Military

directional term meaning at a right angle to the centerline or keel of a vessel.

ABS

American Bureau of Shipping

AFFF

aqueous film-forming foam

Aft or after

at, near, or toward the stern.

Aground

resting on the bottom (refers only to floating craft).

Aids to navigation

charted marks (such as buoys, beacons, lights, and electronic devices) to assist navigators.

Aloft

above the upper deck, as up in the rigging.

AM

amplitude modulated

Amidships

usually in the line of the keel, but sometimes halfway between bow and stern; often contracted to "midships."

Anchor

iron device so shaped as to grip the bottom and hold a vessel at her berth by the chain or rope attached.

Anchor buoy

a small buoy, usually painted a distinctive color, attached to an anchor by a light line and used to indicate the location of the anchor on the bottom.

Anemometer

instrument for measuring wind velocity.

Aneroid barometer

instrument used to measure atmospheric pressure.

ANSI

American National Standards Institute

AR

Army regulation

Arming

a piece of tallow or soap put in the cavity and over the bottom of a lead line.

Astern

behind the vessel; in the direction of the stern.

Athwartship

at right angles to the fore-and-aft line of a vessel; across the vessel in a direction at right angles to the keel.

ATTN

attention

AUTODIN

Automatic Digital Network

Backstay

SEE stay.

Bank

the side of a river channel, especially that part that usually rises above the water level. Also a shallow area of shifting sand, gravel, mud, and so forth (for example, a sandbank or mudbank).

Bar

a ridge or succession of ridges of sand or other substance, especially a formation extending across the mouth of a river or harbor or off a beach, and which may obstruct navigation.

Barrier reef

name given to reefs separated from the adjacent coast by a channel or lagoon.

Batten

long strip of wood or metal used for various purposes aboard ship.

Batten down

to close or make watertight, referring to hatches and cargo.

BC

barge cargo

BD

barge derrick

Beacon

a post or buoy placed over a shoal or bank to warn vessels of danger; also a signal mark on land.

Beam

the maximum width of a vessel, also called breadth.

Becket

loop of rope with a knot at one end to catch in an eye at the other.

Bend

a combination of turns and tucks by which a line is fastened to another one; to tie, as in securing a line to a cleat; to shackle a chain to an anchor; make fast.

Berth

a place for securing a vessel, either in the stream or alongside a wharf or other vessel.

BG

barge, liquid, nonpropelled

Bight

loop or double part of a rope; also, any part of a rope within the ends.

Bilge

the lowest interior position of a ship; the water that accumulates in the bilge is called bilge water.

Bilge pump

a pump used aboard vessels to remove accumulations of water in the bilge.

Binnacle

a compass stand made of nonmagnetic material, serving also to illuminate and protect the compass.

Bitter end

last end of a rope or inboard end of an anchor cable secured to a bitt.

Bitts

pair of heavy posts, set vertically in a deck or on a pier, to which mooring or towing lines are fastened.

Block

grooved pulley or sheave in a frame or shell provided with a hook, eye, or strap, by which it may be attached.

Boat hook

a wooden staff with a metal hook and prod at one end used for fending off or holding on when coming alongside a vessel or a wharf. It is also used for picking up small objects from the water.

Boom

spar having many uses, such as the boom for a sail, a boat boom, or a cargo boom.

Bow

the forward part of a vessel.

Bow anchors

two heavy anchors carried in the forward part of the vessel and ordinarily used in anchoring.

Bowline

a line leading from the bow of a vessel.

BR

barge, refrigerator

Breast line

a mooring line leading at an angle of about 90¡ from the fore-and-aft line of vessel to a wharf or another vessel.

Bridge

raised athwartships platform from which a vessel is steered and navigated.

Broaching to

to be thrown broadside to, in surf, heavy seas, or on the beach.

BS

breaking strain; breaking strength (in pounds)

Bulkhead

partition dividing the interior of a vessel into various compartments.

Bulwark

light plating or wooden extension of the hull above an exposed deck, furnishing protection against weather and loss of material or personnel.

Buoys

floating beacons, moored to the bottom, which by their shape and color convey valuable information as to position (such as channel, anchor, shoal, and rock).

