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ABAFT : Toward the stern of a ship; back; behind; back of; further aft than.
ABEAM : At right angles to the keel.
ABOARD : On or in a ship.
ABREAST : Side by side; over against; opposite to.
ACCOMMODATION LADDER : Stairs slung at the gangway, leading
down the vessel's side to a point near the water, for ship access from small
AFT : Near the stern; toward the stern.
AFTER BODY : That portion of a ship's body aft of the midship
AFTER FRAMES : Frames aft of amidships, or frames near the
stern of the ship.
AFTER PEAK : The aftermost tank or compartment forward of the
AFTER PERPENDICULAR : A line perpendicular to the base line
intersecting the after edge of the stern post at the designed water line. On
submarines or ships having a similar stern, it is a vertical line passing
through the point where the designed water line intersects the stern of the
AIR CASING : A ring-shaped plate coaming surrounding the
stack and fitted at the deck just below the umbrella, to protect the deck from
heat and to help ventilate the fireroom.
AIRCRAFT CARRIER : A vessel designed to carry aircraft and
fitted with a flying deck from which aircraft are launched and on which they
land. A floating flying field which usually operates as a unit of a fleet.
AIR PORT : An opening in the side or deck house of a vessel,
usually round in shape and fitted with a hinged frame in which a thick glass is
secured. The purpose of the air port is to provide light and ventilation to and
vision from the interior of the ship. In some instances the air port is also
provided with an additional solid metal hinged cover for purposes of protection
of the interior should the glass be damaged or to prevent light from showing
ALOFT : In the top or upper rigging; on the yards; above the
AMIDSHIPS : In the vicinity of the middle portion of a vessel
as distinguished from her ends. The term is used to convey the idea of general
locality but not that of definite extent.
ANCHOR : A heavy iron or steel implement attached to a vessel
by means of a rope or chain cable for holding it at rest in the water. When an
anchor is lowered to the bottom, the drag on the cable causes one or more of the
prongs, called flukes, to sink into or engage the ground which provides holding
* Ring (Shackle) - Device used to attach the anchor chain to the shank of the
anchor. The ring is secured to the top of the shank with a riveted pin.
* Shank - The long center part of the anchor running between the ring and the
* Crown - The lower section of the anchor to which the shank is secured. The
shank is fitted to the crown with (on some anchors) a pivot or ball-and-socket
joint that allows a movement from 30o to 45o either way.
* Stock - a crossmember, spar, or rod, that rolls the anchor into an attitude
that enables the flukes to dig into the sea bed. Most newer anchors are
* Arms - The parts that extend from each side of the crown.
* Throat - The inner part of an arm where it joins the shank.
* Fluke or Palm - The broad shield part of the anchor that extends upward from
* Blade - That part of the arm extending outward below the fluke.
* Bill or Pea - Tip of the palm or fluke.
* Cup - on a Mushroom Anchor, the round ground-holding portion corresponding to
the fluke of other designs
ANCHOR'S ACOCKBILL: when the anchor is suspended
perpendicularly from the cathead, ready to be let go.
Anchor's Apeak - when
the anchor cable is drawn in so tight as to bring the ship directly over it.
Anchor's Atrip - when
the anchor is lifted out of the ground. Same as "Anchor's Aweigh".
Anchor's Awash - when
the anchor is hove up to the surface of the water.
Anchor's Aweigh - said
of an anchor, during the weighing (raising) of the anchor, when just clear of
Anchor Ball - a round
black shape hoisted in the forepart of a vessel to show that it is at anchor
Anchor Bell - a warning
bell mounted on the foredeck and rung while at anchor in foggy conditions
Anchor Bend - a very
secure knot used to tie rode to anchor
Anchor Detail - a group
of men who handle ground tackle when the ship is anchoring or getting underway
ANCHOR, BOWER : The large anchors carried in the bow of a
vessel. Three are usually carried, two (the main bowers) in the hawse pipes, or
on bill boards, and a third (spare) lashed on deck or elsewhere about the vessel
for use in the event either of the main bowers is lost. The weight varies with
the size and service of the ship.
ANCHOR BRAKE: The anchor brake, as the name implies, is a
friction brake designed to stop, or hold, the shaft thereby preventing the
anchor from dropping.
ANCHOR BUOY: A small buoy occasionally used to mark the
position of the anchor when on the bottom; usually painted green (starboard) or
red (port), and secured to the crown of the anchor by a buoy rope.
Anchor Chain - chain
attached to the anchor. The chain acts partially as a weight to keep the anchor
lying next to the ground so that it can hold better.
Anchor Chocks - deck
fittings for storing the anchor
Anchor Ice - ice of any
kind that is aground in the sea
ANCHOR, KEDGE : A small anchor used for warping or kedging.
It is usually planted from a small boat, the vessel being hauled up toward it.
The weight varies, being usually from 900 to 1,200 pounds.
Anchor Light - a white
light displayed by a boat or ship at anchor. Two such lights are displayed by a
ship over 150 feet (46 m) in length, Also called a riding light.
Anchor Pocket - a
recess in the bow for storing an anchor; also called a billboard
ANCHOR, SEA : This is not a true anchor, as it does not sink
to the bottom. It is a conical-shaped canvas bag required by the Steamboat
Inspection Service to be carried in each lifeboat. When placed overboard it
serves a double purpose in keeping the boat head-on into the sea and in
spreading a vegetable or animal oil from a container placed inside the bag. It
is sometimes called an oil spreader.
ANCHOR, STREAM : An anchor weighing from about one-fourth to
one-third the weight of the main bowers and used when mooring in a narrow
channel or harbor to prevent the vessel's stern from swinging with the current
or the tide.
Anchor Watch - making
sure the anchor is holding and that the boat is not drifting. Important during
rough weather and at night. Most marine GPS units have an Anchor Watch alarm
ANEMOMETER - an instrument for measuring the speed of the wind
ANEROID BAROMETER - an instrument that determines atmospheric pressure by the
effect of such pressure on a thin-metal cylinder from which the air has been
ANGLE OF ATTACK - the angle between the chord of a sail and the relative wind
or between the chord of a hydrofoil such as a keel or rudder and a vector line
representing the true path through the water, taking the amount of sideslip or
leeway into account. The term applies to a sail only when the relative wind is
forward of the beam.
ANGLE : Same as angle bar.
ANGLE BAR : A bar of angle-shaped section used as a stiffener
and for attachment of one plate or shape to another.
ANGLE BULB : A structural shape having a bulb on one flange
of the angle, used as a frame, beam, or stiffener.
ANGLE COLLAR : A collar or band made of one or more pieces of
angle bar and fitted tightly around a pipe, trunk, frame, longitudinal, or
stiffener intersecting or projecting through a bulkhead or deck for the purposes
of making a watertight or oil tight joint. See Stapling.
ANGLE OF SAIL - the angle between the vessel's compass course and the true
ANTI-FOULING - a type of paint that is resistant to barnacles, moss, seaweed,
marine grass and various other plant and animal life that would want to adhere
to a vessel's hull and slow or damage the hull. There are four basic types:
ablative, sloughing, modified epoxy, and vinyl, all of which usually contain
ANTITRADES - the prevailing westerly winds of the middle latitudes. The winds
to the north of the trade winds which blow in the opposite direction Since the
early square rigged ships could not sail to weather, they had to cross to the
New World on the trades or tradewinds, and return by a more Northerly route in
ANNEAL : To heat a metal and to cool it in such a fashion as
to toughen and soften it. Brass or copper is annealed by heating to a cherry red
and dipping suddenly into water while hot. Iron or steel is slowly cooled from
the heated condition to anneal.
Anti-trip Chine - a flared out aft section of the side and bottom of a boat.
The purpose is to prevent the hard chine of the boat catching a wake or small
wave on a sharp turn.
Apeak or Apeek - 1. more or less vertical. (You may hold your oars apeak,
raise your gaff apeak or be apeak your anchor. 2. (of a dropped anchor) as
nearly vertical as possible without being free of the bottom. 3. (of an anchored
vessel) having the anchor cable as nearly vertical as possible without freeing
the anchor. Sometimes it is necessary to do this in order to let wave action
break the anchor loose.
Aport - on or toward the port side of a ship; as in: “Come ten degrees aport.”
Apparent Horizon - the plane where the earth or water and sky seem to meet
Apparent Time - the time of day indicated by the hour angle of the sun; i.e.
apparent noon locally would be the moment when the sun is at its zenith. A
properly mounted sundial indicates apparent time. The concept is employed when
making navigation calculations. A sun sight at noon and a simple calculation can
produce a very accurate line of longitude
Apparent Wind - the direction and velocity of the wind relative to the speed
and direction of the boat which is derived from the True Wind and Wind of Motion
APPENDAGES : Relatively small portions of a vessel extending
beyond its main outline as shown by transverse and water plane sections,
including such items as shafting, struts, bossings, docking and bilge keels,
propellers, rudder, and any other feature, extraneous to the hull and generally
Apron - a timber fitted abaft the stem to re-enforce the stem and give a
sufficient surface on which to land the hood ends of the planks
ARBOR : The principal axis member, or spindle, of a machine
by which a motion of revolution is transmitted.
ARCHING : Sometimes used in lieu of "hogging".
