CAGE :
-
abbreviation for Cerebral Arterial Gas Embolism.
-
caisson :
-
a protective environment for working underwater, consisting of a
pressurized watertight chamber. Also, a watertight structure
built against a damaged hull to render it watertight; also known
as cofferdam. Also, a float for raising a sunken vessel; also
known as a camel or pontoon. Also, a boatlike structure used as a
gate for a dock or the like.
-
calf :
-
a mass of ice detached from a glacier, iceberg, or floe.
-
cam band :
-
a webbing strap with a cam-action tensioning buckle that's
generally used to secure a diving cylnder to a backplate, a BC
vest or BCD jacket, or some other diving harness.
-
camel :
-
a float for lifting a deeply laden vessel sufficiently to allow
it to cross an area of shallow water; such a buoyancy float is
also called a pontoon. Also, a float serving as a fender, as
between a vessel and a pier.
-
canal :
-
an artificial waterway used for navigation, irrigation, or other
application. Also, a channel or other watercourse, such as a long
narrow arm of the sea that penetrates far inland.
-
canister :
-
a small, special purpose container, such as the absorbent
canister of neutralizing substances for filtration in a
re-breather system, or the housing for the battery pack of a
large and powerful dive light.
-
canister light :
-
a large and powerful dive light with a battery pack contained in
a canister, which typically has a longer and brighter period of
illumination than the smaller flashlight-style lights. A type of
dive light wherein the battery pack is strapped to the diver's
belt or harness while this primary light is hand held; the
battery pack for such a large light may also be attached to the
bottom of a back-mount or side-mount air cylinder.
-
canoe :
-
any of various small, slender, open boats, tapering to a point at
both ends, propelled by paddles or sometimes sails, and
traditionally formed of a light framework that's covered with
bark, skins, or canvas, or formed from a dug-out or burned-out
log, with or without outriggers, or now made of aluminum,
fiberglass, kevlar, and the like, as used for transport, touring,
or recreation.
-
canoe diving / kayak diving :
-
use of a small lightweight vessel for access to remote or obscure
dive sites, especially rivers, as when drift diving; an
alternative to boat or shoreline access.
-
canoe slalom :
-
a competitive event wherein a canoeist maneuvers through a
winding or zigzag course marked by obstacles or barriers, usually
in whitewater.
-
cape :
-
a piece of land jutting into some large body of water, as a point
or headland, promontory or spit. Also, a ship that has good
steering qualities.
-
Cape Horn fever :
-
an illness or inability feigned by malingerers.
-
capillary :
-
one of the minute blood vessels between the terminations of the
arteries and the beginnings of the veins where the gas exchange
takes place between the bloodstream and the tissues or the air in
the lungs.
-
CAPS :
-
abbreviation for Cave mapping software and electronic survey
equipment.
-
capsize :
-
to turn bottom up, to keel over or overturn.
-
capstan :
-
any of various windlasses, rotated in a horizontal plane by hand
or machinery, used for winding in ropes, cables, and the like.
-
carbon dioxide :
-
a colorless, odorless, incombustible gas that's present in the
atmosphere and formed during respiration; it's a metabolic
byproduct of oxygenation that can stimulate respiration or
depress the central nervous system.
-
carbon monoxide :
-
a colorless, odorless, poisonous gas that's produced when carbon
burns with insufficient air; its toxicity derives from its
affinity for hemoglobin, which competitive bond denies oxygen
availability to tissues during inhalation.
-
careen :
-
to cause a vessel to tip, lean, list, sway, or heel over to the
side. Also, to clean or repair the hull of a vessel by laying
onto its side. Also, a headlong rush, as rash, impetuous, or
uncontrolled action.
-
cargo bay :
-
the large central area of a transport vehicle, vessel, or craft
in which payloads and support equipment are carried; also known
as "cargo area", "payload bay", or bay.
-
cargo net :
-
a flexible open-weave mesh, fabricated of fiber or wire, that is
used to conveniently secure, sling-load, or otherwise handle
loose objects that are transported to or from a cargo bay, hold,
or other receptacle. Also, such a mesh used when scaling, as
during insertion or extraction, ingress or egress, but especially
during debarkation from or embarkation of a transport ship.
-
castoff / cast-off :
-
to let a ship go, to loose a vessel from its mooring, or to
launch a boat; also known as shove-off or simply cast, as derived
from 'throw'. Also, to turn the head of a sailing ship away from
the wind, especially when getting underway or during departure.
Also, to discard, reject, or abandon people or things, as a
castaway.
-
catadromous :
-
pertaining to fish that migrate from freshwater to spawn in the
saltwater sea; as distinguished from anadromous.
-
cathead :
-
a projecting timber or metal beam to which an anchor is hoisted
and secured.
-
cat's-paw :
-
a light breeze that ruffles the surface of the water over a small
area. Also, a hitch made in the bight of a rope to hold the hook
of a tackle.
-
catwalk :
-
a narrow walkway, especially one positioned high above the
surrounding area, used to provide access or allow movement.
-
CAUS :
-
abbreviation for Canadian Association for Underwater Sciences.
-
caustic cocktail :
-
a dangerous side-effect from water flooding the scrubber cylinder
of a re-breather, combining with the hydroxide chemical (or other
carbon dioxide absorbent) to form a poisonous alkaline gas that
can burn the mouth or trachea if inhaled.
-
cave :
-
a hollow in the earth that opens more or less horizontally, and
is large enough to admit the passage of a person. Also, to cause
supporting material to collapse or overlying material to fall
(cave-in).
-
cave arrow :
-
designation for line markers that have been emplaced as a safety
precaution to guide swimmers toward the exit; directional line
markers that point the way to an exit.
-
cave diving :
-
swimming underwater into an overhead environment (including
caverns and grottoes, natural springs and sinkholes, mines and
aqueducts), where the exit is not always visible; an underground
excursion that requires specialized training and equipment.
-
cave fill :
-
the practice of overfilling a scuba cylinder to a pressure
significantly above the rated safe working pressure (charging
pressure) so as to extend bottom time (ABT) where an excess of
equipment is not possible, which filling practice is illegal in
some jurisdictions, and significantly increases the risk of
catastrophic failure of the air tank.
-
cave line :
-
any braided synthetic cord of small diameter that's used by scuba
divers as a means of returning to a safe starting point in
underwater conditions of low visibility, or where navigation is
difficult (due to water currents or route circuity); also called
guideline, safety line, distance line, or penetration line.
-
cave reel :
-
a spool containing braided synthetic cord that's used to lay and
recover long lengths of cave line as a safety line or guideline
marking the route and exit for a cave or cavern, wreck or other
entanglement.
-
cavern :
-
a large cave that's mostly or entirely underground, containing
two or more rooms that're interconnected; a large cavity or
passage, naturally occurring with interconnected rooms, the
outermost being illuminated by daylight.
-
cavern diving :
-
swimming underwater into a large overhead environment where the
outermost chamber is illuminated by daylight, such that the exit
remains directly or indirectly visible; an underground excursion
that requires specialized training and equipment.
-
cavitation :
-
the rapid formation and collapse of pockets of vapor in a flowing
liquid of very low pressure, often causing structural damage to
propellers, pumps, and related mechanisms. Also, the formation of
cavities, especially in some part of the human body; as derived
from cavity.
-
cay :
-
a small low island; often called 'key'.
-
C-card :
-
contraction of Certification card, which is a summary
representation by an authorized agency as evidence that the
bearer has completed a certain level of diver training.
-
CCBA :
-
abbreviation for Closed-Circuit Breathing Apparatus.
-
CCR :
-
abbreviation for Closed-Circuit Re-breather.
-
CDAA :
-
abbreviation for the Cave Diving Association of Australia.
-
CDG :
-
abbreviation for the Cave Divers Group of Great Britain.
-
celsius :
-
a temperature scale in which 0 represents the freeze point and
100 the boiling point; also called centigrade. [nb: the degree
intervals of the kelvin scale are the same as celsius, as the
rankine are the same as fahrenheit]
-
CE mark :
-
European manufacturing certificate of approval, as used in
product sales.
-
cenote :
-
the Spanish term (meaning "deep thing") for a limestone sinkhole
[Maya: dzonot], a type of submarine cavern that's afresh water
aquifer; cenotes may be located entirely underground, partly
submerged, at ground level, or as open wells, and are often
connected to other bodies of water.
-
central nervous system :
-
the part of the nervous system comprising the brain and spinal
cord.
-
certificate of admeasurement :
-
a government document showing the registered tonnages of a
commercial vessel.
-
CESA :
-
abbreviation for Controlled Emergency Swimming Ascent, which
involves exhaling while swimming toward the surface, when no
other air is available, so as to prevent lung expansion injury
from breath holding when a diver is out of air.
-
chain :
-
a sequence of metallic rings that pass through one another and
are linked together for use in securing, supporting, or hauling.
Also, a surveyor's measure for establishing distance by a 100
foot (30m) or 66 foot (20m) length, wherein each link is exactly
the same as every other, for ready and consistent computation.
[nb: 12 inches = 1 foot, 3 feet = 1 yard, 6 feet / 2 yards = 1
fathom, 16.5 feet = 1 rod (aka: pole or perch), 66 feet / 4 rods
= 1 chain (90 feet / 15 fathoms = 1 anchor chain), 10 chains /
660 feet (1/8 statute mile) = 1 furlong, 120 fathoms / 720 feet =
1 land cable, 101 fathoms / 606 feet (1/10 nautical mile) = 1
cable, 3 statute miles = 1 land league, 3 nautical miles = 1 sea
league / shot]
-
chain locker :
-
a storage compartment for the proper stowage of cable and hawser
aboard a vessel.
-
chandler :
-
a trader in specialized supplies (eg: ship chandler). Also, a
maker or seller of candles (wax) or soap (tallow); as derived
from 'chandelier'.
-
channel :
-
the bed of a stream, river, or other watercourse or waterway.
Also, the deeper part of a waterway, especially the navigable
route between two bodies of water. Also, an artificial waterway
constructed and maintained for the safe passage of navigable
vessels. Also, a wide strait, as between a continent and an
island. Also, a horizontal timber or ledge built outboard from
the side of a sailing vessel that's used to spread shrouds and
backstays outward; by alteration of "chain wale" (chain-wale).
Also, the longitudinal grooves (from one to eight) that're formed
on the underside of some paddleboards, surfboards, sailboards,
and other watercraft serving as an aid to stability and
maneuverability; an innovation credited to Jim Pollard of
Australia (1970).
-
channeling :
-
the settling of the absorbent chemical in an improperly packed
scrubber canister of a re-breather; as the absorbent material
settles, a passageway for the exhaled CO2-rich gas
passes through the scrubber without being filtered ... this is
not a significant problem in cartridge-style scrubbers.
-
channel marker :
-
a colored or numbered buoy, or other aid to navigation, that's
located alongside a navigable waterway to ensure safe passage;
also called daymark (green or red), can buoy (numbered odd,
colored green), or nun buoy (numbered even, colored red).
[nb: pass along marked channels by staying left of the red
signals and right of the green signals, or by keeping the red
signals on the red side of the boat and green signals on the
green side of the boat]
-
chantey / chanty :
-
a rhythmic work song, especially used by sailors.
-
charging pressure :
-
a rating, permanently marked on the container, indicating the
maximum allowable gauge pressure that may be applied at the time
of filling with breathing gas; the maximum safe working pressure
for a scuba cylinder.
-
Charles' law :
-
the principle that the volume of an enclosed gas is directly
proportional to its absolute temperature, or V=kT (Volume) =
(constant of proportionality)(Temperature); also known as
Gay-Lussac's law.
Also, if pressure is constant, the volume of a gas expands by a
constant fraction as temperature increases.
-
chart :
-
a hydrographic or marine map.
-
chart datum :
-
the level of the lowest tide at a particular place, recorded with
heighths and depths of tides; abbreviated CD.
-
charter :
-
an arrangement by which all or part of a ship, or other
conveyance, is leased for a particular group, journey, or
activity. Also, the trip, journey, tour, or expedition made using
such an arrangement.
-
chart table :
-
the desktop surface, typically horizontal, used for displaying a
marine or hydrographic map, a nautical chart, which is consulted
for known hazards, and upon which an intended course is planned
or the actual course is plotted; the modern electronic version is
known as the "central navigation console".
-
check valve :
-
a valve that only allows fluids or gases to flow in one
direction, such as the mushroom valve in a second stage
regulator, and in the hose assembly of a re-breather, on both the
inhalation and exhalation sides of the loop to keep the gas
flowing in the proper direction.
-
chicken ladder :
-
slang for an inclined plank with transverse traction cleats
that's used as a temporary bridge onto a vessel; a brow or
gangplank, walkway or passageway.
-
chine :
-
an angular intersection of the sides and bottom of a vessel; or a
longitudinal member running behind this intersection.
-
chock :
-
a wedge to fill-in a gap or a device to brace an object, any
support or reinforcement; also called "chock block", and derived
from "choke", as close or tight.
-
chockablock :
-
having the blocks drawn close together, as when the tackle is
hauled to the utmost; crowded together, close or tight.
-
chop :
-
the short irregular motion of a turbulent wave, usually caused by
wind in excess of 12knots velocity. Also, the rough water of a
turbulent lake or sea, as caused by wind or currents.
-
Christmas tree ladder :
-
slang for a boarding ladder formed of a single central rail with
rigidly cantilevered rungs extending outward to the sides, which
permits use while wearing swim fins.
-
chum :
-
an inexperienced or novice sailor, especially someone on his
first float or cruise; also called pollywog, nugget, or fresh
catch.
-
chumming :
-
slang for vomiting overboard when seasick, after the fishing
practice of dumping bait in the water to attract fish.
-
CIRSS :
-
abbreviation for the Italian underwater research association
(Comitato Italiano Ricerche Studi Subacquei).
-
clean :
-
a smooth or glassy ocean surface with very little onshore wind
producing consistent or predictable waves; offshore winds blowing
into the face of the waves can create a clean, groomed
environment.
-
clear the decks :
-
the removal of everything not required so as to have ready access
during seaborne operations.
-
cleat :
-
a strong device, usually metal with one or more projections,
that's used to secure tie-downs, as on a deck or pier [dock
cleat] for mooring. Also, a wedge-shaped block or strip of
resistant material fastened to a surface to serve as a check
(belay) or support; also called a chock. Also, a resistant strip
fastened across a surface, as on a ramp [gangway cleat], to
provide sure footing.
-
clew :
-
either lower corner of a square sail, or the lower after corner
of a fore-and-aft sail. To "spread a large clew" is to carry a
large amount of sail, which will present an impressive
appearance.
-
clew down :
-
to secure a sail in an unfurled position.
-
clew up :
-
to haul the lower corner(s) of a sail up to the yard by means of
(clew) lines.
-
climbing and dropping :
-
turning up and down the face of a wave so as to gain speed while
maneuvering across the wave lineup on a board or small
watercraft.
-
clinker-built :
-
the outside surface of a hull built with each coarse of planks or
plates overlapping the one below, like on a clapboard house; also
called 'lapstrake'.
-
clinometer :
-
an instrument used for determining angles of inclination or
measuring the degree of slope. [nb: not 'inclinometer']
-
closed-circuit / closed-circuit system :
-
an underwater breathing system which does not release exhaled
gasses as exhaust, but filters and recycles the discharge back
into the gas supply; also called "closed-circuit re-breather".
Closed-circuit re-breathers generally supply two breathing gases
to the loop: one is pure oxygen and the other is a diluting gas
(diluent), such as air, nitrox, or trimix. The major task of the
closed-circuit re-breather is to control the oxygen
concentration, known as the oxygen partial pressure, in the
breathing loop and to warn the diver if it is becoming
dangerously low or high as depth changes.
-
closed-circuit re-breather :
-
an intact cycle of breathing gases that produces no discharge of
bubbles and enables long duration dives, as used by many military
and some recreational divers, especially photographers.
Re-breathers using a fully closed-circuit generally supply two
breathing gases to the breathing loop: pure oxygen and a diluent
(eg: air, nitrox, or trimix), and control the oxygen partial
pressure concentrated at any underwater depth. In fully automatic
closed-circuit systems, a metering mechanism injects oxygen into
the breathing loop when it detects that the oxygen concentration
has fallen below the required level. Alternatively, the diver may
be able to manually control the mixture by adding diluent gas or
oxygen, but this is a risky adjustment that can produce dangerous
results with only small volumes added.
-
closed-circuit SCUBA :
-
a self-contained scuba system that allows divers to re-breathe
exhaled air after the removal of CO2 and the addition
of supplemental O2; in contrast with an 'open-circuit'
system, closed-circuit scuba is noiseless and produces no exhaust
bubbles.
-
close-hauled :
-
to sail a vessel as close to the wind as possible, with sails as
flat as possible.
-
closeout :
-
when the crests of all waves in the lineup break simultaneously
as they advance onto the shore.
-
CMAS :
-
abbreviation for Confederation Mondiale des Activitias
Subaquatiques; the World Federation of Underwater Activities,
established in 1959.
-
coaming :
-
the protective rim or raised bulwark surrounding an opening in a
bulkhead or deck that's designed to exclude water; also called a
"knee-knocker" or "shin-scraper".
-
coast :
-
the land beside the sea, as a shore, often serving as a border;
also known as "coastline", and derived from "side wall". Also, to
be sustained or to continue on acquired momentum.
-
cockpit :
-
a sunken, open space, generally in the after part of a small
boat, that provides access to the controls and instruments needed
by the crew when operating a vessel at sea.
-
cold harbor :
-
a place of refuge or retreat, typically primitive, that lacks the
usual amenities, especially fresh water and other creature
comforts; such a haven is also called a cold camp or fly camp.
-
collapse depth :
-
the design depth beyond which the hull structure of a submersible
is presumed to suffer catastrophic failure to the point of total
collapse; such "crush depth" is referenced to the axis of the
pressure hull, and is affected by material defect or decline, by
hull penetrations, or by other relevant factors.
-
comber :
-
a long curling wave.
-
combo-swell / combo swell :
-
a combination of swells from varying directions, which will
generate crossed up and scattered conditions from merging,
overlapping, and colliding waves.
-
command signal :
-
a signal from one diver that requires a response from another
diver; including: OK, Hold, and Surface. The OK hand signal is
formed by connecting the thumb and forefinger in a circle with
the other three fingers extended, or by making a circular motion
with the dive light. The Hold hand signal is a closed fist. The
Surface (turn the dive and exit) hand signal is an upward
pointing thumb with the other fingers in a fist; such termination
is also called "thumbing the dive".
-
companion / companionway :
-
a stair or ladder within the hull of a vessel; a raised and
hooded hatchway transitioning from the deck to the cabin(s) of a
ship.
-
compartment :
-
a partitioned area or space, as a cabin or hold on a vessel.
-
computer :
-
see dive computer.
-
confluence :
-
a flowing together of two or more streams, rivers, or the like
into a singular course or unified movement. Also, their place of
[con]junction into a body of water formed by such confluence.
-
conning tower :
-
the housing over the main entrance to the interior of a
submarine, accommodating its periscope and antennas, and used as
an observation platform; also called the "sail" or fairwater.
-
constriction :
-
a narrow passage or small opening that's not large enough for two
divers to swim through together (ie: minor constriction); or that
requires gear removal to negotiate (ie: major constriction); also
known as a squeeze, restriction, tight, sidemount passage, no
mount.
-
continental margin :
-
the offshore zone that separates the dry-land portion of a
continent from the deep ocean floor, consisting of the
continental shelf, slope, and rise (qqv).
-
continental rise :
-
the gently sloping transition between the continental slope and
the deep ocean floor, usually characterized by the coalescence of
submarine alluvial fans.
-
continental shelf :
-
the part of a continent that's submerged in relatively shallow
sea (about 165 fathoms or 1000 feet in depth); contiguous land
that's underwater. [nb: long period swells of about 20 seconds
duration will begin to feel the ocean floor at about 1000 feet of
depth]
-
continental slope :
-
a steep slope separating a shallow continental shelf and a deep
ocean basin.
-
controlled buoyant lift :
-
an underwater rescue technique that's used for safely raising an
incapacitated diver to the surface.
-
convection :
-
the vertical flow of air, water, or the like, which often entails
a change of temperature or humidity; as distinct from advection.
-
CONVENTID :
-
a diagnostic mnemonic for oxygen toxicity: ....
-
cordelle :
-
a heavy rope formerly used for towing boats on rivers; derived as
a diminutive of 'cord', cordelling is one of the methods of
hauling a watercraft upstream.
-
corduroy :
-
a progressive series of swells that seemingly march inland in a
continuous lineup of ridged or crested waves from the horizon.
-
corners :
-
the end sections of waves; the shoulders of waves down from their
crested peaks.
-
counter lung :
-
the breathing bag portion of a re-breather system, which is
so-called because it operates counter to or opposite of the
diver's lungs.
-
cove :
-
a small indentation or slight recess, usually sheltered, in the
shoreline of a sea, lake, or river.
-
covered berth :
-
a roofed mooring area that's intended to protect a boat from the
effects of sun and weather.
-
coxswain :
-
the person, generally a boatswain's mate, who's in charge of
steering and/or directing the crew of a boat.
-
CPI :
-
Central Pressure Index, being the minimum atmospheric pressure in
the central vortex (or "eye") of a cyclone or hurricane, which is
used to estimate the wind velocities in the storm ... the lower
the CPI, then the faster the wind speed.
-
CPR :
-
CardioPulmonary Resuscitation, being an emergency procedure for
reviving heart and lung function.
-
CPTD :
-
abbreviation for Cummulative Pulmonary Toxic Dose, as related to
the effect of an enriched-air nitrox (EAN) mix.
-
crab :
-
a maneuver in which a craft is headed partly into the wind to
compensate for drift. Also, a mechanical contrivance for hoisting
or pulling heavy weights, a truckle.
-
crack :
-
see buckle.
-
crash-dive / crash dive :
-
to dive rapidly at a steep angle, as when a swimmer imitates the
emergency maneuver of a submarine or other submersible.
-
crawl :
-
a swimming stroke, performed in the prone position, wherein
alternating overarm movements are combined with the flutter kick;
originating as the 'Australian crawl'. Also, a shallow water
enclosure on the seacoast, as used for confining fish, turtles,
and the like. [v: corral; cf: kraal]
-
crease :
-
see buckle.
-
creature feature :
-
slang for a submerged corpse, typically a gruesome one beginning
to suffer the ravages of immersion and marine predation but
either insufficiently bloated to float, or one too decomposed for
gaseous accumulation, but not yet unrecognizable or skeletal.
[nb:the rate of decomposition for a corpse underwater is about
half that of one exposed to the open air]
-
creep :
-
to grapple; to attempt to seize, hold, grip, or fasten. Also,
slang for a grappling iron or grapnel.
-
crepuscular :
-
wildlife that becomes active in the dimness of twilight.
-
crest :
-
the foamy top of a wave; the uppermost part of a swell. Also, the
point of highest flood, as of a tide.
-
cringle :
-
an eye or grommet formed on the boltrope of a sail to permit the
attachment of lines; as derived from "circle".
-
crosshead :
-
a crosspiece on a rudderpost by which the rudder is turned. Also,
a transverse member that's variously employed to transfer
alignment or for transmitting energy.
-
crosstree :
-
either of a pair of horizontal timbers or metal bars spreading
the shrouds on a mast.
-
crown :
-
the part of an anchor at which the arms join the shank; also
called "head".
-
crow's nest :
-
a lookout platform high atop a ship's main mast, or any
observation point with a commanding view.
-
crush depth :
-
properly called collapse depth, being the submergence level at
which the hull or pressure hull of a vessel suffers catastrophic
failure, which is typically well below its design depth; compare
maximum operating depth and test depth.
-
CSAC :
-
abbreviation for Canadian Sub-Aqua Club.
-
cummerbund :
-
the waistband for a buoyancy compensator. [cf: girth, cincture,
surcingle]
-
curl :
-
older term used to describe the concave face of the wave just
before breaking; the 'bowl' area just before the tubular barrel.
-
cutback :
-
a dynamic turn towards the breaking part of the wave, as used
when piloting a raft, board, or watercraft so as to abruptly
change direction while streaking ahead of the curl of a wave,
which enables the repositioned pilot to garner more power from
the wave.
-
cutis marmorata :
-
inflamation of the skin signaled by a mottled reddish
discoloration, being a symptom of decompression sickness; also
called "skin bends".
-
cutwater :
-
the forward edge of the stem of a ship. Also, an upstream face of
a bridge pier or piling, sharp edged or sharply pointed, arranged
for resisting the effects of moving water or ice.
-
cyclone :
-
the word 'cyclone', introduced in 1848 by British meteorologist
Henry Piddington, confused "wheel" with "revolve", but has since
been accepted as the denotation for the large-scale atmospheric
wind-and-pressure system that's characterized by low pressure at
its center and by rotating wind motion (ie: counterclockwise in
the northern hemisphere, clockwise in the southern hemisphere) in
a closed circulation atmosphere.
-
cylinder :
-
the aluminum or steel container that holds pressurized breathing
gas for underwater diving; also known as tank or bottle.
-
Dalton's law :
-
the principle that the total pressure of a gas mixture is equal
to the sum of the partial pressure of its components; or the
total pressure exerted by a mixture of gases is the sum of the
pressures that would be exerted by each of the gases if it alone
were present and occupied the total volume; also called "Dalton's
law of partial pressures", "law of partial pressures", and named
after John Dalton, the English chemist and physicist.
-
dam :
-
an earthen or masonry barrier that's used to obstruct the flow of
water, built across a stream or river. Also, a body of water so
confined by such a barrier; impoundment, reservoir.
-
DAN :
-
abbreviation for Diver's Alert Network.
-
dangly :
-
anything hanging from a divers gear that could result in silting
or an entanglement hazard, such as exposed knobs, consoles,
unsecured straps and lanyards.
-
dasher block :
-
a block at the end of a yard or gaff that's used for supporting a
signal or ensign halyard; also called "jewel block".
-
davit :
-
any of various crane-like devices used on ships for moving
or supporting boats, anchors, and other objects.
-
Davy Jones's locker :
-
the bottom of the ocean, which serves as a graveyard and junkyard
for all that's lost at sea.
-
Dawn Patrol :
-
informal reference to the early morning devotees who are out on
the water at sunrise, before wind disrupts the clean surface
conditions. Also, the surf report broadcasting weather conditions
and water temperature as an early morning forecast for boarders,
rafters, and small boat aficionados.
-
DBAR :
-
abbreviation for decibar, being one tenth of a bar, or
approximately a meter of depth in water.
-
DCAP :
-
abbreviation for Decompression Computation and Analysis Program.
-
DCIEM :
-
abbreviation for Defence and Civil Institute of Environmental
Medicine.
-
DCI :
-
abbreviation for DeCompression Illness, including DeCompression
Sickness (DCS) and Arterial Gas Embolism (AGE).
-
DCS :
-
abbreviation for DeCompression Sickness; also called the bends or
aeroembolism.
-
DCS I :
-
decompression sickness, a syndrome caused by bubbles of inert gas
forming in the tissues and bloodstream during or after ascent
from an underwater dive, involving only muscle and joint pain,
fatigue, and/or skin irritation (itching, rash).
-
DCS II :
-
decompression sickness, a syndrome caused by bubbles of inert gas
forming in the tissues and bloodstream during or after ascent
from an underwater dive, involving the central nervous system,
respiratory system, or circulatory system.
-
DDC :
-
abbreviation for Deck Decompression Chamber.
-
DDRC :
-
abbreviation for Diving Disease Research Center located in
Plymouth, England, being the leading hyperbaric treatment and
research facility in Great Britain.
-
deadhead :
-
a sunken, semisubmerged, or floating object that's a hazard to
navigation.
-
dead in the water :
-
adrift without motive, power or propulsion; also called hull.
-
dead lift :
-
to raise or move something substantial without mechanical
assistance; being any act or exercise requiring a significant
effort.
-
deadlight :
-
a strong shutter able to be screwed against the interior of a
porthole in heavy weather. Also, a thick pane of glass set in the
hull or deck to admit light; sometimes called "bull's-eye".
-
dead-reckoning :
-
estimated calculation of one's present position based upon
compass readings, speed, and distance traveled from the last
known point, with allowances for drift from wind or currents;
also known as "guesstimate" or "by guess and by God".
-
dead water :
-
water eddying beside a moving hull, especially directly astern.
Also, a slack current in part of a river or stream.
-
deadwood :
-
a solid construction, serving only as reinforcement, located
between the keel of a vessel and the stem or sternpost.
-
dead zone :
-
that region, both above and below sea level, where existence
cannot naturally persist nor be temporarily sustained without
life-support supplement or augmentation.
-
"Death from a Boogie Board" :
-
an unofficial mock motto of the R.O.T.C. Surfrider Battalion at
the University of California Santa Barbara ... being a parody of
the unofficial U.S. Army airborne motto: "Death from Above!"
-
debarkation net :
-
a specially prepared type of General Purpose net, cargo net, or
other similar mesh employed when scaling, as during insertion or
extraction, ingress or egress, but especially during debarkation
from or embarkation of a transport ship.
-
deck :
-
a floor-like surface occupying all or most of one level in a
superstructure or hull. Also, the topside of some paddleboards,
surfboards, sailboards, and other watercraft where the pilot
sits, kneels, or stands, hence is often waxed for improved
traction.
-
Deck Grip :
-
proprietary product applied to the top surface of a paddleboard,
surfboard, sailboard, or other watercraft, being a rough surfaced
material that can be glued in place as a patch measuring only a
fraction of an inch thick.
-
deckhead :
-
the undersurface of a deck.
-
deco :
-
truncation of decompression.
-
deco mix :
-
a gas mixture used during decompression, especially nitrox or
pure oxygen used to accelerate decompression.
-
decompression :
-
the gradual reduction in atmospheric pressure experienced after
immersion in deep water or breathing compressed air, resulting in
the equalization of gases in body tissues once they have been
saturated with nitrogen; staged or continuous change from a
higher to a lower ambient pressure always results in a reduction
of gas pressure within the body.
-
decompression buoy :
-
a small float tethered to a line that, when deployed, will
indicate the location of the diver to anyone observing from the
surface.
-
decompression chamber :
-
a controlled environment for raising and lowering atmospheric
pressure with selective air mixtures; also called a hyperbaric
chamber.
-
decompression diving :
-
a diving practice that goes beyond the standard No-Decompression
time/depth limits in order to extend bottom time, which requires
one or more decompression stops during ascent regardless of the
type of equipment used, since decompression only occurs as the
diver ascends; violation of the mandatory in-water stops may
result in decompression sickness.
-
decompression illness :
-
a diagnosis of dysbaric injuries related to underwater diving,
which stem from uncertainty about the mechanistic causation of
similar or related neurological symptoms, when the etiology or
pathophysiology cannot be determined, and is ultimately
immaterial to the treatment regimen. It has been suggested that
this diagnosis encompass all manifestations of diseases following
a reduction in ambient pressure, such as ascending from a dive.
-
decompression sickness :
-
a complex of symptoms caused by the escape of nitrogen bubbles
from solution in the fluids that were absorbed originally at
higher atmospheric pressure, as a result of the abrupt reduction
in that pressure; it is characterized by headache, pain in the
arms, legs, joints, and epigastrium, itching of the skin,
vertigo, dyspnea, coughing, choking, vomiting, weakness and
sometimes paralysis, and severe peripheral circulatory collapse.
It is also known as the bends, aeroembolism, caisson disease, and
decompression disease.
-
decompression stop :
-
the time period that a diver must spend at a constant depth in
shallower water during ascent after diving at greater depth in
order to safely eliminate inert gases from the diver's body so as
to avoid decompression sickness.
-
decompression tables :
-
cards or booklets printed with index and conversion arrays that
allow divers to determine the decompression stops required for a
particular dive profile and breathing gas, so as to avoid
decompression sickness. Decompression tables assume that the dive
is simple and straightforward, an invariable "square dive". These
calculations also determine the requisite surface intervals
between dives. Also called dive tables or tables.
-
deep air :
-
diving to depths greater than 132 feet (40.2m) while using air as
the breathing gas; a practice that subjects the diver to nitrogen
narcosis or inert gas narcosis, which is seemingly undertaken for
its euphoric or narcotic effect.
-
deep diving :
-
any dive below the 60 foot (18.2m) depth by sport divers, or
below the recreational limit of 132 foot (40.2m) depth by
technical divers.
-
deep six :
-
to throw or cast overboard while at sea, as when discarding,
abandoning, or jettisoning something in more than six fathoms of
water; derived from soundings by fathom (6feet), expressed as "by
the deep six" (36feet). Also, burial at sea. [nb: refers only to
objects; people go or fall "overboard"]
-
deep stops :
-
a method of keeping the diluent gas tension at reasonable levels
during a deep dive ascent by introducing more but shorter
intervals throughout the series of decompression stops; this
methodology of "deep safety stops" was formulated by Richard
Pyle, a scientist in Hawaii.
-
deep water :
-
generally, water more than one thousand feet deep, or at least
deeper than one-half the wavelength of the existing waves; water
that's deep enough so that surface waves are not affected by the
bathymetry on the ocean bottom.
-
deep water blackout :
-
usually occurring at a depth of 150ft or more, the diver loses
consciousness and ceases all activity while continuing to
breathe; the diver stops, remains motionless, and seems to go to
sleep.
-
deep water breaks :
-
larger and stronger waves caused by swells steeply transitioning
from deeper to shallower water over a longer period ... sometimes
the result of an irregular seafloor.
-
defogging solution :
-
a natural (spit) or commercial (artificial compound) liquid
that's used as a treatment to prevent condensation on the window
of the diver's mask while underwater.
-
dehydration :
-
the abnormal depletion of water or other bodily fluids during
exertion ... it's an irony to be thirsty while swimming.
-
deliquesce :
-
to become liquid by absorbing moisture from the air. Also, to
melt away.
-
Delrin :
-
brand name of a hard, lightweight, and inflexible polymer that
was synthesized from formaldehyde by DuPont in 1952; initially
known as "synthetic stone", this material is used in
manufacturing cable spools, light housings, belt buckles, knife
handles, and the like.