C

celsius; circumference (in inches)

Capstan

vertical revolving drum, spool-shaped, used generally for heaving in towing or mooring lines.

Cathead

the outside spool on a winch.

CB

citizen's band

C.E.

compass error

C-E

communications-electronics

CEOI

Communications-Electronics Operation Instructions

CF

causeway ferry

CFR

Code of Federal Regulations

CG

Coast Guard

Chafe

to wear down by rubbing the surface of a line against a solid object.

Chafing gear

a guard of canvas, rope, or similar material placed around spars, lines, or rigging to prevent wear.

Chocks

round or oval holes in a vessel's bulwark, sometimes fitted with rollers, through which hawsers and ropes are passed; also blocks of wood for supporting boats, weights, and so on.

Cleat

wood or metal fitting that has two projecting horns to which a line is secured.

CMG

course made good

CO₂

carbon dioxide

Coaming

sidewall of a hatch projecting above the deck around the perimeter of the hatch to prevent water from going below.

Cofferdam

a watertight structure fixed on the side of a vessel for making repairs below the waterline, sometimes constructed on the beach around a part of a vessel.

COG

course over ground

Collision bulkhead

partition in the forward part of a vessel, of sufficiently heavy material, to stand the great strain if the bow is damaged.

Collision mat

heavy square of canvas, roped and fitted with various lines, which can be hauled under the side to plug a leak or shell hole temporarily.

COMDINST

commandant instructions

COML

commercial

Compass error

influences which prevent the compass needle from pointing to the geographic North Pole.

Compass north

an imaginary point toward which the north end of the compass needle actually points; its direction varies with both variation and deviation.

Compass rose

a circle graduated in degrees, clockwise from 0¡ at the reference direction to 360¡ , and sometimes also marked to show compass points. Compass roses are placed at convenient locations on charts to ease measurement of direction.

COMSEC

communications security

Control ship

a ship to guide and act as a headquarters for the control of waterborne traffic.

CONUS

continental United States

Cordage

a general form for line of all kinds.

Coxswain

the enlisted person in charge of a small craft.

CP

command post

CPR

cardio-pulmonary resuscitation

Crane

derrick used aboard ship for swinging boats in and out, also for handling weights.

CW

carrier wave; continuous wave

D

diameter

DA

Department of the Army

DADMS

DMA automated distribution management system

DAJAZA

Department of the Army Judge Advocate

Danger angle

an angle (sighted from a vessel), between two charted objects, which if not exceeded will allow the craft to safely pass a known hazard.

Danger bearing

a bearing, to a charted object, which is used to ensure that a craft will safely pass a certain known hazard, usually used to determine the point where a change of course can be safely made.

Davits

small cranes on a vessel that are used to hoist and lower boats, especially lifeboats.

DC

direct current

D.C.

District of Columbia

DD

Department of Defense

DDCP

Department of Defense Control Point

Deadeye

wooden block through which holes are pierced to receive a lanyard which is used especially with shrouds and stays.

Deadlights

strong shutters that screw down upon air portholes and keep out water in heavy weather.

Dead reckoning

calculation of ship's position kept by observing a vessel's course and distance by the log.

DEV.

deviation

Deviation

angular difference at the vessel between the direction of magnetic north and compass north. An error of the compass caused by the magnetic influence of the iron and steel within the ship itself.

Diesel engine

type of internal-combustion engine in which air is compressed to a temperature sufficiently high to ignite fuel injected directly into the cylinder.

Distribute

delivery, piece by piece, in turn to members of a group.

DMA

Defense Mapping Agency

DMAHC

Defense Mapping Agency Hydrographic Center

DMAHTC

Defense Mapping Agency Hydrographic and Topographic Center

DOD

Department of Defense

Dogs

small, bent metal fittings used to secure watertight doors, hatch covers, manhole covers, and so on to close and fasten as tight as possible.

Double-bottom tanks

watertight tanks formed by placing steel plating a few feet above the skin or outer bottom for the purpose of protecting a vessel if the outer bottom is damaged; used to store oil, water, and so forth.

DR

dead reckoning

Draft

single load of cargo; also refers to the depth of water which a vessel requires to float freely; the depth of a vessel from the waterline to the keel; also a sling load of cargo.