Arc of Visibility - the portion of the horizon over which a lighted aid to
navigation is visible from seaward
Arctic Ocean - the northern polar ocean north of Alaska, Canada, Russia,
AREA OF SECTIONS : The area of any cross section of the
immersed portion of a vessel, the cross section being taken at right angles to
the fore and aft centerline of the vessel.
Argosy - an extremely large ship or fleet of ships, especially merchant
Arm - 1. a branching waterway from a harbor or bay 2. The crosspiece of an
anchor from the crown to flukes
Armada - a fleet of warships
Arming - tallow or other sticky substance placed in the recess at the lower
end of a sounding lead for obtaining a sample of the bottom
Ash Can - World War II slang for a depth charge
Ashore - On shore or beach; as in, "Send someone ashore to find fresh water."
Aspect Ratio - the relationship between the height of a sail and its breadth.
i.e. A sail with a height of 30' and a breadth of 20' has an aspect ratio of
3:2. A tall and narrow sail is said to have a high aspect ratio.
Astarboard - in or toward the direction of the right side of the ship when
facing forward, as in: "Pass the marker, then turn hard astarboard."
ASTERN : Signifying position, in the rear of or abaft the
stern; as regards motion, the opposite of going ahead; backwards.
Astrolabe - a primitive portable insturment used to measure celestial angles.
The predecessor to the sextant.
Astronavigation - Celestial navigation. Determining your positon by sightings
of celestial bodies.
Astronomical Almanac - a catalogue of tables showing the location of various
celestial bodies at specific moments in time throughout the year; consulted by
the navigator in preparation for taking sights of celestial bodies. Such tables
were known as "The Ephemeris" since the 18th C. until 1981 when it was jointly
published by the US and Britian.
Atmospherics - interference in reception of radio communications caused by
natural phenomena such as lightning or sunspots; as in: “Atmospherics are so bad
I can’t understand his transmission.”
Atoll - a roughly circular island created by and of coral, most common in the
South Pacific, surrounding a lagoon
Athwart or Athwartships - at right angles to the fore and aft or centerline
of a ship. Across, from side to side, transverse, across the
line of a vessel's course.
Aurora - a luminous phenomena caused by electrical discharge in the upper
Aurora Australis - an aurora in the southern hemisphere
Aurora Borealis - an aurora in the northern hemisphere
Auto Pilot - an electrical automated steering mechanism used to steer a
preset course based on the apparent wind. These are expensive and very
susceptible to breakdown, but most handy when there is not enough wind to
operate a windvane. Compare to Windvane on this page
Auxiliary - 1. an engine used when there is no wind or for assistance in
approaching a dock, etc. 2. a tender carried on deck
Avast! - given as a command to stop, cease, and desist the action currently
being carried out (archaic term used in movies)
Awash - setting so low in the water that the water is constantly washing
across the top surface
Aweigh - the position of the anchor just as it clears the bottom when raising
Awl - a pointed wooden or steel tool used to poke holes in leather and for
unlaying the ply of a rope for splicing Compare to Marlinespike and Fid
Azimuth - the horizontal direction of a celestial point from a terrestrial
Azimuth Circle - a circular sighting device that fits around the ship's
compass for taking bearings of terrestrial or celestial bodies
ATHWARTSHIP : Reaching across a vessel, from side to side.
AUXILIARIES : Various winches, pumps, motors, engines, etc.,
required on a ship, as distinguished from main propulsive machinery (boilers and
engines on a steam installation).
AWNING : A roof like canopy of canvas suspended above a
vessel's decks, bridges, etc., for protection against sun and weather.
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BACK BAR : Used for the same purpose but on the opposite side
to a bosom bar.
BACK BOARD : A portable back support nicely designed and fitted on the after
side of the stern thwart in a small motor or row boat.
BACK STAY : Stays which extend from all mast levels, except
the lower, to the ship's side at some distance abaft the mast. They serve as
additional supports to prevent the masts going forward and also contribute to
the lateral support, thereby assisting the shrouds.
BAFFLE : A plate or structure placed in the line of flow of
fluids or gases to divert the flow in order to obtain greater contact with
heating or cooling surfaces.
BALANCED RUDDER : A rudder with its axis between the forward
and after edge.
BALK : A piece of timber from 4" to 10" square.
BALLAST : Any weight carried solely for the purpose of making
the vessel more seaworthy. Ballast may be either portable or fixed, depending
upon the condition of the ship. Fixed or permanent ballast in the form of sand,
concrete, lead, scrap, or pig iron is usually fitted to overcome an inherent
defect in stability or trim due to faulty design or changed character of
service. Portable ballast, usually in the form of water pumped into or out of
the bottom, peak, or wing ballast tanks, is utilized to overcome a temporary
defect in stability or trim due to faulty loading, damage, etc., and to submerge
BALLAST TANKS : Tanks provided in various parts of a ship for
introduction of water ballast when necessary to add weight to produce a change
in trim or in stability of the ship, and for submerging submarines.
BALLAST WATER : Sea water, confined to double bottom tanks,
peak tanks, and other designated compartments, for use in obtaining satisfactory
draft, trim, or stability.
BALLASTED CONDITION : A condition of loading in which it
becomes necessary to fill all or part of the ballast tanks in order to secure
proper immersion, stability, and steering qualities brought about by consumption
of fuel, stores, and water or lack of part or all of the designed cargo.
BALSA : A light wood; a South American raft made of light
BARGE : A craft of full body and heavy construction designed
for the carriage of cargo but having no machinery for self-propulsion.
BATTEN : Long, thin, strips of wood, steel, or plastic,
usually of uniform rectangular section used in the drafting room and mold loft
to lay down the lines of a vessel, but sometimes thinned down in the middle or
at the ends to take sharp curves. A strip of wood or steel used in securing
tarpaulins in place. To secure by means of battens, as to "batten down a hatch."
BATTENS, CARGO : A term applied to the wood planks or steel
shapes that are fitted to the inside of the frames in a hold to keep the cargo
away from the shell plating; the strips of wood or steel used to prevent
shifting of cargo.
BATTENS, SEAM : Wood seamstraps which connect the edges of
small boats having a single thickness of planking. They give additional
stiffness to the plank, are continuous, and frames are notched out to fit over
BATTLE CRUISER : A naval vessel having high speed, wide
radius of action, guns of large size and range, and moderate protection; often
defined as a ship cruiser speed and battleship armament, with full protection
against cruisers and smaller vessels and capable of operation in all weather.
BATTLESHIP : A naval vessel having a large displacement, good
speed, large radius of action, maximum armament, maximum protection against gun
fire, bombs, and torpedoes, ability to keep at sea in all weathers and to bear
the brunt of sea fighting as a line-of-battle ship.
BEAM : The extreme width of a ship. Also an athwartship or
longitudinal member of the ship's structure supporting the deck.
BEAM KNEE : A bracket between a frame or stiffener and the
end of a beam; a beam arm.
BEAM LINE : A line showing the points of intersection between
the top edge of the beam and the molded frame line, also called "molded deck
BEAM, TRANSOM : A strong deck beam situated in the after end
of the vessel connected at each end to the transom frame. The cant beams which
support the deck plating in the overhang of the stern are attached to and
radiate from it.
BEAM, PLATE ANGLE : A beam made from a flat plate, with the
flange bent at right angles as by an angle-bending machine.
BEARDING LINE : A term applied to the intersection of the
molded line of planking or plating and the stem, stern post, and keel, usually
in connection with wood shipbuilding.
BEARER : A term applied to foundations, particularly those having vertical web
plates as principal members. The vertical web plates of foundations are also
BEARING : A block on or in which a journal rotates; a bearing-block.
BELL : In pipe fitting, the recessed or enlarged female end of a pipe into which
the male end of the next pipe fits. In plumbing, the expanded female portion of
a wiped joint.
BELL MOUTHED : A term used to signify the open end of vessel or pipe when it
expands or spreads out with an increasing diameter, thus resembling a bell--also
called trumpet mouthed.
BELOW : Underneath the surf the water. Underneath a deck or decks.
BENDING ROLLS : A large machine used to give curvature to plates by passage in
contact with three rolls.
BENDING SLAB : Heavy cast-iron blocks with square or round holes for "dogging
down," arranged to form a large solid floor on which frames and structural
members are bent and formed.
BERTH : A term applied to a bed or a place to sleep. Berths, as a rule, are
permanently built into the structure of the staterooms or compartments. They are
constructed singly and also in tiers of two or three, one above the other. When
single, drawers for stowing clothing are often built in underneath. Tiers of
berths constructed of pipe are commonly installed in the crew space. Also, a
place for a ship.
BETWEEN DECKS : The space between any two, not necessarily adjacent, decks.
Frequently expressed as "Tween Decks."
BEVEL : A term for a plane having any other angle than 90 degrees to a given
reference plane. Also, a small tool similar to a try square except that the
blade is adjustable to taking bevels.
BEVEL, CLOSED : A term applied where one flange of a bar is bent to form an
acute angle with the other flange.
BEVEL, OPEN : A term applied where one flange of a bar is bent to form an obtuse
angle with the other flange. Frame bars in the bow and the stern of a vessel are
give an open bevel to permit access for riveting to shell and to keep the
standing flange parallel to the deck beams.
BIBB : A cock or valve with a bent outlet; strictly, the bent outlet.