-
DEMA :
-
abbreviation for the Dive Equipment and Marketing Association (or
Diving Equipment Manufacturers Association), an organization that
sponsors an annual trade show for the introduction, promotion,
and display of new products.
-
demand valve :
-
a pressure valve, generally placed in the diver's mouth, which
provides gas from the diving regulator when the diver inhales;
also called mouthpiece.
-
demersal :
-
bottom-dwelling marine life that persists at the lowest ocean
layers.
-
depth :
-
the lowest or deepest point of an underwater dive; the maximum
depth reached during the course of a dive.
-
depth gauge :
-
a calibrated device, analog or digital, that indicates the
distance underwater from the surface (sea level) that the
measurement is being taken, as derived from the ambient pressure.
-
DES :
-
abbreviation for Divers' Environmental Survey.
-
descent / ascent line :
-
an anchored line, suspended from a boat or buoy, that's used to
control a diver's rate of ascent or descent, to provide
orientation in strong currents and low light on deep dives, and
to secure reserve gas cylinders for decompression stops; a type
of safety line that's also called "drop line".
-
deviation :
-
the angle of error of a magnetic compass on a given heading as a
result of local magnetism; the declination from true north.
-
diameter indexing safety system :
-
an Intermediate pressure port where a hose attaches, leading to a
demand valve or other apparatus.
-
diaphragm :
-
the musculomembranous partition or wall of muscle and connective
tissue separating the thoracic cavity from the abdominal cavity,
with constriction of this thoraco-abdominal diaphragm being
essential for respiration. Also, a flexible semipermeable
membrane in a first stage regulator that's used to prevent
sea water from contacting the internal parts, which helps to
reduce corrosion and contamination.
-
diel :
-
pertaining to a 24-hour period, as when referring to the regular
daily cycle of an organism's physiology or behavior.
-
diffraction :
-
a modulation of waves in response to an obstacle in the path of
propagation; the process of wave energy filtering into the lee of
obstacles, such as breakwaters, by the transfer of the wave
energy along wave crests, which are smaller than the original
waves.
-
dike / dyke :
-
an embankment for controlling or holding back the waters of the
sea or another body of water. Also, a ditch or causeway. Also, an
embankment, barrier, or other obstacle, especially one made from
excavated material.
-
diluent :
-
a diluting substance, such as oxygen added to nitrogen.
-
DIN :
-
abbreviation for Deutsche Industrie Normen, being the German
industrial standards agency, which proliferated criteria
worldwide before ISO; later construed as 'Das Ist Norm' for "that
is (the) standard"; sometimes (mis-)represented as "Deutsches
Institut fuer Normung". The fitting that connects the first stage
of a regulator to the compressed air tank on a high pressure
scuba system is identified by this DIN standard.
-
ding :
-
see buckle.
-
dinghy :
-
any small boat designed as a tender or lifeboat, whether
propelled by rowing or paddling, by sail or motor, as derived
from coastal transports for passengers and freight.
-
DIN valve :
-
a connection from cylinder to regulator that's identified by its
pressure rating (eg: 200 bar or 300 bar).
-
DIR :
-
a mnemonic for "Doing It Right", which is descriptive of a diving
style as well as the configuration and maintenance of dive
equipment, as promoted by George Irvine III to describe the
practices that he and others derived from Hogarthian principles.
-
direction :
-
the source of wind or water currents; in the marine community,
the direction of winds or waves is always identified as where
it's coming from ... not the direction where it's going.
-
dirt dart :
-
slang for an overloaded diver who has either improperly set his
buoyancy control device (BCD), or whose mechanism has failed,
causing him to rapidly plunge to the seafloor immediately upon
entry into the water; such malfunction is potentially fatal. [cf:
picul]
-
DISS :
-
abbreviation for Diameter Indexing Safety System.
-
dissolve :
-
a solution made by admixed absorption, assimilation, or
incorporation. Also, to liquify formerly discrete elements into a
combined solution; to disintegrate or disperse melted portions in
a solvent. Also, to loose intensity or potency, potentiality or
strength, especially by dilution or debasement. Also, as a
contranym, to separate elements or disunite parts that were
formerly merged or joined; to undo or break apart, to disassemble
or disintegrate, to dismiss or terminate a former bond or
connection.
-
distance line :
-
any braided synthetic cord of small diameter that's used by scuba
divers as a means of returning to a safe starting point in
underwater conditions of low visibility, or where navigation is
difficult (due to water currents or route circuity); also called
guideline, safety line, cave line, or penetration line.
-
ditch :
-
slang for any body of water that's channeled or confined, such as
a river or strait, regardless of size, used informally as a term
of convenient reference.
-
diurnal :
-
day or daytime; daily or daily cycles; as juxtaposed to nocturnal
or seasonal.
-
diurnal thermocline :
-
in general, is established each day by heating of the surface
water and is destroyed the following night by cooling and/or
mixing.
-
dive club :
-
a social group organized to enable training, facilitate dive
ventures, and promote safe practices, especially recreational
scuba diving; sometimes affiliated with a shop or school.
-
dive computer :
-
a waterproof electronic device that measures the dive profile and
displays related safety information; as the dive computer
automatically measures actual depth and elapsed time, it performs
a continuous calculation of the partial pressure of gases in the
body based on the actual dive profile. A dive computer will
address the same problems as decompression tables, but it is also
able to warn of excessive ascent rates and missed decompression
stops, as well as report the water temperature, and the pressure
of the breathing gas remaining in the diving cylinder. A dive
computer reduces the need for the diver to carry a separate watch
and depth gauge, and relieves the diver of computations, which
may be subject to human error.
-
dive flag :
-
a public notice to passing watercraft that underwater swimmers
are beneath the surface; required to be posted on a mast or buoy,
this warning flag exists in two versions: international maritime
signal (code letter 'A'), and North American signal (solid red
with white diagonal stripe).
-
dive marshal :
-
the person responsible for the accountability of students and
equipment during training classes; being responsible for
recording names, checking equipment, recording water entry and
exit times. This safety and security associate functions like a
lifeguard, and is sometimes identified as a "beachmaster".
-
divemaster :
-
a professional who's qualified to oversee scuba diving
operations, as in salvage work or at a school or resort, and is
responsible for procedures and safety, monitoring the whereabouts
of divers underwater or at the surface, and making rescues
whenever necessary.
-
dive platform :
-
see sea deck.
-
dive profile :
-
a two dimensional graphical representation of a complete dive
showing its depth and elapsed time. This profile is often used
when describing a dive's probable decompression obligation. It's
also known as a depth/time profile, and its coordinate charting
is variously configured as square, multilevel, spike, and so
forth.
-
diver down :
-
common reference to the public notice posted by the dive flag
that warns passersby that underwater swimmers are beneath the
surface.
-
Dive Rite :
-
the first manufacturer (1984) to provide specialized cave and
wreck diving equipment.
-
diver propulsion vehicle :
-
an underwater transport for divers and equipment that's used to
extend travel by increasing their speed of movement.
-
dive school :
-
a commercial enterprise offering diving instruction and/or
expeditions; sometimes affiliated with a club or shop.
-
dive shop :
-
a commercial enterprise offering diving equipment and/or
expeditions; sometimes affiliated with a club or school.
-
dive signal :
-
the use of fingerspelling, hand language (as in 'command
signals'), touch signals, and knock or noise signals that're used
to communicate underwater.
-
dive step / diving step :
-
see sea deck.
-
dive tables :
-
numerical tables used by scuba divers to determine the time
limits of dives, according to depth, as well as possible
decompression delays during ascent, and the requisite surface
intervals between repeat dives; also called decompression tables
or tables.
-
diving bell :
-
a chamber with an open bottom in which persons can go underwater
without special apparatus, water being excluded from the upper
part by compressed air fed in by a hose.
-
diving boat :
-
a watercraft or other vessel used as a tender for divers or
others working under water.
-
diving crouch :
-
the deep knee-bend squat performed from a vertical upright stance
on the floor of the sea whenever an object or artifact is to be
secured by a dry suit or hard suit underwater diver wearing a
hard hat sustainment rig; this straight-backed crouch is
performed (instead of bending over at the waist) so as not to
flood the helmet or cause the entrapped air to escape.
-
diving mask :
-
a protective shield worn while under water; also called "face
mask", "swim mask", or simply "mask" (qv).
-
diving reflex :
-
a physiological reflex of humans, other mammals, reptiles, and
birds, that's triggered by immersion in cold water, having the
effect of slowing the heart rate and diverting blood flow to the
brain, heart, and lungs; serving to conserve oxygen until
breathing resumes and to delay potential brain damage.
-
diving stage :
-
see stage.
-
diving suit :
-
any of various waterproof garments for underwater swimming or
diving, especially one that is weighted, hermetically sealed, and
supplied with pressurized air.
-
DM :
-
abbreviation for Dive Master.
-
DMAC :
-
abbreviation for Diving Medical Advisory Committee.
-
DO :
-
abbreviation for Diving Officer.
-
dock :
-
a landing pier or wharf. Also, the space or waterway between two
piers or wharves, as for receiving a ship while in port.
Also, such a waterway, enclosed or open, together with the
surrounding piers, wharves, and other structures. Also, a dry
dock.
-
dodger :
-
an overhead canvas top with front and side panels that's
supported on scantling for protection against windblown rain,
snow, or spray; also known as a spray-hood, an extension may be
added to enclose the aft opening of the dodger.
-
DODO :
-
acronym for Dead Object Drifting Obstacle (or "Dead Or Drifting
Object") indicating inert debris or incidental hazards to
navigation; since such flotsam is not underway, the craft or
vessel must maneuver to avoid collision damage.
-
dog paddle :
-
the most basic or rudimentary swimming stroke, typically
performed in a crouching posture with both arms and legs
fluttering beneath the surface while the head is held above the
surface of the water; performed by imitation, and so-called by
comparison. [v: crawl, breaststroke, sidestroke, trudgen,
butterfly, backstroke]
-
dolphin :
-
any small toothed cetacean, especially one possessed of a
beaklike snout; compare porpoise. Also, a buoy, pile, or cluster
of piles used as a fender or mooring. Also, a rope or strap round
a mast to support the puddening, where the lower yards rest in
the slings.
-
Doppler ultrasound bubble detector :
-
a diagnostic device used in hyperbaric medicine to determine the
presence (by Doppler shift) of bubbles in the bloodstream that
may presage decompression sickness.
-
dory :
-
a small narrow skiff with a high bow, flaring sides, and a flat
bottom.
-
double berth :
-
a mooring that accommodates two boats, with a finger pier on only
one side of each berthed vessel.
-
double blindstitched / double blind-stitched :
-
a construction mode that's considered to be a good watertight
garment that's both flexible and durable; a wet suit seam is
glued together before being sewn halfway through the material on
the outside, turned inside out, and then sewn halfway through the
material on the inside.
-
double paddle :
-
a short-shafted oar with either flat- or scoop-bladed levers at
each end that's usually held by both hands while being moved more
or less in a figure-8 pattern, as used for propelling and
steering a kayak, canoe, or other small boat; also known as a
'double-ended paddle' or 'double-bladed paddle'.
-
doubles :
-
two back-mounted air cylinders banded together and connected by a
manifold so as to allow longer dive time and redundant gas; used
instead of a single air cylinder.
-
double sculls :
-
a type of race for sculls wherein two rowers, each using a pair
of oars, propel this narrow craftin a timed event.
-
double up / doubled up :
-
when two waves combine, creating a more complex and powerful wave
that's forced to break in water shallower than normal, it
generates a hollower or steeper swell that's more challenging.
-
down rail :
-
a paddleboard, surfboard, or sailboard rail (qv) formed by
sloping the topside deck downwards to meet the underside; design
innovation credited to Mike Diffenderfer in the 1960s.
-
downstream valve :
-
a second stage design wherein the gas flow is always positive,
flowing outward from the regulator, such that in the event of a
failure, it will fail free-flow leaking, not shut off.
-
down-the-line :
-
a positional reference from where a rafter, boarder, or boater is
situated on a swell along the breaking line to where someone else
may politely and safely engage that same swell but without
interference; as in skiing, the person already engaged down slope
has the "right of way" over anyone coming later, so separate in
space and time for best effect. This courtesy rule is intended to
separate people desirous of maximizing their access to limited
resources. The objective of "go with the flow" is to acknowledge
natural forces, and to harmonize one's involvement.
-
DPV :
-
abbreviation for Diver Propulsion Vehicle; sometimes called a
"scooter", as used to quickly traverse long distances underwater.
-
Draeger :
-
with reference to the closed-circuit oxygen re-breather, invented
(together with other rescue equipment) by Alexander B.
Dräger, an early 20th century German scientist.
-
Draeger tube :
-
an indicator used to test the quality of a breathing gas.
-
draft :
-
the depth to which a vessel is immersed when bearing a given
load.
-
drag :
-
the resistance and interference that inhibits dynamic flow in
water so as to enable control for navigation and regulation;
overcoming the disruption caused by friction against the flow of
water is not a viable goal ... controlled stability in various
conditions is a warrant of craftsmanship. Drag components and
coefficients include keels, skegs, vanes, channels, fins, and so
forth ... including rudders, drogues, and sweeps.
-
dragrope :
-
a rope that's been attached to something and is then used to drag
or haul it. Also, the end of a rope that's hanging loose or
trailing behind its point of attachment; a trawl.
-
drainage basin :
-
the area drained by a river and all its tributaries; also called
a "catchment area" or "drainage area".
-
drift dive :
-
a dive in which the divers drift with the current, and the dive
boat follows the surface marker buoy (SMB) towed by the freely
drifting divers.
-
D-ring :
-
a metal ring in the shape of a capital letter 'D' that's used on
the harness for attaching items by clipping onto them; chest
mounted D-rings are often bent outward to aid in the clipping
process.
-
drive :
-
the contrapositive of drag and a coefficient of water flow, being
the dynamic process by which a body (albeit the human body or
some form of contoured watercraft) overcomes contact friction so
as to utilize the force in natural currents, or to attain
acceleration by improving the streamlined pressure of
hydrokinetic contact.
-
drogue :
-
a bucket or canvas bag used as a vessel's "sea anchor", causing
resistance to movement of the hull through the water, so as to
decrease speed and/or increase stability.
-
drop-in :
-
the descending movement when someone piloting a paddleboard,
surfboard, sailboard, or other small watercraft moves onto the
face of a wave so as to utilize its natural power; if this move
violates the "right of way" courtesy rule by obtruding into the
down-the-line sequence, it's considered a breach of etiquette.
-
drop line :
-
an anchored line, suspended from a boat or buoy, that's used to
control a diver's rate of ascent or descent, to provide
orientation in low light on deep dives, and to secure reserve gas
cylinders for decompression stops; a type of safety line that's
also called "ascent / descent line".
-
drown :
-
to suffocate by aspirating liquid. Also, to be inundated or
overwhelmed.
-
droxtal :
-
a tiny ice particle, formed by direct freezing of supercooled
water droplets with little growth directly from the vapor,
causing most of the visibility reduction in ice fog; the term
derives from a combination of the words drop and crystal.
-
dryback / dry back :
-
slang for a sailor who has not served aboard a ship at sea,
especially someone who has not experienced naval warfare; being
someone who has not gotten "wet" or been "wetted down".
-
dry bag :
-
a collapsible watertight container used for carrying clothes,
gear, and artifacts; it will float if not overloaded.
-
dry dock :
-
a structure able to contain an entire ship, leaving all parts of
the hull accessible for construction or maintenance.
-
dry suit / drysuit :
-
a close-fitting, double-layered, watertight synthetic garment
with gaskets at neck, wrists, and ankles, as worn by a deep-sea
diver in very cold environments, usually with thermal underwear,
that's designed to protect the diver's body from the water or
pressure by circulating a warm insulating layer of air
internally, which also serves to equalize descent pressures;
originally developed by Bill Barada (1955).
-
DS :
-
abbreviation for Decompression Sickness, which is also known as
the bends, aeroembolism, caisson disease, and decompression
disease.
-
DSEA :
-
abbreviation for Davis Submerged Escape Apparatus, being an early
(1910) type of oxygen re-breather, which was intended primarily
as an emergency escape apparatus for Royal Navy submarine crews;
inspired by the earlier Fleuss system, the DSEA was developed by
Sir Robert Davis, head of Siebe Gorman and Company Ltd., it was
sometimes used for underwater diving and as an industrial
breathing set.
-
DSMB :
-
abbreviation for Delayed Surface Marker Buoy, which flagged
marker float is inflated at the end of a dive.
-
dual regulator system :
-
a reserve regulator that's already situated in series with the
primary, so as to enable an uninterrupted air flow; the use of
two regulators on a single air supply.
-
duck dive / duckdive :
-
to rise slightly while swimming and abruptly plunge one's upper
body downwards, head first, so as to descend as quickly and
smoothly as possible ... ostensibly in imitation of a duck
swiftly diving after prey. Also, when moving upstream against the
current or offshore through wave lines of breakers, whether just
swimming or launching a board or watercraft, pushing under the
face of a breaking wave and then levering upward so as to
penetrate the swell beneath and behind the curl, allowing the
wave to pass over and behind one's push and pop out of the back;
this imitative method was introduced by Shaun Tomson in South
Africa during the 1970s.
-
DUI :
-
Diving Unlimited International, being a manufacturer best known
for dry suits.
-
dump / dumper / dumping :
-
any hollow wave that breaks hard ... typically casting anyone on
it into the deep.
-
dump station :
-
a facility located in a marina, on docks or on shore, that's
specifically designed to receive sewage from the portable toilets
and holding tanks carried aboard vessels.
-
durometer :
-
an apparatus for measuring the Shore hardness of rubber or
plastic, which value is determined by the depth of penetration of
the durometer indenter foot into the specimen material; due to
the resilience of these materials, the indentation recovery time
is sometimes reported along with the hardness reading (eg: ASTM
D2240 00).
-
Dutchman's breeches :
-
the opening of two patches of blue in an otherwise stormy sky,
giving the promise of better weather; being a fancied allusion to
making a pair of short trousers (knickers or knickerbockers) with
small bits of clear sky.
-
Dutchman's log :
-
a rough method of gauging the speed of a vessel by measuring the
elapsed time for a float to travel from an observation point at
the bow to an observation point at the stern, using the known
shipboard distance and the realized time to calculate the rate.
-
Dutch talent :
-
performing any nautical task or chore in an awkward or clumsy,
inept or unskilled manner, being a lubberly performance
exhibiting more brawn than brains; that which is not done in a
shipshape fashion.
-
DV :
-
abbreviation for Demand Valve, which is usually the second stage
of a regulator.
-
dyne :
-
the standard centimeter-gram-second unit of force, equal to the
force that produces an acceleration of one centimeter per second
per second on a mass of one gram. [nb: 1000 dynes = 1 millibar, 1
millibar = 1/1000 bar]
-
dysbaric osteonecrosis :
-
death of a portion of bone that's believed to be caused by
nitrogen embolization, wherein nitrogen bubbles come out of
solution to block the vascular system.
-
dysbarism :
-
medical conditions resulting from changes in ambient pressure.
-
EAD :
-
abbreviation for Equivalent Air Depth, being a conversion of
nitrox to air, so that air tables can be used for dive planning.
-
EAN :
-
abbreviation for Enriched-Air Nitrox, which may be used with
numeric values to identify the specific oxygen content of a gas
(eg: EAN32); also represented as EANx.
-
EAR :
-
abbreviation for Expired Air Resuscitation; the preferred term in
Britain is Artificial Ventilation (AV).
-
easy :
-
formed in a long curve, so as to make a gradual transition
between the bottom and sides of a vessel; or having gently curved
surfaces leading from the middle body to the stern of a vessel,
as of the run of a hull; not abrupt; slack.
-
EATD :
-
abbreviation for European Association of Technical Divers.
-
EAV :
-
abbreviation for Expired Air Ventilation.
-
ebb tide :
-
the reflux of tide or the outflow of falling water from the tidal
current; as opposed to flood tide.
-
EBS :
-
abbreviation for Emergency Breathing System.
-
ECC :
-
abbreviation for External Cardiac Compression.
-
ECU :
-
abbreviation for Environmental Control Unit.
-
eddy :
-
a circular movement of wind or water that develops beside the
main current or adjacent to the primary flow, often as a result
of interruption or interference; a counter current running at
variance with the main current in a stream or other body,
especially one having a rotary or whirling, reversing or churning
motion, as caused by watercourse bends and shoreline or streambed
configuration.
-
eddy hopping :
-
the use of counter currents when maneuvering around the primary
flow of water, either upstream or downstream.
-
eddy line :
-
the transitional boundary between the main current and a variable
or counter current in the same flow of water , especially one
having a churning or whirling motion; the subtle division between
the primary stream and minor upstream or downstream disturbances
to that flow.
-
eddy turn :
-
a dynamic maneuver used to enter or depart a counter current.
-
electro-galvanic fuel cell :
-
an electrical device used to measure the concentration of oxygen
in the breathing gas loop of fully closed-circuit re-breather
systems so as to detect and adjust the partial pressure mixture;
a ppO2 meter / ppO2 meter.
-
El Nino :
-
a warm ocean current of variable intensity that develops along
the western coast of South America after late December, which
sometimes causes catastrophic weather conditions by shifting the
North Pacific jet stream, enhancing tropical cyclone development,
and confusing temperatures by the contrast between the warm water
and cold air; literally derived from "the (Christ) child" for its
occurrence during the yuletide solstice.
-
embarcadero :
-
a pier or wharf, especially a waterfront section that's been
commercially developed.
-
END :
-
abbreviation for Equivalent Narcotic Depth, being the depth at
which air would cause as much narcosis as a given EAN mix at a
specific depth.
-
enriched-air nitrox :
-
a breathing gas that contains more oxygen than normal air and a
corresponding decrease in the amount of nitrogen; an air mix
containing more than 21 percent oxygen, usually made by mixing
air and oxygen; abbreviated EAN or EANx.
-
ensign :
-
a flag or banner, as a naval standard used to indicate
nationality; derived from insignia (ensigne) serving as a badge
of office or emblem of authority. Also, the lowest ranking
commissioned officer in the U.S. Navy or Coast Guard, rating next
below a lieutenant junior grade; derived from standard bearer.
-
EPDM :
-
a perflourinated material that's resistant to oxygen erosion, as
used to make O-rings.
-
epilimnion :
-
the layer of water above the thermocline, being that overlying
region of a thermally stratified lake or reservoir in which there
is a rapid decrease in temperature with water depth.
-
EPIRB :
-
Emergency Position-Indicating Radio Beacon, being a global
maritime distress and safety broadcast device that's required by
Coast Guard boating regulations; a signal device, usually carried
aboard maritime craft, that when activated in an emergency will
broadcast its location to search aircraft and orbital satellites
to enable rescue.
-
epoxy / epoxy resin :
-
any of a class of resins derived by polymerization from epoxides
that're used chiefly in adhesives, coatings, and castings; when
manufacturing some paddleboards, surfboards, and sailboards, a
polystyrene blank is used with epoxy resin because polyester
resins will not bond properly.
-
equalization :
-
the forcing of air into an open space (eg: dive mask) or cavity
(eg: middle ear) so as to attain balance or to offset increasing
hydrostatic pressure; used to prevent a "squeeze".
-
equatorial tide :
-
a semimonthly tide that appears when the moon is over the
equator.
-
equatorial trough :
-
the quasi-continuous belt of low atmospheric pressure that lies
between the subtropical high-pressure belts of the northern and
southern hemispheres.
-
equivalent air depth :
-
the underwater depth at which air would cause as much
decompression obligation as nitrogen (eg: nitrox, trimix) with a
given O2 concentration.
-
erythropoiesis :
-
the making of red blood cells.
-
erythropoietin :
-
a hormone that stimulates production of red blood cells and
hemoglobin in the bone marrow.
-
esplanade :
-
an open level space, especially one serving for public access
along a shore.
-
EST :
-
Expanded Seam Technology, being a "stitchless" wet suit made by
weaving hexagonal panels together in resistant patterns that are
mainly used in super cold water wet suits; developed by a skin
graft specialist in the late 1990s.
-
estuary :
-
that part of the lower course (mouth) of a river in which the
river's current meets the sea's tide. Also, an arm or inlet of
the sea at the lower end of a river.
-
eurybathic :
-
freshwater or marine life that can tolerate a wide range of
depths; as opposed to stenobathic.
-
eustachian tube :
-
a canal extending from the middle ear to the pharynx; eponymously
after Bartolommeo Eustachio, an Italian anatomist. By permitting
air to leave or enter the middle ear, this tube equalizes air
pressure on either side of the eardrum.
-
even keel :
-
when the fore and aft draft of a vessel is the same on both
sides; floating level at the waterline.
-
exhaust valve :
-
a one-way or non-return valve that's incorporated into the
exhaust hose to keep the exhaled air flowing in the proper
direction, and prevent excessive back pressure.
-
exposure protection :
-
any garment worn to prevent bodily injury from temperature,
abrasion, contamination, or predation; may be augmented by
insulators, repellents, and other aids.
-
exposure suit :
-
a garment worn by divers for thermal protection. Also, a high
visibility insulated garment worn while working topside when
unprotected immersion may be life-threatening; this survival
coverall is sometimes called a "pumpkin suit" due to its color.
-
extratropical :
-
a fall season weather condition wherein a tropical cyclone has
lost the energy from its warm core and the remnants tend to merge
with a cold winter-type storm, creating an unstable situation
that often supercharges the storm with very intense wind speeds
and extremely large waves.
-
eye / eye of the storm :
-
an area of low pressure in the centre of a tornado or typhoon,
cyclone or hurricane; an opening in storm clouds that's
relatively calm.
-
eye of the wind :
-
in nautical parlance, the direction from which the wind is
blowing.
-
eyewall / eyewall cloud :
-
a deep, thick band of clouds that either partially or completely
surrounds the relatively calm center of a tropical cyclone,
tornado, typhoon, or hurricane.
-
face :
-
the steepening front of a wave as it moves shoreward. The height
of a wave is measured from the top lip of its crest down across
its face to the depth of its trough.
-
face mask :
-
a protective shield worn while under water; also called "swim
mask", "diving mask", or simply "mask" (qv).
-
fade :
-
the weakening of a wave as it passes from shallow water to deeper
water closer to shore.
-
fahrenheit :
-
a temperature scale in which 32 represents the freeze point and
212 represents the boiling point. [nb: the degree intervals of
the kelvin scale are the same as celsius, as the rankine are the
same as fahrenheit]
-
fairlead :
-
a rigging guide or fitting for pulley, thimble, block, or CAPSTAN
which prevents chafing of the line.
-
fairwater :
-
a hydrodynamic structure on a ship designed to direct or deflect
the flow of water; being the modern name for the conning tower of
a submarine.
-
fairway :
-
an unobstructed passage or area, being the navigable portion of a
waterway.
-
fall :
-
the part of the rope of a tackle to which the power is applied in
hoisting. Also, the flap opening at the front of some types of
men's trousers [eg: breeches].
-
fan :
-
the "rooster-tail" of thrown-up spray that's temporarily
suspended in the air behind a hard slicing turn that's executed
by a rapidly moving water-skier, surfer, or watercrafter.
-
fantail :
-
the open area near the stern of a vessel, which may have
bulwarks; also called the afterdeck.
-
farmer John wet suit / farmer Jane wet suit :
-
informal reference to a sleeveless neoprene wet suit with long
legs that's worn by boaters in mild weather as insulation against
cold water shock; this garment, which somewhat resembles bib
overalls, may be augmented by a waterproof shirt or jacket in
case of dropping temperatures.
-
fast :
-
made or held secure, as firmly fixed in place. Also, firmly tied,
as a knot. Also, closed and made secure, as a hatch or cover,
door or shutter. Also, close or near.
-
fast ice :
-
ice that is grounded on or attached to the bottom of an area
covered by shallow water.
-
fathom :
-
a nautical unit of length equal to 6 feet (1.8 m); as derived
from "span of arms" or embrace. Also, to measure depth by means
of a sounding line; to sound.
-
Fathometer :
-
the trademarked brand name of a sonic depth finder; often used
generically.
-
FAUI :
-
abbreviation for the Federation of Australian Underwater
Instructors.
-
favonian :
-
mild or favorable; propitious, by reference or allusion to the
west wind.
-
feathering :
-
the condition of a wave when the crest begins to show a little
whitewater as the wave face steepens, just prior to the wave
breaking, which is most often seen with offshore winds.
-
fender :
-
any shield or cushion, buffer or bumper that's hung over the side
of a vessel to lessen shock or to prevent hull chafing, such as a
balk of timber, a bundle of rope, a rubber tire, or the like;
derived by shortening from defender, as a guard.
-
fetch :
-
one of the three key elements (along with wind velocity and wind
duration) used when forecasting the characteristics of waves in a
storm area or in a wave generation area; this fetch length is the
swell generating area where sea or ocean waves are created by
consistently blowing winds, determining wave height and
periodicity. Also, to move or maneuver nautically; to arrive or
reach by water.
-
FFA :
-
a "Feet First Ascent", being a common problem for inexperienced
dry suit users.
-
FFDS :
-
abbreviation for Federation Francais de Speleologie.
-
FFM :
-
abbreviation for Full Face Mask.
-
FFW :
-
abbreviation for Foot/Feet of Fresh Water, a depth measurement.
-
FGV :
-
abbreviation for Free Gas Volume.
-
fHe :
-
the fraction of helium in a gas mixture.
-
fiberglass :
-
a material consisting of extremely fine filaments of glass that
are combined in yarn and woven into fabrics, used in masses as a
thermal and acoustical insulator, or embedded in various resins
as a sturdy laminate to make boat hulls, surfboards, fishing
rods, and the like; derived as the generic form of the
trademarked brand name 'Fiberglas' ... its application to a
watercraft hull or board is informally known as a "glass job".
-
fid :
-
a long, smooth, tapered, wooden tool used to open the strands of
a rope or line for splicing.
-
fiddlehead :
-
a billethead (or scrollhead) having a form similar to the volute
carved at the upper end of a violin.
-
figurehead :
-
a carved bust or full-length figure that's built into the bow of
a sailing ship.
-
fin :
-
a horizontal winglike appendage (rudder) to the underwater
portion of a hull, often adjustable, as the planes for
controlling the dive of a submarine, or the fin keel for damping
the roll of a surface vessel. Also, a vertical control surface
(skeg or keel) mounted to the underside of a paddleboard,
surfboard, sailboard, or other small watercraft to aid in
stability when maneuvering; often mounted singly, in pairs, or in
triplets (eg: "Thruster" configuration of two ahead and one
behind). Also, slang for one of a pair of paddlelike devices,
usually made of rubber, that are worn on the feet as an aid in
swimming and underwater diving; imitative of the broad flat limbs
or the membranous organs of aquatic animals that are used for
steering and propulsion; also called swim fin or flipper. Also,
slang for the human hand.
-
finger float :
-
an access walkway that defines the size of a berth; also known as
a finger pier, so called from its finger-like resemblance. [v:
phalanx, phalange]
-
finger pier :
-
a structural extension from a dock that's delineated for the
berthing or mooring of vessels (or other watercraft) for the
purpose of embarking or disembarking, and for wet storage; also
known as finger float.
-
first stage :
-
the initial phase of pressure reduction by the regulator
assembly, set to deliver intermediate air pressure from the high
pressure air cylinder to the second stage of the regulator.
-
firth / frith :
-
a long, narrow indentation of the seacoast.
-
fish :
-
any short, wide paddleboard, surfboard, or sailboard; originating
as a stubby, wide nosed, broad swallow-tailed board with two fins
mounted on the underside, as invented by Steve Lis of San Diego.
-
fjord / fiord :
-
a long, narrow arm of the sea, bordered by steep cliffs, that's
usually formed by glacial erosion. Also, in Scandinavia, a bay.
-
flag :
-
see pennant, burgee, ensign, signal flag.
-
flagella :
-
a long lash-like appendage that serves as an organ of locomotion
in protozoa, algae, sperm cells, and other microorganisms. [v:
dinoflagellate]
-
flagship :
-
the primary or principal vessel of a group or line; typically the
best or most important one, as the headquarters ship or boat with
the superior crew.
-
flank speed :
-
the maximum possible speed of a ship; in the progression of
prescribed standard speeds, an increase faster than full speed.
[v: amain]
-
flat :
-
a condition of the water at sea wherein there are no swells or
waves, winds or currents; having a glass-like appearance.
-
flatstitched / flat-stitched :
-
a wet suit seam that's glued together before being sewn through
the material; although secure and flexible, such a penetrated
attachment leaks, so this construction, which is also known as
"flatlocked", is generally reserved for warmer water excursions.
-
flip-flop entry :
-
see backward roll entry.
-
flipper :
-
slang for one of a pair of paddlelike devices, usually made of
rubber, that are worn on the feet as an aid in swimming and scuba
diving; imitative of the broad flat limbs or the membranous
organs of aquatic animals that are used for steering and
propulsion; also called fin or swim fin. Also, slang for the
human hand.
-
float :
-
something that floats or something for buoying up, being a hollow
object, inflated container, or buoyant material that tends to
remain at, or to return to the surface of water, such as a
pontoon or raft, water wings or life preserver. Also, an inflated
bag to sustain a person in water; a life preserver. Also, a
floating platform that's attached to a wharf, bank, or the like,
and is used as a landing. Also, a hollow, boat-like structure
under the wing or fuselage of a seaplane or flying boat, keeping
it afloat in water; also called a pontoon. Also, slang for a tour
aboard ship at sea; being a cruise out from port and back. Also,
an unspecified number of ships operating together in the same
area as a single or unified group.
-
floater :
-
a maneuver performed by paddleboarders, surfboarders,
sailboarders, and other watercrafters wherein the pilot
weightlessly balances upon the broken foam atop a pitching lip on
a breaking wave; this sustained floating atop the wave's energy
can be concluded by moving rearward onto the back of the
developing swell, or forward onto the standing face of the wave.