DSC

Digital Selective Calling

DSN

Defense Switched Network

Dunnage

loose material placed on the bottom of the hold above the ballast; used to stow cargo.

E

east

Ebb current

tidal current flowing out to sea.

EMP

electromagnetic pulse

Engine room

compartment containing the propulsion machinery of a vessel.

Ensign

flag; the emblem of a vessel's nationality.

EP

estimated position

EPIRB

emergency position-indicating radio beacon

Equator

that great circle which lies midway between the poles.

Estimate

an opinion or judgment of the nature, character, or quality of something.

ETA

estimated time of arrival

Eye splice

loop spliced in the end of a line.

F

Fahrenheit; friction

Fairlead

fittings or devices used in preserving the direction of line, chain, or wire so that it may be delivered fairly, or on a straight lead, to the sheave, drum, and so on.

Fairway

the ship channel part of the river or harbor where the navigable channel for large vessels lies.

Faking down

to lay down rope in long or circular turns (coils) so that each turn of rope overlaps the next one underneath in such a way that the rope is clear for running.

Fall

by common usage, the entire length of rope used in a tackle such as (plural) boat falls and cargo falls.

Fantail

extreme after deck of a vessel; after section of the main deck; upper and round part of the stern.

Fast

secure; also, secure with a mooring line.

Fathom

a nautical measure equal to 6 feet; used as a measure of depth of water.

FC

floating causeway

Fenders

a device of canvas, wood, or rope used over the side to take the shock of contact between vessel and wharf or other vessel when alongside.

Fid

a tapering pin, usually of wood, used to open the strands of line for splicing.

Fire-main system

permanent fire-control installation for an entire vessel consisting of water pipes, plugs to which hoses are attached, pumps, valves, and controls.

Flagstaff

small vertical spar at the stern on which the ensign is hoisted while a vessel is at anchor.

Flood current

tidal current flowing in from the sea.

FM

field manual; frequency modulation

fm

fathom

Fore

parts of a vessel at or adjacent to the bow; also parts between the mid-ship section and stern.

Fore and aft

lengthwise of a ship.

Forecastle

the upper deck forward of the foremast and included in the bow area.

Forestay

SEE stay.

Foul

entangle or impede.

Frames

skeleton structure, or ribs, of a vessel.

Freeboard

distance from the waterline to the top of the main deck, measured amidships.

ft

feet

GA.

gauge

Gale

wind with a velocity of 34 to 48 knots.

Galley

a vessel's kitchen.

Gangway

passageway or ladder up a ship's side.

Gear

general term for a collection of spars, ropes, blocks, and equipment.

GI

government issue

GMDSS

Global Marine Distress and Safety System

GPM

gallons per minute

GPS

global positioning system

Gripes

metal fastenings for securing a boat in its cradle; canvas bands fitted with thimbles in their ends and passed from the davit heads over and under a boat for securing for sea.

Ground tackle

anchor gear.

GT

gross tons

Gunwale

the uppermost continuous strake in a vessel's side; the upper edge of a vessel's hull.

Guy

steadying rope used to support a spar in a horizontal or inclined position.

h

hour

Harbor master

officer charged with executing regulations respecting the use of a harbor.

Hard over

turning the wheel as far as possible in a given direction.

Hatch

opening in a deck giving access to cargo holds.

Hawsepipes

iron castings in a bow of a vessel through which anchor chains run.

Hawser

large line or rope such as mooring or towing line.

Headway

a vessel's motion forward or ahead.

Heave to

to hold a vessel at sea without way; to check a vessel's way.

Heaving line

a light flexible line thrown to another vessel in order to allow a larger line or object to be transferred over.

Helm

the machine by which a vessel is steered.

HF

high frequency

Hitch

a tie for fastening by which a line is fastened to another object, either directly or around it, so that it will hold temporarily and can be readily undone.

Hold

space between the lowermost deck and the bottom of a vessel that is used for the stowage of ballast, cargo, and stores.

HQ

headquarters

HQDA

Headquarters, Department of the Army

HT

height

Hull

framework of a vessel, including all decks, but exclusive of masts, yards, riggings, and all outfit or equipment.

Hurricane

a cyclonic storm in the Western Hemisphere whose winds blow with a velocity of 64 knots or over.