BIGHT : A loop or bend in a rope; strictly, any part between the two ends may be
termed the bight.
BILGE : The rounded portion of a vessel's shell which connects the bottom with
side. To open a vessel's lower body to the sea.
BILGE PLATES : The curved shell plates that fit the bilge.
BILGES : The lowest portion of a ship inside the hull, considering the inner
bottom where fitted as the bottom hull limit.
BILL BOARD : An inclined platform, fitted at the intersection of the forward
weather deck and the shell, for stowing an anchor. It may be fitted with a
tripping device for dropping the anchor overboard. Seldom fitted since the
stockless anchor has come into general use.
BINNACLE : A stand or case for housing a compass so that it
may be conveniently consulted. Binnacles differ in shape and size according to
where used and the size of the compass to be accommodated. A binnacle for a
ship's navigating compass consists essentially of a pedestal at whose upper end
is a bowl-shaped receptacle having a sliding hoodlike cover. This receptacle
accommodates the gimbals supporting the compass. Compensating binnacles are
provided with brackets or arms on either side, starboard and port, for
supporting and securing the iron cylinders or spheres used to counteract the
quadrantal deviation due to the earth's magnetization of the vessel. This type
of binnacle is usually placed immediately in front of the steering wheel, having
its vertical axis in the vertical plane of the fore-and-aft centerline of the
BITTER END : The inboard end of a vessel's anchor chain which is made fast in
the chain locker.
BITTS : A terms applied to short metal or wood columns extending up from a base
plate secured to a deck or bulwark rail or placed on a pier and to timbers
extended up through and a short distance above a deck for the purpose of
securing and belaying ropes, hawsers, cables, etc. Also called bollards.
BITUMASTIC : A black tarlike composition largely of bitumen or asphalt and
containing such other ingredients as rosin, portland cement, slaked lime,
petroleum, etc. It is used as a protective coating in ballast and trimming
tanks, chain lockers, shaft alleys, etc.
BLEEDER : A small cock, valve, or plug to drain off small quantities of fluids
from a container or system.
BLIND PULLEY : A circular block of hard wood with rounded edges perforated by
several holes having grooves running from them to one side of the block. One of
these blocks is secured to an end of a part of the standing rigging, as a
shroud, and another to the chain plate or to some part of the ship and the two
are connected to one another by a lashing passing through the holes. Commonly
called "dead eyes".
BLINKER LIGHTS : Two electric lanterns secured at the ends of the signal yard
and operated by controllers and a telegraph key for use in night signaling by
BLOCK : The name given to a pulley or sheave, or a system of
pulleys or sheaves, mounted in a frame or shell and used for moving objects by
means of ropes run over the pulleys or sheaves. The prefixes, single, double,
triple, etc., indicate the number of pulleys or sheaves in the block. The five
principal parts of a block are (a) the shell, or outside frame, (b) the sheave,
on which the rope runs, (c) the pin, on which the sheave turns, (d) the strap,
by which the hook is held in position and which provides bearing for the pin,
and (e) the hook, which may be open, sister, or shackle and fixed or swivel. The
opening between the top of the sheave and the shell is called the swallow, that
between the bottom of the sheave and the shell is called the breech, and the
device attached to the bottom of the block opposite the hook for securing the
standing part of the fall to the block is called the becket.
BLOCK, CHEEK : A half shell block with a single sheave bolted
to a mast or other object which serves as the other half shell or cheek. Usually
used in connection with halyards.
BLOCK, FIDDLE : A block having two sheaves of different
diameters placed in the same plane one above the other.
BLOCK, SNATCH : A single sheave block having one side of the
frame hinged so that it can be opened to allow the bight of a rope to be placed
on the sheave, thus avoiding the necessity of threading the end of the rope
through the swallow of the block. Usually employed as a fair lead around
BLOWER : A mechanical device used to supply air under low
pressure for artificial ventilation and forced draft, usually of the centrifugal
BOARDING : The act of going on board a ship.
BOBSTAYS : The chains or ropes attached underneath the outer
end of the bowsprit and led aft to the stem to prevent the bowsprit from jumping
up. Where two are fitted they are called the inner and the cap bobstays; when
three are fitted they are called the inner, the middle, and the cap bobstays.
BODY PLAN : A plan consisting of two half transverse
elevations or end views of a ship, both having a common vertical center line, so
that the right-hand side represents the ship as seen from ahead, and the
left-hand side as seen from astern. On the body plan appear the forms of the
various cross sections, the curvature of the deck lines at the side, and the
projections, as straight lines of the water lines, the bow and buttock lines,
and the diagonal lines.
BOILER : Any vessel, container, or receptacle that is capable
of generating steam by the internal or external application of heat. The two
general classes are fire tube and water tube.
BOILER CASING : Walls forming a trunk leading from the boiler
room to the boiler hatch, which protect the different deck spaces from the heat
of the boiler room, etc.
BOILER ROOM : A compartment in the hold, in the middle or
after section of a vessel, where the boilers are placed.
BOLLARDS : See "bits".
BOLSTER PLATE : A piece of plate adjoining the hawse hole, to
prevent the chafing of the hawser against the cheek of a ship's bow. A plate for
support like a pillow or cushion. A piece of timber used as a support. A
BOLT : A metal rod used as a fastening. With few exceptions,
such as drift bolts, a head or shoulder is made on one end and a screw thread to
carry a nut is cut on the other.
BOLTING UP : Securing by means of bolts and nuts parts of a
structure in proper position for permanent attachment by riveting or welding. A
workman employed on this work is called a "bolter-up".
BONJEAN CURVES : Curves of areas of transverse sections of a
ship. The curves of the moments of these areas above the base line are sometimes
BONNET : A cover used to guide and enclose the tail end of a
BOOBY HATCH : An access hatch from a weather deck protected
by a hood from sea and weather. The hood is often fitted with a sliding cover to
BOOM : A term applied to a spar used in handling cargo, or to
which the lower edge of a fore-and-aft sail is attached.
BOOM TABLE : An outrigger attached to a mast or a structure
built up around a mast from the deck to support the heel bearings of booms and
to provide proper working clearances when a number of booms are installed on or
around one mast.
BOOT TOPPING : An outside area on a vessel's hull from bow to
stern between certain waterlines to which special air, water, and
grease-resisting paint is applied; also the paint applied to such areas.
BORING BAR : A portable, heavy duty tool, used for boring,
counter boring, reboring, facing, grooving, etc., where true alignment is of
BOSOM : The inside of an angle bar.
BOSOM BAR : An angle fitted inside another.
BOSOM PLATE : A plate bar or angle fitted in the bosoms of
two angle bars to connect the ends of the two angles as if by a butt strap.
BOSS : The curved, swelling portion of the ship's underwater
hull around the propeller shaft.
BOSS PLATE : The plate that covers the boss.
BOTTOM : That portion of a vessel's shell between the keel and the lower turn of
BOTTOM, OUTER : A term applied to the bottom shell plating in
a double bottom ship.
BOTTOM PLATING : That part of the shell plating which is
below the water line. More specifically, the immersed shell plating from bilge
BOW : The forward end of the ship. The sides of the vessel at
and for some distance abaft the stem, designated as the right-hand, or starboard
bow, and the left-hand, or port bow.
BOW LINES : Curves representing vertical sections parallel to
the central longitudinal vertical plane of the bow end of a ship. Similar curves
in the aft part of a hull are called buttock lines. Also, a rope leading from
the vessel's bow to another vessel or to a wharf for the purpose of hauling her
ahead or for securing her.
BOWSPRIT : A spar projecting forward over the bow for the
purpose of holding the lower ends of the head sails.
BRACE : A rope attached to the yard arm, used to alter the
position of the yard arm in a horizontal plane. The operation is known as
trimming the sail.
BRACKET : A steel plate, commonly of triangular shape with a
reinforcing flange on its free edge, used to connect two parts such as deck beam
to frame, frame to margin plate, etc.; also used to stiffen or tie beam angles
to bulkheads, frames to longitudinals, etc.
BRAILS : Ropes rove through blocks fastened to a spar and
attached to the leech of sail. The overhauling of these ropes gathers the sail
up against the spar.
BRAZING : The joining of certain metals by the use of a hard
BREADTH, EXTREME : The maximum breadth measured over plating or planking,
including beading or fenders.
BREADTH, MOLDED : The greatest breadth of the vessel measured
from heel of frame on one side to heel of frame on other side.
BREADTH, REGISTERED : Measured amidships at its greatest
breadth to outside of plating.
BREAK OF FORECASTLE or POOP : The point at which the partial decks known as the
forecastle and poop are discontinued.
BREAKWATER : A term applied to plates or timbers fitted on a
forward weather deck to form a V-shaped shield against water that is shipped
over the bow.
BREAST HOOK : A triangular-shaped plate fitted parallel to
and between decks or side stringers in the bow for the purpose of rigidly
fastening together the peak frames, stem, and outside plating; also used, in
conjunction with the above duties, to fasten the ends of side stringers firmly
BRIDGE : A high transverse platform, often forming the top of
a bridge house, extending from side to side of the ship, and from which a good
view of the weather deck may be had. An enclosed spaced called the pilot house
is erected on the bridge in which are installed the navigating instruments, such
as the compass and binnacle, the control for the steering apparatus, and the
signals to the engine room. While the pilot house is generally extended to
include a chartroom and sometimes staterooms, a clear passageway should be left
around it. As the operation of the ship is directed from the bridge or flying
bridge above it, there should also be a clear, open passage from one side of the
vessel to the other. The term is also applied to the narrow walkways, called
connecting bridges, which connect the bridge deck with the poop and forecastle
decks. This type of bridge is usually found on tankers and is desirable whenever
bulwarks are not fitted.