Also, slang for a corpse that's risen by bloat to the surface;
once gases pass off (usually by venting during predation), the
corpse again sinks to the seafloor. [nb:the rate of decomposition
for a corpse underwater is about half that of one exposed to the
open air]
-
floating garage / floating tender garage :
-
a hollow interior within the hull of a ship or within the chamber
of a moored platform, that admits surface vessels through a
water-tight opening (shell door) situated at sea level; this
configuration obviates the need for a boarding ladder or an
elevating hoist.
-
floe :
-
a sheet of floating ice, or a detached portion thereof, chiefly
on the surface of the sea that's smaller than an ice field; also
called ice floe, as derived from "layer".
-
floeberg :
-
a mass of ice floes resembling an iceberg.
-
flood :
-
to fill a space with water. Also, a rising tide; an elevation in
sea level.
-
flood tide :
-
the inflow of rising water from the tidal current; as opposed to
ebb tide.
-
flotsam :
-
wreckage or refuse found floating on water; as derived from
"float".
-
flow meter :
-
a visual indicator that displays the rate at which a gas (or
fluid) is flowing, as in a re-breather or oxygen analyzer.
-
flow restrictor :
-
a device inserted into a flow line to fractionally limit the
volume of gas so that variations in pressure cannot affect sensor
metering.
-
flowstone :
-
a layered deposit of calcium carbonate that's been left by thin
sheets of flowing water, as in a cave.
-
fluke :
-
the retentive part of an anchor that catches in the seafloor,
especially the flat triangular piece at the end of each arm.
Also, the barbed head of a harpoon, spear, arrow, or the like.
Also, a stroke of good luck or a chance happening; an
accidentally successful act or event.
-
flume :
-
a deep narrow defile containing a mountain stream or torrent.
Also, an artificial channel or trough used for conducting water.
-
flutter kick :
-
a type of kick used in the crawl wherein both of the swimmer's
legs make rapid up-and-down movements, alternately rotating from
the hips, while the knees remain rigid.
-
flux :
-
continuous change, passage, movement, or flow, as the flowing-in
of the tide.
-
flying bridge :
-
a small open deck, situated above the main cabin or pilothouse of
a vessel, having duplicate navigational equipment and bridge
controls; also called "bridge deck" or "monkey island".
-
flying boat :
-
a high-winged passenger / cargo aircraft with a boat-bottomed
hull and two- or four-engines that operates from the surface of
the water.
-
flying gangway :
-
a raised fore-and-aft catwalk permitting safe passage when the
weather deck of a ship is washed by heavy seas; also called
"monkey bridge".
-
fN2 / fN2 :
-
the fraction of nitrogen in a gas mixture.
-
foam :
-
an aggregation of small bubbles formed into a froth on the
surface of a liquid by agitation, fermentation, or the like.
Also, a liquid material (eg: polyethylene, polyurethane, etc)
into which minute gas bubbles are dispersed in order to form a
molded lightweight solid, often firmly resiliant.
-
foil :
-
the foremost working part or section, especially that which is
thinnest when backed or reinforced by a thicker or heavier
portion ... the leading edge of a fin or the outer edge of a
prop, the forward edge of a rudder or the front of a paddleboard,
surfboard, or sailboard. Also, a truncation of airfoil or
hydrofoil. Also, anything that makes something else seem better
by contrast; anyone who makes somebody else seem better by
contrast. Also, to frustrate success, prevent achievement, or
thwart accomplishment; a check, repulse, or defeat.
-
following sea :
-
an overtaking current that approaches a vessel from its stern.
-
footie :
-
a waterproof (neoprene) sock-like foot covering, serving to
insulate and protect the diver's foot and ankle, that's worn
inside open-heeled flippers or fins; also called "bootie" or
"bootee".
-
footrope :
-
a ROPE suspended beneath a yard or spar to give footing to a
person handling sails. Also, the portion of the boltrope to which
the lower edge of a sail is sewn.
-
forecastle :
-
(fohk-suhl) the part of the weather deck forward of the foremast,
which may have bulwarks. Also, a superstructure at or immediately
aft of the bow or prow of a vessel, that's used as a shelter for
stores and machinery, or as quarters for sailors.
-
forecastle deck :
-
a partial weather deck on top of a forecastle superstructure;
also called a topgallant forecastle.
-
forecastle head :
-
the extreme fore part of a forecastle superstructure. Also, the
extreme fore part of the main weather deck of a vessel that has
no forecastle superstructure.
-
forerunner :
-
a preceding wave; a precursor swell advancing at 1.5 times the
wave periodicity.
-
forward roll entry :
-
a self-protective water entry method in which the fully equipped
standing diver bends forward from the waist into a body tuck from
a pier, deck, or other platform elevated not more than 7ft (2m)
above sea level, with face mask held in place, allowing the
back-mounted air tank to strike the water surface first, and then
continues the partial somersault underwater into a prone swimming
position; any extra gear or bottles ride in the diver's protected
"breadbasket" for a safe and secure entry. This method is used
when either the giant stride entry or backward roll entry methods
would not be suitable.
-
fO2 / fO2 :
-
the fraction of oxygen in a gas mixture.
-
foul :
-
that which is clogged or obstructed with foreign matter. Also,
stormy or inclement, as foul conditions that impede navigation.
Also, obstructed or entangled, as a foul anchor. Also, a
collision, to collide; as derived from "to stink".
-
founder :
-
the wrecking or sinking of a vessel.
-
fountainhead :
-
the origin or source, as the spring from which a stream flows.
-
FPS :
-
abbreviation for the Imperial system of measure: Foot, Pound,
Second.
-
freak wave :
-
an abnormally large wave that occurs on a seemingly random basis
in the oceans; this unpredictable sea wave is also known as a
rogue wave, sleeper wave, sneaker wave, and king wave. Of
enormous proportion, great in height and steepness, these
unexpected waves sometimes travel in a direction at an angle to
the prevailing seas, or occur where waves meet opposing currents.
-
freeboard :
-
the portion of the side of a vessel's hull that's above the
water; in particular, the distance between the uppermost fully
watertight deck and the demarcated official load-line. Also, the
vertical distance from the water surface to the top of the deck
of a vessel or dock.
-
freeboard / freeboarding / tow-in surfing :
-
the act of riding a surfboard (ie: towboard) behind a motorboat
or sailboat, which is similar to water skiing.
-
freeboard deck :
-
the uppermost deck on a cargo vessel that's officially considered
to be watertight: also called upper deck, it's used as the level
from which the plimsoll marks are measured.
-
free diving / free-diving :
-
underwater diving without supplemental air or breathing
equipment; also called breath-hold diving or skin diving.
-
freeing port :
-
an opening in the bottom of a bulwark used for the rapid drainage
of a weather deck in heavy seas; a type of scupper.
-
freshet :
-
the sudden rise in the level of a stream, or a flooding that's
caused by heavy rains or by the rapid melting of snow and ice.
Also, a freshwater stream that flows into the sea.
-
frog kick :
-
a type of kick used in the breaststroke wherein both of the
swimmer's legs are bent at the knees, simultaneously extended
outward, and then forcefully brought together.
-
frogman :
-
nickname for a scuba diver, especially one on a military mission.
-
FSW :
-
abbreviation for Foot/Feet of Sea (or Salt) Water, a depth
measurement.
-
fuel dock :
-
a dedicated structure, or a delineated area on a larger structure
(ie: pier, dock, bulkhead, etc), that is specifically used for
the dispensing of boat fuel; also called "marine service
station", "fuel dispensing facility", or "fueling station".
-
Fujita scale :
-
a scale indicating the speed or force of cyclonic wind, as that
of a tornado or waterspout.
-
Fujiwara effect :
-
the effect of two tropical cyclones when they rotate about each
other, which is caused by a lack of steering winds in the upper
atmosphere.
-
full face mask :
-
a protective shield worn while under water, often with an
insulating hood, so as to safeguard the diver against exposure to
cold temperatures or other extremes.
-
full fathom five :
-
an alliterative allusion to an underwater depth of thirty feet,
or approximately one atmosphere of pressure (that is, double the
pressure at sea level), which was once a formidable barrier for
breath-hold diving. Also, a poetic expression meaning a full
change or a complete alteration that's beyond human control or
influence; a total transformation.
-
fullsuit / full-suit :
-
a wet suit that covers the entire body; known as "steamer" in
Australia.
-
funboard / funboarding :
-
a compromised surfboard design that combines the superior
paddling attributes of a traditional longboard, but stripped of
some of its unwieldy length and bulk, so that the rider may
experience some boogie board or shortboard maneuverability.
-
FV :
-
abbreviation for Floodable Volume.
-
gaff :
-
a metallic hook attached to a long handle that's used for landing
large fish, or for fishing objects from the water. Also, a spar
rising aft from a mast, primarily used to support the head of a
quadrilateral fore-and-aft sail (gaff sail). Also, to be
subjected to ridicule or harsh treatment.
-
gaiter :
-
a lower leg covering for a dry suit, which wrap is used to
restrict or constrict that airspace so as to help maintain body
position and buoyancy control; a "squeezer" added to improve trim
on deep dives.
-
gale :
-
a very strong wind; properly, a wind of 32-63mph, as measured on
the Saffir-Simpson scale.
-
gallery :
-
a projecting balcony or structure on the quarter or stern of a
ship; a long covered area, narrow and open at one or both sides,
that's used as a walkway or corridor.
-
galvanic corrosion :
-
a phenomenon that occurs when disparate metals contact one
another, which deterioration may be slow or fast, depending upon
the level of acidity or alkalinity, and is augmented by the
addition of sea water. [cf: voltaic pile]
-
galvanize / galvanization :
-
an electrochemical technique for coating metal, especially iron
or steel, with a protective layer of zinc as a preservative
against decomposition.
-
gangplank :
-
a narrow plank, often inclined with transverse traction cleats,
that's used as a temporary bridge onto a vessel; a brow serving
as a walkway or passageway.
-
gangway :
-
a narrow walkway or passageway. Also, an opening in the railing
or bulwark of a vessel for use as a passageway. Also, a temporary
bridge at the opening in the railing or bulwark of a vessel; also
known as a brow or gangplank.
-
gantline :
-
a rope rove through a single block that's hung from a spar, mast,
funnel, or other stanchion, used as a means of hoisting workers,
tools, flags, or the like; as derived from earlier "girtline",
being a line for girding.
-
gasket :
-
a rubber, metal, or rope ring that's placed around a join or
opening so as to make it watertight ... the ankles and wrists of
a wet suit are traditionally rolled around such a closure to
prevent leakage. Also, a light line for securing a furled sail to
a boom, gaff, or yard; as derived from 'plaited cord'.
-
gasoline alley :
-
an aisle, corridor, passageway, or gangway connecting the
bulkheads of several fuel storage and engine compartments in the
bowels of a ship.
-
gasp reflex :
-
an involuntary physiological response to suddenly plunging into
very cold water (50°F or less), which automatic reaction
contributes to hypothermia and drowning; the human body cannot be
habituated to such shocking immersion ... only somewhat
accommodated by protective preparation.
-
gat :
-
a passage or channel that extends inland from a shore; derived
from "hole" or "opening".
-
gauge pressure :
-
a measure of pressure that doesn't include the effect of the
atmosphere, such as a submersible pressure gauge (SPG).
-
Gay-Lussac's law :
-
the principle that, for relatively low pressures, the density of
an ideal gas at constant pressure varies inversely with the
absolute temperature of the gas; also called Charles' law, and
named after Joseph Louis Gay-Lussac, a French chemist and
physicist.
-
gel coat / gelcoat :
-
a mixed coating of resin with a catalyst so as to force the
gelling setup, which is applied during the laminating process,
just after the initial layer of fiberglass; this hot-coat sanding
resin is blended with waxes so as to fill any holes and smooth
any bumps while hardening and sealing the finish on paddleboards,
surfboards, sailboards, and other small watercraft.
-
Gel Cell :
-
brand name of a sealed lead-acid battery pack that will function
in any position without spilling or leaking, as used with
canister lights.
-
geyser :
-
a geothermic hot spring that intermittently spews fountain-like
jets of water and steam into the air; as literally derived from
'gusher', from one ("Icel Geysir") so-called in Iceland.
-
giant stride entry :
-
the most common water entry method in which the fully equipped
standing diver takes a long step from a pier, deck, or other
platform into the water, with chin tucked and mask securely held,
and then immediately closes legs together in a scissor-kick as
soon as the water surface has been broken, to stay shallow and
remain upright for a quick check of equipment before making a
controlled descent; also called "spread-eagle" jump and
"lifesaving" leap. Any extra gear and bottles are either held in
the hands or are lowered separately on ropes.
-
gig :
-
a small lightweight boat propelled by long oars, as a scull or
dinghy. Also, a long, thick-handled fork with barbed tines that's
used to spear fish and frogs; derived by shortening of 'fishgig'
and 'fizgig'. Also, a device that commonly consists of four hooks
secured back-to-back, which is used to drag through a school of
fish so as to hook them through the body.
-
giggles 'n' bangs :
-
slang for the hull noise, from creaks and groans to thumps and
pops, induced by the effects of high pressure at greater depths
on submerged vessels.
-
gimlet / gimblet :
-
to rotate a suspended anchor to a desired position.
-
glassy :
-
a windless surf condition in which the texture of the ocean's
surface is flat, smooth, and very clean.
-
glory hole :
-
the quarters on a ship that are occupied by the stewards or
stokers. Also, a small storeroom within the hull of a ship,
usually at the stern; also called "lazaretto". Also, an enclosed
space or locker for stowing loose gear. Also, a place for
concealing valuables, a cache hideaway or treasure trove.
-
gloss coat / glosscoat :
-
a final coat of thin resin that's applied as a hard finishing
layer, producing a slick shiny surface on paddleboards,
surfboards, sailboards, and other small watercraft.
-
GMT :
-
Greenwich Mean Time, set (since 1884) at the 0 meridian of 24
global time zones; being the same as Zulu, and adjusted in
"universal time" (UTI/UTC) for deviations from "international
atomic time" (IAT). Also known as the 'prime meridian'; sometimes
mistakenly cited as "Greenwich Meridian Time".
-
goat locker :
-
the Chief Petty Officer's quarters aboard a submarine; derived
from the space where a milch goat was kept aboard sailing ships.
-
goggles :
-
large spectacles furnished with special lenses and reinforced
rims for the protection of the eyes from injury.
-
Gold Line :
-
brand name of a vivid yellow nylon rope (kernmantle), durable and
resilient, that's pre-positioned as a perpetual guideline in
caves that are regularly visited by tourists.
-
gondola :
-
a narrow, open, flat-bottomed small boat with low sides and a
docked tail, that's rowed by an oarsman at the stern, and used to
navigate the coastal European waterways off the Mediterranean
Sea.
-
gore :
-
a triangular piece of material inserted in a garment, sail, or
the like, to give it greater width or a desired shape. [cf:
godet, gusset] Also, one of the panels, usually tapering or
shaped, making up a garment or other fabric construction.
-
goring :
-
the triangular area along a leech of a square sail, created by
the presence of a gore.
-
gox :
-
abbreviation for gaseous oxygen.
-
GPS :
-
abbreviation for Global Positioning System, being a satellite
based method of triangulation used during navigation; high-tech
successor to sextant.
-
grab rope :
-
a rope supported so as to afford a hold for anyone walking up a
gangplank, working aloft, and so forth; also known as "grab
line".
-
gradient :
-
the rate of change with respect to distance of a variable
quantity, as temperature or pressure, in the direction of maximum
change; used as a vector of angle during ascent or descend.
-
granny line :
-
a line which goes from the stern platform or transom to the
anchor line; also called "gerry line".
-
grapnel :
-
a device consisting of one or more hooks or clamps that's used
for holding or grasping; also called a "grapple", "grappling
iron", "gang hook", or "creep". Also, a small anchor or
anchor-like device with three or more flukes that's used for
grappling or dragging; as derived from "grape hook".
-
grapple :
-
to hold or make fast to something, as with a grapnel or grappling
iron, a gang hook or creep; to seize or fasten. Also, to struggle
or wrestle with something, such as a problem or an obstacle.
-
green flash :
-
a green coloration, caused by atmospheric refraction of the
upper portion of the sun, that's occasionally seen as the sun
rises above or sinks below the horizon; also known as "Neptune's
wink" when observed at sea, and "zodiacal light" for its
occurrence in a narrow band called the 'zodiac' or plane of the
ecliptic.
-
green sulfur bacteria :
-
a group of green or brown bacteria that occur in aquatic
sediments, sulfur springs, and hot springs, which utilize reduced
sulfur compounds instead of oxygen.
-
green water :
-
sea water that doesn't break up into spray or spume, especially
the solid swell or wave that washes aboard a vessel.
-
grot-hole :
-
a colloquialism for a small insignificant cave with no further
leads, usually tight and difficult to manoeuvre.
-
grotto :
-
a cave or cavern; a subterranean chamber. Also, an artificial
cavern-like recess.
-
groundswell / long-period swell :
-
a broad, deep swell or rolling of the sea that's due to a distant
storm or gale; as a general rule, the longer and harder the wind
blows over a greater distance of ocean, then the larger the swell
and the longer the period between successive waves ... the longer
the swell period (at 16 seconds or more), then the deeper the
swell energy extends below the ocean's surface, which may reach
to and interact with (refract) the seafloor.
-
groundwater :
-
water in a below ground aquifer that flows from high to low areas
except when a pressure gradient causes the water to move against
gravity, at a speed related to the magnitude of the pressure
gradient and the permeability of the aquifer. Groundwater
intersects surface water through springs, streams, rivers, lakes,
swamps, and other features.
-
growler :
-
a small iceberg, but one large enough to be a navigational
hazard.
-
groyne / groin :
-
a small jetty extending from a shore to prevent beach erosion.
-
guard rail :
-
a railing system, including a top rail, located along the edge of
a walkway, gangway, passageway, stairway, or other transit
surface so as to minimize the possibility of an accidental fall;
also called handrail or safety rail.
-
guess-warp :
-
a rope fastened to a vessel or wharf, and used to tow or haul a
boat or vessel into place; also called "guess-rope".
-
guideline :
-
an emplaced rope or cord that serves to direct someone's passage
over unfamiliar terrain; a safety line laid temporarily through
an entanglement or maze that marks the route and establishes the
entrance, which is retrieved by the last diver when exiting.
-
guide pile :
-
a pile that holds a floating dock on location, and allows the
dock to rise and fall with changing water levels.
-
gulf :
-
a portion of an ocean or sea that's partly enclosed by land.
Also, a deep hollow, as a chasm or abyss. Also, any great or wide
separation. Also, something that engulfs or swallows up.
-
gunk hole :
-
a quiet anchorage, as in a cove, used by small yachts.
-
gunnel :
-
see gunwale.
-
gun tackle :
-
a tackle composed of a fall rove through two single blocks and
secured to one of them so as to secure a mechanical advantage of
two or three, neglecting friction, depending on the arrangement.
-
gunwale / gunnel :
-
the upper edge of the side or bulwark of a vessel. Also, the
sheer strake of a wooden vessel; the uppermost strake beneath the
plank-sheer.
-
gusset :
-
a small triangular piece or panel that's inserted along the arm
of a wet suit to improve the fit, reinforce the material, and
facilitate movement (especially paddling).
-
gut :
-
a narrow passage, as a channel of water. Also, to remove the
vital or essential parts from something.
-
guts :
-
from the abdomen or bowels, fortitude and determination. Also,
the inner working parts of a device or mechanism.
-
gypsyhead :
-
a flanged drum on a winch that's used for winding in lines.
-
gyre :
-
a ring-like system of ocean currents rotating clockwise in the
northern hemisphere and counterclockwise in the southern
hemisphere. Also, any circular course or motion; as derived from
'ring'.
-
hadal :
-
pertaining to the biogeographic region of the ocean bottom below
the abyssal zone; below approximately 20,000 feet, being the
greatest ocean depths.
-
Haldanean / Haldanian :
-
a relative theory by John Scott Haldane that nitrogen is taken up
and given off in exponential fashion during a dive, and that
there is some safe ratio of pressure change for ascent;
decompression models of tissue saturation and desaturation based
on the principles (eg: critical ratio hypothesis) described by
J.S. Haldane.
-
half deck :
-
the portion of the deck below the upper or spar deck, and aft of
the mainmast on a sailing ship.
-
half-time :
-
the time required for body tissue to absorb or release half of
the total gas required to reach equilibrium with the surrounding
gas pressure.
-
halocline :
-
a well-defined vertical salinity gradient in ocean or other
saline water; a visible boundary, like a barrier of mist, between
layers of water of different salinities.
-
halyard :
-
any of various lines or tackles for hoisting a flag,
sail, spar, or other object into position.
-
handy :
-
term of approbation for capable seamen or skillful sailors who
are dexterous and adroit, deft and nimble; not lubberly. Also, a
craft or vessel that is easily maneuvered, responsive to
controls.
-
hang :
-
slang for a diver remaining stationary at a particular depth or
location for a specific time, especially when performing a staged
decompression.
-
hang tank :
-
an extra air tank of breathing gas that's staged on the ascent
line at the decompression stop.
-
harbor :
-
a natural or artificial part of a body of water, situated along
the shore or coast, that's deep enough to anchor a ship and
provide protection against winds, waves, and currents; often
having docks or other port facilities. Also, any place of shelter
or refuge, a haven or retreat, an asylum or sanctuary, such as a
cold harbor.
-
hard-and-fast :
-
a ship run aground. Also, something unalterable.
-
hard hat :
-
the helmet used with a dry suit during underwater construction
and salvage diving; the two-part helmet (bonnet and corselet)
includes viewing ports and connectors for air and communication
lines; this configuration has remained the standard arrangement
since its original development (1836) by George Edwards.
-
hard suit :
-
slang for the Atmospheric Diving Suit, being an articulated
self-contained hard-shell protective body covering for deep
underwater explorations (2000ft at a max 6-8hrs) without
obligatory decompression stops during ascent.
-
harness :
-
an arrangement of webbing straps with quick release buckles
that's worn by a diver for attaching the buoyancy compensator,
backplate, air tanks, and any peripheral apparatus or gear.
-
harpoon :
-
a spear-like missile, barbed with a tethering line attached,
that's thrown or shot so as to spear fish or other sea life.
-
hatch :
-
an opening in the DECK of a vessel used as a passageway, or the
cover over such an opening; also called a "hatchway" (not a
"watertight door" in a BULKHEAD).
-
hawsepipe :
-
an iron or steel pipe situated in the stem or bow of a vessel
through which an anchor cable passes.
-
hawser :
-
a heavy cable used for mooring or towing [nb: this line is never
called a 'rope'].
-
head :
-
a toilet or lavatory on a boat or ship. Also, the forepart of a
vessel; its bow or stem. Also, the part of an anchor at which the
arms join the shank; also called "crown". Also, the upper edge of
a quadrilateral sail, or the upper corner of a jib-headed sail.
-
heading :
-
the course or direction of travel for a person, party, or vessel.
Also, the angle between the axis of a vessel and some reference
line.
-
head sea :
-
a formation of waves running in a direction opposite to that of a
vessel.
-
headway :
-
forward movement, advancement, or progress. Also, the interval of
time or distance, relative to the situation or circumstances,
between two vessels traveling in the same direction over the
same route. [cf: forereach]
-
heave :
-
to lift or hoist. Also, to forceably throw something, especially
a weighted line (eg: heaving line). Also, to pull or haul on a
rope, line, cable, or the like. Also, the rise and fall of the
waves or swell of a sea. Also, the vertical rise and fall of a
craft or vessel. Also, to halt or stop the advance of a craft or
vessel ("heave to") by causing it to lose headway. Also, to move
in a certain direction or into a certain position or situation,
as "the ship hove into sight". Also, to vomit, retch, keck,
regurgitate, throw-up, upchuck, barf, toss cookies, ralph,
disgorge, nausea, mal de mer, or puke.
-
heave-ho :
-
an exclamatory call or chant used by sailors when hauling or
working, especially used to signal that the anchor's aweigh.
-
heaving line :
-
a light or thin cord or rope, with its trailing end weighted by a
knot, that's used to toss overboard to a swimmer or small boat,
or to a wharf or mole, or between vessels for transferring larger
cables; also known as a "messenger line" or "throw line".
-
heliair :
-
a blended breathing gas consisting of a mixture of oxygen,
nitrogen, and helium, that's often used during the deep phase of
dives using Technical diving techniques. The helium and air blend
has a 21:79 ratio of oxygen and nitrogen.
-
heliox :
-
a blended breathing gas consisting of a mixture of oxygen and
helium, that is often used during the deep phase of dives using
technical diving techniques. Since sound travels faster in heliox
than in air, voice formants are raised, making divers' speech
incomprehensible to people not accustomed to it. Being more
expensive, its use is often limited to commercial dives.
-
helium :
-
an inert, colorless, odorless, tasteless chemical element, which
exists, except in extreme conditions, only as a gas. It is not
toxic and has no known biological effect. It is the second most
abundant element in the universe, with its boiling and melting
points among the lowest of the elements; significant amounts are
found on earth only in natural gas. Helium is used in cryogenics,
in deep-sea breathing systems, for inflating balloons, and as a
protective gas for many purposes. Because helium does not create
problems with narcosis to the same extent as nitrogen, it's
therefore used for very deep diving.
-
helm :
-
the steering apparatus, as a wheel or tiller, by which a vessel
is navigated. Also, the point, position, or location of control.
[nb: where the ship's steering wheel has been replaced by levers
or joysticks for controlling propulsion pods and thrusters, the
helm is called an "integrated bridge system workstation"]
-
Henry's law :
-
the principle that the amount of a gas that dissolves in a liquid
is proportional to the partial pressure of the gas over the
liquid, provided that no chemical reaction takes place between
the liquid and the gas; or the amount of gas that will dissolve
in a liquid at a given temperature is almost directly
proportional to the partial pressure of that gas; as devised by
William Henry, an English chemist.
-
Hg :
-
the chemical symbol for mercury [hydrargyrum: liquid silver; by
analogy with aurum, argentum, etc].
-
HID :
-
abbreviation for High Intensity Discharge, being a technology
that generates high intensity white-blue lighting underwater with
very low battery power.
-
high pressure cylinder :
-
steel air cylinders that're used at fill pressures of 3,500 psi
(230 bar).
-
high seas :
-
the open sea or ocean that's beyond the limit of a country's
territorial waters; also called "international waters".
-
Hogarthian / Hogarthian configuration :
-
a minimalistic arrangement of streamlined equipment that's
intended to maximize gas efficiency for extended cave diving,
including enough redundancy for decompression stops; as advocated
by William Hogarth Main, a Florida cave diver. [v: ultralight]
-
hogging :
-
the behavior of a ship when only its midships area is supported
by the crest of a wave, leaving the bow and stern unsupported by
troughs.
-
hoise :
-
to hoist, haul, or rouse, to pull together, as derived from
"hissa" and "huzzah" work chants.
-
hoist :
-
any lifting apparatus, such as tackle or boom; derived from
hoise.
-
hold :
-
the cargo space in the hull of a vessel, especially between the
lowermost deck and the bottom. Also, any individual compartment
or bay of a larger cargo space that's closed by bulkheads and has
its own hatch or hatchway; as a variant derived from hole.
-
holdfast :
-
something used to hold or secure a thing in place.
-
holding tank :
-
any retention system (eg: Type III Marine Sanitation Device)
on-board a vessel that functions by receiving and holding sewage,
which is periodically emptied at approved pumpout sites or dump
stations, or discharge beyond the 3 mile offshore limit (except
within federally designated No-Discharge Areas).
-
holiday diver :
-
someone who engages in underwater swimming while on vacation, as
an excursion or expedition, but rarely dives when close to home;
also called "leisure diver" or "tourist". [nb: many holiday
divers do not venture below the 33 foot depth of one standard
atmosphere, and most do not venture below the 90 foot depth of
two atmospheres, due to the need for mixed breathing gases,
decompression stops, and technical training]
-
hollow sea :
-
an ocean wave formation in which the rise from troughs to crests
is very steep.
-
hood :
-
a soft neoprene garment worn over the head (and neck) as thermal
insulation or impact protection; made integral with a wet suit,
connectable or separate, with a nylon or polypropylene rashguard
lining, it's often accompanied by a full face mask. [cf:
balaclava, coif, pileus/pîlos]
-
hook :
-
slang for an anchor of any style, also called "killick", as used
as a retainer or brake.
-
hookah :
-
surface-supplied compressed air apparatus that's used by several
divers in series during shallow dives in calm waters; the air is
delivered to the divers through a long hose.
-
horsecollar :
-
slang for the old style floatation device worn around the
neck, known as the adjustable buoyancy lifejacket (ABLJ),
replaced by the buoyancy compensator (BC) or buoyancy control
device (BCD).
-
hot spring :
-
a thermal spring having water warmer than 98°F / 37°C,
which water is usually heated by emanation from or passage near
hot or molten rock.
-
hovercraft :
-
a passenger vehicle that rides on a cushion of air, that's kept
aloft by fans and driven forward by propellers; trademarked name
for an air-cushioned vehicle (ACV).
-
Hovering Act :
-
an international law that restricts or forbids the loitering of
vessels (foreign or domestic) within the prescribed limits of a
coastal nation; this act stipulates that foreign vessels may be
boarded, and their shipping manifests checked by the appropriate
government officials, when beyond the three-mile limit of a
coastal nation.
-
HP :
-
abbreviation for high pressure.
-
HP hose :
-
the high pressure hose that connects the first stage of the
regulator to the air pressure gauge; a hose designed to accept
high pressure cylinder gas without rupturing.
-
HPNS :
-
High-Pressure Nervous Syndrome, being a secondary reaction caused
by the use at depth of trimix breathing gases containing helium;
also called "helium tremors".
-
HRC :
-
Hyperbaric Rescue Craft; a self-contained, self-propelled escape
module used by saturation divers when weather or other emergency
conditions jeopardize their life-support.
-
HSAI :
-
abbreviation for Handicapped Scuba Association International.
-
hull :
-
the outermost and lowermost hollow portion of a ship or other
vessel, together with its framework support structure, that
floats partially submerged while supporting its infrastructure
and superstructure; the external "shell" or "skin" of a boat or
amphibious craft enabling it to float. [nb: the hull on European
ships bears a resemblance to fish, while the hull on Asian junks
bears a resemblance to waterfowl] Also, to drift, as a ship or
other craft, without power or propulsion; also called "dead in
the water".
-
hurricane :
-
a violent cyclonic storm, occurring especially in the
northwestern and midwestern Atlantic and its tropical inlands,
having wind speeds of or in excess of 74mph, as measured on the
Saffir-Simpson scale; derived from "Hurakan", the name of the
Caribbean Indian storm god. [nb: 'hurricane' is the term used for
such violent storms occurring in the northern hemisphere between
the 'prime meridian' (0°) and the 'international date line'
(180°); elsewhere it's called a 'cyclone' or 'typhoon']
-
hurricane deck / hurricane-deck :
-
a deck at the top of a passenger steamer, having a roof supported
by light scantlings; also called "awning deck" or "shade deck".
-
hurricane season :
-
weather conditions favor the development of tropical
disturbances, especially in the Inter-Tropical Convergence Zone
(ITCZ) five degrees or more above or below the equator, during
the period 1 June through 30 November in the Atlantic, Caribbean,
and Gulf of Mexico, during the same period of 1 June through 30
November in the central Pacific, and during the period 15 May
through 30 November in the eastern Pacific.
-
hurricane warning :
-
a forecast issued by the National Hurricane Center that sustained
winds of 64 knots (74mph) or higher are expected to occur in a
specific area within 24 hours or less.
-
hurricane watch :
-
a forecast issued by the National Hurricane Center that sustained
winds of 64 knots (74mph) or higher are expected to occur in a
specific area within 36 hours or less.
-
H-valve :
-
a single cylinder tank valve with two outlets that provides for
dual regulators.
-
HWL :
-
abbreviation for High Water Level.
-
hydrodynamics :
-
the branch of fluid dynamics that deals with liquids; the science
dealing with the laws governing water or other liquids in motion.
[v: hydromechanics, hydrokinetics]
-
hydrofoil :
-
a winglike surface form that creates perpendicular thrust against
water so as to lift a vessel to which these members are attached
while that vessel is moving. Also, a vessel with such members
attached.
-
hydrogen :
-
a colorless, odorless, flammable gas, being the lightest and most
abundant of the elements; It has been proposed as a substitute
for helium in deep commercial and military diving.
-
hydrogeology :
-
the science dealing with the occurrence and distribution of
underground water.
-
hydrograph :
-
a graph of the water level, or rate of flow, of a body of water
as a function of time, and showing the seasonal change.
-
hydrography :
-
the science of the measurement, description, and mapping of the
surface waters of the earth, especially pertaining to navigation.
-
hydrokinetics :
-
the branch of hydrodynamics that deals with the laws governing
liquids or gases in motion.
-
hydrologic cycle :
-
the natural sequence by which water passes into the atmosphere as
water vapor, precipitates to earth, and returns to the atmosphere
through evaporation. [cf: osmotic (or reverse osmosis)
filtration]
-
hydrology :
-
the science dealing with the occurrence, circulation,
distribution, and properties of the waters of the earth and its
atmosphere. [v: hydrometeorology]
-
hydromancy / hydromantie / hydromanteía :
-
divination by means of interpreting the appearance of water, or
by interpreting the motions of water.
-
hydrometeorology :
-
the study of atmospheric water in its various forms (eg: clouds,
fog, rain, ice crystals, hail, etc), especially precipitation, as
it affects the water supply, flood control, agriculture, power
generation, and so forth.
-
hydrometer :
-
an instrument for determining the specific gravity of a liquid,
commonly consisting of a graduated tube that's weighted to float
upright in the liquid whose specific gravity is being measured.
-
hydronaut :
-
a person specially trained to work in deep-sea vessels for the
purposes of research and rescue; an Americanism introduced during
the Vietnam-era.