Hz

hertz

IAW

in accordance with

IMCO

Inter-Governmental Maritime Consultative Organization

IMO

International Maritime Organization

in

inch(es)

Inboard

toward the centerline of a vessel; also the side next to a wharf or another vessel.

ISO

International Organization for Standardization

Jack staff

short, vertical flagpole at the bow of a ship from which the union jack is flown when a vessel is at anchor or moored.

Jury rig

a term applied to temporary structures, such as masts and rudders, used in an emergency.

Jury rudder

makeshift rudder used to steer a vessel when the rudder is damaged.

KC

kilocycles

Kedge

to move a vessel by carrying out a light anchor in a boat, dropping it overboard, and hauling the vessel up to it.

Keel

the timber or series of connected plates running from stem to sternpost on the bottom of the centerline of a vessel.

Keelson

timber or steel springer on top of the keel and used for strengthening a vessel's structure.

kHz

kilohertz

Knot

a unit of speed equal to 1 nautical mile per hour; also any tie or fastening formed with a line.

KT

kiloton

Lanyard

rope used to make anything fast, especially a short piece reeved through deadeyes, connecting shrouds, stays, and so on, to side of vessel.

LARC-LX

lighter, amphibious resupply cargo, 60-ton

LASH

lighter aboard ship

Latitude

angular distance north or south from the earth's equator measuring 0¡ at the equator and 90¡ at either pole.

Lazarette

a compartment used for storage purposes in the stern of a vessel.

LBP

length between perpendiculars

LCM

landing craft, mechanized

LCPL

landing craft, personnel, large

LCU

landing craft, utility

LCVP

Landing craft, vehicle, personnel

Lead line

weighted line with markings, which indicate the depth of water, also known as hand lead.

Leadsman

one who takes soundings or determines the depth of water by use of a lead line or hand lead.

Lee

the side opposite to that from which the wind blows.

Leeward

being in or facing the direction toward which the wind is blowing; (the lee side); being the side opposite the windward.

Left-hand propeller

when viewed from astern the propeller that turns counterclockwise while driving the boat ahead.

Left rudder

the movement of the rudder to the left of the centerline of the boat.

LF

low frequency

Lifeboat

small boat of wood, metal, or wood and metal placed aboard a vessel, with standard, prescribed equipment for use in emergencies.

Life lines

lines stretched fore and aft along the decks to give the crew safety against being washed overboard; lines thrown on board a wreck by a lifesaving crew; knotted lines secured to the span of lifeboat davits for hoisting and lowering ropes through to a man overboard.

Life jacket

an apparatus of buoyant material, usually kapok, designed to keep a person afloat.

Life raft

raft kept buoyant by cylindrical air chambers, designed to keep survivors of a disaster afloat for rescue.

Life ring

cork ring covered with canvas that is designed to support a person in water.

Line-throwing guns

guns used for lifesaving purposes that throw lines, attached to an eye in the shank of the projectile, from one vessel to another or to the shore; may be mounted or shoulder-type.

List

the inclination of a vessel to one side; as a list to port or a list to starboard.

LMSR

large, medium speed RO/RO

LNL

letter-number-letter

LOA

length overall

Locker

a chest, box, or compartment to stow things in.

LOD

line of departure

Logbook

book containing the official record of a vessel's activities and other data relevant to its navigation, which furnishes a complete chronological history of the vessel; often called log.

LO/LO

lift on/lift off

Longitude

a position measured as so many degrees east or west of the prime meridian.

Lookout

person stationed above decks for observing and reporting objects seen.

LOP

line of position

LOTS

logistics over-the-shore

LS

line size

LSV

logistics support vessel

LT

large tug

Lubber line

a fine black line drawn on an enameled plate inside of the bowl of a magnetic compass, indicating the centerline (along the keel) of the ship.

LWL

load waterline

m

minute(s)

MA

mechanical advantage

MAG

magnetic

Magnetic compass

main navigational aid on a vessel.

Magnetic course

the angle between magnetic north and the intended track of the vessel over the bottom.

Magnetic north

the direction of the magnetic North Pole from the ship; the direction in which the compass needle points when not affected by deviations.

Main deck

first complete deck running the full length of a vessel.

Maneuver

to make a series of changes in direction and position for a specific purpose.