BRIDGE HOUSE : A term applied to an erection or
superstructure fitted about amidship on the upper deck of a ship.
BRIDGE, NAVIGATING, or FLYING : The uppermost platform
erected at the level of the top of the pilot house. It generally consists of a
narrow walkway supported by stanchions, running from one side of the ship to the
other and the space over the top of the pilot house. A duplicate set of
navigating instruments and controls for the steering gear and engine room
signals are installed on the flying bridge so that the ship may be navigated in
good weather from this platform. Awnings erected on stanchions and weather
cloths fitted to the railing give protection against sun and wind.
BROKEN BACKED : Said of a vessel when, owing to insufficient
longitudinal strength, grounding, or other accident, her sheer is reduced or
lost, thereby producing a drooping effect at both ends.
BROW : A gangplank, usually fitted with rollers at the end
resting on the wharf to allow for the movement of the vessel with the tide. See
BUCKLE : A distortion, such as a bulge; to become distorted;
to bend out of its own plane.
BUCKLER : Generally, but not exclusively, applied to various
devices used to prevent water from entering turret gun ports, hawse and chain
BUCKLING : The departure of a plate, shape, or stanchion from
its designed plane or axis when subjected to load or to strains introduced
during fabrication, thereby reducing its ability to carry loads.
BUILDING SLIP : An inclined launching berth where the ship is
BULKHEAD : A term applied to any one of the partition walls
which subdivide the interior of a ship into compartments or rooms. The various
types of bulkheads are distinguished by the addition of a word or words,
explaining the location, use, kind of material or method of fabrication, such as
fore peak, longitudinal, transverse, watertight, wire mesh, pilaster, etc.
Bulkheads which contribute to the strength and seaworthiness of a vessel are
called strength bulkheads, those which are essential to the watertight
subdivision are watertight or oiltight bulkheads, and gastight and fumetight
bulkheads serve to prevent gas or fumes from leaving or entering certain parts
of a vessel.
BULKHEAD, AFTER PEAK : A term applied to the first transverse
bulkhead forward of the stern post. This bulkhead forms the forward boundary of
the after-peak tank and should be made watertight.
BULKHEAD, COLLISION : The foremost transverse watertight
bulkhead in a ship which extends from the bottom of the hold to the freeboard
deck. It is designed to keep water out of the forward hold in case of collision
damage. Usually, this is the fore peak bulkhead at the after end of the fore
BULKHEAD, JOINER : Wood or light metal bulkhead serving to
bound staterooms, offices, etc. and not contributing to the ship's strength.
Included under this head are corrugated metal, pressed panel, pilaster,
aluminum, stainless steel, etc.
BULKHEAD STIFFENER : Members attached to the plating of a
bulkhead for the purpose of holding it in a plane when pressure is applied to
one side. The stiffener is generally vertical, but horizontal stiffeners are
used and both are found on same bulkheads. The most efficient stiffener is a T
section; flat bars, angles, channels, zees, H and I sections are commonly used.
BULKHEAD, SWASH : A strongly built, nontight bulkhead placed
in oil or water tanks to slow down the motion of the fluid set up by the motion
of the ship.
BULKHEAD, WIRE MESH : A partition or enclosure bulkhead, used
largely in store rooms, shops, etc., made of wire mesh panels.
BULLDOZER : A machine, usually hydraulic or electric, for
bending bars, shapes or plates while cold.
BULWARK : A term applied to the strake of shell plating or
the side planking above a weather deck. It helps to keep the deck dry and also
serves as a guard against losing deck cargo or men overboard. Where bulwarks are
fitted, it is customary to provide openings in them which are called freeing
ports, to allow the water that breaks over to clear itself.
BULWARK STAY : A brace extending from the deck to a point
near the top of the bulwark, to keep it rigid.
BUMPED : A term applied to a plate which has been pressed or
otherwise formed to a concave or convex shape. Used for heads of tanks, boilers,
BUNK : A built-in berth or bed.
BUNKER : A compartment used for stowage of coal or oil fuel.
BUOYANCY : Ability to float; the supporting effort exerted by
a liquid (usually water) upon the surface of a body, wholly or partially
immersed in it.
BUOYANCY, RESERVE : The floating or buoyant power of the unsubmerged portion of the hull of a vessel. Usually referred to a specific
condition of loading.
BURDEN : The carrying capacity of a vessel expressed in long
BURNERS : Men who operate gas torches for burning plates and
shapes to proper sizes for assembly into the structure.
BURR : The rough, uneven edge of a sheared or burned plate or
around a punched or burned hole. Also a washer shaped piece of metal through
which the rivet is inserted and against which the rivet point is riveted over.
BUTT : That end or edge of a plate or timber where it comes
squarely against another piece, or, the joint thus formed. The long edge of a
plate is called the edge and the short edge is called the end.
BUTTOCK : The rounded-in overhanging part on each side of the
stern in front of the rudder, merging underneath in the run.
BUTTOCK LINES : The curves shown by taking vertical
longitudinal sections of the after part of a ship's hull parallel to the ship's
keel. Similar curves in forward part of hull are "bow lines".
BUTT STRAP : A term applied to a strip of plate serving as a
connecting strap between the butted ends of the plating. The strap connections
at the edges are called seam straps.
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CABIN : The interior of a deck house, usually the space set aside for the use of
officers and passengers.
CAISSON : A watertight structure used for raising sunken vessels by means of
compressed air. Also the floating gate to close the entrance to a drydock.
CALIBER : The term applied to the inside diameter of a cylinder, tube, or pipe.
The length of a naval gun is frequently expressed in terms of its caliber.
CALKING : The operation of jamming material into the contact area to make a
joint watertight or oiltight.
CAM : A projective part of a wheel or other simple moving piece in a machine,
shaped to give predetermined variable motion in repeating cycles to another
piece against which it acts.
CAMBER, ROUND OF BEAM : The weather decks of ships are
rounded up or arched in an athwartship direction for the purpose of draining any
water that may fall on them to the sides of the ship where it can be led
overboard through scuppers. The arching or rounding up is called the camber or
round of the beam and is expressed in inches in connection with the greatest
molded breadth of the ship in feet, thus, "the main deck has a camber of 10
inches in 40 feet." It is measured at the center line of the ship at the
greatest molded breadth and is the distance from the chord to the top of the
CAMEL : A decked vessel having great stability designed for
use in lifting sunken vessels or structures. A submersible float used for the
same purpose by submerging, attaching, and pumping out. See also caisson. A
wooden float placed between a vessel and a dock acting as a fender.
CANT : A term signifying an inclination of an object from a
perpendicular; to turn anything so that it does not stand perpendicular or
square to a given object.
CANT FRAME : A frame the plane of which is not square to the keel.
CAPPING : The fore and aft finishing piece on top of the
clamp and sheer strake at the frame heads in an open boat; called a covering
board, margin plank, or plank sheer in a decked-over boat.
CAPSTAN, STEAM : A vertical drum or barrel operated by a
steam engine and used for handling heavy anchor chains, heavy hawsers, etc. The
engine is usually nonreversing and transmits its power to the capstan shaft
through a worm wheel. The drum is fitted with pawls to prevent overhauling under
the strain of the hawser or chain when the power is shut off. The engine may be
disconnected and the capstan operated by hand through the medium of capstan
CARGO : Merchandise or goods accepted for transportation by
CARGO BOOM : A heavy boom used in loading cargo. See "boom".
CARGO HATCH : A large opening in the deck to permit loading of cargo.
CARGO MAT : A mat, usually square and made of manila rope,
used to protect the deck covering while taking stores, etc., on board.
CARGO NET : A square net, made in various sizes of manila
rope or chain, and used in connection with the ship's hoisting appliances to
load cargo, etc., aboard the vessel.
CARGO PORT : An opening, provided with a watertight cover or
door, in the side of a vessel of two or more decks, through which cargo is
received and discharged.
CARLINGS : Short beams forming a portion of the framing about
deck openings. Also called headers when they support the ends of interrupted
CASINGS, ENGINE and BOILER ROOMS : The walls or partitions
forming trunks above the engine and boiler spaces, providing air and ventilation
and enclosing the uptakes. They extend somewhat above the weather deck, or
superstructure deck if fitted, and are of sufficient size to permit installation
and removal of engines and boilers. Doors are fitted at the several deck levels
to permit access to the gratings and ladders.
CAVIL : A heavy timber fastened to the forward or after bitts
about midway between the base and top to form a cleat. The bitt so built.
CEILING : A term applied to the planking with which the
inside of a vessel is sheathed. Also applied to the sheet metal or wood
sheathing in quarters and storerooms.
CEILING, FLOOR : Planking fitted on top of the floors or
double bottom in the cargo holds.
CEILING, HOLD : Thick strakes of planking fastened to the
inside flanges or edges of the framing in the cargo holds.