-
hydropathy / hydrotherapy / hydrotherapeutics :
-
the use of water in the treatment of disease or injury; a method
of treatment for disease or injury by immersing the body or body
part in soothing baths, by sprays for wounds, by heated pools for
stiffened joints, by taking water internally, or any combination
thereof.
-
hydrophone :
-
a device for detecting sounds transmitted through water, as for
detecting or locating marine life or other objects moving
underwater.
-
hydroplane :
-
a hydrofoil attachment to an airplane enabling it to glide on the
surface of the water; a seaplane. Also, a high-powered,
lightweight boat with a stepped bottom or hydrofoils, enabling it
to plane across the surface of the water at high speeds. Also, a
horizontal rudder (qv) used for submerging or elevating a
submarine.
-
hydro-ski :
-
a hydrofoil attached to a seaplane to aid in take-offs and
landings.
-
hydrosphere :
-
the water on the surface or surrounding the globe, including all
the water in the streams and rivers, lakes and oceans, and the
water in the earth's atmosphere. [v: hydrometeorology]
-
hydrostatic pressure :
-
fluid force exerted on the body's equilibrium, such as the amount
of pressure from the weight of water above a submerged diver.
-
hydrostatic test :
-
the required annual examination of pressurization tanks that are
filled with water instead of air.
-
hyperbaric chamber :
-
a steel vessel in which atmospheric pressure can be raised or
lowered by air compressors, used to treat aeroembolism, and to
provide a selective air mixture environment for certain medical
procedures; also called a decompression chamber.
-
hypercapnia :
-
the presence of an excessive amount of carbon dioxide in the
blood. A result of shallow skip breathing or excessive
hyperventilation in free diving, as well as Deep Diving on
compressed air. Hypercapnia will let nitrogen narcosis increase
as well as making it more likely that oxygen toxicity will occur;
heat loss can be increased, Heart rate and rhythm altered, and
decompression illness will be more likely to occur.
-
hyperventilation :
-
prolonged rapid or deep breathing that's undertaken in a
deliberate effort to extend the duration of a free dive,
resulting in excessive oxygen levels in the blood, often with
accompanying dizziness, chest pain, and tingling of extremities,
then culminating in the presence of an excessive amount of carbon
dioxide in the blood (hypercapnia).
-
hypolimnion :
-
the layer of water below the thermocline, being that underlying
region of a thermally stratified lake or reservoir in which there
is a rapid decrease in temperature with water depth.
-
hypothermia :
-
a subnormal body temperature; a drop in the body's core
temperature as a result of exposure to cold. [nb: heat is
transferred from the human body at a rate of twenty-five to
seventy times more in water than in air]
-
hypoxemia :
-
the inadequate oxygenation of the blood.
-
hypoxia :
-
an abnormal bodily condition in which oxygen intake is
insufficient or utilization is inadequate to sustain normal
activity; often exhibited as unconsciousness.
-
IAHD :
-
abbreviation for the International Association of Handicapped
Divers.
-
IAND :
-
abbreviation for the International Association of Nitrox Divers.
-
IANTD :
-
abbreviation for the International Association of Nitrox and
Technical Divers; alternatively as the International Association
of Nitrox and Trimix Divers ... a group of recreational divers
with technical diving qualifications.
-
IAT :
-
International Atomic Time, being a system of time based on atomic
clocks that measure the second as the international standard unit
(SI) of defined time.
-
ice anchor :
-
a large, hooklike device for setting in ice to anchor a vessel,
or to provide a hold for a hawser in warping it along; also
called "ice drag".
-
iceberg :
-
a large mass of ice, detached from a glacier, and floating out to
sea.
-
iceblink :
-
a yellowish luminosity near the horizon or on the underside of a
cloud that's caused by the reflection of light from sea ice; also
called "blink", as derived from 'blink' meaning gleam, twinkle,
glitter, or shine.
-
ice-crystal haze :
-
a type of very light ice fog composed only of ice crystals (no
droxtals or water vapor) that's usually associated with ice
crystal precipitation, and is observable to altitudes as great as
7000m. Viewed from the ground, ice-crystal haze may be dense
enough to hinder observation of celestial bodies, sometimes even
the sun. However, when viewed from above, the ground is usually
visible and the horizon only blurred. For very sparse ice-crystal
haze during daytime, sunlight reflecting from crystal faces
produces sparkling in the air, which crystallization is commonly
known as "diamond dust".
-
ice diving :
-
a type of penetration diving that typically has only a single
point of entry/exit through the overhead ice layer, so requires
advanced training, specialized gear and insulated clothing, a
rescue partner and a recovery environment; ice diving is
primarily undertaken for commercial, scientific, or military
purposes. The ice diver frequently combines buoyancy control
devices due to their importance, and is tethered to the surface
by a recovery line that's also used to communicate with the
standby support team ... shifting pack ice has the potential to
pinch the tether and close-off access. Underwater time for
decompression is complicated by extreme temperature, and thermal
exposure suits are not a substitute for shelter ... descent and
ascent may be augmented by use of a pod or bathyscaphe. Redundant
systems should include an environmentally sealed regulator
together with alternate air and duplicate buoyancy arrangements,
and most ice divers wear a full face mask with a protective hood.
-
icefall :
-
a jumbled mass of ice in a glacier. Also, a mass of ice
overhanging a precipice. Also, ice falling from a glacier,
iceberg, or the like.
-
ice fog :
-
a type of fog partly composed of suspended ice crystals and
droxtals, that occurs at very low temperatures, and usually in
clear, calm weather in high latitudes; because the sun is usually
visible, it may cause halo phenomena. Ice fog is almost always
present at air temperatures of -13°F/-45°C in the
vicinity of a source of water vapor, such as herds of animals,
volcanoes, the open water of fast-flowing streams or of the sea,
and especially products of combustion for heating or propulsion.
Ice fog is also known as "ice-crystal fog", "frozen fog", "frost
fog", "frost flakes", "air hoar", "rime fog", and "pogonip".
-
ice foot :
-
a belt of ice frozen to the shore, formed chiefly as a result of
the rise and fall of the tides.
-
IDEA :
-
abbreviation for the International Diving Educators Association.
-
impoundment :
-
a body of water confined within an enclosure, as a reservoir.
-
inch of mercury :
-
a unit of atmospheric pressure, being the pressure equal to that
exerted by a column of mercury one inch high under standard
conditions of temperature and gravity (ie: 33.864 millibars);
abbreviated "in Hg".
-
independent doubles :
-
an arrangement of double cylinders without a manifold, as used
with side-mounts, which requires a complete regulator setup for
each cylinder.
-
inert :
-
having little or no ability to act, react, or interact; having no
inherent power of motion or resistance.
-
inert gas :
-
any chemically inert gaseous element, such as helium, neon,
argon, krypton, xenon, and radon; found in group 8A or 0 of the
periodic table, and also known as "noble gas".
-
inflator valve :
-
the valve on a buoyancy compensator where a low pressure hose
from the second stage can be used for inflation; typically
includes a mouthpiece for oral inflation.
-
inlet :
-
an indentation of a shoreline, usually long and narrow, such as a
small bay or arm. Also, a narrow passage between islands. Also, a
point of entry or place of admission; entrance.
-
Ino :
-
a sea goddess who rescued Odysseus from drowning by giving him a
magic veil.
-
in stays :
-
heading a fore-and-aft-rigged vessel into the wind with sails
shaking, as when coming about.
-
intercostal :
-
between the ribs; the muscles between the ribs which contract
during inspiration to increase the volume of the chest cavity.
-
intermediate pressure :
-
a step-down pressure from the high pressure scuba cylinder to the
ambient pressure at depth, making regulator function more
consistent; common intermediate pressure (IP) is 120-180 psi
(8-12 bar).
-
International Ice Patrol :
-
an annual U.S. Coast Guard patrol of the North Atlantic ocean
during the ice season to ascertain the locations of icebergs so
as to warn ships at sea: undertaken after a 1914 agreement among
fourteen maritime countries.
-
International Orange :
-
a shade of bright orange, highly visible at a great distance and
in murky weather, that's been used since 1955 to color rescue or
emergency gear, safety devices and appliances, survey equipment
and vehicles, including boats and aircraft, hangars and control
towers; also known as "safety orange" or "blaze orange".
-
interstitial emphysema :
-
gas trapped in the chest after lung barotrauma.
-
intertidal :
-
pertaining to the littoral region that is above the low-water
mark and below the high-water mark.
-
IP :
-
Intermediate Pressure, being the pressure between the first and
second stages of a regulator.
-
iridescence :
-
a play of lustrous, changing colors.
-
ischemia :
-
a local deficiency of blood supply that's produced by obstacles
to the arterial flow, by vasoconstriction, or by other
inadequacies of a part or organ.
-
island :
-
a tract of land that's completely surrounded and detached; as
derived from isolate. [nb: a seaman defines an island as a hazard
to navigation that's inhabited by drunks, whores, thieves,
farmers, and other lubbers who were stupid enough to abandon the
ship!]
-
isle :
-
any island, especially when small.
-
islet :
-
a very small island.
-
ISO :
-
abbreviation for the International Standardization Organization.
-
isobar :
-
an imaginary line (often contoured) connecting all points of
equal barometric pressure, as one drawn on a weather map or
chart.
-
isobath :
-
an imaginary line (often contoured) connecting all points of
equal depth below the surface of a body of water, as one drawn on
a map; derived from "of equal depth". Also, a similar line that's
used for indicating the depth below the surface of the earth of
an aquifer or the top of the water table, as one drawn on a map.
-
isotherm :
-
a curve (often contoured) representing changes in volume and
pressure while at the same temperature; derived from "of equal
temperature".
-
isthmus :
-
a narrow strip of land, bordered on both sides by water,
connecting two larger bodies of land; also called a neck or
strait.
-
ITCZ :
-
Inter-Tropical Convergence Zone, a region situated between the
Tropic of Cancer and the Tropic of Capricorn, being parallels of
latitude twenty-three degrees above and below the terrestrial
equator ... the zone that spawns monsoons and tropical storms.
-
IUC :
-
abbreviation for the Irish Underwater Council.
-
jackline :
-
a rope, webbing, or wire cable that's strung from padeyes or
cleats along the port and starboard sides of a ship, from bow to
stern, during foul weather and limited visibility, so that a
safety harness ("jackline harness") can be connected, allowing
passengers and crewmembers to move safely on the topside deck
whenever there's a risk of falling or being swept overboard; a
temporary safety rigging to secure lives aboard a vessel during
hazardous conditions.
-
jack-up rig :
-
a buoyant hull fitted with several movable legs, each fitted with
'spud can' feet to help distribute the load so the rig doesn't
sink too deeply into the seafloor, which serve to raise this
mobile platform and its machinery as a unit above the surface of
the sea, once properly positioned at the desired location.
-
Jacob's ladder :
-
a flexible ladder consisting of rope, cable, or chain side-rails
and fixed wooden or aluminum rungs, as used on vessels and
aircraft; also called a "pilot ladder" or "jack ladder", "caving
ladder" or "scaling ladder", as derived from the Biblical dream
of a ladder ascending from earth to heaven. Also, a webbing or
rope ladder deployed for insertions and/or extractions of people
employing transport vessels or aircraft instead of debarkation
nets or rappel lines.
-
jam the bottle / jamming the bottle :
-
slang for filling the steel or aluminum cylinder with pressurized
breathing gas for use in scuba diving; bleeding compressed air
into a portable tank for breathing underwater.
-
Jasper reel :
-
a reel that has the handle located on one side of the spool,
instead of the top, so as to more easily payout (and retrieve)
guideline when exploring new cave passages; as advocated by Woody
Jasper, a Florida cave diver.
-
jetsam :
-
goods or supplies that are deliberately cast overboard from a
vessel so as to lighten or stabilize it in an emergency, as
derived from "jettison"; such cargo typically sink where
castaway, but may be later washed ashore.
-
Jet Ski :
-
the trademarked brand name that's become generic for a motorized
"individual watercraft"; a jet-propelled boat that's ridden like
a motorcycle across the surface of a body of water.
-
jetty :
-
a pier or structure of stones, piles, or the like, projecting
into a body of water to protect a harbor, deflect the current, or
other stabilization. Also, a wharf or landing pier. Also, the
piles or wooden structure protecting a pier.
-
jewel block :
-
a block at the end of a yard or gaff that's used for supporting a
signal or ensign halyard; also called "dasher block".
-
jibe :
-
to alter course so that a fore-and-aft sail, or its boom, shifts
from one side to the other when running before the wind.
-
johnboat / john boat :
-
a light, square-ended, flat-bottomed skiff.
-
jolly boat :
-
a light boat carried at the stern of a sailing vessel.
-
Jonah :
-
a person or thing regarded as bringing misfortune or bad luck; a
jinx, as derived from the minor prophet in the Bible who's thrown
overboard from his ship for his impiety.
-
Jonline :
-
a length of line typically used to attach to a shot line or
anchor line to provide horizontal spacing for decompressing
divers at the same stop depth.
-
Joule's law :
-
the principle that the internal energy of a given mass of an
ideal gas is solely a function of its temperature; a secondary
law of thermodynamics [v: joule = SI unit of energy] named after
James Prescott Joule, an English physicist.
-
jury mast :
-
a temporary mast that has been erected to replace one that was
lost or destroyed.
-
jury-rig :
-
to repair or assemble something hastily, or from whatever is at
hand, as for temporary use; to improvise an expedient or
makeshift.
-
J-valve :
-
a spring-loaded mechanism which shuts off a diver's air supply
when reduced to a certain tank pressure, as was formerly used to
trigger the switch to the reserve air supply, and compel the
diver's ascent; superseded by the submersible pressure gauge
(SPG).
-
karst :
-
an irregular limestone terrane featuring sinkholes, fissures,
caverns, and underground streams that's caused by erosion from
carbon dioxide enriched water.
-
kayak / kaiak / kyak / kyack / qayaq :
-
a double-ended Eskimo canoe with a skin cover on a light
framework that's made watertight by a flexible closure around the
waist of the occupant, and is propelled with a double-bladed
paddle; a commercially made small boat that has been created to
resemble the original Eskimo design, but is manufactured in a
variety of modern materials for sporting or touring applications.
-
kayak diving / canoe diving :
-
use of a small lightweight vessel for access to remote or obscure
dive sites, especially rivers, as when drift diving; an
alternative to boat or shoreline access.
-
kedge :
-
to advance a vessel or load along a waterway by pulling
incrementally, as with a small anchor; as derived from to tie or
fasten. Also, the small anchor used for such incremental hauling.
-
keel :
-
a central fore-and-aft structural member in the bottom of a
boat's or ship's hull, extending from the stem to the sternpost;
in Asia it's known as a "dragon's spine". Also, to turn or upset
something so as to bring the wrong side uppermost, as when a
vessel is overturned or capsized ("keel over"). Also, in a
steady, stable, or calm state; as "on an even keel".
-
kelvin :
-
the base unit of temperature in the International System of Units
(SI) which is defined to be 1/273.1 of the triple point of water.
[nb: the degree intervals of the kelvin scale are the same as
celsius, as the rankine are the same as fahrenheit]
-
kernmantle :
-
a synthetic-fiber rope constructed with a plaited sheath
surrounding an inner core of either parallel or twisted core
strands.
-
kettle-bottom / kettle-bottomed :
-
denoting a wide, flat-bottomed hull formerly used for merchant
sailing vessels.
-
kevel :
-
a sturdy bit, bitt, bollard, or the like, on which the heavier
lines and hawsers of a ship may be secured.
-
key :
-
a reef or low island; properly called 'cay'. Also, a pin, bolt,
wedge, or other piece that's inserted into a hole or space so as
to hold the parts of a mechanism together. Also, slang for a unit
of measure (mass) equivalent to one kilogram (kg).
-
kick board :
-
a training aid used primarily in swimming pools to improve the
technique (eg: flutter, frog, scissors, etc) or to strengthen the
leg movements used in various swimming strokes; this molded
polystyrene board can also be clamped between the swimmer's legs
to improve and strengthen the arm pull movements used in various
swimming strokes ... likewise, this lightweight training aid can
also be used in calm outdoor waters, such as lakes and inlets.
-
kilo :
-
short for kilogram, being the base SI unit of mass; the metric
value of 1000 grams, with 1 kg equal to 2.21 lb. Also, short for
a unit of force, equal to the force that produces an acceleration
of 9.80665 meters per second per second when acting on a mass of
one kilogram. Also, short for kilometer, being the base SI unit
of length; the metric value of 1000 meters, with 1 km equal to
3280.8 ft or 0.621 mi.
-
king wave :
-
see sneaker wave, rogue wave.
-
kit :
-
collective reference to all of the diving equipment required to
make an underwater dive. [v: kit 'n' caboodle]
-
km :
-
abbreviation for KiloMeter, a unit of length equal to 1000
meters, or equivalent to 3280.8 feet or 0.621 mile.
-
knee-knocker :
-
slang for the protective rim or bulwark surrounding an opening in
a bulkhead or deck, designed to exclude water; this coaming is
also called a "shin-scraper".
-
knighthead :
-
either of a pair of upright members (apostle) flanking and
securing the bowsprit of a ship at the bow, often used as mooring
bitts. Also, a plate at the fore end of a forecastle through
which a spike bowsprit passes on a topgallant sailing ship.
-
knot :
-
a constrictive interlacement used for fastening rope, line, cord,
and the like. Also, a unit of speed equal to one nautical mile
(or about 1.15 statute miles) per hour. Also, a unit of measure,
being either one nautical mile, or a line marked 47'3" (13.79m)
long.
-
Kraton :
-
the brand name (GLS trademark) of a synthetic rubber
(thermoplastic polymer) that can be molded to form a handle that
provides a non-slip grip while retaining flexibility. [v:
gutta-percha, India rubber, para rubber]
-
K-valve :
-
a simple on/off valve; a standard yoke-style valve without a
reserve lever.
-
ladderwell :
-
the staircase, usually skeletonized, whether fitted with rungs or
steps, with or without handrails ("ladderrail"), running between
decks on-board ships.
-
lagan :
-
goods that are deliberately thrown or sunk in the sea but are
attached to a buoy so that they may be recovered, being a form of
jetsam; as derived from a net laid in the sea.
-
lagoon :
-
any small body of shallow water that's connected to a larger body
by an intermittent or restricted flow, or separated from the sea
by a natural barrier of dunes or reefs.
-
lake :
-
a considerably sized body of either fresh or salt water that's
surrounded by land.
-
Lake guns :
-
the name given to mysterious booming sounds that seemingly come
from nearby phenomena situated offshore at Seneca Lake, New York.
-
lambert :
-
the centimeter-gram-second (cgs) unit of luminance or brightness,
equivalent to 0.32 candles per square centimeter and equal to the
brightness of a perfectly diffusing surface emitting or
reflecting one lumen per square centimeter; abbreviated: L.
-
Lambert's law :
-
the law that the luminous intensity of a perfectly diffusing
surface in any direction is proportional to the cosine of the
angle between that direction and the normal to the surface, for
which reason the surface will appear equally bright from all
directions; also called "cosine law", named after the German
mathematician Johann Heinrich Lambert. [v: Beer-Lambert law of
optics; Willebrord van Roijen Snell law of refractive index]
-
landfall :
-
land that's been sighted, approached, and reached from sea; a
navigational challenge necessitating precautions due to the
disruption of currents and other water flows around the landmass.
-
landing :
-
a place where persons or goods are landed, as from ship to shore,
shore to ship, or from ship to ship; also called landing
platform. [cf: float, stage]
-
lapstrake / lap streak :
-
a hull of clinker-built (qv) construction.
-
laryngospasm :
-
severe constriction of the larynx in response to the introduction
of water or noxious stimuli; commonly called choking.
-
LAT :
-
abbreviation for the Lowest Astronomical Tide.
-
latitude :
-
an imaginary circle on the earth's surface formed by the
intersection of a plane parallel to the plane of the equator,
bearing east and west, and designated in degrees of latitude
north or south of the equator along the arc of any meridian of
longitude; also known as "parallel of latitude".
-
lave :
-
to flow along, against or past; as the tide washes the shore, or
when a current washes the seafloor.
-
lay line :
-
term used by cave divers to designate the initial exploration
line in a previously unexplored ("virgin" or 'booty') cave
system.
-
leach :
-
to dissolve the soluble constituents out of a permeable medium
(eg: ashes, soil, etc) by the percolation of water or another
liquid; as derived from 'leak' or 'infusion'.
-
leachate :
-
a solution resulting from leaching, as of soluble constituents
from soil, landfill, and the like, by downward percolating ground
water.
-
lead :
-
an opening or direction that affords passage to a place, such as
an open channel through a field of floating ice. Also, the
direction of a rope, wire, or chain. Also, the distance between
the center of lateral resistance and the center of effort of a
sailing ship, usually expressed decimally as a fraction of the
water-line length.
-
leading edge :
-
the edge of an airfoil or propeller blade that's facing in the
direction of motion. [v: chord] Also, the forward edge of a mass
of air or water.
-
leader :
-
any of various devices, smooth and open, for guiding a running
rope; also called 'lead'.
-
league :
-
a unit of distance which has varied at different times and
places, apparently originating as the Gaulish equivalent of 1.5
Roman miles, but lately measures about 3 miles (4.8km) in
English-speaking countries.
[nb: 12 inches = 1 foot, 3 feet = 1 yard, 6 feet / 2 yards = 1
fathom, 16.5 feet = 1 rod (aka: pole or perch), 66 feet / 4 rods
= 1 chain (90 feet / 15 fathoms = 1 anchor chain), 10 chains /
660 feet (1/8 statute mile) = 1 furlong, 120 fathoms / 720 feet =
1 land cable, 101 fathoms / 606 feet (1/10 nautical mile) = 1
cable, 3 statute miles = 1 land league, 3 nautical miles = 1 sea
league / shot]
-
LED :
-
abbreviation for light emitting diode, a rugged and robust
electron tube that's replacing traditional incandescent bulbs in
portable lights.
-
ledge :
-
a reef, ridge, or line of rocks in a body of water.
-
lee :
-
the part that's sheltered, or the side that's turned away from
the wind; the point or quarter away from the direction of the
prevailing wind.
-
leech :
-
either of the lateral edges of a square sail; or the after edge
of a fore-and-aft sail.
-
leech line :
-
a line for hauling the middle of a leech of a square sail up to
the yard.
-
leech rope :
-
a boltrope along a leech.
-
leeward :
-
in the direction away from the prevailing wind; toward the point
or quarter away from which the wind blows; moving toward a
sheltered or protected place that's out of the wind.
-
leeway :
-
the drift of a vessel from its course or heading due to
crosswinds or currents [cf: leeward, windward]. Also, a margin
of space, time, or materials, being an extra or surplus; a degree
or element of freedom, of latitude.
-
leisure diver :
-
see holiday diver, recreational diver.
-
Leucothea / Leukothea :
-
a sea goddess in classical mythology who gave Odysseus a veil as
a float after a storm had destroyed his raft; also known as "the
white goddess", and later deified as Ino.
-
Lexan :
-
a trademarked brand of hard, tough, transparent polycarbonate
resin that's used to make shatterproof windows, protective
goggles, and other practically unbreakable objects. [nb: a
preliminary treatment of polycarbonate (eg: Lexan) windows with
acetone / dimethylketone will sufficiently compromise its
inherent structure so that it will shatter under impact]
-
lifeboat :
-
a double-ended accessory craft, also called a dinghy or tender,
required to be available on any aircraft or vessel operating on
or over water, usually stocked with a limited supply of medical
equipment and survival provisions, so as to enable passengers and
crew to be rescued from sinking. Also, a similarly constructed
and mounted watercraft that's provisioned for shore-based rescues
at sea.
-
life car :
-
a watertight container used in marine rescue operations since the
mid-19th century that has been suspended from a hawser so it can
be hauled back and forth between a stranded or wrecked vessel and
the shore; also called safety car or ark.
-
life jacket :
-
a sleeveless jacket of buoyant or inflatable construction that's
used for supporting the wearer in deep water so as to prevent
drowning; this wearable life preserver (or "personal flotation
device") is also called "life vest" or "air jacket" (British).
-
lifeline :
-
a line or rope available for saving life, as one attached to a
lifeboat, or a heave line cast from a vessel. Also, any of
various lines running above the decks, between spars or other
structures of a ship or boat, giving sailors something to guide
or grab when in danger of falling overboard or washing away.
Also, the line by which an underwater diver is lowered and
raised. Also, any of several anchored lines used by swimmers for
support.
-
life raft :
-
a manufactured raft, often inflatable, that's stowed for use in
emergencies, as when a ship must be abandoned or when a plane is
downed at sea.
-
lifesaving leap :
-
see giant stride entry.
-
lift bag :
-
a type of underwater balloon or specialized buoyancy compensator
that can be attached to a submerged object, or group of netted
objects, inflated with air, and raised to the surface without
great exertion; available in either small or large capacity, and
may be joined in series for heavier loads.
-
lift capacity :
-
the amount of buoyancy provided by a buoyancy compensator, which
varies by size and by environment (eg: water temperature, water
salinity, etc).
-
lighter :
-
a large, open, flat-bottomed vessel used to transport cargo from
ship to wharf, often towed or pushed; a sailless junk or barge
used to ferry passengers, especially when reserved for pageants.
-
limber hole :
-
any of a series of holes pierced through a frame or floor to
allow the passage of accumulated moisture. [cf: weep hole]
-
limnology :
-
the scientific study of bodies of fresh water, such as lakes and
ponds, with reference to their biological, geographical,
physical, and other features.
-
line :
-
a rope, cable, or other cordage used on a vessel or at sea. Also,
any actual or representative connection, as in communications.
Also, a course of direction, as a route or heading. Also,
indication of a boundary or limit, as a demarcated safety zone.
Also, an outline or contour.
-
line squall :
-
a storm that advances along a front forming a more or less
definite line.
-
liquescent :
-
becoming liquid; tending toward a liquid state; melting.
-
list :
-
to lean to one side, or to cause to incline toward one side, as a
ship or other vessel; sway or careen.
-
littoral :
-
pertaining to the shore of a lake, sea, or ocean. Also,
pertaining to the biogeographic region between the sublittoral
zone and the high-water line on ocean shores, and sometimes
including the supralittoral zone above the high-water line. Also,
pertaining to the region of freshwater lake beds from the
sublittoral zone up to and including damp areas on shore.
-
littoral drift :
-
see beach drift.
-
load-line mark :
-
any of various lines marked on the sides of a cargo vessel to
indicate the depth to which a vessel may be immersed under
certain conditions; also represented as load-line, load line, or
boottop.
-
loch :
-
a lake. Also, a partially protected or landlocked bay; a narrow
arm of the sea.
-
lock :
-
an enclosed chamber in a canal, dam, or other impoundment with
gates at each end, that's used for raising or lowering vessels
from one level to another by admitting or releasing water. Also,
short for an air lock or decompression chamber.
-
locked-in :
-
a precarious position for a vessel at sea during a violent storm
wherein that vessel is unable to escape the powerful waves
blocking it on either side. Also, informal allusion to a surfer
who rides inside the barrel or tube of a wave, inside the hollow
part under the curling lip.
-
log / logbook :
-
a record of a diver's history that catalogues, at a minimum, the
date, location, depth, duration, type, gear, and sequential
total of dives; many divers include transport, party, weather,
and any observations or incidents.
-
log line :
-
the trailing line by which a log or patent log is streamed from a
vessel in naval navigation.
-
longboard :
-
a surfboard resembling the traditional Hawaiian pattern, being at
least nine feet in length and 22-24inches in width with a broad
rounded nose and tail; commonly called a "gun" for use on big
waves, longboards are more stable, float better, and catch waves
more easily.
-
longitude :
-
an imaginary circle on the earth's surface formed by the
intersection of a plane parallel to the plane of the prime
meridian at Greenwich, bearing north and south with conjunction
at the poles, and designated in degrees of longitude east or west
of the prime meridian along the arc of any parallel of latitude;
also known as "meridian of longitude".
-
loop :
-
a sand bar that encloses (or nearly encloses) a body of water.
-
lost river :
-
common referent for a flowing waterway that disappears
underground at one or more points during its course of travel.
-
lotic :
-
pertaining to or living in flowing water; as derived from "wash".
-
low pressure cylinder :
-
steel air cylinders that're used at fill pressures of 2,400 psi
(160 bar).
-
low pressure inflator :
-
an extra hose from the second stage regulator that provides air
to inflate the buoyancy compensator through the inflator valve;
typically includes a mouthpiece for oral inflation.
-
low volume mask :
-
a mask which has a smaller area between the glass and the diver's
face, usually with separate lenses for each eye, such that less
air is required to be purged when it becomes flooded.
-
lox :
-
abbreviation for liquid oxygen.
-
loxodrome :
-
see rhumb / rhumb line.
-
LP :
-
abbreviation for low pressure.
-
LP hose :
-
the low pressure hose that connects the first stage of the
regulator to the second stage or inflator.
-
LPM :
-
abbreviation for Liters Per Minute; a measurement of the flow
rate of a liquid or gas.
-
lubberly :
-
to be awkward or inexperienced around watercraft, such as a
"landlubber"; also represented as "slubberly" for careless and
"Dutch talent" for unskilled; to be "ham-handed" rather than
"dab-handed".
-
lubber's hole :
-
an open space near the top on a mast through which a sailor may
pass to reach a perch, instead of climbing out on the futtock
shrouds. [v: futtock shroud: any of several metal rods secured at
their lower ends to a futtock band and at their upper ends to a
futtock plate, connecting the lower mast to the topmast rigging]
-
luff :
-
to set the helm so as to bring the head of a ship closer or
directly into the wind, with sails shaking. Also, to raise or
lower the outer end of the boom of a crane or derrick, moving its
load horizontally.
-
LWL :
-
abbreviation for Low Water Level.
-
main deck :
-
the uppermost weatherproof deck on a vessel, running the full
length of the ship.
-
mainstay :
-
anything that serves as chief part or primary support; including
an essential person, such as the "anchorman" or "right-hand man".
Specific naval use as the stay that secures the mainmast forward.
-
main walkway :
-
a floating structure in a marina to which finger floats are
attached so as to define individual berths, and to provide
pedestrian access between the berths and a marginal walkway or
the shore.
-
makefast :
-
any structure to which a ship is tied up, as a bollard or buoy.
Also, to securely tie onto such a structure.
-
make 'n' mend :
-
traditionally, a half-day off from normal ship's work for the
care and repair of personal use items, to make and/or mend items
of personal clothing.
-
make way :
-
an informal directive to get out of someone's way; a warning to
get out of the way of something that's not responsive, or is out
of control.
-
making way :
-
when a vessel is proceeding by its own power, whether manual or
mechanical propulsion; also represented as "making headway".
-
manifold :
-
a connection that enables a single regulator to access the
breathing gas in both pressure tanks; a double cylinder system
that's connected by a heavy duty crosspiece with a valve in the
center.
-
manometer :
-
an instrument for measuring the pressure of a fluid, consisting
of a liquid filled tube, the level of which indicates the fluid
pressure in decibars (dbar) or bars on a calibrated scale.
Pressure is commonly measured by its ability to displace a column
of liquid in a tube, which is often expressed in a measure of
that liquid (eg: inches of mercury). [nb: a rule of thumb used by
divers states that the pressure exerted by ten metres depth of
water is approximately equal to one atmosphere]
-
marginal walkway :
-
a floating structure in a marina that provides pedestrian access
between two or more main walkways and the shore, and may serve as
a platform for lighting, fuel stations, sewage pumpout
facilities, lift stations, and utility lines.
-
marina :
-
a boat basin offering dockage and services for recreational small
watercraft, including wet and dry storage.
-
marker :
-
a high visibility indicator, typically luminous or reflective or
brightly colored, that's used to designate the correct or safest
path through an entanglement or maze; also called "route marker"
or "trip beacon", "guidepost" or "signpost", these signals may be
temporary or semi-permanent, and employed whenever a safety line
is inappropriate. [v: lodestar, polestar]
-
marl :
-
a friable earthy deposit consisting of clay and calcium
carbonate, as floating suspended in murky or turbid waters, and
coating anything drawn from those waters; an archaic term for
earth or soil. Also, to wind a rope or cable with marline, every
turn being secured by a hitch; as derived from "ensnare"
(marlyn).
-
marline / marlin :
-
light cordage of two-fiber strands, laid up left-handed.
-
marlinespike / marlinspike :
-
a smooth, tapered, steel tool used to open the strands of a wire
cable for splicing.
-
Martini's law :
-
an approximation for a relative comparative scale of competence
and coordination, wherein each 50 feet of depth breathing air
underwater is the equivalent of one martini consumed on an empty
stomach; a condition most noticeable at depths of 100 feet of sea
water (fsw) and below.
-
mask :
-
a protective cover consisting of a skirted transparent window
(ie: plexiglas) constructed to provide air space between the eyes
and the exterior water, permitting both eyes to see in the same
plane, and usually made of neoprene, silicone, or another
synthetic rubber. A regular diving mask covers only the eyes and
nose, while a full face mask encloses the entire face. The mask
is also called a "swim mask", "face mask", or "diving mask", and
is also available in a low volume style that has a smaller area
between the glass and the diver's face, usually with separate
lenses for each eye, such that less air is required to be purged
when it becomes flooded.
-
mask squeeze :
-
an uncomfortable or painful condition created when the air inside
the dive mask is compressed by the external pressure, causing a
suction on the face and eyes that swells delicate tissues, which
can cause permanent eye damage if not equalized; this imbalance
can be alleviated by exhaling through the nose.
-
mast :
-
a structure rising above the hull of a ship for holding spars,
rigging, and associated equipment. Also, any upright pole, post,
or support, as for a radio aerial. Also, the support for a crane
or derrick, boom or davit, yardarm or block 'n' tackle.
-
maximum operating depth :
-
the depth at which the partial pressure of oxygen (ppO2 /
ppO2) of a gas mix exceeds a safe limit. Also, the
lowest safe depth at which a submarine or other submersible is
not to exceed during normal operations; this "never exceed depth"
is a determination made by naval authority in consideration of
design and manufacturing limits, and has been specified as half
(Europe) or two-thirds (USN) of the test depth.