Marlinespike

an iron or steel pin that tapers to a sharp point used to splice wire rope.

MARPOL

marine pollution

Mast

long pole or spar rising from the keel through the decks, to sustain yards, booms, sails, and other rigging.

Maximum ebb

the greatest speed of an ebb current. The ebb is the tidal current moving away from land or down a tidal stream.

Maximum flood

the greatest speed of a flood current. The flood current is the tidal current moving toward land or up a tidal stream.

MAYDAY

general distress call.

MD

Maryland

Meridians of longitude

great circles of the earth which pass through both poles and are used to establish location in east-west direction.

Mess

group of persons eating together; the meal so taken; to supply with messes or to eat them.

Messenger

light line made fast to a hawser in order to heave the latter in.

Messenger line

a small line used to haul in a heavier line.

MF

maritime frequency

MHz

Megahertz

Midships

SEE amidships.

MILSTAMP

Military Standard Transportation and Movement Procedures

MILSTRIP

Military Standard Requisitioning and Issue Procedures

MILVAN

military-owned demountable container

Mix

to combine or blend into one mass; to combine with another.

Moored

lying with both anchors down; tied to a pier or anchor buoy; also to secure a vessel other than by anchoring with a single anchor.

Mooring lines

cables or ropes used to tie up a vessel.

MOS

military occupational specialty

MPH

miles per hour

MQB

Marine Qualification Board

MQO

marine qualification officer

MSR

main supply route

MT

megaton

N

north

NATO

North Atlantic Treaty Organization

NBC

nuclear, biological, chemical

NCO

noncommissioned officer

NCS

network control station

NE

northeast

NFPA

National Fire Protection Association

NM

nautical miles

NNE

north by northeast

No

number

NOAA

National Oceanic and Atmospheric Administration

NOS

National Ocean Survey

NSA

National Security Agency

NW

northwest

OBA

oxygen-breathing apparatus

ODS

Office of Distribution Services

Offshore wind

a wind blowing from the land.

Outboard

toward the side of a vessel in relation to the centerline or outside the vessel entirely; also, the side away from a wharf or vessel alongside.

Pad eye

metal eye permanently secured to a deck or bulkhead, to which lines and cables may be secured.

PAN

personal area network

Pass a line

to carry a line to or around something, or to reeve through and make fast.

Painter

line in the bow of a small boat for towing or making fast.

Pay out

to let out a line or cable secured on board.

Pelorus (dumb) compass

dummy compass used to take sightings, determining the vessel's relative position to another object.

Pennant

small flag of various forms flown on a vessel, in which the long narrow flag is flown at the masthead and the triangular one is flown as a signal; short rope on pendant.

PFD

personal floatation device

Pier

a wharf which projects into a harbor, with water and accommodations for berthing vessels on two or more sides of it.

PKP

purple-K

POL

petroleum, oils, and lubricants

Port side

the left side of a vessel looking forward, indicated by a red running light when underway at night; an opening in a vessel's side; a harbor for cargo operations.

Potable water

drinkable water, meeting standards set by the US Public Health Service.

Prow

that part of the bow of a ship above water.

psi

pounds per square inch

Psychrometer

a dry and a wet thermometer placed on one instrument used to determine relative humidity and dew point.

PT

pusher tug

Quarter

general area from the middle of a vessel to the extreme stern; also to proceed with the quarter to the wind or sea; to bring the sea or wind first on one quarter and then on the other.

R. Fix

running fix

Range lights

two white lights on the mast in the forward part of a vessel; the second range light is in line in back of and higher than the first one.

Rat guard

funnel-like protective device placed over hawsers or mooring lines to keep rats from getting aboard.

RC

reserve component

Reef

a ridge of rock or coral lying at or near the surface of the water which could pose a danger to vessels; also, in sailing vessels, to reduce the area of the sail.

Reeve

pass or thread a rope through a block.

Relative humidity

the percentage of water saturation of the air.

Relay

to wind a line around a belaying pin or cleat to make it secure or to stop it.

Rig

a vessel's upper works; to fit out.

Rigging

the ropes of a ship; collective term for all the stays, shrouds, halyards, and lines that support a vessel's mast and booms and operate its movable parts; may be a "standing" or "running" rigging.