CENTER LINE : The middle line of the ship from stem to stern
as shown in any water line view.
CENTER OF BUOYANCY : The geometric center of gravity of the
immersed volume of the displacement or of the displaced water, determined solely
by the shape of the underwater body of the ship. It is calculated for both the
longitudinal location, forward or aft of the middle perpendicular, and the
vertical location above the base line or below the designed waterline.
CENTER OF FLOTATION : The geometric center of gravity of the
water plane at which the vessel floats, forward or aft of the middle
perpendicular. It is that point about which a vessel rotates longitudinally when
actuated by an external force without change in displacement.
CENTER OF GRAVITY : The point at which the combined weight of
all the individual items going to make up the total weight of the vessel may be
considered as concentrated; generally located longitudinally forward or aft of
the middle perpendicular and vertically above bottom of keel or below a stated
CENTER OF LATERAL RESISTANCE : The point through which a
single force could act and produce an effort equal to the lateral resistance of
the vessel. It is ordinarily assumed to coincident with the center of gravity of
the immersed central longitudinal planes.
CENTER OF PRESSURE : The point in a sail or an immersed plane
surface at which the resultant of the combined pressure forces acts.
CENTRAL LATERAL PLANE : The immersed longitudinal vertical
middle plane of a vessel.
CHAFING GEAR: A guard of canvas or rope put around spars,
mooring lines, or rigging to prevent them from wearing out by rubbing against
CHAFING PLATE : A plate fitted to take the wear due to
dragging moving gear or to protect ropes from wearing where they rub on sharp
edges. Also fitted on decks under anchor chains.
CHAIN LOCKER : Compartment in forward lower portion of ship
in which anchor chain is stowed.
CHAIN LOCKER PIPE: CHAIN PIPE : The iron-bound opening or
section of pipe leading from the chain locker to the deck, through which the
chain cable passes.
CHAIN PLATE : A bar or plate secured to the shell of a vessel
to which the standing rigging is attached.
CHAINS : Usually refers to heavy chains attached to the
anchor. Also applied to the lower parts of standing rigging which are attached
to the chain plates.
CHAIN STOPPER : A device used to secure the chain cable when
riding at anchor, thereby relieving the strain on the windlass and for securing
an anchor in the housing position in the hawse pipe. Stoppers differ widely in
construction. For the smaller cables they are of rope, usually hemp, with a
stopper knot or an iron toggle in the outer end and a lanyard for lashing to the
cable. For larger cables wire rope is used in lieu of hemp, while for the
largest cables the stoppers are of heavy chain fitted with slip hooks and
turnbuckles for adjusting and for equalizing the strain when more than one
stopper is attached to a cable. According to its use a chain stopper is termed a
"riding stopper" or a "housing stopper". The inner end of the stopper is
attached to a deck pad by means of a shackle or lashing.
CHAMFER : A bevel surface formed by cutting away the angle of
two intersecting faces of a piece of material.
CHART HOUSE : A small room adjacent to the bridge for charts
and navigating instruments.
CHINE : The line formed by the intersection of side and
bottom in ships having straight or slightly curved frames.
CHINSING : The inserting of oakum or cotton between the plank
edges of boats to secure watertightness. Also called calking.
CHIPPER : A workman who chips, cuts, or trims the edges of
plates, shapes, castings or forgings, using either hand or pneumatic tools, in
order to secure a good calking edge, fit or finish.
CHOCK : A term applied to oval-shaped castings, either open
of closed on top, and fitted with or without rollers, through which hawsers and
lines are passed. Also applied to blocks of wood used as connecting or
reinforcing pieces, filling pieces, and supports for life boats. Also applied to
the brackets fitted to boiler saddles to prevent fore and aft motion and to
small brackets on the webs of frames, beams and stiffeners to prevent tipping of
CLAMP : A metal fitting used to grip and hold wire ropes. Two
or more may be used to connect two ropes in lieu of a short splice or in turning
in an eye. Also a device, generally operated by hand, for holding two or more
pieces of material together, usually called a "C" clamp. In small boats, the
main longitudinal strength member at the side and under the deck beams in
decked-over boats, and at the gunwale in open boats.
CLEATS : Pieces of wood or metal, of various shapes according
to their uses, usually having two projecting arms or horns upon which to belay
ropes. The term Cavil is sometimes applied to a cleat of extra size and
CLINCH : To spread or rivet the point of a pin or bolt upon a
plate or ring to prevent it from pulling out; to turn the point of a nail back
into the wood to give it greater holding power.
CLINOMETER : An instrument used for indicating the angle of roll or pitch of a
CLIP : A four- to six-inch angle bar welded temporarily to
floors, plates, webs, etc. It is used as a hold-fast which, with the aid of a
bolt, pulls objects up close in fitting. Also, short lengths of bar, generally
angle, used to attach and connect the various members of the ship structure.
CLOSE BUTT : A riveted joint in which the ends of the
connected members are brought into metal-to-metal contact by grinding and
pulling tight by clips or other means before the rivets are driven.
CLUB-FOOT : A fore foot in which displacement or volume is placed near the keel
and close to the forward perpendicular, resulting in full water lines below
water and fine lines at and near the designed water line, the transverse
sections being bulb-shaped. Also called a bulb or bulbous bow.
COAMING, BULKHEAD : A term applied to the top and bottom strakes of bulkheads,
which are usually made thicker than the remainder of the plating and which act
as girder web plates in helping to support the adjacent structure.
COAMING, HATCH : A frame bounding a hatch for the purpose of stiffening the
edges of the opening and forming the support for the covers. In a steel ship it
generally consists of a strake of strong vertical plating completely bounding
the edges of a deck opening.
COAMING, HOUSE : A term applied to the narrow vertical plates bounding the top
and bottom of a deck house, made somewhat thicker than the side plating and
forming a frame for the base and top of the house. Also applied to the heavy
timbers which form the foundation of a wood deck house.
COAMING, MANHOLE : The frame worked around a manhole to stiffen the edges of the
plating around the opening and to provide a support for the cover.
COCK : A valve which is opened or closed by giving a disc or a tapered plug a
quarter turn. When a plug is used it is slotted to correspond with the ports in
COCKPIT : A term used in connection with small boats to refer to an uncovered,
sunken place or pit, usually for the accommodation of passengers.
COFFERDAMS : Void or empty spaces separating two or more compartments for the
purpose of insulation, or to prevent the liquid contents of one compartment from
entering another in the event of the failure of the walls of one to retain their
COLLAR : A piece of plate or a shape fitted around an opening for the passage of
a continuous member through a deck, bulkhead, or other structure to secure
tightness against oil, water, air, dust, etc.
COLLIER : A vessel designed for the carrying of coal, which may or may not be
fitted with special appliances for coal handling.
COLLISION MAT : A large mat used to close an aperture in a vessel's side
resulting from a collision.
COMPANION : The cover over a companionway.
COMPANIONWAY : A hatchway or opening in a deck provided with a set of steps or
ladders leading from one deck level to another for the use of personnel.
COMPARTMENT : A subdivision of space or room in a ship.
COMPASS : The compass is the most important instrument of navigation in use on
board ship, the path of a ship through the water depending on the efficient
working and use of this instrument. There are two types of navigational
compasses, the magnetic, which has long been in use, and the gyroscopic, which
has been developed within recent years. The former is actuated by the earth's
magnetism, the latter by that property of a rapidly rotating body by which, when
it is free to move in different directions, it tends to place its axis parallel
to the earth's axis, that is, north and south.
COMPASS, GYROSCOPIC : The gyroscopic compass may have one or more gyroscopes. It
is usually located as nearly at the rolling axis of the ship as possible and in
a protected place. The directive force of a gyroscope, while 100 times more
powerful than that of the magnetic needle, is still further amplified by an
auxiliary electric motor sufficiently powerful to operate the compass card in
azimuth. Repeater compasses, installed wherever desired about the ship, are
operated by the master compass containing the gyroscopes by a simple electric
follow-up system. The gyroscopic compass is not affected by magnetism from any
source. It points to the true north, not the magnetic pole, and hence required
no calculations for corrections. It is not affected by cargo or any type of
magnetic field which may surround it and it is not disturbed by jars. It has
become standard equipment in navies and is coming into more general use on
COMPASS, MAGNETIC : There are two kinds of magnetic compasses, the Dry Card
Compass and the Liquid Compass. The Dry Compass consists essentially of a number
of magnetic needles, suspended parallel to each other, and fastened to the rim
of a circular disc that has a paper cover upon which are marked the points of
the compass and the degrees. This card rests upon a pivot centered in the
compass bowl, which in its turn is suspended by gimbals in the binnacle or
stand, the latter having means for lighting the card at night and for adjustment
of compass errors due to magnetism of the ship. In the Liquid Compass, the bowl
is filled with alcohol and water or with oil. The needles are sealed in parallel
tubes and form a framework which connects the central boss with the outer rim,
the whole resting upon a pivot in the compass bowl. Upon the rim are printed the
points and degrees. The liquid compass is less susceptible to vibration and
shock. The "Standard Compass" on board ship is a magnetic compass.