-
MCD :
-
abbreviation for Massive Catastrophic Decompression; also known
as "explosive decompression", wherein air pressure erupts through
the human body as a result of improper nitrogen off-gassing after
deep-sea diving.
-
MDEA :
-
abbreviation for the Multinational Diving Educators Association.
-
MDT :
-
abbreviation for Maximum Dive Time.
-
meander line :
-
a zigzag traverse made to define the approximate margin of a
natural body of water, as for mapping or surveying.
-
mediastinum :
-
the area in the chest that lies between the lungs, is bounded by
the sternum, the spinal column, and the diaphragm, and contains
the heart, esophagus, trachea, and other thoracic structures;
term derives from "a low ranking slave".
-
MEKP :
-
methyl ethyl ketone peroxide, a noxious toxic chemical used in
small quantities as a catalyst for hardening polyester resin.
-
Mercator projection / Mercator's projection :
-
a conformal map used chiefly in navigation, wherein any rhumb
line is represented as a straight line, intersecting at right
angles, such that the scale varies with latitude and areal size,
and the shapes of large areas are consequently distorted; also
known as "Mercator's map projection", eponymously after Gerardus
Mercator (Gerhard Kremer), the Flemish cartographer.
-
meridian of longitude :
-
the proper or formal name for 'longitude', being an imaginary
line on the earth's surface connecting all points bearing north
and south that are equidistant from the prime meridian at
Greenwich, which on most maps are shown in multiples of five
degrees east or west. Parallels of latitude and meridians of
longitude together form a grid by which any point on the earth's
surface can be specified.
-
messenger :
-
a smaller line used to haul a heavier line or cable across an
intervening space; also known as "messenger line", "heaving
line", or "throw line".
-
metabolism :
-
the sum of the physical and chemical processes in an organism by
which its substance is produced, maintained and destroyed, and by
which energy is made available. [cf: anabolism, catabolism]
-
meters of sea water :
-
a unit of pressure, which varies slightly with temperature and
salinity, but a practical convention accepts that each meter of
sea water imposes a pressure of 0.1 bar (DBAR), or that each
meter is equivalent to 0.1 atmosphere (0.1013 bar); abbreviated
msw.
-
MFW :
-
abbreviation for Metres of Fresh Water.
-
MGR :
-
abbreviation for Mixed Gas Re-breather.
-
MGRS :
-
Military Grid Reference System, being a standardized lat-long
scale that's superimposed upon a topographical map projection of
the earth's surface for the accurate and consistent position of
locations, or the computation of direction and distance between
locations.
-
MHW :
-
abbreviation for Mean High Water.
-
millrace :
-
the channel in which the strong and rapid current of water
driving a mill wheel flows to the mill. Also, the strong and
rapid current of water diverted to this utility.
-
mil-spec polypropylene :
-
a tough, heat-resistant, semi-rigid thermoplastic that offers a
combination of outstanding physical, chemical, and mechanical
properties, with superior working temperature and tensile
strength, is light in weight, resistant to staining, and has a
low moisture absorption rate.
-
minisub :
-
a small submarine, holding only one or a few persons, as used in
naval special operations, underwater explorations, or when
conducting underwater experiments; a contraction of miniature
submarine, and also called "midget sub".
-
mistpoeffers :
-
the name given to mysterious booming sounds that seemingly come
from nearby occurrences at sea, being situated off the coast of
Holland and Belgium.
-
mixed gas :
-
any breathing medium that is blended with oxygen and other gases,
having either a single inert gas (eg: heliox, nitrox) or multiple
inert gases (ie: trimix).
-
MKS :
-
abbreviation for the metric system of measure: Metre, Kilogram,
Second.
-
MLW :
-
abbreviation for Mean Low Water.
-
MOD :
-
abbreviation for Maximum Operating Depth, being the deepest that
a diver can safely go using a particular gas mixture [eg: EAN32
at 132 fsw (40m)].
-
mole :
-
a breakwater, groyne / groin, or jetty used to form or protect an
anchorage or harbor, to reinforce or protect a pier, wharf, or
quay.
-
monkey block :
-
a small single block that swivels. Also, the blocks fastened to a
yard or yardarm through which buntlines are rove.
-
monkey bridge :
-
a small open deck, situated above the main cabin or pilothouse of
a vessel, having duplicate bridge controls; also called "flying
bridge" or "bridge deck". Also, a raised fore-and-aft catwalk
permitting safe passage when the weather deck is washed by heavy
seas; also called "flying gangway".
-
monkey fist / monkey's fist :
-
a casting knot (often a figure-8 on a bight) added to the
trailing-end of a rope or line to lend weight and direction for
throwing; a ball-like knot used as an ornament or as a throwing
weight at the end of a line; sometimes called "monkey paw" or
"monkey's paw" by a fancied resemblance. [nb: may be made by
tying a bag of lead shot to the end of a rope]
-
monkey island :
-
slang for a flying bridge (qv) on top of a pilothouse or chart
house.
-
monkey jacket :
-
a short, close-fitting serge jacket or coat that was formerly
worn by sailors; also called "jackanapes jacket", being so-called
from its resemblance to a jacket worn by an organ-grinder's
monkey.
-
monkey rail :
-
in modern vessels, a small railed perch above the ship's stern
enclosing standing room that permits an officer to supervise the
handling of mooring-lines when docking, or to observe loading and
unloading; in older vessels, a topgallant rail above the
quarterdeck or poop bulwarks (quarter boards).
-
monkey tail :
-
slang for any of various short ropes or light lines.
-
moonpool :
-
the pond contained within the hull of a surface ship or in the
chamber of a moored platform that provides subsurface access to
the surrounding waters, especially for launching and recovering
submarine vessels through an underwater opening (shell door);
such a reservoir is generally capable of being sealed and
isolated from the rest of the environment as a safety precaution.
-
moor :
-
to secure a ship, boat, or other vessel in a particular place by
lines, cables, or anchors.
-
mooring pile :
-
a pile situated at the entrance to and in the center of a double
berth, to which both vessels may be secured.
-
mossback :
-
an old fashioned sailor, as from a canny fish or wise turtle,
especially a traditionalist, conservative, or reactionary; also
called a sea dog, old salt, or shellback.
-
motorboat :
-
a vessel propelled by a small but powerful internal-combustion
engine that's mounted inboard or outboard.
-
mouthpiece :
-
the demand valve receptacle, held in the diver's mouth, at the
terminus of the regulator assembly of a scuba apparatus; a
similar device (without pressure stage) terminates a snorkel.
-
MSW :
-
abbreviation for Metres of Sea (or Salt) Water, a pressure
measurement.
-
mudlump :
-
an Americanism for a small temporary island at the mouth of a
river; a short-lived islet of clay or silt formed by deposits
within a river delta.
-
multiday :
-
a dive series with a surface interval of more than 24 hours
between consecutive dives; dives that require a substantial delay
so extending the time on station; juxtaposed to single-day.
-
multilevel dive / multilevel diving :
-
a dive profile that extends over more than one depth, expending
time at each, before finally returning to the surface; juxtaposed
to square dive / square diving.
-
mushroom valve :
-
a small flexible valve, such as is used as an exhaust valve in
second stage regulators and as a check valve in the mouthpiece of
re-breathers.
-
NACD :
-
abbreviation for the National Association for Cave Diving; also
represented as NA4CD.
-
NACDS :
-
abbreviation for the National Association of Commercial Diving
Specialists.
-
NASDS :
-
abbreviation for National Association of Scuba Diving Schools,
formed in 1962, which merged with Scuba Schools International
(SSI) in 1999.
-
narrows :
-
a narrow part of a strait, river, channel, ocean current, or
other body of constricted water.
-
NAUI :
-
abbreviation for National Association of Underwater Instructors,
which was formed as a nonprofit professional organization in
1959, spawning the Professional Association of Diving Instructors
(PADI) in 1966.
-
nautical mile :
-
officially known as the "International Nautical Mile", being a
unit of distance at sea or in the air equal to 1.852 kilometers.
Also, a unit of distance, formerly used in the U.S. for
navigation, equal to 6080.20 feet (1853.25 m), or the length of a
minute of latitude at the latitude in question (decreasing toward
the poles); abbreviated NM. [nb: a "geographic mile" is the
length of a minute of longitude on the equator]
-
NDC :
-
abbreviation for National Diving Council.
-
NDL :
-
abbreviation for No-Decompression Limit.
-
NDO :
-
abbreviation for National Diving Officer.
-
NDS :
-
No Decompression Stop, being a no decompression limit established
by dive tables.
-
NDSTC :
-
abbreviation for the Naval Dive and Salvage Training Center.
-
neck :
-
a strait or channel; narrows. Also, a narrow strip of land
bounded by water, as an isthmus or a cape.
-
NED :
-
abbreviation for the Network of Egghead Divers.
-
NEDU :
-
abbreviation for the Naval Experimental Diving Unit.
-
neo-Haldanean / neo-Haldanian :
-
decompression models based on later modifications (eg: critical
difference hypothesis) of the principles described by John Scott
Haldane.
-
nephelometer :
-
an instrument for studying the density of suspended particles in
a liquid by measuring the degree to which the suspended particles
scatter light (backscatter); as derived from 'cloud' +
'measure'. Also, an apparatus containing a series of barium
chloride standards used to determine the number of bacteria in a
suspension.
-
Neptune :
-
the god of water in the Roman religion; being an indigenous god
of fertility who was later identified with Poseidon, the Greek
god of the sea; a festival, the Neptunalia, was annually (July
23) celebrated in his honor. Also, used allegorically to
represent the sea or ocean.
-
NERC :
-
abbreviation for the National Environment Research Council in
Great Britain.
-
neritic :
-
pertaining to the region of water lying directly above the
sublittoral zone of the sea bottom; also called neritic zone.
-
newton :
-
the base unit of force in the International System of Units (SI)
which is equal to the force that produces an acceleration of one
meter per second per second on a mass of one kilogram.
-
niggerhead :
-
slang for an isolated coral outcropping, or any knob-like
solitary protrusion, such as pillow lava, often semisubmerged,
that's a hazard to navigation. Also, naval slang for a small
winch or capstan. Also, old reference in the British Navy for a
mooring post made from a cannon, buried muzzle upright, that's
capped with a slightly oversized ball. Also, a large decorative
knot, used to finish a special line or lanyard (such as one
suspended from the clapper of a ship's bell); sometimes called
"Turk's Head".
-
night diving :
-
because some sealife is nocturnal, or behaves differently at
night, many sport divers (who rarely venture below the 33 foot
depth of one standard atmosphere) encounter a new world when
diving underwater at night. [nb: in open water, sunlight does not
penetrate below a depth of 90 feet or two atmospheres of
pressure]
-
NiMH :
-
abbreviation for Nickel Metal Hydride, being a high capacity
rechargeable battery that's more tolerant of abuse and resistant
to overcharging than nickel-cadmium batteries.
-
nip :
-
an abrupt turn or twist in a rope. Also, a part of a rope or
chain bound by a seizing or nipper. Also, to seize a taut rope to
another rope.
-
nipper :
-
a short rope for seizing an anchor cable to a messenger from a
capstan.
-
nitrogen :
-
a colorless, odorless, inert gaseous element that constitutes
about 78% of the volume of the atmosphere and is present in
combined form in organic tissues; it's used by divers in varying
concentrations as part of the breathing gas mixture, with
specific side-effects (eg: nitrogen narcosis, decompression
sickness).
-
nitrogen narcosis :
-
a stupor or euphoria, also called "rapture of the deep", that's
induced in deep-sea divers when nitrogen from air enters the
blood at higher than atmospheric pressure.
-
nitrox :
-
a gas mixture of nitrogen-oxygen with an oxygen content other
than 21%, with "oxygen-enriched air" and "enriched-air nitrox"
rated greater than 21%, that's used to extend the
no-decompression limit; the most common nitrox mixtures are NOAA
Nitrox I at 32% oxygen and NOAA Nitrox II at 36% oxygen.
-
nm :
-
the abbreviation for nautical mile, also known as "International
Nautical Mile". [cf: geographic mile]
-
NOAA :
-
abbreviation for the National Oceanic and Atmospheric
Administration, a scientific agency in the U.S. Department of
Commerce; which is responsible for describing the earth's
environment and predicting changes in conserved or managed
resources.
-
NOB :
-
abbreviation for the underwater diving association in Holland
(Nederlands Onderwater Bond).
-
noble gas :
-
any chemically inert gaseous element, such as helium, neon,
argon, krypton, xenon, and radon; found in group 8A or 0 of the
periodic table, and also known as "inert gas".
-
nocturnal :
-
night, nighttime, or nightly; as juxtaposed to diurnal.
-
no-decompression :
-
a dive that does not require any staged stops during the return
ascent to the surface; a dive profile scheduled by the use of
tables or computer.
-
no-decompression limit :
-
a mathematical representation, plotted in minutes, of the
theoretical amount of nitrogen that body tissues can absorb
without substantial risk of decompression sickness.
-
no-mount / dismount :
-
the removal of back-mounted air tanks, together with any other
bulky gear, which is pushed through an opening ahead of the diver
when required to squeeze through constricted passages or wedge
into confined spaces while exploring under water; a method of
stripping down to essentials when otherwise too bulky to pass
through a narrow aperture.
-
NRMI :
-
abbreviation for the Naval Medical Research Unit.
-
NSS-CDS :
-
abbreviation for the National Speleological Society – Cave
Diving Section.
-
oar :
-
a long shaft with a broad blade at one end that's used as a lever
for rowing, or otherwise propelling, or for steering a boat.
Also, to traverse or to make one's way by (or as if by) rowing.
-
oarlock :
-
any of various devices providing a fixed pivot for an oar in
rowing, especially a crutch-like or ring-like metal contraption
that can swivel while projecting above the boat's gunwale; also
called rowlock.
-
observation deck :
-
an elevated platform situated so as to provide visitors with a
panoramic view of their surroundings, usually uncovered and open
to the sky, whether this spectacular outlook area is built onto
touring ships or tall buildings, cliff faces or mountain aeries.
-
ocean :
-
the vast body of salt water that covers almost three-fourths of
the earth's surface, and commonly subdivided into geographic
regions named the Atlantic, Pacific, Indian, Arctic, and
Antarctic.
-
oceanic :
-
anything living in, generated by, or pertaining to the ocean,
especially the vast region of water lying above the bathyal,
abyssal, and hadal zones of the sea bottom. Also, pertaining to
the islands of Oceania, its peoples, their languages and
cultures.
-
oceanicity / oceanity :
-
the degree to which the climate of a (coastal or inland) place is
influenced by the sea.
-
oceanography :
-
the branch of physical geography dealing with the ocean.
-
oceanology :
-
the science concerned with the practical application of
oceanography.
-
octo :
-
short for octopus, an alternate regulator.
-
octopus :
-
slang for a backup or secondary regulator, usually attached to
the same first stage as the primary regulator, and especially
used in an out-of-air situation when aiding a buddy diver.
-
OEA :
-
abbreviation for Oxygen Enriched Air, which designation is often
synonymous with nitrox.
-
off-gas :
-
the elimination of inert gases (such as nitrogen) from the
diver's body so as to avoid decompression sickness.
-
OK / okay :
-
a hand signal indicating safe and sound, correct or satisfactory,
approval or agreement, being a gesture that forms an open circle
with the thumb and forefinger, with the other three fingers
spread and extended; also known as A-OK, this signal is also
represented by making a circular motion with the dive light. This
acknowledgement of status should not be confused with a
"thumbs-up" sign, which means ascend.
-
old salt :
-
slang for an experienced sailor or master mariner; also called a
sea dog, shellback, mossback.
-
OMS :
-
Ocean Management Systems, being a manufacturer best known for low
pressure steel tanks.
-
on-gassing :
-
the absorption of nitrogen into various tissues that takes place
as the partial pressure of nitrogen increases with depth.
-
on the beach :
-
someone who is not engaged in seafaring or not involved in marine
activities; being unemployed or without a ship; being withdrawn
or idle; being inactive or retired.
-
on the same wavelength :
-
sharing values, ideas, or impulses; a predilection or partiality
for thinking and acting in harmony.
-
OOA :
-
abbreviation for Out Of Air; the emergency situation when a diver
has no breathing gas; also called "out-of-gas".
-
open-circuit SCUBA :
-
a scuba system that either recycles part of the exhaled air back
into the breathing loop through a re-breathing scrubber,
supplementing as necessary and exhausting the remainder, or
discharges all of the exhaled air outside of the breathing loop.
In contrast with 'closed-circuit scuba', this arrangement is
commonly used in recreational diving, where noise and bubbles are
not important considerations.
-
open sea :
-
the main body of a sea or ocean, especially that part which is
outside territorial waters, and is either not enclosed or is only
partially enclosed by land.
-
open water :
-
a designation, by various certifying authorities, of the primary
level of scuba training; abbreviated OW. Also, a diving
environment without obstacles or obstructions between the diver
and the surface.
-
open water diving :
-
basic recreational diving that's performed in an unobstructed
environment, one other than a swimming pool, such as an ocean or
lake, river or quarry.
-
O-ring :
-
a small replaceable gasket, made of rubber or some other pliable
synthetic (eg: neoprene, butyl, nitrile, Thiokol, Viton, EPDM),
classified by size and hardness, which is used to close or seal
watertight fittings. [cf: washer]
-
orlop :
-
the lowest deck above the space at the bottom of the hull of a
ship; also called orlop deck.
-
OS :
-
O.S. Systems, Inc, being a manufacturer best known for shell dry
suits.
-
OSHA :
-
Occupational Safety and Health Administration, an agency of the
U.S. government.
-
OTT :
-
abbreviation for Oxygen Tolerance Test.
-
OTU :
-
abbreviation for Oxygen Toxicity Unit.
-
outfall :
-
the outlet, discharge, or drainage of a river or other
watercourse, whether surface or subterranean.
-
outrigger :
-
the framework that extends outward from the side of a small boat
to support a float that increases stability. Also, a spar rigged
outward from a ship's rail or the like, as for extending a sail.
Also, a projecting beam, as for supporting a hoisting tackle.
Also, a bracket extending outward from the side of a shell or
skiff to support an oarlock; or the boat itself so modified.
-
overboard :
-
over the side of a ship or boat, especially into the water. Also,
to metaphorically go to extremes, as in behavior, speech, or the
like.
-
overhead :
-
a ceiling-like covering of the exposed support members
for the above compartment in a vessel. Also, an obstruction to a
direct vertical ascent to the open water at the surface, as when
cave diving or ice diving.
-
overhead dive :
-
underwater diving in wrecks or caves, or elsewhere without
unobstructed open water to the surface.
-
overlay :
-
a transparent sheet that's placed over a map or chart for noting
corrections, instructions, additional information, and the like.
-
OW :
-
abbreviation for Open Water; basic qualification for 'open water'
certification can be earned after four hours of classroom (or
computer) instruction, and the completion of four escorted scuba
dives to a depth of 60 feet (18m).
-
oxygen :
-
a colorless, odorless, inert gaseous element that constitutes
about 21% of the volume of the atmosphere and is present in
combined form in organic tissues; it's used by divers in varying
concentrations as part of the breathing gas mixture, with
specific side-effects (eg: hypoxia, oxygen toxicity).
-
oxygen clean :
-
removing contaminants from an object so that nothing will
adversely react with high pressures of oxygen; the removal of
hydrocarbons (eg: oils and silicones) from an oxygen environment.
-
oxygen compatible :
-
materials that are suitable for exposure to oxygen, especially
those that have been cleaned to remove any contaminants that
could react with high oxygen pressures.
-
oxygen debt :
-
a deficiency of oxygen in the body resulting from strenuous
physical activity.
-
oxygen re-breather :
-
the oldest type of re-breather, as once commonly used by navies,
supplying only pure oxygen, which is toxic when inhaled under
pressure, thus limiting its use to a depth of 20-30 feet (under 1
ATM). In some re-breathers, the oxygen cylinder has two first
stages in parallel, one is constant flow and the other is a plain
on-off valve called a "bypass"; both feed into the same exit
pipe, which feeds the breathing bag. Some simple oxygen
re-breathers had no constant-flow valve, but only the bypass, and
the diver had to operate the valve at intervals to refill the
breathing bag as the oxygen was used. Oxygen re-breathers are
sometimes used when decompressing from a deep open-circuit dive,
because breathing pure oxygen makes the nitrogen diffuse out of
the blood more quickly.
-
oxygen partial pressure :
-
the concentration of oxygen in an air mixture, especially when
combined in a dilute re-breathing or closed-circuit loop.
-
oxygen toxicity :
-
an abnormal bodily condition in which an increased concentrations
of oxygen intake has over-exposed body tissues, which can result
in convulsions or unconsciousness, leading to death by drowning;
being a characteristic risk of breathing mixed gases under
pressure.
-
P :
-
abbreviation for pressure.
-
pack ice :
-
a large area of floating marine ice whose pieces are driven
together by wind and current; also called ice pack.
-
packet :
-
a small vessel that carries mail, goods, and passengers on a
regular and fixed route; the first ships to keep a schedule,
regardless of payload. Also, a small package or parcel.
-
paddle :
-
a short, flat- or scoop-bladed oar that's usually held by both
hands while being moved more or less through a vertical arc, as
used for propelling and steering a canoe or other small boat.
Also, any of the blades by which a water wheel is turned. Also,
any of various similar implements used for turning, mixing,
stirring, swirling, or beating any given medium. Also, an
animal's use of its blade-like limbs or appendages (eg: flipper,
fin, etc) to move through water or across the land.
-
paddleboard / paddleboarding :
-
a variant type of surfboard with one end rounded and the other
tapered to a point, which is used chiefly in competition, in
touring, and in lifesaving; the use of a more or less broad flat
board, rigid or inflatable, extending from seven to sixteen feet
in length, some with a keel or skeg, many with deck plugs for
securing equipment, that's propelled by a paddle across smooth or
rapid water from a prone, seated, kneeling, or standing position
as a form of recreation or touring, including rafting, fishing,
paddle-surfing, snorkling or skindiving. It has developed as a
primitive form of boating, like a kayak or canoe without
gunwales, since the mid-20th century; the sport has been extended
to include lake or channel racing, shooting river rapids, and
low-impact backwater sightseeing. Depending upon temperature and
weather conditions, paddleboarders usually wear part or all of a
wet suit as environmental protection. [cf: paddleboat, pedalboat]
-
PADI :
-
abbreviation for Professional Association of Diving Instructors;
formed in 1966 from the National Association of Underwater
Instructors (NAUI), it's become the world's largest diver
training and recreational diving membership organization.
-
PADUA :
-
abbreviation for the Pennsylvania Analysis of Decompression for
Undersea and Aerospace.
-
painter :
-
a rope, usually secured at the bow, that's used to fasten a boat
to a ship, to a stake or bollard, and so forth; as derived from
"a cord intended for hanging things on".
-
paint pot :
-
in geological parlance, a spring or pit filled with boiling mud
of varied colors; also known as "mud pot".
-
pan :
-
a drifting piece of flat thin ice, as formed on a bay or shore;
term derived from face. Also, a natural depression in the ground,
as one containing water, mud, or mineral salts. Also, an
artificial depression in the ground, as made for evaporating sea
water so as to obtain salt.
-
parachute flotation bag / parachute float bag :
-
an open-ended parabolic float, often rigged in pairs, that can be
attached to a sunken object and lifted to the surface by
inflation; because it's not completely enclosed (eg: caisson,
camel, pontoon), maintaining proper balance or equilibrium is
crucial, but this control factor is offset by the convenience in
a less-bulky setup and more streamlined dismantling.
-
parallel of latitude :
-
the proper or formal name for 'latitude', being an imaginary line
on the earth's surface connecting all points bearing east and
west that are equidistant from the equator, which on most maps
are shown in multiples of five degrees north or south. Because of
their special position, four fractional parallels are also shown:
Tropic of Cancer, Tropic of Capricorn, Arctic Circle, and
Antarctic Circle. Parallels of latitude and meridians of
longitude together form a grid by which any point on the earth's
surface can be specified.
-
partial pressure :
-
the pressure exerted by any component gas in a mixture of gases,
such as oxygen in air; the pressure that a gas in a mixture of
gases, or dissolved in a liquid, would exert if it occupied the
same volume as the mixture at the same temperature.
-
party :
-
a specific individual, especially one affiliated with others.
Also, a group gathered for some special purpose or temporary
task, such as a search party. Also, a social gathering for
recreation or entertainment, usually involving conversation and
refreshments; as derived from share.
-
pascal :
-
the base unit of pressure in the International System of Units
(SI) which is equal to one newton per square meter; abbreviated
Pa.
-
Pascal's law :
-
the law that an external pressure applied to a fluid in a closed
vessel is uniformly transmitted throughout the fluid; named after
the French philosopher and mathematician Blaise Pascal.
-
passageway :
-
an interior hallway that permits horizontal travel within a ship,
as an aisle, corridor, or alley used as a pathway or walkway.
-
patent foramen ovale :
-
openable flap between the two thin-walled upper chambers (atria
or auricle) of the heart that receive blood from the veins and
force it into the ventricles.
-
patent log :
-
any of various devices used for determining the speed of a ship
by means of a vaned rotor streamed at the end of a trailing log
line upon which it exerts torsion that's transmitted to a
registering mechanism on-board; also called "screw log".
-
PDC :
-
abbreviation for personal dive computer.
-
PDIC :
-
formed in 1965 as Professional Diving Instructors College, later
changing its name to Professional Diving Instructors Corporation
in 1984, which provides training in a retail environment.
-
pea jacket :
-
a blue, double-breasted, coarse woolen jacket worn by seamen or
sailors; also called peacoat. [ety: pee / pey / pie (coarse wool
blend); pijekkat]
-
pelagic :
-
pertaining to the open seas or oceans; also called pelagic zone.
Also, living at or near the surface of the ocean, as certain
organisms growing far from land.
-
pelican hook / slip hook :
-
a hook-like device that's used for holding the link of a chain,
the eye of a grommet, or the like, which consists of a long
shackle with a hinged rod held closed with a sliding ring.
-
penetration line :
-
see distance line, cave line, guideline or safety line.
-
pennant :
-
a long tapering flag or burgee, as used for signaling or
identification.
-
percolate / percolation :
-
the passing of a liquid through a porous body, as water trickling
through a filter, as petroleum seeping through porous rock, or as
contaminants leaching through permeable soil.
-
permanent thermocline :
-
a temperature gradient in a body of water that's not affected by
the seasonal and diurnal changes in surface forcing; it is
therefore located below the yearly maximum depth of the mixed
layer and the influence of the atmosphere.
-
PFD :
-
Personal Floatation Device; a life preserver in the form of a
buoyant or inflatable vest.
-
phosphorescence :
-
the property or appearance of being luminous at temperatures
below incandescence, as from slow oxidation or after exposure to
light or other radiation. Also, any luminous radiation emitted
from a substance after the removal of the exciting agent, as a
phosphorescent wake.
-
pier :
-
a structure supported by flotation [floating pier] or built on
posts extending from land [fixed pier] out over water that's used
for access to or from the water (as a landing place for ships),
and for other activities. Also, a square pillar used for support,
as of bridge spans.
-
pierhead :
-
the outermost end of a pier or wharf. Also, informal regional
reference to a breakwater.
-
pile :
-
a long slender structural member, typically composed of wood,
concrete, steel, or plastic, that's driven into the seafloor of a
basin or inlet to secure and guide docks.
-
pilothouse :
-
an enclosed structure on the deck of a ship from which it can be
navigated; also known as wheelhouse.
-
pitch :
-
the up or down nosing of a ship about its transverse axis. Also,
longetudinal oscillation or linear plunge, as a ship's
alternating bow and stern rocking. Also, the distance that a
given propeller would advance in one revolution.
-
pitch-pole :
-
a vessel capsizing lengthwise, due to waves cresting higher than
the keel length.
-
plain sailing :
-
sailing on waters that are free of hazards or hindrances; being
an easy course or unobstructed way.
-
plane sailing :
-
sailing a course that was plotted by a navigational method that
didn't refer to the curvature of the earth. [v: spherical
sailing]
-
plank :
-
a timber, thicker than a board, used on the deck or strake of
boats and ships; also used as a brow or gangway (ie: gangplank).
-
plank owner :
-
a sailor who's been aboard since the vessel was commissioned into
service; also called "plank holder". Also extended to persons who
formed an initial party or the original group on an extended
venture, project or voyage.
-
plankton :
-
the aggregate of passively drifting, or somewhat motile,
organisms occurring in a body of water, primarily comprising
microscopic algae and protozoa. [v: phytoplankton, zooplankton]
-
pleura :
-
one of a pair of serous membranes, each of which covers the
outside of a lung, and folds back to line the corresponding
inside of the chest wall and diaphragm.
-
Plexiglas :
-
the trademarked brand name of a lightweight, transparent plastic
material (methyl methacrylate) that can be molded or cut to form
tempered shields, prescription lenses, and many other objects.
-
plimsoll mark :
-
a contrasting line or band painted on the exterior hull of a
merchant ship indicating its load level or depth level from the
weight of its cargo; also known as Plimsoll line, load-line mark,
load-line, boottop, or waterline.
-
plot :
-
to determine by means of measurements or coordinates, and to mark
on a map or chart, a graphic plan or transparent overlay, the
resultant course of a vessel or craft. Also, the place, located
on or near the bridge, that's used for performing such
calculations; also called "nav plot".
-
plume :
-
a moving fluid body that's rising or expanding, vertically or
longitudinally, as of smoke or water; a flow or current that has
been variously generated, as by subsurface heat or subterranean
quakes. [v: megaplume]
-
plunge :
-
to rush or dash with headlong haste; to throw oneself impetuously
or abruptly into some situation, circumstance, condition, matter,
or the like; to bring suddenly or forcibly into some decision or
conclusion. Also, to forcibly thrust something or to suddenly
cast someone into a penetrable substance; to be immersed into a
roiling mix, or to be submerged into a liquid. Also, a leap or
dive, as into water; to cast oneself, or fall as if cast, into
water, a hole, a shaft, or the like. Also, to descend abruptly or
precipitously, as a cliff, ledge, road, or the like. Also, to
pitch forward abruptly or violently, as a ship heaving along its
longitudinal axis.
-
plunge basin :
-
a cavity formed by the action of falling water at the base of a
waterfall or cataract.
-
plunge pool :
-
the churning water in a plunge basin, often generating a
turbulent vortex; a light water pool, often of large size and
situated either on the surface or underground, which occurs at
the bottom of a waterfall or at the end of river rapids. [cf:
water pocket, swirlhole]
-
pneumothorax :
-
the presence of air or gas in the pleural cavity as a result of
compression or penetration, disease or inducement; a collapsed
lung.
-
Poiseuille's law :
-
the law that the velocity of a liquid flowing through a capillary
is directly proportional to the pressure of the liquid and the
fourth power of the radius of the capillary, and is inversely
proportional to the viscosity of the liquid and the length of the
capillary; named after Jean Leonard Marie Poiseuille, a French
physiologist. [v: Poiseuille's viscosity coefficient,
Poiseuille's space]
-
pollywog :
-
an inexperienced or novice sailor, especially someone on his
first float or cruise; also called chum, nugget, or fresh catch.
-
polyethylene / polythene :
-
a plastic polymer of ethylene.
-
polynya :
-
an irregularly shaped area of persistently open (unfrozen) water
that is sustained by warming winds or currents of ocean heat,
which often occur near coasts, fast ice, or ice shelves; an area
of unfrozen sea water surrounded by ice, as derived from 'empty'
or 'open' [usspolynii (Russian)].
-
polypropylene :
-
a plastic polymer (molecular compound) of propylene
(C3H5) that's chiefly used for molded
parts, electrical insulation, packaging, and fibers for wearing
apparel.
-
polyurethane :
-
a thermoplastic polymer used to form insulation, sheeting,
fabrics, and resin, having very good chemical and abrasion
resistance, excellent strength, and resistance to the growth of
microorganisms; 15-mil polyether aromatic polyurethane maintains
its flexibility at low temperatures and can be seam welded
(eliminating fittings), which reduces failure points.
-
POM :
-
abbreviation for polyoxymethylene (aka: acetal resin, poly
glycol, polyacetal, and polyformaldehyde), an engineering
thermoplastic used to synthesize precision parts requiring high
abrasion resistance, low friction coefficient, high heat
resistance, high stiffness, excellent dimensional stability, good
electrical and dielectric properties, and low water absorption;
under slightly different formulations, this heat and pressure
formed (eg: injection-molding or extrusion) semi-crystalline
polymer has been marketed as Delrin, Celcon, Hostaform, Duracon,
Kepital, Iupital, and Ultraform when making gears and fasteners,
hinges and insulators, lock mechanisms and knife handles. [nb:
POM is not as strong as ABS or aluminum]
-
pond :
-
a body of water, smaller than a lake, which is sometimes
artificially formed, as by damming a stream. Also, to collect
into a pool, puddle, pan, or other pound; as derived from
"impoundment". [v: dub]
-
pony bottle :
-
common term for a secondary gas cylinder carried by divers as a
redundant air source; supplied with their own first and second
stages, these tanks can be used as an alternate or emergency air
source.
-
pool :
-
a small body of standing water; pond. Also, a still, deep place
in a stream. Also, any small collection of liquid on a surface;
puddle. Also, a subterranean accumulation; reservoir.
-
poop :
-
a wave breaking or taking seas over the stern of a vessel. Also,
a superstructure or poop deck at the stern of a vessel.
-
poop deck :
-
a weather deck on the superstructure at the stern of a
vessel, which may have bulwarks.
-
porpoise :
-
any of certain toothed cetaceans having a blunt or rounded snout;
derived from sea hog or hog fish; compare dolphin. Also, to leap
clear of the water, as when a speeding boat hits a wave and
leaves the surface.