Right-hand propeller

when viewed from astern, the propeller that turns clockwise while driving the boat ahead.

Right rudder

the movement of the rudder to the right of the centerline of the boat.

RORO

roll on/roll off

R.P.M.

revolutions per minute

RRDF

RO/RO Discharge Facility

RSOI

Reception, Staging, Onward Movement and Integration

Rudder

flat structure hung vertically on the sternpost, just aft of the screw, and used to steer a vessel by offering resistance to the water when turned to an angle with the centerline.

Rudder amidships

the position of the rudder when it parallels the keel line of the vessel.

Rules of the road

the international and national regulations governing sailing of all vessels.

Running lights

all lights required to be shown during peacetime by a vessel that is under way.

S

south

SAR

search/air rescue

SB

size block

Scope

length of anchor chain or cable to which a vessel is riding.

Screw

propeller, located at a vessel's stern.

Screw current

the current caused by action of the propeller in water. It is discharged as a rotary current in the direction opposite to that of the vessel's movement.

Scuppers

small drains in a vessel's bulwark which are located near the deck.

Scuttle

to sink a vessel either by boring holes in her bottom or by opening her sea cocks; valves.

SE

southeast

Sea

disturbance of the ocean due to the wind (nautical sense).

Sea anchor

a device, normally a cone made out of canvas, which is put over (with a line attached) to reduce the vessel's speed over the water and to hold the bow or stern into the wind and sea. It is used when high wind and seas restrict the free navigation of vessels. Because of its construction, the sea anchor creates a drag in the water, thus reducing the speed of the vessel.

Sea buoy

last buoy before deep water that marks the channel to a harbor.

Sea cock

valve connecting with the outside sea water in the lower part of vessel which can be used to flood various parts.

Set

the direction in which a current flows; also, the direction in which a vessel is forced by the action of current or wind, or the combined force of both.

SF

safety factor; standard form

Shackle

U-shaped iron link with a removable pin that is used to make lines or blocks fast.

Shaft

rod transmitting power from a vessel's engine to its propeller.

Shaft alley

watertight passage enclosing the shaft and its supporting bearings; also "shaft tunnel."

Sheave

a grooved wheel or pulley inside a block over which a line runs.

Sheer

a sudden change in course; also, the longitudinal upward curve of the deck of a vessel when viewed from the side.

SHP

strain on the hauling part

Shrouds

guy ropes or cables that support a mast by running athwartship from top of the mast to both sides of the vessel.

Skeg

wood or metal arm extending abaft the keel with a bearing at its after end. It supports the rudder and protects the propeller.

Skin

the inside or outside of a ship's planking or plating.

SL

skill level

SMG

speed made good

Snatch block

block which can be opened on one side to receive a bight or rope.

SOA

speed of advance

SOG

speed over ground

SOP

standard operating procedure

SOS

save our ship

Soundings

depth of water surrounding a vessel which is determined by use of lead line or other equipment.

Span

piece of wire or rope fastened at each end to a fixture, such as a davit head.

Spar

pole, such as a mast or boom.

Splice

to join two ropes together by interweaving strands.

Spring line

a mooring line leading at an angle of about 45¡ from the fore-and-aft line of a vessel to a wharf or another vessel.

SSB

single side band

ST

small tug

Stadimeter

an instrument for measuring the distance to an object when the length or height of the object is known.

Stand

to maintain one's position; to perform duties.

Starboard side

right side of a vessel looking forward; indicated by a green running light when underway at night.

Station bill

bill posted in the crew's quarters and other conspicuous places listing the station of the crew at maneuvers and emergency drills; sometimes called muster roll.

Stay

a line or wire running fore and aft, used to support a mast, spar, or funnel; may be "forestay" or "backstay."

Stbd

starboard

Steerageway

slowest speed at which the rudder will act to change a vessel's course.

Stem

the vertical or nearly vertical forward extension of the keel, to which the forward ends of the strakes are attached.

Stern

the after end (rear) of a vessel.

Stern line

a line leading from the stern of a vessel.

Sternpost

timber or steel bar extending from the keel to main deck at the stern of a vessel.

STON

short ton

Storm

a marked disturbance in the normal state of the atmosphere; also, a wind with a velocity of 55 to 65 knots.