COMPASS, RADIO : This apparatus is used to determine the direction from which a
radio wave is sent and the location of the sending station. It consists of a
coil of wire wound around a frame and mounted on a vertical shaft which can be
rotated. The radio wave is received by the operator, being loudest when the coil
is at right angles to the wave and ceasing when the coil is parallel to the
wave. Positions are determined by plotting the bearings to two known sending
stations. The apparatus is especially valuable when a vessel is sufficiently
close to the shore to contact two sending stations.
COMPOSITE VESSEL : A vessel with a metal frame and a wooden shell and decks.
CORDAGE : A comprehensive term for all ropes of whatever size or kind on board a
COTTER, KEY : A solid key or wedge used to secure a wheel on a shaft or the
COTTER, SPRING : A round split pin used to lock a nut on a bolt. The pin is
passed through a hole in the bolt outside of the nut and the ends of the pin
opposite its head are forced apart by a chisel or similar tool, thus preventing
the cotter from slipping out.
COUNTER : That part of a ship's stern which overhangs the stern post, usually
that part above the water line.
COUNTERSINK : A term applied to the operation of cutting the sides of a drilled
or punched hole into the shape of the frustrum of a cone. Also applied to the
tool with which countersinking is done.
COUNTERSUNK HOLE : A hole tapered or beveled around its edge to allow a rivet or
bolt head or a rivet point to seat flush with or below the surface of the
riveted or bolted object.
COUNTERSUNK RIVET : A rivet driven flush on one or both sides.
COUPLING : A device for securing together the adjoining ends of piping,
shafting, etc., in such a manner as will permit disassembly whenever necessary.
Flanges connected by bolts and pipe unions are probably the most common forms of
CRADLE : A support of wood or metal shaped to fit the object which is stowed
CRADLE, BOAT : The heavy wood or metal supports for a ship's boat, cut to fit
the shape of the hull of the boat and usually faced with leather, in which the
boat is stowed.
CRADLE, LAUNCHING : The structure of wood, or wood and steel, which is built up
from the sliding ways, closely fitting the shell plating, which supports the
weight of the ship and distributes it to the sliding ways when a ship is being
launched. The extent of the cradle and the number of sections into which it may
be divided depends on the weight and length of the ship.
CRADLE, MARINE RAILWAY : The carriage on which the ship rests when being docked
on a marine railway.
CRANE : A machine used for hoisting and moving pieces of material or portions of
structures or machines that are either too heavy to be handled by hand or cannot
be handled economically by hand. Bridge, gantry, jib, locomotive, and special
purpose cranes are used in shipyards.
CRIBBING : Foundations of heavy blocks and timbers for supporting a vessel
during the period of construction.
CROSS-SPALL : A temporary horizontal timber brace to hold a frame in position.
Cross-spalls are replaced later by the deck beams.
CROSS TREES : A term applied to athwartship pieces fitted over the trees on a
mast. They serve as a foundation for a platform at the top of a mast or as a
support for outriggers.
CROWN : Term sometimes used denoting the round-up or camber of a deck. The crown
of an anchor is located where the arms are welded to the shank.
CROW'S NETS : A lookout station attached to or near the head of a mast.
CRUISER : A high speed vessel designed to keep at sea for extended periods and
in which protection against gun fire is subordinated to speed and long radius of
action. Light cruisers and heavy cruisers are so designated in accordance with
the calibre of the guns carried. Used largely for scouting and convoy work.
CRUTCH : A term applied to a support for a boom. Also applied to the jaw of a
boom or gaff.
CUDDY : A galley structure on deck; a small cabin.
CUTWATER : The forward edge of the stem at or near the water line is called the
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DAGGER : A piece of timber that is fastened to the poppets of
the bilgeway and crosses them diagonally to keep them together. Dagger applies
to anything that stands in a diagonal position in a fore and aft plane.
DAGGER PLANK : One of the planks which unite the heads of the poppets or stepping-up pieces of the cradle on which the vessel rests in
DAVIT : A device used to lower and raise ship's boats and
sometimes for other purposes. The rotary, or most common type, consists of a
vertical pillar, generally circular in section, with the upper portion bent in a
fair curve and having sufficient outreach to clear the side of the ship plus a
clearance. Each ship's boat has two davits, one near its bow and one near its
stern; they both rotate, lifting the boat, by means of blocks and falls
suspended from the overhanging end, from its stowage position on deck and
swinging it clear of the ship's side. This type of davit is usually stepped in a
socket attached to the side of the vessel or on the deck next below the boat
deck near the side and held in place at the boat deck by a keeper or bearing.
DEAD EYE : See "Blind Pulley".
DEAD FLAT : The midship portion of a vessel throughout the
length of which a constant shape of cross section is maintained.
DEADLIGHT : A applied to a port lid or cover; a metal shutter
fitted to protect the glass in a fixed or port light. Often incorrectly applied
to a fixed light in a deck, bulkhead or shell.
DEAD RISE : The angle which the straight portion of the
bottom of the floor of the midship section makes with the base line. It is
expressed by the number of inches rise above the base line in the half-beam of
DEADWEIGHT : The difference between the light displacement
and the full load displacement of a vessel; the total weight of cargo, fuel,
water, stores, passengers, and crew and their effects that a ship can carry when
at her maximum allowable draft.
DEADWEIGHT CARGO : The number of tons remaining after
deducting from the deadweight the weight of fuel, water, stores, dunnage, and
crew and their effects necessary for use on a voyage. Also called "useful" or
"paying deadweight", "deadload", and "burden".
DEADWOOD : The reinforcing structure built in between the
keel and keelson in the after body of a ship or back of the joint between the
stem and the keel in the fore body.
DECK : A deck in a ship corresponds to a floor in a building.
It is the plating, planking, or covering of any tier of beams above the inner
bottom forming a floor, either in the hull or superstructure of a ship. Decks
are designated by their location as upper deck, main deck, etc., and forward
lower deck, after superstructure deck, etc. The after portion of a weather deck
was formerly known as the quarter deck and on warships is allotted to the use of
DECK BOLT : A special type of bolt used to secure the planks
of a wood deck to the frames or deck plating.
DECK, BULKHEAD : The uppermost continuous deck to which all
main transverse bulkheads are carried. This deck should be watertight to prevent
flooding adjacent compartments if a compartment is bilged.
DECK, FREEBOARD : The deck to which the classification
societies require the vessel's freeboard to be measured. Usually the upper
DECK HEIGHTS : The vertical distance between the molded lines
of two adjacent decks.
DECK HOUSE : A term applied to a partial superstructure that
does not extend from side to side of a vessel as do the bridge, poop, and
DECK LINE : See "Beam line".
DECK MACHINERY : A term applied to capstans, windlasses,
winches, and miscellaneous machinery located on the deck of a ship.
DECK PLANKS, or PLANKING : A term applied to the wood
sheathing or covering on a deck. Oregon pine, yellow pine, and teak are most
commonly used. The seams between the planks should be thoroughly caulked.
DECK PLATING : A term applied to the steel plating of a deck.
DECK STRINGER : The strip of deck plating that runs along the
outer edge of a deck.
DECK, TURTLE : A term applied to a weather deck that is
rounded over from the shell of the ship so that it has a shape similar to the
back of a turtle. Used on ships of the whaleback type and on the forward weather
deck of torpedo boats.
DEEP FLOORS : A term applied to the floors at the ends of a
ship which are deeper than the standard depth of floor at amidships.
DEEP TANKS : Tanks extending from the bottom or inner bottom
of a vessel up to or higher than the lowest deck. They are fitted with hatches
so that they may be used for cargo when the vessel is loaded in lieu of the
ballast water carried when the vessel is "light." They are placed at either end
or both ends of the machinery space as deemed necessary.
DEEP WATERLINE : The waterline at which the vessel floats
when carrying the maximum allowable load.
DEPTH MOLDED : The vertical distance from the molded base
line to the top of the uppermost strength deck beam at side, measured at
midlength of the vessel.
DERRICK : A device consisting of a kingpost, boom with
variable topping lift, and necessary rigging for hoisting heavy weights, cargo,
DESTROYER : A naval vessel of small displacement and high
speed, armed with light, rapid-fire guns and deck torpedo tubes, used for convoy
and scouting work and as a protection to capital ships [originally "torpedo boat
destroyer"]. Larger vessels of this type are called destroyer leaders.
DIAGONAL LINE : A line cutting the body plan diagonally from
the frames to the middle line in the loft lay-out and usually a mean normal to a
group of frames of similar curvature, representing a plane introduced for line
DISHED PLATES : Plates, generally of circular shape, which
have been furnaced or pressed into a concave form.
DISPLACEMENT : The volume of fluid displaced by a freely
floating and unrestrained vessel, the weight of which exactly equals the weight
of the vessel and everything on board at the time the displacement is recorded.
Displacement is expressed in either cubic feet or in tons of salt or fresh
DISPLACEMENT CURVES : Curves drawn to give the displacement
of the vessel at varying drafts. Usually these curves are drawn to show the
displacement in either salt or fresh water, or in both, the salt water curves
being based on 35 cubic feet to a ton and fresh water curves on 36 cubic feet to
a ton. Corrections are made from these basic standards for variable density of
DISPLACEMENT, DESIGNED : The displacement of a vessel when
floating at her designed draft.
DISPLACEMENT, FULL LOAD : The displacement of a vessel when
floating at her greatest allowable draft as established by the classification
societies. In warships, an arbitrary full load condition is established.