-
port :
-
the left-hand side of a vessel or craft when facing forward, and
designated by the color red; formerly known as larboard
(larborde) or loadboard for the "loading side" set against the
wharf. Also, a place with docking facilities for ships to load or
unload passengers or cargo, as a "port of entry" or "port of
call". Also, an exterior opening or aperture on a craft or vessel
for various uses, including portal and porthole.
-
portage :
-
to carry a boat and supplies overland from one navigable waterway
to another. Also, the route over which such a carry is done.
-
porthole :
-
a small, round, window-like opening, usually covered with a
hinged watertight glass closure, set into the side of a vessel
for admitting air and light.
-
Poseidon :
-
the god of the sea and protector of all waters in the Greek
religion. After the fall of the Titans, Poseidon was allotted the
sea. He was worshiped especially in connection with navigation;
but as the god of fresh waters, he was also worshiped as a
fertility god. Poseidon was represented as extremely powerful,
with a violent and vengeful disposition. He carried the trident,
with which he could split boulders and cause earthquakes. When
Laomedon failed to pay him for building the walls of Troy,
Poseidon sent a sea monster to ravage the Troad and years later
vengefully assisted the Greeks in the Trojan War. His grudge
against Odysseus is one of the themes of the Odyssey. He was the
husband of Amphitrite, who bore him Triton, and by others he
fathered many more sons, who usually turned out to be strong,
brutal men (like Orion) or monsters (like Polyphemus). In
Thessaly and other areas he was important as Hippios, god of
horses, and was the father of Pegasus. The Romans identified him
with Neptune.
-
pot :
-
slang for the hyperbaric chamber used as a sustained environment
in saturation diving.
-
pothole :
-
a hole cut into submerged bedrock by the erosive action of sand
and gravel that's whirled about by eddying water; a more or less
cylindrical hole formed in rock by the grinding action of the
detrital material in eddying water. Also, a cave opening
vertically from the ground surface. [cf: swirlhole, moulin]
-
power head / powerhead :
-
a type of spear gun that uses a sealed pistol cartridge to propel
a barbed dart under water, as for specimen collecting, hunting,
or self-protection, with or without an attached trailing line.
-
pp :
-
abbreviation for partial pressure, wherein the total pressure of
a gass mixture is the sum of all the partial pressures of the
component gases.
-
PPA :
-
abbreviation for polyphthalamide (aka: high performance
polyamide), a type of semi-crystalline nylon that's used as a
heat resistant metal replacement; under slightly different
formulations, this thermoplastic resin is manufactured under
trade names Amodel, Grivory, Ultramid T, VESTAMID HTplus, and
Zytel.
-
ppHe :
-
the partial pressure of helium in a gas mixture.
-
ppN2 / ppN2 :
-
the partial pressure of nitrogen in a gas mixture.
-
ppO2 / ppO2 :
-
the partial pressure of oxygen in a gas mixture.
-
ppO2 meter / ppO2 meter :
-
an oxygen-sensitive electro-galvanic fuel cell that automatically
monitors and measures the concentration of oxygen in the
breathing gas loop of fully closed-circuit re-breather systems so
as to detect and adjust the partial pressure mixture.
-
pressure :
-
the exertion of force upon a surface by a substance (eg: object,
fluid, gas, etc) in contact with it; such a force per unit area
is measured by pascal (Pa), newton, pounds per square inch (PSI),
pound-force per square inch absolute (PSIA), pound-force per
square inch gauge (PSIG), bar, decibar (dbar), millibar (mb), or
dyne.
-
pressure hull :
-
the inner, pressure-resistant hull of a submarine or other
submersible; the crush depth of a submersible is affected as much
by the buoyancy of a submersible as by the physical resistance of
its pressure hull.
-
pressure ridge :
-
a fracture wall produced by the compression of grinding and
colliding ice floes.
-
pressure suit :
-
an airtight protective suit that can be inflated to maintain
approximately normal atmospheric pressure on a person in an
aberrant or anomalous environment; also called pressurized suit.
-
professional diver :
-
a certified underwater swimmer who is paid for diving, especially
military or commercial, salvage or construction/destruction.
-
promenade deck :
-
all or part of an upper deck on a ship where passengers can
stroll without interfering with shipboard operations.
-
promontory :
-
a high point of land or rock projecting beyond the shoreline over
water; a "headland". Also, a projecting bluff or plateau
overlooking a lowland. Also, any conspicuous elevation; eminence.
-
propeller :
-
a device having a revolving hub with radiating blades that
rotates in a fluid (eg: water, air) for propelling a craft by
thrust; made of cast iron or steel, bronze or composite alloy,
it's mounted singly before the rudder, or twinned to either side
of the keel, having evolved from fixed to variable pitch to
achieve constant speed, and counter rotating to balance torque
when mounted in multiples; simultaneously invented in 1837 by
Swedish-American engineer John Ericsson and English inventor Sir
Francis P. Smith to supersede the less efficient paddle wheel.
-
protozoan / protozoon :
-
any of various one-celled protist organisms that usually obtain
nourishment by ingesting food particles, rather than by
photosynthesis: which phyla is classified according to its means
of movement, as by pseudopod, flagella, or cilia.
-
prow :
-
the forepart of a craft or vessel, designated by the color white;
also called bow or stem.
-
PSI :
-
abbreviation for Pounds per Square Inch, a measure that's used to
describe the force of pressure acting on a given area; 1 psi
approximately equals 6.895 kPa.
-
PSIA :
-
abbreviation for Pounds-force per Square Inch Absolute, which is
the gauge rating plus sea level atmospheric pressure.
-
PSID :
-
abbreviation for Pounds per Square Inch Difference, which refers
to a measurement of the difference between two pressures.
-
PSIG :
-
abbreviation for Pounds-force per Square Inch Gauge.
-
PSISG :
-
abbreviation for Pounds per Square Inch Sealed Gauge, which
measures the difference in pounds per square inch between a
chamber of air sealed at atmospheric pressure and the pressure at
the measuring point.
-
PSIVG :
-
abbreviation for Pounds per Square Inch Vented Gauge, which
measures the difference between the measuring point and the local
pressure.
-
PTC :
-
abbreviation for Personal Transfer Capsule.
-
puddle :
-
a small pool of water or other liquid. Also, slang for any body
of water, regardless of size, used informally as a term of
convenient reference. [v: dub]
-
pulpit :
-
on smaller ships and other watercraft, a safety rail rising from
the deck near the bow, and extending around it.
-
pumpkin suit :
-
see exposure suit.
-
pumpout site :
-
a facility that pumps out and receives sewage from a holding tank
on-board a vessel; also called pumpout station.
-
punt :
-
a small, flat-bottomed boat of shallow draft with square ends
that's propelled by poling; derived from 'push'. [nb: punter: the
person who propels a small boat along its route by poling]
-
purge valve :
-
an actuator that will clear or empty a device by replacement upon
demand, as to vent a regulator of water with a burst of air by
manually depressing a plunger.
-
purl :
-
to flow with curling or rippling motion, as a shallow stream does
over stones. Also, a circle or curl made by the motion of water,
as a ripple or eddy; possibly derived from "bubble up" or "gush"
[Norwegian 'purla']. Also, to flow with a murmuring sound.
-
P-valve :
-
a dry suit accessory that enables a male diver to void his
bladder during a dive; consists of a condom-like catheter, which
convenience can cause several harmful side-effects. [cf: Texas
catheter]
-
Pyle stops :
-
the addition of brief decompression stops inserted halfway
between the conventional decompression stops when ascending from
deep dives; also known as "deep stops" and named after Richard
Pyle, who pioneered the methodology.
-
quarterdeck :
-
that part of a vessel's weather deck running from midship to the
stern or poop deck, and which may have bulwarks.
-
quay :
-
a landing place constructed along the edge of a body of water,
typically built of solid masonry.
-
quickwater :
-
that part of a river or stream having a strong current.
-
race :
-
the channel of a strong or rapid current of water, or the bed of
any stream. Also, an artificial channel leading a strong or rapid
current of water to or from a place where its energy is utilized
(eg: millrace). Also, a strong or rapid current of water, as in a
river or in the sea.
-
radial flow :
-
a type of scrubber canister wherein the absorbent carbon dioxide
gas flows from the center to the outside.
-
raft :
-
a floating platform that's constructed or manufactured of more or
less rigid materials that're buoyant, such as a lashed-together
assemblage of planks and casks, or an inflatable rubber raft.
-
raft ice / rafted ice :
-
ice in cakes or sheets that piles atop or overlaps one another;
an ice floe that overlaps another ice floe. Also, an ice floe
that transports embedded organic debris (eg: soil, rock, etc)
from the shoreline out to sea.
-
rafting :
-
the practice of traveling on rivers and streams by raft, as a
form of entertainment or sport.
-
rail :
-
the outer edge of a paddleboard, surfboard, or sailboard where
the topside and underside conjoin, usually in a rounded
equidistant meeting; this edge is a significant element in
executing turns.
-
rankine :
-
an absolute temperature scale with a degree interval equal to
fahrenheit. [nb: the degree intervals of the kelvin scale are the
same as celsius, as the rankine are the same as fahrenheit]
-
Raoult's law :
-
this law states that the addition of solute to a liquid lessens
the tendency for the liquid to become a solid or a gas due to a
lowering of the concentration of water molecules; quantitatively,
the solvent's vapor pressure in solution is equal to its mole
fraction times its vapor pressure as a pure liquid, but this
mathematical relation is accurate only for dilute solutions; the
vapor pressure of mixed liquids is dependent on the vapor
pressures of the individual liquids and the molar vulgar fraction
of each present in solution; named after F.M. Raoult.
-
rapid ascent :
-
a too swift or uncontrolled ascent toward the surface, being
faster than the currently recommended rate of 60 feet (18m) per
minute, which may be caused by overinflation, poor buoyancy
control, being underweight, or panicked.
-
rapids :
-
the part of a watercourse where the current runs very swiftly,
often caused by volumetric compression or physical constriction;
also known as 'quickwater'.
-
rapture of the deep :
-
phrase coined by Jacques Y. Cousteau for nitrogen narcosis.
-
ratline :
-
any horizontal ropes or rigging lines used as steps when
ascending or descending; so-called from the small ropes crossing
the shrouds on a sailing ship that sailors used to go aloft.
-
RBT :
-
abbreviation for Residual Bottom Time.
-
RDP :
-
abbreviation for Recreational Dive Planner.
-
reach :
-
a straight portion of a river or channel between two bends. Also,
a level portion of a canal, as between locks; sometimes called
"pound". Also, any continuous stretch or uniform extent of
something, as 'a reach of dunes'. Also, a point of sailing in
which the wind is within a few points of the beam, either forward
of the beam (close reach), directly abeam (beam reach), or abaft
the beam (broad reach). Also, to sail with the wind forward of
the beam but so as not to require sailing close-hauled.
-
re-breather / rebreather :
-
an underwater breathing apparatus that cleanses and recycles
captured air back into the air supply; a method of re-using
exhaled breath so that it can be re-inhaled, being a
self-contained device used to regulate and re-circulate breathing
gases so that diving time can be extended and dive functions will
be quieter. The closed-circuit re-breathing system (CCR) does not
release exhaled gasses as exhaust, but filters and recycles the
discharge back into the gas supply, which is accomplished by
scrubbing CO2 and adding O2 as necessary to
maintain a constant partial pressure of oxygen. The semi-closed
circuit re-breathing system (SCR), which also uses a scrubber,
releases a portion of each breath into the water while the same
portion of new breathing gas is injected into the cycle.
-
recalculation dive :
-
a dive where thirds are re-calculated during its course, usually
at or near another exit.
-
recompression :
-
a repressurization treatment for air embolism or decompression
sickness, where an individual is re-introduced to a controlled
high pressure environment, as in a decompression or hyperbaric
chamber, and gradually returned to normal pressure.
-
recompression chamber :
-
a repressurization environment, where atmospheric pressure may be
adjusted with selective air mixtures, as used to treat certain
diving disorders such as air embolism or decompression sickness.
-
recreational diving :
-
swimming underwater with or without breathing aids (snorkel or
scuba), as for leisure and enjoyment; also called "sport diving".
[nb: many recreational divers do not venture below the 33 foot
depth of one standard atmosphere, and most do not venture below
the 90 foot depth of two atmospheres, due to the need for mixed
breathing gases, decompression stops, and technical training]
-
red flash :
-
a red coloration of the lower portion of the sun, occasionally
seen as the sun rises above or sinks to the horizon.
-
red tide :
-
a brownish red discoloration of marine waters that's caused by a
huge aggregation of flagellates and/or dinoflagellates that often
produce a potent neurotoxin that contaminates shellfish.
-
redundancy :
-
the provision of a duplicate system or of superfluous equipment
as a backup, so as to reasonably prevent failure or harm (eg:
double inflator, stage bottle, extra light, etc) in the event of
loss or failure with a primary.
-
reef :
-
a ridge of rocks or sand, often of coral debris, at or near the
surface of the water. Also, to make something secure with tie
downs. Also, part of a sail that is ("shortened") rolled and tied
down to reduce the area exposed to the wind.
-
reef knot :
-
a square knot, wherein the ends cross in different directions,
coming out alongside the standing parts, which allows the bights
to tighten, producing a secure knot that's used for tying things
down; also called "flat knot".
-
reflect / reflection :
-
a form of backwash wherein a wave rebounds from an immovable
barrier, or bounces off a hard surface, and merges back into the
advancing swell, which often creates spectacularly peaky waves.
-
refract / refraction :
-
the bending or turning of swells by interaction with the
seafloor, or by interaction with opposing currents; when any part
of a wave encounters resistance, it will fragment as its energy
is absorbed, dissipated, dispersed, or redirected before its
ultimate convergence or final collapse. An irregular seafloor can
change the direction and velocity of wave energy, as well as
combine them.
-
regulator :
-
a scuba diving device that lowers the level of pressurized air,
typically to that at sea level (1 ATM); a reduction valve that
controls the flow of breathing gas from the reservoir to the
mouthpiece. A device on scuba equipment for regulating the rate
at which a constant pressure of compressed gas is fed through a
breathing tube in proportion to the depth of water.
-
repeat dive :
-
any dive whose profile is affected by a previous dive; also
called repetitive dive, and typically involves a surface interval
delay.
-
reservoir :
-
a natural or artificial place where water is collected and stored
for use; impoundment. Also, a receptacle or chamber for holding a
liquid or fluid. Also, a subterranean accumulation of liquid or
gas held in porous and permeable sedimentary rock; pool.
-
residual bottom time :
-
additional time to be spent on the bottom when calculating the no
decompression limits for a successive dive in a repetitive dive
sequence; abbreviated RBT.
-
residual nitrogen time :
-
the hypothetical amount of nitrogen absorbed in body tissues
after a dive, which is represented by minutes added to the
no-decompression limit for a repetitive dive; RNT is an off-gas
dive table calculation.
-
respiration :
-
the act of breathing or respiring; the inspiratory and expiratory
processes; being the inhalation and exhalation of air in the
oxidation of organic compounds occurring within tissues and
cells, producing energy for cellular processes, and the
byproducts of carbon dioxide and water. An exchange of gases
between a living organism and its environment.
-
respiratory arrest :
-
the cessation of breathing; apnea.
-
respiratory system :
-
the organs and tissues involved in drawing oxygen into the body
and removing carbon dioxide; in mammals, includes the nasal
cavity, pharynx, trachea, bronchi, lungs, and the diaphragm.
-
reverse block :
-
when the internal pressure of an air space is greater than the
external pressure.
-
reverse squeeze :
-
the effect of pressure during ascent on enclosed spaces that
contain air (eg: dive mask, dry suit) or body cavities (eg:
sinuses, middle ear), which discomfort or pain can be relieved by
equalization.
-
rhumb / rhumb line :
-
a curve on the surface of a sphere that cuts all meridians at the
same angle, being the path taken by a vessel or aircraft that
maintains a constant compass direction; also called "loxodrome",
wherein a map projection, as of Mercator's projections, appear as
straight lines.
-
RIB :
-
abbreviation for Rigid Inflatable Boat, or Rigid-hull Inflatable
Boat; having a solid keel surrounded by large inflatable tubes as
the hull, which may also be called a "squidgie".
-
rigging :
-
lifting or hauling tackle. Also, the ropes and other lines used
on a ship to support the masts and spars, to work the sails and
yards.
-
riptide / rip tide :
-
a tide that's in opposition to other tides, causing a violent
disturbance in the sea; a powerfully channeled current of water
that flows away from the shore, through the surf zone, and past
the line of breaking waves, which typically occurs where there's
an outflow into the surfline or a shoreline of turbulent
breakers, dissipating as it moves farther offshore.
-
risk :
-
according to numerous surveys conducted in different countries
since the proliferation of recreational scuba diving, which is
less hazardous than professional diving, underwater swimming is
40-90 times more dangerous than driving an automobile. [cf:
parachuting is safer than driving]
-
river :
-
a natural stream of water of fairly large size that's flowing in
a definite course or channel, or in a series of diverging and
converging channels. Also, a similar stream of something other
than water, as "a river of lava" or "a river of ice".
-
RMV :
-
abbreviation for Respiratory Minute Volume.
-
RNT :
-
abbreviation for Residual Nitrogen Time.
-
RNLI :
-
abbreviation for the Royal National Lifeboat Institution in
Britain.
-
RNPL :
-
abbreviation for Royal Naval Physiological Laboratory in Great
Britain.
-
rocker :
-
aka: bottom curve
-
rode :
-
the line, cable, or chain that secures an anchor. Also, the line
or chain that connects a buoy to an anchor.
-
rogue wave :
-
an abnormally large wave that occurs on a seemingly random basis
in the oceans; this unpredictable sea wave is also known as a
freak wave, sleeper wave, sneaker wave, and king wave. Of
enormous proportion, great in height and steepness, these
unexpected waves sometimes travel in a direction at an angle to
the prevailing seas, or occur where waves meet opposing currents.
-
roll :
-
axial plunge, swaying or rocking, as of a ship's alternating side
to side, port to starboard movement.
-
roller :
-
a long, unbroken, swelling wave that advances slowly.
-
rolling wave :
-
a long heavy sea wave as it advances toward the shore.
-
rotameter :
-
an instrument for measuring the rate of flow of a liquid,
consisting of a tapered vertical tube in which a small float is
forced upward until its weight balances the fluid force; derived
as a partial translation of "rotational measure".
-
rotten ice :
-
ice that's pitted or honeycombed from melting.
-
round turn :
-
a wrap of rope or line around an object one-and-a-half times so
as to reduce the load over a small diameter (less than 3"), or
to relieve knot tension by increasing friction.
-
ROV :
-
abbreviation for Remotely Operated Vehicle.
-
rowboat :
-
a small open boat propelled by the leverage of an oar, or a
number of oars, that's used as a transport or touring conveyance.
-
rowlock :
-
see oarlock.
-
RSTC :
-
abbreviation for the Recreational Scuba Training Committee.
-
rudder :
-
a vertical blade at the stern of a vessel that can be turned to
change the vessel's direction when the vessel is in motion. Also,
any means of directing or guiding a course. [cf: hydroplane]
-
rudderhead :
-
the upper end of a rudderpost to which a tiller, quadrant, or
crossbar yoke is attached.
-
rudderpost :
-
the vertical member on which a ship's rudder is mounted; a
sternpost.
-
rule of thirds :
-
the practice of dividing the volume of air (in cubic feet or psi)
into thirds: with one third for the penetration, one third for
the exit, and one third for emergency use; also called "thirds".
-
runabout :
-
a small motorboat that's used for recreation.
-
running knot :
-
a slipknot.
-
running light :
-
any of various navigation or warning lights that are required to
be displayed by a vessel when operating between sunset and
sunrise, or during inclement weather or other low visibility
conditions.
-
running noose :
-
a loop formed in a cord or rope by means of a slipknot; it binds
tighter as the cord or rope is pulled; also called "slip noose".
-
running rigging :
-
rigging used for handling sails, yards, and the like; as
contrasted with standing rigging. Also, rigging used for handling
cargo.
-
SAA :
-
abbreviation for the Sub-Aqua Association.
-
SAC :
-
abbreviation for Surface Air Consumption.
-
SAELO :
-
abbreviation for Supply Activated Exhaust Cut-Off Valve.
-
SAFE :
-
a mnemonic for "Slowly Ascend From Every dive" that's used in
PADI training.
-
safety car :
-
see life car.
-
safety line :
-
a line connecting paired divers when visibility is marginal or
compromised. Also, a guideline laid temporarily through an
entanglement or maze that marks (tactually and/or visually) the
route to and from the established entrance; this guideline is
retrieved by the last diver when exiting. Also, any line rigged
on a vessel (eg: lifeline) or from a float (eg: ascent / descent
line) for the protection of divers and crew.
-
safety stop :
-
a specific period of time spent at a particular depth to assist
in nitrogen off-gassing during a dive ascent; a safety stop,
which is not mandatory by definition, should still be performed
even within no decompression limits.
-
Saffir-Simpson scale :
-
a scale indicating the speed or pressure of cyclonic storms,
enumerated 1-5, and commonly expressed as "Category #" [ie:
Category 1: 65-82 kts/74-95 smph @ 980 mb/28.94" hg; Category 2:
83-95 kts/96-110 smph @ 965-979 mb/28.50-28.91" hg; Category 3:
96-113 kts/111-130 smph @ 945-964 mb/27.91-28.47" hg; Category 4:
114-135 kts/131-155 smph @ 920-944 mb/27.17-27.88" hg; Category
5: +135 kts/+155 smph @ 919 mb/27.16" hg]; also cited
as "Safford-Simpson Scale".
-
sagging :
-
the behavior of a ship when only its bow and stern are supported
by wave crests, leaving the midships area unsupported in the
trough.
-
sailboard / sailboarding :
-
see windsurf / windsurfing.
-
sailor :
-
a seaman or seafarer; also called swabby, squid, gob, anchor
clanker, or old salt.
-
sailor dive / sailor's dive :
-
a head-first plunge into water with the diver's body fully
extended while their hands and arms remain at their sides.
-
Saint Adjutor :
-
venerated in the Latin church as the patron saint of swimmers,
boaters, and drowning victims; also known as Adjutor of Vernon.
As a knight in the First Crusade, he escaped Muslim persecution
and captivity by calming the sea with holy water and the sign of
the Cross before swimming away in his chains; he became a hermit
in his later life.
-
Saint Christopher :
-
the "Christ-bearer" was once a saint and martyr of the Greek and
Latin churches, but the patron saint of travelers was dropped
from the liturgical calendar in 1969; he was the protecting saint
against floods, fires, and earthquakes, and his image was
believed to keep the viewer from harm.
-
salinity :
-
the degree or proportion of a saline solution, including mineral
and chemical salts.
-
sally ship :
-
to cause a vessel to list alternately from side to side by
shifting crewmembers or a party of passengers back and forth
across its main deck so as to free a grounded hull by altering
its trim, enabling a stranded vessel to withdraw.
-
salt water aspiration syndrome :
-
a reaction in the lungs that's caused by inadvertently inhaling a
mist of sea water, especially from a faulty demand valve.
-
salty :
-
to be sharp, witty, or piquant. Also, to be vulgar or
coarse. Also, to be ship shape or squared away. Also, to be
experienced or knowledgeable, be "handy as an old salt".
-
salty dog :
-
any item lost or destroyed during operations at sea. Also, slang
for an experienced or knowledgeable person, as an "old salt" or
"sea dog". Also, a cocktail of gin or vodka mixed with grapefruit
juice that's served (like a margarita) in a salt-rimmed glass.
-
salvage :
-
saving a ship or its cargo. Also, saving anything from shipwreck,
fire, or other danger or peril; as to retrieve, recover, or
rescue. Also, compensation given to those who save a ship or its
cargo.
-
sand bar :
-
a mass of sand formed in a river or sea by the action of tides or
currents, often as an obstruction to navigation.
-
SAR :
-
abbreviation for Search And Rescue. [nb: Search and Recovery or
Search and Retrieval is the operation conducted to collect the
remains of a deceased person or corpse]
-
saturation :
-
the complete uniting, by solution or combination, of one
substance with another; to impregnate or imbue thoroughly; the
degree to which a gas is dissolved in the blood or tissues.
-
saturation diving :
-
diving performed after the body is fully saturated with nitrogen,
which is a much longer time period underwater than is permitted
in recreational diving tables; a decompression regime that
enables commercial divers to maintain high pressure gas levels in
their tissues so as to work underwater for weeks.
-
sault :
-
a waterfall or rapid of frothy water running over shoals; as
derived from 'leap'.
-
SAUU :
-
abbreviation for South African Underwater Union.
-
scantling :
-
a dressed timber of relatively slight width and thickness, or a
rolled metal member of similar dimensions, used for support or
framing in a vessel. Also, the dimension, in cross section, of a
framing member; as derived from a small quantity or amount
(scant, gauge).
-
scattering :
-
when swells from different directions overlap or collide, the
surf breaks up into distinct peaks or separate waves.
-
SCBA :
-
abbreviation for Self-Contained Breathing Apparatus, such as
arrangements used by firefighters.
-
schralp :
-
a surfing loanword, being a compliment for performing
extraordinarily well under difficult circumstances. Also, slang
for flaying the skin off of one's hands while actively engaged.
-
scissors kick :
-
a type of kick used in the sidestroke wherein both of the
swimmer's legs make forceful scissor-like motions.
-
scooter :
-
slang for a diver propulsion vehicle (DPV).
-
SCOR :
-
abbreviation for the Scientific Committee on Oceanic Research, a
subcommittee of the International Council of Scientific Unions.
-
scow :
-
any flat-bottomed vessel with a rectangular hull and sloping
ends, such as a barge, sailboat, rowboat, johnboat, dory, punt,
gondola, dinghy, or skiff; as derived from "ferryboat".
-
SCR :
-
abbreviation for Semi-Closed Circuit Re-breather.
-
screw :
-
slang for propeller (qv).
-
Scripps Institution of Oceanography :
-
a research facility, established 1901 and transferred to the
University of California at La Jolla in 1912, which maintains
several ships and marine laboratories to conduct studies; in
1952, it became the first North American center to instruct
civilians on the proper use of scuba equipment, which program was
transferred to the Los Angeles County Department of Parks and
Recreation in 1954, and then to the YMCA (ie: Underwater
Instructor Certification Course) in 1959.
-
scrubber :
-
an integral component of a re-breather system containing a
chemical that reacts with exhaled gas to remove carbon dioxide
(CO2).
-
SCUBA :
-
acronym for Self Contained Underwater Breathing Apparatus; a
portable breathing device for free-swimming divers. An
experimental underwater breathing system was first employed by
Dr. Freminet in 1772. In 1825, a helmeted "diving dress" with a
self-contained air tank was introduced by William James. The
double-hosed "aqua-lung" was invented (1942) during WWII by Emile
Gagnan and Jacques Y. Cousteau.
-
scuba orienteering / scuba-o :
-
a competitive underwater sport wherein scuba divers swim a
designated circuit that's marked by buoys while using compass
navigation and mechanical distance measurement devices; points
are awarded for speed and accuracy in completing the defined
course without surfacing.
-
scuba tank :
-
see tank, cylinder, bottle.
-
scud :
-
to run quickly or move hurriedly, as wind driven clouds or mist.
Also, to run a boat or ship before a gale with little or no sail
set.
-
scull :
-
an oar mounted on a fulcrum at the stern of a small boat that's
moved from side to side (sweep) so as to propel the boat forward
in the water. Also, either of a pair of oars rowed simultaneously
by one rower. Also, a boat propelled by an oar or pairs of oars,
especially a narrow, light, racing boat containing up to four
rowers, each of whom is equipped with a pair of oars.
-
scupper :
-
a drain situated at the edge of a deck that's exposed to the
weather, allowing accumulated water to debouch into the sea or
into the bilges.
-
scuttle :
-
a small hatch or port, or its hatchway cover, located in the top,
sides, or bottom of a vessel. Also, to deliberately sink
something, or to intentionally ruin or destroy something.
-
SDC :
-
abbreviation for Submersible Decompression Chamber.
-
SDI :
-
abbreviation for Scuba Diving International, being a
non-technical qualification agency created in 1999 by Technical
Diving International (TDI).
-
sea :
-
the salt waters that cover the greater part of the earth's
surface, the subdivisions of which are more or less definitely
marked off by land boundaries (eg: North Sea, Ross Sea, Bering
Sea, Coral Sea, Mediterranean Sea, etc). Also, one of the seven
seas; ocean. Also, a large lake or landlocked body of water.
Also, the degree or amount of turbulence of a body of water, as
caused by the wind. Also, a large wave, or the waves. Also, the
work, travel, and shipboard life of a sailor.
-
sea anchor :
-
any of various devices, such as a drogue or buoy, that are
dropped overboard at the end of a cable, causing resistance to
movement of the hull through the water, so as to decrease speed
and/or increase stability while holding the bow of a vessel into
the wind.
-
seabed :
-
the seafloor (qv).
-
sea change :
-
a major transformation or alteration, especially a striking one
brought about by the weather at sea.
-
sea chest :
-
a container for holding personal belongings aboard ship.
-
seacock :
-
a valve in the hull of a ship for admitting sea water into some
internal chamber, as for ballast.
-
sea daddy :
-
slang for a sailor's mentor or sponsor.
-
sea deck :
-
a fixed stern platform positioned at sea level that's separated
from the main deck by a transom; also called a "dive step" or
"dive platform", this diving deployment platform is often rigged
with a 'granny line' or 'gerry line' to assist in the recovery of
swimmers back onto the boat. [nb: not to be confused with 'well
deck' or 'diving stage']
-
sea fence :
-
a durable mesh suspended from a cable that's strung between buoys
so as to isolate or confine a select area, usually for protective
purposes; extending to the seafloor, the mesh is typically sized
to permit the passage of fishes, but not people.
-
seafloor :
-
the solid surface underlying a body of water; also called seabed.
-
sea gate :
-
a navigable channel giving access to the sea.
-
sea legs :
-
the ability to adjust one's sense of balance to the constant
motion of a ship at sea, especially while remaining free of
seasickness.
-
sea level :
-
the surface of the sea at a mean horizontal plane between high
and low tides. [nb: the curvature of the earth restricts
visibility at sea level to only three nautical miles (3nm)]
-
seaman :
-
a sailor or seafarer; also called swabby, squid, gob, anchor
clanker, or old salt.
-
seamount :
-
an undersea mountain rising prominently above the seafloor but
having its summit well below the surface of the water; also known
as tablemount. [nb: not tableland]
-
seaplane :
-
a fixed-wing or rotary-wing aircraft fitted with hydrofoil floats
for take-offs and landings on the surface of the water.
-
seaport :
-
a port, harbor, or anchorage that accommodates seagoing vessels.
-
sea room :
-
unobstructed space at sea in which a vessel can maneuver.
-
Sea Scout :
-
a Boy Scout (BSA) program emphasizing watercrafts and boating
skills, including swimming and diving.
-
sea serpent :
-
an imaginary, snake-like or dragon-like marine animal of enormous
size or imposing presence. Also, the constellation Hydra.
-
seashore :
-
land along the sea between the ordinary high-water and low-water
marks; shore.
-
sea smoke :
-
a steam or evaporation fog that's formed when water vapor is
added to air which is much colder than the vapor's source, most
commonly when very cold air drifts across relatively warm water;
also called "water smoke", "arctic sea smoke", "antarctic sea
smoke", and "frost smoke".
-
sea snow :
-
underwater sediment suspended such that it resembles snowfall, as
resulting from currents or other disturbances, and so obscures
the diver's visual perception of his surroundings; the
interference in underwater visibility caused by floating
particulate or suspended particles, which turbidity or opacity is
often blindingly reflective (backscatter) when artificial
illumination is used.
-
seasonal thermocline :
-
a temperature gradient in a body of water that's not affected by
the diurnal changes in surface forcing; in general, it is
established each year by heating of the surface water in the
summer, and is destroyed the following winter by cooling at the
surface and wind-driven mixing.
-
sea wall :
-
a strong wall or embankment that serves as a breakwater, or is
used to prevent the encroachment of tidal or flooding waters.
-
SEBA :
-
abbreviation for Submarine Escape Breathing Apparatus.
-
second-foot :
-
a unit of measure for liquid flow, especially of rivers, being
equal to one cubic foot per second. [nb: one cubic foot of water
weighs approximately a quarter of a ton]
-
second mate :
-
the officer of a merchant vessel who's next in command and
responsibility beneath the first mate; also called 'second
officer'.
-
second stage :
-
the second phase of pressure reduction by the regulator assembly,
set to deliver low air pressure from the medium pressure of the
first stage of the regulator to the breathable air at the
mouthpiece.
-
sediment / sedimentation :
-
mineral or other organic matter that's deposited by air, water,
or ice; the insoluble matter that settles, after suspension, to
the bottom of a liquid, and accumulates there; as derived from
'sit'. [v: lees, dregs]
-
seiche :
-
an occasional but sudden oscillation of the water in a lake, bay,
estuary, reservoir, or other containment that produces
fluctuations in the water level, which are caused by wind,
earthquakes, landslides, avalanches, changes in barometric
pressure, and so forth.
-
semi-closed circuit re-breather :
-
a re-breather that continuously vents a small amount of excess
gas from the system while the breathing gas is injected at a
constant rate to the diver. Semi-closed circuit equipment
generally supplies only one breathing gas (eg: air, nitrox, or
trimix) that has a maximum operating depth that is safe for the
depth of the scheduled dive. The oxygen mixture must be carefully
chosen to avoid toxicity or hypoxia as the work rate of the dive
changes. Semi-closed circuit equipment, which is fairly simple
and inexpensive, provides good underwater duration for military
and recreational divers.
-
semi-dry suit :
-
a wet suit with wrist and ankle seals to reduce the entry and
exit of water.
-
service float :
-
a floating structure equipped to supply oil, fuel, water, sewage
pumpout, and other related services to boats.
-
service pressure :
-
the pressure at which a device is rated to work; not the test or
hydrostatic pressure.