Stow

to put away, to lock up for safekeeping in a proper place.

Strake

continuous line of plates running from bow to stern that contributes to a vessel's skin.

Stranded

of a vessel, run ashore.

Strongback

fore-and-aft spar extending from stem to stern on a lifeboat and serving as a raised spreader for a boat cover; also a strong bar placed across a hatch opening to hold hatch boards or covers.

Superstructure

any structure built above the top full deck.

Surf

the breaking swell or waves on a shore or shelving beach; breakers collectively.

Surf line

that point offshore, where waves and swells become breakers. The water area from this point to the beach is known as the surf zone.

Surge

the swell or heave of the sea; to slack off a line.

SW

southwest

Swell

the unbroken rise and fall of the sea surface persisting after the originating cause of the motion has ceased; a succession of long noncrested waves, as that continuing after a gale or other disturbance some distance away.

Swim

to propel oneself in water by natural means.

SWL

safe working load for a single part of a line.

SZ

surface zero

T

true north

TB

technical bulletin

Tackle

a combination of lines and blocks working together and giving a mechanical advantage to assist in lifting or moving.

Tail block

block having a rope about it and an end hanging several feet from it.

Tarpaulin

heavy, treated canvas used as a cover.

TC

Transportation Corps

Tidal current

the flow of water caused by the rise and fall of the tide.

Tiller

bar of iron or wood connected with the rudderhead and lead line, usually forward, in which the rudder is moved as desired by the tiller, and quadrant is the form of tiller most frequently used in modern vessels.

TM

technical manual

TNT

trinitrotoluene

Topside

above decks, such as on the weather deck or bridge.

Towing bitts or towing posts

vertical posts on a vessel to which towing or mooring lines are secured.

TRADOC

United States Army Training and Doctrine Command

Trim

difference in draft at the bow and stern of a vessel; manner in which a vessel floats on the water, whether on an even keel or down by the head or stern; shipshape. To adjust a vessel's position in the water by arranging ballast, cargo, and so on. To arrange for sailing; to assume, or cause a vessel to assume, a certain position, or trim, in the water.

Trough

the hollow between two wave crests or swells.

Turnbuckle

link threaded on both ends of a short bar that is used to pull objects together.

TW

total weight

UCMJ

Uniform Code of Military Justice

UEL

upper explosive limit

UL

Underwriter's Laboratories

Underway

a vessel is said to be underway when she is not anchored, moored, aground, or beached.

Union Jack

flag consisting of the blue star-studded field in the corner of the national ensign, flown at the jack staff by ships at anchor.

US

United States (of America)

USAML

United States Army Marine License

USCG

United States Coast Guard

VA

Virginia

VAR.

variation

Variation

angular difference at the vessel between the direction of true north and magnetic north.

Vehicle

liquid content which acts as a binding and drying agent in paint.

VHF

very high frequency

W

west; weight

Wake

a vessel's track or trail through the water.

Watch

period of time on duty, usually 4 hours in length; the officers and crew who tend the working of a vessel during the same watch.

Way

motion or progress through the water.

Weather

toward the point from which the wind blows; the side toward the wind; the windward.

Weather deck

deck having no overhead protection; uppermost deck.

Weigh

to raise the anchor off the bottom.

Wharf

projecting platform of timber, stone, or other material which extends into water deep enough for vessels to be accommodated alongside for loading or unloading.

Wheel

the instrument attached to the rudder by which a vessel is steered.

Whipping

the lashing of the end of a rope.

Winch

a piece of machinery, which operates a shaft, fitted with a drum or drums upon which lines or cables are wound to hoist or haul an object.

Windlass

apparatus in which horizontal or vertical drums or wheels are operated by means of a steam engine or motor for handling heavy anchor chains, hawsers, and so on.

Windward

toward the wind; being in or facing the direction from which the wind is blowing.

Wings

platforms on either side of the bridge.

WO

warrant officer

Yard

spar crossing a mast horizontally.

Yardarm

outer quarter of a horizontal spar attached to the mast athwartships, equipped with blocks for reeving signal halyards.

Yaw

to steer badly, zigzagging back and forth across the intended course of a boat; to go out of the line of course.