DISPLACEMENT, LIGHT : The displacement of the vessel complete
with all items of outfit, equipment, and machinery on board, but excluding all
cargo, fuel, water, stores, passengers, dunnage, and the crew and their effects.
Naval and merchant practice differs in one particular; in the former the
machinery weights are dry, while the merchant light condition includes the water
and oil in the machinery with boilers at steaming level.
DOCK : A basin for the reception of vessels. Wet docks are
utilized for the loading and unloading of ships. Dry docks are utilized for the
construction or repair of ships.
DOCKYARD : A shipyard or plant where ships are constructed or
DOG : A short metal rod or bar fashioned to form a clamp or
clip and used for holding watertight doors, manholes, or pieces of work in
DOG SHORES : Diagonal braces placed to prevent the sliding
ways from moving when the shores and keel blocks are removed before launching.
Dog shores are the last timbers to be knocked away at a launching. Also called
"daggers" or "dagger shores".
DOLLY BAR : A heavy steel bar used to hold against the heads
of rivets while the points are being clinched when the space is not sufficient
to permit the use of a regular holding-on tool.
DOLPHIN : A term applied to several piles that are bound
together, situated either at the corner of a pier or out in the stream and used
for docking and warping vessels. Also applied to single piles and bollards on
piers that are used in docking and warping.
DONKEY ENGINE : A small gas, steam, or electric auxiliary
engine set on the deck and used for lifting, etc.
DOOR, AIRTIGHT : A door so constructed that when closed it
will prevent the passage of air under a small pressure. Used on air locks to
boiler rooms under forced draft and in similar locations.
DOOR FRAME : The frame surrounding a door opening on which
the door seats.
DOOR, JOINER : A light door fitted to staterooms and quarters
where air and watertightness is not required. Made of wood, light metal, and
metal-covered wood. Metal joiner doors with pressed panels are extensively used.
DOOR, WATERTIGHT : A door so constructed that, when closed,
it will prevent water under pressure from passing through. A common type
consists of a steel plate, around the edges of which a frame of angle bar is
fitted, having a strip of rubber attached to the reverse side of the flange that
is fastened to the door plate. The strip of rubber is compressed against the toe
of the flange of an angle-iron door frame by dogs or clamps.
DOOR, WEATHERTIGHT : A term applied to outside doors on the
upper decks which are designed to keep out the rain and spray.
DOUBLE BOTTOM : A term applied to the space between the inner
and outer skins of a vessel called respectively the "inner bottom" and "shell",
usually extending from bilge to bilge and for nearly the whole length of the
vessel fore and aft, and subdivided into water or oil tight compartments. In
some cases, and generally in warships, the inner bottom is carried above the
bilges to a deck at or near the waterline. Where more than one inner skin is
fitted, as is sometimes the case, the two spaces are known as the "lower bottom
tank" or "void" and the "upper bottom tank". The outer skin is known as the
"shell", the skin next to it as the "lower inner bottom", and the third skin as
the "upper inner bottom".
DOUBLING PLATE : An extra plate secured to the original
plating for additional strength or to compensate for an opening in the
DOWEL : A pin of wood or metal inserted in the edge or face
of two boards or pieces to secure them together.
DRAFT, DRAUGHT : The depth of the vessel below the waterline
measured vertically to the lowest part of the hull, propellers, or other
reference point. When measured to the lowest projecting portion of the vessel,
it is called the "draft, extreme"; when measured at the bow, it is called
"draft, forward"; and when measured at the stern, the "draft, aft"; the average
of the draft, forward, and the draft, aft is the "draft, mean", and the mean
draft when in full load condition is the "draft load".
DRAFT MARKS : The numbers which are placed on each side of a
vessel near the bow and stern, and often also amidships, to indicate the
distance from the number to the bottom of the keel or a fixed reference point.
These numbers are six inches high, are spaced twelve inches bottom to bottom
vertically, and are located as close to the bow and stern as possible.
DRAG : The designed excess of draft, aft, over that forward,
measured from the designer's waterline. The drag is constant and should not be
confused with trim.
DRIFT : When erecting the structure of a ship and rivet holes
in the pieces to be connected are not concentric, the distance that they are out
of line is called the drift. This should be corrected by reaming the holes, but
common practice, which is prohibited in naval work, is to drive tapered pins,
called "drift pins", into the unfair holes to force them into line.
DRIFT PIN : A conical-shaped pin gradually tapered from a
blunt point to a diameter a little larger than the rivet holes in which it is to
be used. The point is inserted in rivet holes that are not fair, and the other
end is hammered until the holes are forced into line.
DRY DOCK, FLOATING : A hollowing floating structure of L- or
U-shaped cross section, so designed that it may be submerged to permit floating
a vessel into it, and that it may then raise the vessel and itself so that the
deck of the dock and consequently the bottom of the vessel is above the level of
the water. The bottom of a floating dry dock consists of one or more pontoons or
rectangular-shaped vessels with high wing structure erected on one or both sides
according to whether the section is to be L- or U-shaped. The deck of the
pontoon is fitted with stationary keel blocks and movable bilge blocks which can
be pulled under a vessel from the top of the wing structure. Pumps are fitted in
the wings by which the dock can be quickly submerged or raised. Floating dry
docks are used for repairing and painting the under-water portions of vessels
and for docking a damaged vessel.
DRY DOCK, GRAVING : A basin excavated at a waterway and
connected thereto by gates or a caisson which may be opened to let a vessel in
or out and then closed and the water pumped out. The dock is fitted with
stationary keel blocks and movable bilge blocks, which usually are fitted on
rack tracks, allowing them to be pulled under a vessel before the water is
pumped out. Graving docks are common in navy yards, and although more expensive
to construct than floating dry docks, they are practically permanent and supply
a more rigid foundation for supporting a ship. The gate of a graving dry dock is
usually a caisson which is a complete vessel in itself, having a strong
rectangular-shaped keel and end posts which bear against the bottom sill and
side ledges at the entrance of the dry dock. The caisson is designed so that its
draft may be adjusted by water ballast until it bears against the sill and
ledges and is equipped with flood valves and power pumps to make this
adjustment. When a ship is to be docked, sluice valves in the caisson or in the
deck structure are opened until the water in the dock reaches the same level as
the water outside. The caisson is then floated to one side, allowing a vessel to
enter the dock. The caisson is then floated back to close the entrance,
completely separating the basin from the waterway, and after the vessel is lined
up over the keel blocks the water is pumped out of the dry dock.
DRY DOCK, RAILWAY : A railway dock consists of tracks built
on an incline on a strong foundation and extending from a distance in-shore
sufficient to allow docking a vessel of the maximum size for which the dock is
built, to a distance underwater sufficient to allow the same vessel to enter the
cradle. The cradle running on the tracks may be of wood or steel fitted with
keel and bilge blocks and sufficiently weighted to keep it on the track when in
the water. A hoisting engine with a winding drum or wild cat is fitted at the
in-shore end of the railway which operates the cradle by a cable or chain. This
type of dry dock is used for docking small ships. It is commonly called a
DUCTILITY : That property of a material which permits its
being drawn out into a thread of wire.
DUNNAGE : Any material, such as blocks, boards, paper,
burlap, etc., necessary for the safe stowage of stores and cargo; also used in
reference to staging, etc., used by workmen during building or repair
DUPLICATING PIPE : A piece of tubing, generally brass, used
with paint to transfer rivet hole layout from template to plate. The end of the
pipe is dipped in paint, and while still wet is pushed through each template
hole, leaving an impression on the plate. Also called a "marker".
DUTCHMAN : A piece of wood or steel fitted into an opening to
cover up poor joints or crevices caused by poor workmanship.
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ECCENTRIC : A form of crank in which a circular disk set
eccentrically upon a shaft forms both the crank web and the crank pin and
converts circular to rectilinear motion. This rectilinear travel is usually
short relative to the diameter of the shaft so that an ordinary form of crank is
EDGE : An abrupt border or margin, a bounding or dividing line, the part along
EDGE, SIGHT : That edge of a strake of plating which laps outside another strake
and is, therefore, in plain sight.
ELASTIC LIMIT : The limit of stress intensity within which a material will
return to its original size and shape when the load is removed and hence not
take a permanent set.
ELBOW-ELL : A pipe fitting that makes an angle between adjacent pipes, always 90
degrees unless another angle is stated.
ELECTRODE : Either a positive or negative pole or terminal in an electric
circuit. See "polarity".
ENGINE ROOM : Space where the main engines of a ship are located.
ENTRANCE : The forward underwater portion of a vessel at or near the bow. The
angle formed between the center line of the ship and the tangent to the designed
waterline is called the angle of entrance.
EQUILIBRIUM, NEUTRAL : The state of equilibrium in which a vessel inclined from
its original position of rest by an external force tends to maintain the
inclined position assumed after that force has ceased to act.
EQUILIBRIUM, STABLE : The state of equilibrium in which a vessel inclined from
its original position of rest by an external force tends to return to its
original position after that force has ceased to act.
EQUILIBRIUM, UNSTABLE : The state of equilibrium in which a vessel inclined from
its original position of rest by an external force tends to depart farther from
the inclined position assumed after that force has ceased to act.
ERECTION : The process of hoisting into place and joining the various parts of a
ship's hull, machinery, etc.