-
set and drift :
-
the tangential deflection of a ship from its intended course
under the influence of wind and current, with 'set' being the
direction of that deflection, and 'drift' being the speed in
knots of the displacement.
-
sextant :
-
an astronomical instrument used at sea to determine latitude and
longitude by measuring angular distances, especially the
altitudes of the sun, moon, and stars; as derived from the "sixth
part of a unit".
-
SGA :
-
abbreviation for Siebe Gorman Amphibian, from the British firm of
Siebe Gorman and Company Ltd., headed by Sir Robert Davis.
-
shallows :
-
the shallow part of a body of water; shoal.
-
shark pod / shark prod :
-
a handheld device carried by a diver that's intended to repel a
shark by administering an electrical field pulse; also known as a
"shark punch" or "shark shield".
-
sheer :
-
to swerve or deviate from a course, as a divergence. Also, in
shipbuilding, the fore-and-aft upward curve of the hull of a
vessel at the main deck or bulwarks. Also, the position in which
a ship at anchor is placed to keep it clear of the anchor. Also,
any very steep perpendicular or vertical extension; precipitous.
-
sheet :
-
a thin line, cord, or wire used in reeving tackle and the rigging
of sails [nb: like a hawser, it is never called a rope]. Also, a
sail on a boat or ship.
-
shell :
-
a long, narrow, lightweight boat used for rowing by one or more
persons, especially when racing. Also, any hard protective case,
or an enclosing cover, as in imitation of the crust-like exterior
of some plants and animals. Also, the plating or planking forming
the exterior hull of a ship.
-
shellback :
-
an experienced sailor, especially someone who has crossed the
equator and undergone the arcane rites of Neptune; also called a
sea dog, old salt, or mossback.
-
shell door :
-
a water-tight or pressure-resistant opening in the hull of a
ship, or in the chamber of a moored platform, that admits limited
access (surface or subsurface) to the hollow interior for
staging, docking, and associated tasks.
-
shelter deck :
-
a weather deck covering a space that's not considered to be fully
watertight. Also, the 'tween deck beneath this weather deck.
-
shingle :
-
small waterworn stones or pebbles. Also, the area, such as a
beach or riverbed, where these small stones or pebbles wash up,
lying in a loose mass.
-
shipmate :
-
a companion or comrade who serve together on the same vessel;
often extended in camaraderie to any seaman or sailor in the
"brotherhood of the sea".
-
ship's complement :
-
persons permanently assigned to a ship, its permanent party or
staff, as distinguished from those temporarily on-board for
transport or a cruise; often misspelled "ship's compliment".
-
shipshape :
-
everything in proper order, trim and tidy; also called snug or
salty.
-
shiver :
-
to shake, quiver, quaver, or tremble with chill ("the shivers"),
being an involuntary physiological response of muscular
contractions that are intended to increase the lowered body
temperature with activity. Also, the shaking of sails on a vessel
headed too close to the wind.
-
shoal :
-
a place where the depth of water is shallow, especially where the
seafloor (eg: sandbank, sand bar) is visible at low tide. Also, a
large number of things, as a school of fish or throng of people.
-
shore :
-
the land along the edge of a sea, lake, or river, including a
beach, tideland, or shoal; especially a 'seashore', being that
ground between the ordinary high-water and low-water marks. Also,
a supporting post or beam, a prop or strut, especially one braced
against the side of a building or a ship in drydock.
-
shore diving :
-
scuba diving that starts (and finishes) from the shoreline;
ground-level entry into and exit from the water.
-
shoreline :
-
that boundary where the shore and water meet.
-
shorty suit :
-
a lightweight wet suit with short sleeves and knee-length legs,
made of thin rubber or neoprene in either one or two pieces, for
use in warm waters.
-
shot :
-
a unit of measure for anchor chain equal to 15 fathoms (90 feet,
27m). Also, an obsolete unit of measure equal to a league (3
nautical miles or 4.8km); as derived from 1.5 Roman miles, which
seems to be the origin of the conventional claim for a three-mile
limit of territorial waters extending offshore.
[nb: 12 inches = 1 foot, 3 feet = 1 yard, 6 feet / 2 yards = 1
fathom, 16.5 feet = 1 rod (aka: pole or perch), 66 feet / 4 rods
= 1 chain (90 feet / 15 fathoms = 1 anchor chain), 10 chains /
660 feet (1/8 statute mile) = 1 furlong, 120 fathoms / 720 feet =
1 land cable, 101 fathoms / 606 feet (1/10 nautical mile) = 1
cable, 3 statute miles = 1 land league, 3 nautical miles = 1 sea
league / shot]
-
shot line / shotline :
-
a rope suspended in the water from a buoy or float that's
weighted at its trailing end so as to hang vertically without
touching the seafloor, as used for decompression stops.
-
shove-off :
-
to launch (as in "launch the boat") or to execute (as
in carry-on), sometimes expressed as castoff. Also, slang for
leave / depart or go away / get away / get out.
-
showboat :
-
anyone or anything that stands-out; anything done more
for attention than for practicality or function, as a show-off or
razzle-dazzle. Formerly a flamboyantly theatrical steamboat.
-
shroud :
-
any of a number of fixed ropes or wires that converge from the
head of a ship's mast and keep it from swaying.
-
SI :
-
abbreviation for Surface Interval. Also, the abbreviation for the
International System of [physical] Units, which includes meter
(length), kilogram (mass), second (time), ampere (electric
current), kelvin (temperature), mole (amount of substance), and
candela (luminous intensity).
-
side-mount :
-
an equipment configuration wherein the air tanks are attached to
the side of the diver, between the arms and torso, which
arrangement is used for low bedding plane passages with very
little vertical clearance, a situation where the back-mount
configuration is problematic.
-
sidestroke :
-
a swimming stroke wherein the body is turned sideways in the
water, the hands pull alternately, and the legs perform a
scissors kick.
-
signal flag :
-
a small cloth panel, distinctively colored and patterned, used to
post messages or notices on a ship's superstructure; also called
burgee or pennant.
-
significant wave :
-
in ocean wave forecasting, a fictitious wave with a size and
interval equal to the average height and period of the highest
one-third of actual waves that pass a fixed measuring point. The
generation of waves on water does not result in a uniform wave
height, but in a spectrum of waves distributed from the smallest
capillary waves to the largest freak waves; within this spectrum
there is a finite possibility of each of the wave heights to
occur, with the largest waves being the least likely (only 1 in
1000 waves will be nearly double the significant wave height or
higher). The wave height most commonly observed and forecast is
the "significant wave height", which is defined as the average of
the one third highest waves.
-
silt :
-
fine sand, earthy matter, or the like that's carried by moving or
running water, and deposited as sediment on the bed of a channel
or seafloor. [v: siltation]
-
silt-out :
-
a complete loss of visibility caused by the turbidity or opacity
of disturbed silt, typically from careless finning.
-
single berth :
-
a mooring that accommodates one boat, with a finger pier on each
side of the berthed vessel.
-
single-day :
-
a dive series with a surface interval of less than 24 hours
between consecutive dives; a single day of diving, regardless of
the number of dives completed in that period; juxtaposed to
multiday.
-
singles :
-
the use of only one air cylinder when diving.
-
single sculls :
-
a type of race for sculls wherein one rower, using a pair of
oars, propels this narrow craftin a timed event.
-
sinkhole :
-
a hole formed in soluble rock by the action of water, which
serves to conduct surface water to an underground passage. Also,
a depressed area in which drainage, waste, or debris collects;
pan.
-
siphon :
-
a tube or pipe that uses atmospheric pressure to draw liquid from
one level to another, especially when mechanically transferring
the contents of one container to another. Also, an outlet or
drain in the bedrock or seafloor that draws water into a lower
level pool or chamber; as opposed to a spring or seep. Also, a
projecting tubular part of some animals through which liquid
enters or leaves their body, such as mollusks, chitons, squids,
and octopuses.
-
SIT :
-
abbreviation for Surface Interval Time.
-
skeg :
-
any flat protrusion or projection on the outside of the hull
supporting a rudder at its lower end, located abaft a sternpost
or rudderpost. Also, an extension of the keel of a small craft
that's designed to improve steering; as derived from cutwater.
-
ski :
-
see water ski / water-skiing.
-
skiff :
-
any of various types of boats small enough for sailing or rowing
by one person.
-
skimmer :
-
slang for a Boston whaler, shaped like an elongated rowboat
but mounting an outboard motor. Also, slang for any sailor aboard
a surface ship or boat, for their behavioral similarity to
gull-like birds that feed from sea level.
-
skin :
-
informal term for a thin exposure suit, typically made of spandex
(eg: Lycra) or other polyurethane fabric, that's used in warm
water diving; may also be worn under a wet suit; also called
"skin suit".
-
skin-diver :
-
a person who engages in skin diving.
-
skin diving :
-
free-breathing and free-swimming underwater diving, often
performed with only a face mask and flippers, without a
protective suit or supplemental air; elapsed time and depth are
determined by breath-hold duration.
-
skin suit :
-
informal term for a thin exposure suit, typically made of spandex
(eg: Lycra) or other polyurethane fabric, that's used in warm
water diving; may also be worn under a wet suit; also called
"skin".
-
slack :
-
not tight, taut, firm, or tense; lax or loose. Also, slow,
sluggish, or indolent; as when the wind, water, or tide is moving
very slowly. Also, the part of a rope, sail, or the like, that
hangs loose, without strain upon it. Also, a cessation in a
strong flow, as of a current at its turn. Also, negligent;
careless; remiss.
-
slack packing / slack-packing / slackpacking :
-
when the individual quantity of personal gear and equipment, food
and tools, which loadout is normally borne by each climber or
trekker, is instead shuttled from stage to stage by others using
physical strength or mechanical advantages so as to spare the
primary person undue "wear and tear", fatigue or stress, in
advancing toward the objective; the practice of ferrying excess
weight by phased intervals so as to make the trip more pleasant
... the sectional traveler usually carries a day pack or fanny
pack to avoid being stranded or inconvenienced en route while
servitors or porters, pack animals or lift vehicles bear the
major portion of the load.
-
slack water :
-
water that is free of currents, especially a body of water that's
between tides. Also, the time period when water is between tidal
currents, as at the cessation of flow when a current turns.
-
SLAM :
-
abbreviation for Scuba Lifesaving and Accident Management, a YMCA
diver rescue course.
-
sleeper wave :
-
see sneaker wave, rogue wave.
-
sling / sling-eye :
-
a strap, band, or the like, forming a loop by which something may
be suspended or carried. Also, a rope, chain, net, or the like
used for hoisting cargo, or for holding it while being hoisted.
Also, a chain for supporting a hoisting yard.
-
sling bottle :
-
see stage bottle.
-
slings :
-
the middle area of a hoisting yard where the hoisting chains are
attached.
-
slingshot valve :
-
see Y-valve.
-
slip :
-
a space in a dock, or between two wharves for a vessel to lie in;
a berth. Also, an inclined plane, sloping to the water, on which
vessels are built or repaired.
-
SLJ :
-
abbreviation for Surface Life Jacket.
-
sludge :
-
a deposit of mud, mire, or ooze at the bottom of a body of water.
Also, any of various sediment deposits or mixtures of finely
powdered substances with some type of liquid. Also, a slurry of
broken ice floating on the sea. Also, slang for strong coffee.
-
slue / sluing :
-
to turn or swing around, especially when pivoting or rotating
about its own axis.
-
sluice :
-
an artificial channel for conducting water, sometimes surplus,
often fitted with a gate ("sluice gate") for regulating the flow;
also called a sluiceway. Also, to flush or cleanse something with
a rush of water; as derived from "exclude".
-
slurry :
-
a thin mixture of an insoluble substance suspended in a liquid.
-
slush :
-
partly melted snow. Also, liquid mud; watery mire. Also, waste or
refuse, especially from cooking. Also, a mixture of grease and
other materials used for lubrication.
-
SMB :
-
abbreviation for Surface Marker Buoy, being a flag-marked float
with an ascent / descent line suspended for an underwater diver.
-
smuggler's trap :
-
a compartment or well aboard ship, usually concealed, that's used
to hide transported contraband, from munitions to medicines,
including persons, so as to avoid confiscation or taxation; being
a temporary stash, hidey-hole, or hideaway, wherein 'trap'
derives from "suitcase" and not "contrivance".
-
snaking :
-
netting stretched between the BULWARK and LIFELINE, or between
the GUNWALE and footrope on a vessel to prevent objects
(including people during storms) from falling overboard.
-
snap hook :
-
a small utility coupling device of metal or thermoplastic with a
spring-loaded gate, which is typically non-locking and not
intended for load-bearing stresses.
-
sneaker wave :
-
an exceptional wave that's much higher and steeper than the waves
in an average series of rollers, even on a calm day of
unspectacular breakers, and because it's unpredictable, its
turbulent appearance is unavoidable and surprising to small craft
boaters and off-shore swimmers, surf casters and shoreline
climbers, beachcombers and coastal trekkers; also known as rogue
wave, freak wave, sleeper wave, and king wave.
-
snorkel :
-
a J- or S-shaped tube through which a swimmer can breathe while
moving at or near the surface of a body of water; often used
while skin diving.
-
snowblink :
-
a white luminosity on the underside of clouds that's caused by
the reflection of light from a snow surface; also called "blink",
as derived from 'blink' meaning gleam, twinkle, glitter, or
shine.
-
snub :
-
to suddenly stop a moving rope by cinching it up against a solid
object; to abruptly check the paying-out of a running line by
making it fast to a fixed point. Also, to halt the movement of an
object or craft by securing it with a fixed tether.
-
snubber line :
-
rope used to check a vessel's way when being warped into a dock
or basin.
-
snuba :
-
a portmanteau word, joining SNorkel and scUBA, that's used to
designate an introductory experience of underwater swimming with
close supervision that doesn't involve training or certification.
The swimmer, who is tethered to a dive certified guide, uses the
regular mask, fins, and weight belt, but the mouthpiece is
connected to a long hose that feeds air from a series of tanks or
a compressor on the surface. This tandem dive experience, with
the least amount of paraphernalia, introduces the novice to the
underwater world without intimidation. A raft with outboard
handles is often used as the dive platform to increase the
swimmer's confidence. This method is a popular initiation for
tourists visiting the tropics, and is usually restricted to
protected areas, where wind, current, and waves are negligible.
These escorted dives are usually brief and are limited to depths
no greater than 20 feet.
-
snug :
-
a trim, tidy, or compactly arranged ship or its parts; shipshape.
Also, a compact and confined harbor or anchorage. Also, to lie
closely together; to nestle closely.
-
solo diving :
-
the practice of diving underwater without a partner, which
activity is not recommended and is not permitted on charter
boats; at a minimum, the availability of an alternate air source
is recommended.
-
SONAR :
-
acronym for SOund NAvigation Ranging, a method of
active or passive echolocation for detecting submerged objects;
used extensively by marine researchers and the military, SONAR
was invented in 1906 by Lewis Nixon to detect icebergs.
[nb: the velocity and distance that sound travels in either air
or water depends upon atmospheric pressure, medium temperature,
salinity, molecular density, and turbulence; such that under
equivalent conditions, sound moves faster in salt water than in
fresh, faster in fresh water than in air]
-
soniferous / sonify :
-
conveying or producing sound, as a "sonified layer" or an
"ensonified area"; obstructed or obscured by turbulence.
-
sound :
-
a relatively narrow passage of water between larger bodies of
water, or between the mainland and an island. Also, an inlet,
arm, or recessed portion of the sea. Also, to measure or try the
depth of water at sea by letting down a lead or plummet at the
end of a line, or by some equivalent means. Also, to examine or
test the seafloor or the bottom of a deep hole with a lead that
brings up adhering bits of matter. Also, to go down (to touch
bottom) or to plunge downwards; to dive. Also, to seek, fathom,
or ascertain by examination or investigation. Also, the sensation
produced by stimulation of the organs of hearing by vibrations
transmitted through the air or some other elastic medium, which
travel at approximately 12miles/minute through air and 52
miles/minute through water; the particular auditory effect
produced by a given cause.
[nb: the velocity and distance that sound travels in either air
or water depends upon atmospheric pressure, medium temperature,
molecular density, and turbulence; such that under equivalent
conditions, sound moves faster in salt water than in fresh,
faster in fresh water than in air. The audible range of sound
wave frequencies for humans is 20 - 20,000 Hz; above which
ultrasonic waves may be felt, instead of heard.] [cf: ultrasound]
-
spar :
-
a stout pole, such as a mast, yard, boom, gaff, or the like.
-
spar deck :
-
the upper or main deck of a vessel, extending from stem to stern.
-
spearfish / spearfishing :
-
to fish underwater using a barbed spear-like implement or a gun
that shoots barbed darts.
-
spear gun :
-
a device for shooting (by compressed air, recoil springs, or
elastic bands) a barbed missile under water, with or without an
attached trailing line.
-
spew :
-
foam, froth, or scum that's been discharged or ejected, as "spew
forth".
-
SPG :
-
abbreviation for Submersible Pressure Gauge.
-
spherical sailing :
-
a method of navigation in which the curvature of the earth is
taken into consideration when plotting a course; also called
"circular sailing".
-
spicule :
-
one of the small, hard, calcareous or siliceous bodies that serve
as the skeletal elements of various marine and freshwater
invertebrates; also known as sclerite. Large spicules, visible to
the naked eye, are referred to as megascleres, while smaller
microscopic ones are termed microscleres.
-
spindrift :
-
spray swept along the surface of the sea by a violent wind.
-
spit :
-
saliva or spittle, as a natural secretion ejected or expectorated
onto the window of the diving mask to prevent fogging. Also, a
narrow point of land projecting into a body of water. Also, a
long narrow shoal extending from the shore. Also, any of various
rods, pins, or the like used for particular purposes.
-
splash :
-
slang for an underwater dive.
-
splice :
-
to join rope together by darning or interweaving strands with a
marline spike or awl; to repair or reinforce rope by interweaving
strands. Also, to unite timbers or conjoin spars by overlapping
and binding their ends.
-
split fins :
-
a set of flippers or fins that work like an underwater propeller.
-
sport diving :
-
swimming underwater with or without breathing aids (snorkel or
scuba), as for leisure and enjoyment; also called "recreational
diving". [nb: many sport divers do not venture below the 33 foot
depth of one standard atmosphere, and most do not venture below
the 90 foot depth of two atmospheres, due to the need for mixed
breathing gases, decompression stops, and technical training]
-
spray :
-
droplets of water that are broken-up and blown or cast into the
air. Also, any liquid or other material in particle form that's
discharged into the air.
-
spray cover / spray deck :
-
a water-repellent cover spread over the gear loaded in an open
boat; this arrangement limits the amount of whitewater and/or
rainfall that enters the open boat. [nb: unlike a kayak, this
skirting shield doesn't seal the weather out of a boat, nor does
it protect the paddler from getting wet]
-
spray skirt / sprayskirt :
-
a garment worn by a canoeist that attaches to the spray cover to
keep water out of the craft.
-
spread-eagle jump :
-
see giant stride entry.
-
spring suit :
-
a rubber or neoprene wet suit that covers the diver's torso,
having short sleeves and long or short legs, as worn in temperate
climes.
-
spud can :
-
slang for the foot on a leg of a jack-up rig, which is designed
to spread the load so that the platform doesn't sink too deeply
into the seafloor.
-
spume :
-
foamy matter floating on a liquid, as froth churned by a
turbulent sea.
-
SPUMS :
-
abbreviation for the South Pacific Underwater Medical Society.
-
squall :
-
a sudden violent wind, often accompanied by rain, snow, or sleet;
as derived from "shriek". [nb: regional variants include
Abroholos, Barat, Borasco, Brubu, Chubasco, Churada, Papagayo,
Suestado, Sumatra, Tehuantepecer, and the like]
-
square away :
-
to prepare something for inspection or operation; to get
organized or ready for something, such as a drill or evolution.
-
squared away :
-
someone who is smart or capable; something that performs well, is
responsive and effective.
-
square dive / square diving :
-
a dive profile wherein the diver descends immediately to full
depth, then remains at that level for the duration until
resurfacing. This profile is approximately rectilinear when
plotted in a coordinate system, where one axis is depth and the
other is duration; juxtaposed to multilevel dive / multilevel
diving.
-
squat :
-
the tendency of a motorcraft or vessel to draw more water astern
when in motion forward than when stationary or halted. Also, a
thing of little or no value, as naught or nothing, rush or zilch,
cipher or nullity, zip or zero. Also, the minimum amount or
degree, as the least bit.
-
squeeze :
-
the effect of pressure during descent on enclosed spaces that
contain air (eg: dive mask, dry suit) or body cavities (eg:
sinuses, middle ear), which discomfort or pain can be relieved by
equalization. Also, the experience of a diver going through a
narrow passage, small opening, or constriction.
-
squeezer :
-
see gaiter.
-
squid :
-
slang for a seaman or sailor; also called swabby or gob.
-
SRT :
-
abbreviation for Single Rope Technique.
-
SRTM :
-
Shuttle Radar Topography Mapping, being the collection and
analysis of Interferometric Synthetic Aperture Radar data by
several agencies cooperating to form a dynamic digital layout of
earth's features.
-
SSAC :
-
abbreviation for Scottish Sub-Aqua Club, organized in 1953 to
instruct and govern recreational scuba diving in Scotland.
-
SSI :
-
abbreviation for Scuba Schools International, formed in 1970,
which merged with the National Association of Scuba Diving
Schools (NASDS) in 1999.
-
stage :
-
the platform of the elevator used to transport hard hat or hard
suit divers to the deep-sea floor, to recover them and any small
objects; also called "diving stage", and derived from "standing
place".
-
stage bottle :
-
the secondary scuba cylinder that is used to carry different gas
mixtures for consumption during various phases of decompression,
as used by technical divers. Also, a tank used to carry extra
breathing gas so as to extend dive time; also called "sling
bottle".
-
staged decompression :
-
regular timed stops at particular depths during ascent to allow
for nitrogen off-gassing; the prescribed safe rate of ascent for
off-gassing a diver is 30 feet per minute while rising to the
surface.
-
stainless steel :
-
chromium-based alloys of steel that have been variously
formulated to resist heat, corrosion, and other deficiencies of
unaugmented steel; a high strength ferrous metal that "stains
less" than regular steel. [eg: 304 is a versatile grade of
stainless steel that has excellent forming and welding
characteristics; 316 is a marine grade of stainless steel that's
highly resistant to pitting and crevice corrosion in chloride
environments]
-
stanchion :
-
an upright bar, beam, post, or support, as used when securing or
supporting something.
-
standard atmosphere :
-
a standard unit of atmospheric pressure, having a value of 1013.2
millibars, of 29.9213 inches, or of 760 millimeters of mercury.
Also, an arbitrarily determined vertical distribution of
atmospheric pressure, temperature, and density, which is assumed
to have physical constants that conform to parametric equations,
as used for certain scientific calculations (eg: the design of
pressure altimeters).
-
standard diving dress :
-
the typical dry suit worn with hard hat diving.
-
standing rigging :
-
rigging on a boat that remains permanently in position as a means
of steadying various spars, shrouds, stays, and the like; as
contrasted with running rigging.
-
starboard :
-
the right-hand side of a vessel or craft when facing forward, and
designated by the color green; formerly known as steerboard for
the "steering side".
-
stateroom :
-
a private room or compartment on a ship, or other conveyance.
-
stay :
-
any of various strong ropes or wires for supporting, securing, or
steadying masts, funnels, and the like; also represented as
stayed or stay·ing, as derived from "to hold in place". Also,
something used to support or steady a thing, as a prop or brace;
a strip or rod used to stiffen or strengthen. Also, to put a
sailing ship on the other tack; to change to the other tack.
-
steam fog :
-
fog formed when water vapor is added to air that is much colder
than the vapor's source, most commonly when very cold air drifts
across relatively warm water. No matter what the nature of the
vapor source, the water vapor, upon becoming mixed with and
cooled by the cold air, rapidly condenses. It should be noted
that although advection of air is necessary to produce steam fog,
it differs greatly from an advection fog in the usual sense,
which is caused by warm, moist air moving over a cold surface.
Steam fog is commonly observed over lakes and streams on cold
autumn mornings as well as in polar regions. It is sometimes
confused with ice fog, but its particles are entirely liquid.
Steam fog is also called "sea smoke", "arctic sea smoke",
"antarctic sea smoke", "frost smoke", "water smoke", "sea mist",
and "steam mist".
-
stem :
-
an upright at the forward part of a vessel into which the side
timbers or plates are jointed, designated by the color white;
also called bow or prow.
-
stenobathic :
-
freshwater or marine life that can tolerate limited changes in
depth; as opposed to eurybathic.
-
stern :
-
the back or rear of a craft or vessel; designated by the color
black.
-
sternpost :
-
an upright member rising from the after end of a keel; a
rudderpost or propeller post.
-
storm :
-
a disturbance of normal atmospheric conditions that manifests
itself by strong or heavy winds, and often accompanied by rain,
thunder and lightning, snow, hail, or sleet. Alternatively,
either an instance of heavy precipitation (eg: rainstorm,
snowstorm) unaccompanied by strong winds, or a sudden and violent
wind (ie: windstorm) alone.
-
storm warning :
-
a showing of storm signals subsequent to an alert notification of
severe winds and threatening weather, especially cyclonic
conditions [nb: Tropical Depression: 20-34 kts/23-39 smph;
Tropical Storm: 35-64 kts/40-73 smph; Hurricane: 65+
kts/74+ smph].
[nb: due to axial tilt during earth's rotation, the hemispheric
seasons are not the same length, with the southern summer /
northern winter being the shortest season, and northern summer /
southern winter being the longest]
-
strainer :
-
slang for the sieve-like obstruction in a waterway that sifts
objects and debris from the flow, often occluding the flow by
accumulation; a hazardous trap that can drown the unwary.
-
strait :
-
a narrow passage of water connecting two larger bodies of water,
often involving a strong or swift current. Also, an isthmus or
neck. Also, a position of difficulty, distress, or need (eg: dire
straits).
-
strake :
-
the joining of planks end-to-end in a continuous coarse; a
continuous course of hull planks or plates on a ship.
-
stream :
-
a body of water of indeterminate size that flows in a channel or
watercourse, such as a river, rivulet, freshet, brook, rill, run,
streamlet, or runnel. Also, a steady current or continuous flow
in water, as in a river or the ocean. Also, to place an object in
the water at the end of a line that's attached to a vessel;
trawl.
-
streamline / streamlined :
-
designed or organized so as to engender maximum efficiency; to
alter in order to render more efficient or to make as simple as
possible. Also, a teardrop line of contour offering the least
possible resistance to a current of air, water, or the like;
optimally shaped for the most effective motion or conductivity.
-
streamline flow :
-
the flow of a fluid past an object such that the velocity at any
fixed point in the fluid is constant, or varies in a regular
manner; the predictable path of suspended particles that are
moving steadily and without turbulence in a fluid medium past an
object. [cf: turbulent flow; v: hydrodynamics, fluid dynamics]
-
strobe :
-
a high-intensity light with a variable frequency flash, as used
in signaling and photography.
-
subcutaneous emphysema :
-
an abnormal distention of skin tissue by air or other gas; also
called subdermal emphysema.
-
sublittoral :
-
of or pertaining to the biogeographic region of the ocean bottom
between the littoral and bathyal zones; from the low water line
to the edge of the continental shelf, or to a depth of
approximately 660 feet. Also, situated in the zone of a lake
extending from the lowest depth of rooted photosynthetic plants
to the level at which the photosynthetic rate of flora equals the
respiration rate.
-
submarine :
-
a vessel that can be submerged and navigated under water; also
known as sub, guppy, pig boat, boomer, sewer pipe, clockwork
mouse, and the like.
-
submergence recovery vehicle :
-
an air-transportable deep-sea submarine; abbreviated SRV.
-
submersible :
-
a boat or other vessel that's capable of submerging and operating
under water, such as a submarine. Also, a device designed for
underwater work or exploration, such as a bathyscaphe.
-
submersible pressure gauge :
-
a meter, either analog or digital, that monitors and displays the
amount of air pressure remaining in the scuba cylinder; a
required item of scuba gear that monitors air supply during the
course of a dive.
-
subsurface :
-
below the surface, especially that of a body of water.
-
suicide clip :
-
a hardware device with a spring-loaded angular gate, which can
inadvertently engage and attach a diver to an underwater object,
or can accidentally disengage from a guideline or other
connection; also called "boat clip" or "marine snap link".
-
sunami :
-
misspelling of tsunami (qv).
-
sunshade :
-
a fly or awning that's been rigged with scantling over an open
deck to provide protection from the intensity of direct sunrays,
also called bimini top.
-
super saturation :
-
an unstable situation where the pressure of a gas dissolved in
the blood or tissues is higher than the ambient pressure of that
gas.
-
supralittoral :
-
pertaining to the region of a lake or ocean shore that is above
the shoreline but is often damp from spray or capillary action of
the water.
-
surf :
-
the swell of the sea that breaks in a foamy mass or line upon a
sloping shore or upon shoals. Also, to float (surfing) or swim
(body-surfing) on the crest of a wave toward shore.
-
surface detection aid :
-
any device that's carried by a diver to help maintain contact
with the dive boat or to enable the diver to attract attention
when injury or dislocation requires rescue at sea; items include
strobe, flare, dye marker, flag, SMB, whistle, EPIRB, and the
like.
-
surface interval :
-
a period of time spent on the surface between dives, especially a
delay between repeat dives; abbreviated SI.
-
surface marker buoy :
-
a float that may be fixed or towed denoting a dive site, to which
an ascent line may be attached, and which may be used as a safety
device to warn when divers are swimming underwater; abbreviated
SMB.
-
surface supplied compressed air diving :
-
underwater diving with the breathing air continuously supplied by
an air hose from a compressor on the surface, which can be used
for both professional and sport diving.
-
surfactant :
-
an active substance produced in the lungs to reduce surface
tension in alveoli and small airways, and that coats the lungs to
prevent their collapse.
-
surfline :
-
the offshore line where the mass of the sea breaks against a
shallow or sloping shore, creating foamy breakers from the tidal
current that advances inland.
-
surfrider / surfriding :
-
to steer a paddleboard, surfboard, sailboard, or other small
watercraft (eg: canoe, kayak, raft, etc) on the crest of a wave
flowing downstream or toward the shore; also known as 'wave
rider'.
-
swabby :
-
slang for a seaman or sailor; also called squid or gob.
-
sweep :
-
a large oar sometimes used in small vessels so as to assist the
rudder or to propel the craft by a curving movement or swinging
stroke. Also, the steady, driving motion of something, as of the
wind or a current, especially when continuous. Also, to
thoroughly observe or extensively search an area, as in a wide
circuit. Also, to conduct an underwater search by towing a drag
under the surface of the water.
-
swell :
-
a long and unbroken wave, or a series of such "rollers".
-
swim fin / swimfin :
-
one of a pair of paddlelike devices, usually made of rubber, that
are worn on the feet as an aid in swimming and scuba diving;
imitative of the broad flat limbs or the membranous organs of
aquatic animals that are used for steering and propulsion; also
called fin or flipper.
-
swim ladder :
-
a temporary boarding ladder (qv) that's hung over the side of a
boat from the gunnel / gunwale for the ready recovery of swimmers
out of the surrounding water; typically flexible (like a Jacob's
ladder) for convenient stowage.
-
swim mask :
-
a device consisting typically of a transparent glass or plastic
panel fitted into a flexible rubber gasket that fits snugly
around the eyes, over the cheeks, and usually over the nose; also
called "face mask" or "diving mask", as used by scuba and skin
divers.
-
swim platform :
-
see sea deck.
-
swimsuit :
-
a garment worn for swimming or for recreational activities in and
around water; also called swimming suit or bathing suit.
-
swirlhole :
-
a more or less circular hole that's been eroded in the rock of a
streambed (present or past) by eddying water, with or without the
mechanical action of sediments up to the size of cobblestones.
[cf: pothole]
-
tables :
-
decompression tables; also called dive tables.
-
Table 6 :
-
the most common treatment procedure for decompression sickness as
outlined by the U.S. Navy; consisting of oxygen breathing with
air breaks at a maximum pressure of 2.8 ATA with typical
treatment times of 285 minutes.
-
tackle :
-
any specialized apparatus, equipment, or gear, including
rigging. Also, a leverage system of pulleys.
-
tadpole :
-
nickname for a frogman trainee.
-
taffrail :
-
the upper part of the stern of a ship. Also, a safety rail above
the stern of a ship.
-
tank :
-
slang for the steel or aluminum cylinder of pressurized breathing
gas that's used in scuba diving; also called "bottle".
-
tarn :
-
a small mountain lake, pond, or pool, especially one situated in
a cirque, corrie, or cwm.
-
TBT :
-
abbreviation for Total Bottom Time.
-
TDI :
-
abbreviation for Technical Diving International; a certification
agency for the technical aspects of recreational scuba diving.
-
TDT :
-
abbreviation for Total Dive Time.
-
technical dive / technical diving :
-
an underwater dive deeper than 132 feet (40.2m) using a breathing
gas other than compressed air, and requiring at least one
decompression stop during ascent. This category also encompasses
overhead dives, and the use of special training or equipment.
-
tekkie / techie :
-
a technical and gadget oriented diver ... the more the better! A
tekkie dive profile always uses exotic gas mixtures, and a tekkie
BCD has at least six D-rings attached! A tekkie dive maximizes
complexity and difficulty! A tekkie aspires to be the most
authoritative expert ... on everything!
-
telltale :
-
any of various devices or mechanisms for alerting, indicating, or
registering, including a suspended line, ribbon, or feather hung
so as to indicate wind direction.
-
tempest :
-
a violent windstorm with rain.
-
tender :
-
an auxiliary watercraft, such as a dinghy or motorboat, that's
carried or towed by a larger vessel so as to "attend" to its
needs; as derived from 'attender'.
-
tender garage :
-
a hollow interior within the hull of a ship or within the chamber
of a moored platform, that admits surface or subsurface vessels
through a water-tight or pressure-resistant opening (shell door)
for staging, docking, and other tasks associated with auxiliary
vessels.
-
tension leg rig :
-
a permanently moored floating platform that's used for offshore
excavation and development, the structure of which is tethered in
deep water (300-1500m), rendering the rig impervious to vertical
movement.
-
test depth :
-
the rated maximum safe depth to which a submarine or other
submersible is tested by actual or simulated submergence, as
based upon design and manufacturing limits.
-
thermal :
-
a distinct heat signature that's detected in air or water,
whether generated by a radiant, electrical, or magnetic source,
which is subject to measurement and/or assessment, and which
presence may be partly or temporarily masked (ANTI-THERMAL).
-
thermobaric :
-
(forthcoming);
-
thermocline :
-
an underwater layer of boundary water that differs in temperature
and salinity from those bordering it above and below; it is the
region in a thermally stratified body of water which separates
warmer oxygen-rich surface water from cold oxygen-poor deep water
and in which temperature decreases rapidly with depth. Also, a
layer in a large body of water, such as a lake, that sharply
separates regions differing in temperature, so that the
temperature gradient across the layer is abrupt. Also, the
intermediate summer or transition zone in lakes that's situated
between the overlying epilimnion and the underlying hypolimnion,
defined as that middle region of a thermally stratified lake or
reservoir in which there is a rapid decrease in temperature with
water depth. Typically, the temperature decrease reaches 1°C
or more for each meter of descent (equivalent to 0.55°F per
foot).
-
thermodynamics :
-
the science concerned with the relations between heat and
mechanical energy or work, and the conversion of one into the
other.
-
thirds :
-
the practice of dividing the volume of air (in cubic feet or psi)
into thirds: with one third for the penetration, one third for
the exit, and one third for emergency use; also called the "rule
of thirds".
-
thorax :
-
the part of the mammalian trunk between the neck and the abdomen,
containing the heart and lungs in a bony cage of ribs, sternum,
and vertebrae, and separated from the lower trunk by the
diaphragm; also known as the chest.
-
throughflow :
-
the horizontal movement of water beneath the saturated land
surface once it has infiltrated the less permeable compacted
soil, moving downwards and sideways under gravity and running
underground until it reaches a river, lake, or other body of
water. Also, the transport of ocean water in a horizontal current
from one body to another by way of a channel (such as the
Indonesian throughflow) as an adjustment in sea levels, with or
without the augmented movement of seasonal winds; also known as
an "oceanic conveyor belt".
-
throw line :
-
a light cord or thin rope, with its trailing end weighted by a
knot, that's used to cast across an intervening space or to toss
between footholds for transferring larger cables; also known as a
"messenger line" or "heaving line".
-
thumbing the dive :
-
a command signal used to terminate the dive and direct other
divers to exit to the surface; this "thumbs-up" hand signal
consists of an upward pointing thumb with the fingers of that
same hand closed into a fist.
-
thumbs-up :
-
a hand signal indicating ascent; not to be mistaken for a gesture
of approval or agreement.
-
thwart :
-
passing or lying crosswise or across; transverse or athwart.
Also, a transverse member spreading the gunwales of a small boat,
canoe, or the like. Also, a seat across a boat, as one used by a
rower.
-
tidal range :
-
the difference in height between the highest (hwl) and lowest
(lwl) water levels occurring about every 12-hours.
-
tidal wave :
-
common reference to a large, destructive ocean wave that was
produced by a seaquake, hurricane, or other cataclysm. Also,
either of the two great wavelike swellings of the ocean surface
that move around the earth on opposite sides and give rise to
tides, as caused by the attraction of the moon and sun.
-
tide :
-
the periodic rise and fall of the waters of the ocean and its
inlets, produced by the attraction of the moon and sun, and
occurring about every 12-hours. Also, the inflow, outflow, or
current of water at any given place resulting from the waves of
tides. Also, a flood tide, being the inflow of rising water.
Also, betide; to happen or befall.
-
tide gate :
-
a gate that permits water to flow through when the tide moves in
one direction, but closes automatically when the tide moves in
the opposite direction. Also, a restricted passage through which
the tide flows swiftly, such as a strait. [cf: water gate]
-
tidehead :
-
the inland limit of the tide.
-
tiller :
-
a bar or lever fitted to the head of a rudder that's used for
turning the rudder when steering.
-
timberhead :
-
the top end of a timber, rising above the deck and serving for
belaying ropes or attaching lines. Also, a bollard resembling
this in position and use.
-
time to fly :
-
the surface interval (SI) that must elapse after underwater
diving so as to reduce tissue gas concentrations to a level where
the risk of decompression sickness is acceptable, due to the
pressure reduction experienced in normal commercial airliners.
-
TNT :
-
abbreviation for Total Nitrogen Time.
-
TOD :
-
abbreviation for Theoretical Ocean Depth.
-
toe rail :
-
the raised lip at the edge of a weather deck that's designed to
prevent someone's feet from slipping or sliding overboard.
-
tongue :
-
a narrow strip of land extending into a body of water; cape.
Also, a section of ice projecting outward from the submerged part
of an iceberg.
-
topside :
-
on deck, or on the outer-surface of the hull above the waterline,
often refers only to the main deck; also known as "topsides".
-
tornado :
-
the word 'tornado' is a metathetic variant of "tronada", a
violent thunderstorm, which is characterized as a violent
funnel-shaped windstorm occurring over localized land.
-
torr :
-
a unit of pressure, being the pressure necessary to support a
column of mercury one millimeter high at 0°C at standard
gravity, and equal to 1333.2 microbars; eponymously after
Evangelista Torricelli, an Italian physicist.
-
Torricelli's law :
-
the law that states that the speed of flow of a liquid from an
orifice is equal to the speed that it would attain if falling
freely a distance equal to the height of the free surface of the
liquid above the orifice; named after Evangelista Torricelli, an
Italian physicist.
-
Torrid Zone :
-
that part of the earth between the tropics of Cancer and
Capricorn, which is characterized by a year-round hot climate.
-
total bottom time :
-
the amount of time that a diver spends underwater, being the sum
of actual bottom time and residual nitrogen time.
-
touch signal :
-
contact communications used in a low visibility environment;
including: Go (by a push), Stop (by a pull), Back Up (by several
rapid pulls), Turn (by taps on side to move), Exit (by taps on
head).
-
tourist :
-
see holiday diver, recreational diver.
-
towboard / towboarding :
-
a heavier than usual surfboard that's specifically designed for
skimming the surface of big waves while being towed behind a
motorboat; such a surfboard is marked by reductions in length,
width, and thickness (but stronger fiberglass) with the addition
of footropes or footstraps secured to deck plugs for increased
rider security.
-
towhead :
-
a sand bar in a river, especially a sand bar with a stand of
cottonwood trees.
-
tow-in surfing / freeboard / freeboarding :
-
the act of riding a surfboard (ie: towboard) behind a motorboat
or sailboat, which is similar to water skiing.
-
trachea :
-
the tube that extends from the larynx to the bronchi, which
serves as the principal passageway for air to and from the lungs;
this airway is also called the windpipe.
-
trailing edge :
-
the rear edge of a moving object, especially a propeller blade or
airfoil. [v: chord] Also, the rear edge of a mass of air or
water.
-
trailing line :
-
a recovery line suspended in the water from a moving craft or
vessel; also called trawl or trawl line. Also, a safety line
that's temporarily laid to mark the route and establish
boundaries; a rope or cord emplaced to direct someone's passage
over unfamiliar or confusing terrain; also called guideline,
distance line, lay line, cave line, or penetration line. Also, in
naval navigation, the mechanism by which a log or patent log is
streamed from a vessel; also called log line.
-
tramp :
-
a freight vessel that transports cargo wherever the shippers
direct, having no regular schedule and no fixed port or route;
also called "tramp steamer" or "tramp ship".
-
transition layer :
-
the stratified layer of a body of water that's situated between
the mixed layer and the undisturbed fluid beneath it; being the
uppermost (epilimnion) thermocline or the thermocline closest to
the surface at any given time. Also, the capping inversion or
entrainment zone at the top of the convective mixed layer. Also,
the statically stable layer near the base of convective clouds in
the Tropics. Also, the thin layer that separates thicker layers
of different characteristics.
-
transom :
-
a flat termination at the stern of a ship above the water line;
or any of the transverse beams attached to the sternpost of a
ship that strengthen the stern.
-
travel gas :
-
the breathing mixture used for descent and ascent.
-
trawl :
-
a recovery line trailing from a moving craft or vessel, which
enables divers or swimmers to be extracted from a body of water
by attaching themselves onto the line while the craft or vessel
continues, without stopping to embark the departing personnel,
who are later transferred to their host ship; this term derives
from "trail", and is also called "trawl line" or "dragrope". [nb:
fishermen use a "trawl net"]
-
tread :
-
to maintain the body in an erect posture or upright position in
the water, with the head above the surface, as performed by a
pumping or cycling movement of the legs, similar to a stepping or
walking motion, with the arms used for balance and stability;
also called "duck paddling". Also, used figuratively to represent
the maintenance of the status quo, without making any progress;
being static or dormant, fixed or unchanging.
-
trench :
-
a long narrow depression in the deep-sea floor, being the site of
one or more ocean deeps.
-
trestletree :
-
either of a pair of beams supporting the crosstrees at the head
of a ship's mast.
-
trident :
-
a three-pronged spear-like device or weapon that's
characteristically associated with Poseidon or Neptune; as
derived from "having three teeth".
-
trigger snap :
-
a hardware device used to attach gear to the diver's harness; it
has a swivel on one side and a split circular other end with one
side of the split being a spring-loaded lever (trigger).
-
trim :
-
the set of a ship in the water, especially the most advantageous
posture with respect to the intended course and the prevailing
conditions; also called attitude adjustment. Also, to adjust the
sheets of a sailing vessel so that it floats on an even keel;
level at the waterline. Also, the most advantageous posture or
the balanced set of any body in the water, especially a swimmer
or diver.
-
trimix :
-
a breathing gas mixture of nitrogen, helium, and oxygen.
-
trim party :
-
the directed movement of passengers or crew aboard ship so as to
alter the trim of that vessel; originally used aboard submarines
to increase the rate of ascent or descent; this practice is
sometimes used to harass inexperienced helmsmen. [cf: body
English]
-
trim weight :
-
weights attached to the diver that allow adjustment for trim and
swimming position. Also, weight (eg: ballast, cargo, etc) aboard
ship that can be positioned or shifted so as to effect the proper
balance or the greatest stability.
-
triple point :
-
the particular temperature and pressure at which the solid,
liquid, and gaseous phases of a given substance are all at
equilibrium with one another.
-
Tropic of Cancer :
-
a parallel of latitude that marks the farthest point (23.5°N)
north of the equator where the sun's rays fall vertically.
-
Tropic of Capricorn :
-
a parallel of latitude that marks the farthest point (23.5°S)
south of the equator where the sun's rays fall vertically.
-
trough :
-
a gutter-like channel or conduit for conveying water. Also, a
long, wide, and deep depression in the ocean floor having gently
sloping sides, being wider and shallower than a trench (qv).
Also, any long depression or hollow, as between two ridges on a
weather chart; an elongated area of relatively low barometric
pressure.
-
truck :
-
a circular piece of wood fixed on the head of a mast or the top
of a flagstaff, usually containing small holes for the roving
through of signal halyards. Also, any of various wheeled frames
used for transporting large or heavy objects, including packages
and cartons, trunks and crates; also called dolly or hand truck.
Also, miscellaneous articles of little worth; odds and ends.
-
trudgen / trudgen stroke :
-
a swimming stroke, performed in the prone position, wherein
alternating overarm movements are combined with a rotating
scissors kick; often used in rescue swimming with the swimmer's
head held erect out of the water; eponymously after John Trudgen,
a late 19th century British swimmer. [nb: may also be executed
like a breaststroke using the frog kick, but with alternating
overarm movements]
-
tsunami :
-
an unusually large sea wave produced by a seaquake or undersea
volcanic eruption; originating in Japanese as "harbor wave".
-
tube / barrel :
-
the space inside a tubular breaking wave between the lip and
face; a curling hollow opening in a comber.
-
turbidimeter :
-
a device for measuring the turbidity or opacity of water or any
other liquids.
-
turbulence / turbulent :
-
being in a state of agitation or disorder; manifesting a violent
commotion or tempestuous disturbance, such as exhibited by the
haphazard secondary motion caused by eddies within a moving
fluid, or by irregular motion of the atmosphere, as that
indicated by gusts and lulls in the wind; term derives from
'restless'. [v: tumult / tumultuous]
-
turbulent flow :
-
the flow of a fluid past an object such that the velocity at any
fixed point in the fluid is inconstant, changeable, or varies in
an irregular or unpredictable manner; the variable path of
suspended particles that are moving erratically or eccentrically
in a fluid medium past an object. [cf: streamline flow; v:
hydrodynamics, fluid dynamics]
-
Turk's Head :
-
a large decorative knot, used to finish a special line or lanyard
(such as one suspended from the clapper of a ship's bell);
sometimes called "Nigger Head" or "niggerhead".
-
turn :
-
to pass or twist a rope entirely around an object; as derived
from "round off" or "make circles". Also, a single circular or
convoluted shape, as of a coiled or wound rope.
-
turn the tide :
-
an expression of figurative reversal, as to reverse the course of
events, especially from one extreme to another; as derived from
the literal reversal of flow.
-
'tween deck :
-
any space between two continuous decks in the hull of a vessel,
as between a shelter deck and a freeboard deck.
-
Type III MSD :
-
the Type III Marine Sanitation Device, a sewage retention system
or holding tank (qv).
-
typhoon :
-
a tropical cyclone or hurricane of the western Pacific, its seas
and inland areas; as derived from Chinese for great wind. [cf:
Greek Typhoeus / Typhon]
-
UASR :
-
abbreviation for the Underwater Association for Scientific
Research in Great Britain.
-
UBA :
-
abbreviation for Universal Breathing Apparatus.
-
UBMS :
-
abbreviation for the Undersea BioMedical Society in the United
States.
-
UIS :
-
abbreviation for the International Speleological Union (Union
Internationale de Speleologie).
-
UNCLOS :
-
the United Nations Convention on the Law of the Sea.
-
undercurrent :
-
a water current that flows below the upper currents or beneath
the surface.
-
undertow :
-
any strong subsurface current that's moving in a direction
different from that of the surface current, especially the
seaward flow of subsurface water from waves breaking on a beach.
-
underway / under way :
-
a moving vessel, as a boat or ship that's no longer at anchor or
in port; a vessel that's not stationary, is in motion relative to
the seafloor, but may not be under its own propulsive power.
-
UNESCO :
-
the United Nations Educational, Scientific and Cultural
Organization.
-
upper deck :
-
the uppermost continuous deck that is capable of being made
watertight; also called freeboard deck.
-
upstream valve :
-
a valve that functions against the flow of pressure (instead of
with the flow of pressure), such that if it fails, this valve is
safely closed in the 'off' position.
-
UPTD :
-
abbreviation for Unit Pulmonary Toxic Dose.
-
USN :
-
United States Navy.
-
USOA :
-
abbreviation for the Underwater Society of America.
-
UTI / UTC :
-
Universal Time International is the former designation for the
current Universal Time Coordinated, both of which are adjustments
of Greenwich Mean Time (GMT) or Zulu time to minimize its
divergence from international atomic time (IAT); also called
"universal time". In response to rapid transportation, Congress
enacted the Standard Time Act in 1883, which became crucial for
scheduling during WWII. The Uniform Time Act was enacted in 1966
and amended in 1986 to standardize Daylight Savings Time. The
convention for adopting GMT as the prime meridian was approved
1884.
-
UTM :
-
Universal Transverse Mercator, a naval navigation reference which
dispenses with latitude and longitude grid lines in favor of
digital metric coordinates that are accurate to within 100m.
-
Valsalva maneuver :
-
an attempt to adjust pressure in the middle ear by forcibly
expelling air against a closed glottis, or against closed lips
and pinched nostrils, which inflates the Eustachian tubes while
decreasing intrathoracic pressure, hampering venous return to the
heart; eponymously after Antonio M. Valsalva, an Italian
anatomist.
-
vampire gauge :
-
slang for a penetration monitor that samples blood gas (abg)
diffusion at the wrist, which is used on deep underwater dives.
-
van der Waals equation :
-
the Johannes van der Waals formula is a gas law involving the
pressure, temperature, and volume of real gas variations, instead
of ideal gas at absolute temperature, and is given as: (P +
a/v2) (v - b) = RT, or (pressure + constant value
a squared)(volume minus constant value b) = (real gas
temperature).
-
veer :
-
said of the wind when it changes. Also, to slacken a cable and
let it run out. [v: pay]
-
veer and haul :
-
to alternately pull on and slacken a rope or line, as in warping,
until the vessel gains headway.
-
velocity :
-
the rapidity of motion, swiftness of action, or speed of
operation; the time rate of change of position of a body in a
specified direction. See wind velocity, wave group velocity.
-
venous gas embolism :
-
a condition in which gas bubbles enter the venous system and
cause damage by blocking blood flow to vital organs, most
commonly the heart and lungs; abbreviated VGE, and also called
"air embolism".
-
VENTID :
-
a diagnostic mnemonic for oxygen toxicity: Vision, Ears, Nausea,
Twitching, Irritation, Dizziness.
-
vertigo :
-
a dizziness or disordered condition brought on by the inequality
of pressures in the inner ear; a sign of ear barotrauma that may
range from minor ear squeeze to perforation of the eardrum.
-
VGE :
-
abbreviation for Venous Gas Embolism.
-
VIP :
-
abbreviation for Visual Inspection Program, being the visual
inspection of the interior (and exterior) of a scuba cylinder to
warrant its integrity, as performed annually by a trained
equipment technician.
-
visibility :
-
the viewing distance or visual capacity for underwater objects as
factored by bottom composition, turbidity, suspended matter, and
water temperature.
-
visual reversal :
-
a perceptual distortion where the distance to an underwater
object appears farther away than the actual distance.
-
volcano :
-
a hill or mountain having a cup-like crater at its summit, which
is formed around the vent in the earth's crust through which
lava, ashes, steam and other gases are expelled into the
atmosphere, either continuously or at irregular intervals.
-
volute :
-
an object having a spiral, twisted, or rolled-up conformation,
especially the turn or whorl of a spiral seashell. Also, the
scrolled ornament terminating a handrail or cutwater.
-
vortex :
-
a whirling mass of water, especially one operating with the force
of suction, as a whirlpool.
-
V-weight :
-
a weight placed between a set of air cylinders to offset an
undesired buoyancy or to adjust a diver's trim.
-
wake :
-
the track of waves left by a vessel moving through water; as
derived from a "hole in the ice". Figuratively, as "in the wake
of", means consequently or closely behind.
-
wale :
-
any of certain strakes of thick outside planking on the sides of
a wooden ship.
-
waler :
-
a structural member that's fastened along the edges of a dock
system to hold it together, to provide stability, and to protect
the flotation pontoons and utility feeds.
-
Wallacea :
-
a biogeographical transition zone of islands between the Sunda
shelf and the Sahul shelf, an area separating Australia from
Southeast Asia for the past seventy million years. Initially
recognized for its significance by the British naturalist Alfred
Russel Wallace, it marks the division between two major faunal
groups: oriental animals (elephants, tigers, and apes) and
Australasian animals (marsupials and monotremes). The so-called
"Wallace Line", which runs between Bali and Lombok, is a boundary
that separates the ecozones of Asia and Australasia, with the
organisms living west of this line related to Asiatic species,
and most of the species east of this line endemic to Australia,
New Guinea, New Zealand, and neighboring islands.
[v: Weber's Line, Huxley's Line, Lydekker's Line]
-
wall diving :
-
underwater exploration along the face of a vertical surface
(cliff or quarry, pit or drop-off), which requires good buoyancy
control to avoid angling upward to the surface or downward to the
seafloor.
-
warp :
-
a rope smaller than a cable and used as mooring lines. Also, to
move a vessel from one place to another by means of incremental
hauling on a rope made fast to some fixed object, or to a kedge
(kedging).
-
warm spring :
-
a thermal spring having a temperature of up to 98°F /
37°C, which water is usually heated by emanation from or
passage near hot or molten rock.
-
washing machine / washer machine :
-
slang for the churning turbulence generated by a whirlpool,
plunge pool, riptide, undertow, or waterspout, which can be
disorienting and potentially dangerous to swimmers and divers.
-
watch :
-
a lookout, guard, sentinel, or selected crewmembers who serve as
such while aboard a vessel. Also, a period of time during which
part of the crew is on duty attending to the workings of their
ship. Also, one of the periods (usually four hour blocks) into
which the day and/or night is subdivided while at sea.
-
watch-and-watch :
-
the necessity to stand alternate watches, due to an absence or
incapacity of other crewmembers; variously arranged as 4- or
6-hours on- and off-duty until the situation changes; this
routine is also called "port and starboard" or "port and stupid"
... an exhausting schedule that can inadvertently generate
mistakes and accidents.
-
watch bill :
-
a roster of regularly scheduled duties assigned to crewmembers.
-
watch cap :
-
a soft stocking-cap, knitted of dark blue wool and worn with a
turned-up cuff folded at the bottom, that's suitable for wear
during cold weather by seamen or sailors. [cf: balaclava, coif,
pileus/pîlos]
-
watercourse :
-
any natural channel conveying water, seasonally or otherwise, as
a river or stream; a waterway. Also, a conduit or canal made for
the conveyance of water, as a race or aqueduct.
-
watercraft :
-
any type of boat, ship, or seagoing vessel; a waterborne
conveyance. Also, skill in boating, or ability in watersports and
related recreations.
-
waterfall :
-
a steep fall or flow of water in a watercourse from a rocky
height, as over a precipice; a cascade or cataract.
-
waterfront :
-
land on the edge of a body of water. Also, the part of a city or
town on the land beside a body of water.
-
waterhead :
-
the source of a river or stream; a fountainhead. Also, a body of
water that's been impounded as a reservoir for irrigation or
other utility.
-
water hole :
-
a depression in the surface of the ground that contains water, as
a pond or pool, including a cavity in the dry bed of a river that
contains water. Also, a hole in the frozen surface of a lake,
pond, stream, or the like. Also, a source of drinking water, as a
spring or well. [cf: watering hole]
-
waterline / water-line / water line :
-
the line in which water at its surface borders upon a floating
body; being just the part of the outside of a ship's hull that's
at the level of the water. Also, any of a series of lines on the
shipwright's architectural hull plans of a vessel that represent
the level to which the vessel is immersed or the bottom of the
keel. Also, a tube, pipe, or hose for conveying liquids.
-
waterlocked :
-
enclosed entirely, or almost entirely, by water. Also, living in
water cut off or shut away from the sea. [cf: landlocked]
-
waterlog :
-
to cause a boat, ship, or other vessel to become uncontrollable
as a result of flooding. Also, to soak, fill, or saturate with
water so as to make soggy or useless; apparently derived as a
back-formation of waterlogged.
-
waterlogged :
-
excessively saturated with, or as if with, water; so filled or
flooded with water as to be heavy or unmanageable.
-
watermanship :
-
skill in rowing or boating.
-
water plane :
-
the horizontal area of a ship when measured at the waterline.
-
water pocket :
-
a cavity at the foot of a cliff formed by the falling action of
an intermittent stream; also known as a 'plunge basin' (qv).
-
watershed :
-
the area or region drained by a stream, river, or other
watercourse. Also, an important point of division or transition.
-
water ski / water-skiing :
-
to plane over the surface of water at the end of a towline drawn
by a motorboat or sailboat using a single or paired set of skis
that are shorter and broader than snow skis, some with a keel or
skeg. [cf: wakeboarding]
-
watersport :
-
an activity played within or on the surface of water, or a
recreation practiced within or on the water's surface.
-
waterspout :
-
a funnel-shaped or tubular portion of a cloud that's so laden
with mist and spray that it resembles a solid column of water
connecting the ocean, or other body of water, to the sky; a
tornado at sea.
-
waterway :
-
any natural channel conveying water, seasonally or otherwise, as
a river or stream; a watercourse.
-
wave duration :
-
one of the three key elements (along with wind velocity and fetch
length) used when forecasting the characteristics of waves in a
storm area or in a wave generation area; it's the length of time
that the wind blows in the same direction over the swell
generating area (or fetch).
-
wave group velocity :
-
in deep water, a group of waves moves at a different rate than
its components; the successive individual waves within a wave
group move twice as fast as the overall wave group.
-
wavelength / wave length :
-
the distance, measured in the direction of propagation of a wave,
between two successive points in the wave that are characterized
by the same phase of oscillation.
-
wave rider / wave riding :
-
to steer a paddleboard, surfboard, sailboard, or other small
watercraft (eg: canoe, kayak, raft, etc) on the crest of a wave
flowing downstream or toward the shore; also known as
'surfrider'.
-
waveson :
-
goods that appear upon the waves or floating at sea after a
shipwreck.
-
way :
-
movement or passage through water, as being underway or making
headway. Also, a ramp, usually two or more, along which the hull
of a boat slides when being launched.
-
weather deck :
-
the uppermost continuous deck on a ship that's without overhead
cover, and so is fully exposed to the weather.
-
weight belt :
-
a buckled belt worn around a diver's waist which holds enough
weights to offset the diver's buoyancy.
-
weight system / weighting system :
-
the addition or subtraction of weights to a diver's gear so as to
offset the diver's buoyancy as calculated for a particular dive
profile; the use of weights as buoyancy compensators.
-
well :
-
a natural or artificial hole, as a depression or reservoir, for
the containment of water, or to supply a spring or fountain.
Also, a part of a weather deck between two superstructures,
extending from one side of a vessel to the other.
-
well deck :
-
a space on the weather deck of some ships that lies at a lower
level, between a raised forecastle or poop and the superstructure
of the bridge, which can be flooded to embark and disembark
boats, landing craft, or amphibious tractors.
-
welter :
-
to be rolled, tossed, or tumbled about by the waves or winds of
the sea. Also, to become deeply involved or extensively entangled
in a confused mass or jumbled upheaval; a muddle, commotion,
turmoil, or tumult.
-
wet suit / wetsuit :
-
a close-fitting rubber or neoprene garment with a nylon or
polypropylene rashguard lining that's worn by a skin or scuba
diver in cold water, that allows a thin insulating layer of water
to collect between the diver's body and the suit, in order to
retain body heat; invented in 1952 by Hugh Bradner, a physicist
at the University of California in Berkeley.
-
whaleboat :
-
a long, narrow, open boat designed for quick turning and use in
rough seas; also known as a whaler or Boston whaler, it was
formerly used in whaling, but now mainly for sea rescue.
-
wharf :
-
a structure built on the shore of a harbor or estuary, or
projecting into such a body of water, for the mooring of vessels
and the transfer of passengers or cargo.
-
whiff :
-
a slight gust of wind or puff of air; a vagrant eddy, mild
susurrus, or gentle zephyr. Also, a single inhalation or
exhalation of air; a shallow or slight breath. Also, a slight
trace of smell, or hint of odor.
-
whimsy / whimsey :
-
an odd or capricious windstorm that creates turbulent water.
-
whip :
-
to overlay or cover cordage or rope with thread or line, as for
prevention of damage by friction, fraying, or raveling [cf:
puddening, mousing, baggywrinkle]. Also, a tackle consisting of a
fall rove through a single standing block (single whip), or a
fall secured at one end and rove through a single running and a
single standing block (double whip). Also, the hose used for
filling compressed air tanks.
-
whipping :
-
the binding on the end of a line or wire to prevent unraveling.
-
whirlpool :
-
a swift circular motion of water, caused by the meeting of
opposing currents, often producing a downward spiral.
-
whitecap :
-
a broken wave with a foaming crest; also called "white horses"
for their dancing movement.
-
white squall :
-
a strong sudden gust of wind that arises without warning,
exhibited by broken water or whitecaps; usually seen in whirlwind
form during clear weather in the tropics.
-
white water :
-
frothy water, as in whitecaps and rapids. Also, light-colored
sea water over a shoal or sandy bottom.
-
white-water rafting / whitewater rafting :
-
to quickly float downstream through frothy rapids and churning
falls on a buoyant raft or in an inflated inner-tube, in a
lightweight boat (canoe or kayak) using paddles, or in a small
dinghy using body English for steering; after moving over or
through rapids, conveyances may be beached along the route for
recuperation, nature study, or over-night encampment.
-
whole gale :
-
a wind of 55-63mph, as measured on the Saffir-Simpson scale.
-
wildcat :
-
that portion of a windlass that engages the links of the anchor
chain so that it can be heaved in. [cf: pawl, dog]
-
winch :
-
a machine having a drum on which to coil a rope, cable, or chain
used for hauling, pulling, or hoisting; sometimes called a
"windlass".
-
winding :
-
the act or process of turning a vessel end for end between buoys,
or along-side a wharf or pier.
-
winding hole :
-
the place in a canal or channel where long and/or narrow boats
are able to turn around; also known as "winded".
-
windlass :
-
a mechanical device used to pull in cable or chain, such as an
anchor rode; a capstan or winch.
-
windless :
-
a cranked handle used for mechanical winding. [cf: capstan-bar,
handspike]
-
wind sail :
-
a sail rigged over a hatchway, ventilator, or the like, that's
used to divert moving air downward into the vessel.
-
windsock :
-
a tapered tubular cloth vane ("weather vane") or TELLTALE, that
pivots to catch the wind, swinging freely so as to indicate the
direction toward which the wind is blowing.
-
windsurf / windsurfing / sail-surfing / sailboard / sailboarding
/ board-sailing :
-
a surface water activity developed in the late 1950s that enables
a primitive form of sail-surfing to acquire low-impact
sightseeing, touring, and recreation by use of minimal equipment,
consisting of a broad, flat, rigid board, extending from ten to
nineteen feet in length, some with a keel or skeg, many with deck
plugs for securing equipment, usually with footropes or
footstraps added for increased rider security, and a
free-rotating universal joint that mounts the mast, boom, and
sail for propelling the entire rig ... all of which is dependent
upon the area of the sail, the weather conditions, the intended
application, the skill of the pilot, the size and weight of the
sail-surfer. Invented by Alfred Seltz on Lake Le Homme Diu near
Alexandria, MN for its sporting potential, and separately by S.
Newman Darby on the Susquehanna River in Pennsylvania using a
pivoting "square rigged" sail; although considered to be
"surfing's ginger haired cousin" (Robby Naish), windsurfers can
perform jumps, spins, inverted loops, and other aerial or
freestyle maneuvers that cannot be matched by any sailboat.
-
windswell / short-period swell :
-
a local effect upon a section of the sea caused by a temporary
windstorm, wherein shallower swells of shorter duration and
closer periodicity (at 15 seconds or less) are generated by
passing weather; these storm swells usually don't interact with
the seafloor, so do not refract.
-
wind velocity :
-
one of the three key elements (along with wind duration and fetch
length) used when forecasting the characteristics of waves in a
storm area or in a wave generation area; it's ...
-
windward :
-
in the direction of the prevailing wind; toward the point or
quarter from which the wind blows.
-
wings :
-
informal term for inflatable bladders (air cells) that ride on
either side (surrounding) of back-mounted tanks, and have a
specified lift capacity, generally from 35 to 100 pounds; a
back-mounted buoyancy compensator.
-
within limits :
-
representation of a dive profile that conforms to the table
limits specified for the safe conditions of a dive.
-
woe betide :
-
distress comes, suffering comes to pass, trouble happens, grief
is visited upon, befallen by sorrow; not bêtise or betied.
[cf: woebegone (beset with woe)]
-
Woods Hole Oceanographic Institution :
-
a research facility, established 1930 and situated at a seaport
in Falmouth, at the southwestern extremity of Cape Cod, which
uses several ocean-going vessels and marine laboratories to study
oceanography, biology, meteorology, geology, and geophysics;
Woods Hole is also the site of the U.S. Marine Biological
Laboratory, and the U.S. Bureau of Commercial Fisheries
Biological Laboratory and Aquarium.
-
wrap :
-
technique for attaching guideline to a rock, especially at the
secondary tie-off.
-
wreck diving :
-
underwater exploration of shipwrecks and other sunken vessels,
especially for salvage or historical research.
-
yardarm :
-
either end of a center-mounted spar or yard; also called stick.
In modern vessels, the place where flags and pennants are often
attached.
-
yaw :
-
the rotation of a ship about its vertical axis so as to cause its
longitudinal axis to deviate from the heading in its horizontal
plane; the deviating motion or axial oscillation of a vessel
from its straight course or stable attitude.
-
YMCA :
-
abbreviation for Young Men's Christian Association.
-
Y-valve :
-
an air tank valve with two outlets; a dual outlet valve shaped in
the form of the letter 'Y' that's used with single cylinders;
also called a slingshot valve.
-
zeroth :
-
coming in a series before the first, as the zeroth level of
energy.
-
zeroth law of thermodynamics :
-
the principle that any two systems in thermal equilibrium with a
third system are in thermal equilibrium with each other.
-
zip tie :
-
ratcheted plastic strip that is used to securely attach accessory
items to a bolt clip; used in lieu of tied line.
-
Z-knife :
-
a line-cutter consisting of a handle and blade guard with a razor
blade inside a slot.
-
Zodiac :
-
brand name of an inflatable squad-sized assault boat with a stern
plate for the optional mounting of an outboard motor, wherein the
equipment is stowed inside the craft while the troops sit on the
inflated sides to direct it; designed by aquanaut Jacques Y.
Cousteau. [v: Avon, Parker, Brunswick]
-
Zulu :
-
the military's universal time designator coordinated with the
prime meridian of GMT or UTI / UTC.
-
Zytel :
-
brand name for a number of different formulations of high
strength, abrasion and impact resistant nylon engineered by
DuPont with varying proportions of fiberglass (13%-60%) added for
stiffness; some of these thermoplastic polyamide formulations
(including polyphthalamide) are reinforced with glass, mineral,
rubber, Kevlar, or Teflon in order to achieve specific
characteristics.
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