EVAPORATOR : An auxiliary for supplying fresh water, consisting of a salt water
chamber heated by coils or nests of tubing through which live steam is
circulated, converting the water into steam which is passed to a condenser or
distiller to make up loss of boiler feed water or for other purposes requiring
EVEN KEEL : When a boat rides on an even keel, its plane of flotation is either
coincident with or parallel to the designed waterline.
EXPANSION JOINT : A term applied to a joint which permits linear movement to
take up the expansion and contraction due to changing temperature or ship
EXPANSION TANKS : Overflow tanks used to provide for expansion, overflow, and
replenishment of oil in stowage or cargo tanks.
EXPANSION TRUNK : A trunk extending above a hold which is intended for stowage
of liquid cargo. The surface of the cargo liquid is kept sufficiently high in
the trunk to permit of expansion of the liquid without danger of excessive
strain on the hull or of overflowing, and of contraction of the liquid without
increase of the free surface and its accompanying effect upon the stability of
EXTRA STRONG : The correct term or name applied to a certain class of pipe which
is heavier than standard pipe and not as heavy as double extra strong pipe.
Often, but less correctly, called extra heavy pipe.
EYE : A hole through the head of a needle, pin, bolt, etc. or a loop forming a
hole or opening through which something is intended to pass, such as a hook,
pin, shaft, or rope. A "worked eye" is one having its edges rounded off like a
ring, while a "shackle eye" is drilled straight through, permitting an inserted
bolt or pin to bear along its entire length.
EYE BOLT : A bolt having either a head looped to form a worked eye or a solid
head with a hole drilled through it forming a shackle eye.
EYES : The forward end of the space below the upper deck of a ship which lies
next abaft the stem where the sides of the ship approach very near to each
other. The hawse pipes are usually run down through the eyes of a ship.
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FABRICATE : To shape, assemble, and secure in place the
component parts in order to form a complete whole. To manufacture.
FACE PLATE : A flat plate fitted perpendicular to the web and
welded to the web plate, or welded or riveted to the flange or flanges of a
frame, beam stiffener, or girder to balance the continuous plating attached to
the opposite flange of the member.
FACTOR OF SAFETY : The ratio between either the ultimate
strength of the elastic limit of the material and the allowed working stress.
The former is usually referred to as the "nominal factor of safety" and the
latter as the "real factor of safety". Elastic materials may have both nominal
and real factors of safety, while for those materials having approximately the
same values for ultimate strength and elastic limit, the distinction between
real and nominal factors of safety is nonexistent.
FAIR CURVES : Curves which do not in any portions of their
entire lengths show such changes of direction as to mark those portions as out
of harmony in any respect with the curves as a whole or with the other portions
of the curves.
FAIR or FAIR UP : To so draw the lines of a vessel that the
defined surfaces will show no irregularities throughout their entire extent. To
line up the frames of a vessel under construction to their proper position.
Rivet holes are said to be fair when corresponding holes in the members joined
FAIRLEADER : A fitting or device used to preserve or to
change the direction of a rope, chain, or wire so that it will be delivered
fairly or on a straight lead to a sheave or drum without the introduction of
extensive friction. Fairleaders, or fairleads, are fixtures as distinguished
from temporary block rigs.
A term applied to plating fitted to form a shape similar to a frustrum of a cone
around the ends of shaft tubes and strut barrels to prevent an abrupt change in
the streamlines. Also applied to any casting or plating fitted to the hull of a
vessel for the purpose of preserving a smooth flow of water.
To lay a rope or chain down in long bights side by side or in coils in regular
order so that it will run out clear or can be easily and rapidly paid out. Also
one complete circle of a coil of rope.
By common usage, the entire length of rope used in a tackle, although a strict
adherence to the term would limit its application to that end to which the power
is applied. The end secured to the block is called the standing part, the
opposite end, the hauling part.
The overhanging stern section of vessels which have round or elliptical after
endings to uppermost decks and which extend well abaft the after perpendicular.
A strip of wood used on covering openings in joiner work.
A rope or chain used to moor a vessel to a wharf, designated in accordance with
the end of the boat with which it is used as bow-fast or stern-fast. See
A nautical unit of length used in measuring cordage, chains, depths, etc. The
length varies in different countries, being six feet in the United States and in
Pieces of wood which form the rim of a wheel.
The term applied to various devices fastened to or hung over the sides of a
vessel to prevent rubbing or chafing against other vessels or piers. On small
craft, as tug boats, fenders of timber faced with hardwood or flat steel plate,
or of steel structure run fore and aft on the outside of the vessel above the
waterline and are firmly secured to the hull. Wood spars, bundles of rope, woven
cane, or rope-covered cork are hung over the sides by lines when permanent
fenders are not fitted.
A wood or metal bar used to support the weight of a topmast or a top-gallant
mast when in position, being passed through a hole or mortise at its heel and
resting on the trestle trees or other support. Also a hardwood tapering pin or
tool, used by sailmakers and riggers to open the strands of a rope, eye,
grommet, etc., A "hand fid" is rounded at the ends, a "standing or cringle fid"
is larger than a hand fid and has a flat base.
Framework built around a weather-deck hatch through which the smoke pipe passes.
FIDLEY DECK :
A partially raised deck over the engine and boiler rooms, usually around the
FIDLEY HATCH :
Hatch around smokestack and uptake.
FIFE RAIL; PIN RAIL :
A term applied to a rail worked around a mast and fitted with holes to take
belaying pins for securing the running gears.
A term applied to the metal filling in the bosom or concave corners where abrupt
changes in direction occur in the surface of a casting, forging, or weldment.
A projecting keel. A thin plane of metal projecting from hull, etc.
FIRE CONTROL :
Pertaining to the direction, the control, and the firing of the vessel's
FITTINGS, PIPE :
A term applied to the connections and outlets, with the exception of valves and
couplings, that are attached to pipes.
FIXED LIGHT :
A thick glass, usually circular in shape, fitted in a frame fixed in an opening
in a ship's side, deck house, or bulkhead to provide access for light. The fixed
light is not hinged. Often incorrectly called a dead light.
Flag pole, usually at the stern of a ship; carries the ensign.
A term used to express the same meaning as flare, but more properly used to
denote the maximum curl or roll given to the flare at the upper part, just below
the weather deck.
FLANGE : The turned edge of a plate or girder which
acts to resist bending. The turned edge of a plate or shape for tying in
intersecting structural members. A casting or forging attached to or worked
integral with a pipe to form a disk, normal to the axis of an exterior to the
pipe, for connecting lengths of pipe.
The spreading out from a central vertical plane of the body of a ship with
increasing rapidity as the section rises from the water line to the rail. Also a
night distress signal.
A small partial deck, built without camber.
FLOATING POWER :
The sum of the utilized and the reserve buoyancy of a vessel, or the
displacement of the completely watertight portion of the vessel when fully
submerged. The utilized buoyancy is that buoyancy required to support the weight
of the vessel.
FLOODABLE LENGTH :
The length of a vessel which may be flooded without sinking her below her safety
or margin line. The value of the floodable length of a given vessel varies from
point to point throughout her length due to change in form. Similarly at a given
point it varies from time to time, depending upon the condition of loading and
the permeability of the cargo.
A plate used vertically in the bottom of a ship running athwartship from bilge
to bilge usually on every frame to deepen it. In wood ships, the lowest frame
timber or the one crossing the keel is called the floor.
The palms or broad holding portions at the arm extremities of an anchor, which
penetrate the ground.
A fusible material or gas used to dissolve or prevent the formation of oxides,
nitrides, or other undesirable inclusions formed in welding and brazing.
Bottom boards of walking flats attached to the inside of the frames of small
boats where deep floors are not fitted.
A term used in indicating portions or that part of a ship at or adjacent to the
bow. Also applied to that portion and parts of the ship lying between the
midship section and stem; as, fore body, fore hold, and foremast.
FORE AND AFT :
Lengthwise of a ship.
A short structure at the forward end of a vessel formed by carrying up the
ship's shell plating a deck height above the level of her uppermost complete
deck and fitting a deck over the length of this structure. The name applied to
the crew's quarters on a merchant ship when they are in the fore part of the
The lower end of a vessel's stem which is stepped on the keel. That point in the
forward end of the keel about which the boat pivots in an endwise launching.
See "breast hook".
FORE PEAK :
The extreme forward end of the vessel below decks. The forward trimming tank.
A mass of metal worked to a special shape by hammering, bending, or pressing
FORK BEAM :
A half beam to support a deck here hatchways occur.
In the direction of the stem.
FORWARD PERPENDICULAR :
A line perpendicular to the base line and intersecting the forward side of the
stem at the designed waterline.
A term applied to the underwater portion of the outside of a vessel's shell when
it is more or less covered with sea growth or foreign matter. It has been found
that even an oily film over the vessel's bottom will retard the speed, while sea
growth will reduce a vessel's propulsive efficiency to a large extent. Also,
obstructed or impeded by an interference, etc.
To fit and bed firmly. Also, equipped.
To sink as the result of entrance of water.
A term generally used to designate one of the transverse ribs that make up the
skeleton of a ship. The frames act as stiffeners, holding the outside plating in
shape and maintaining the transverse form of the ship.
FRAME, BOSS :
A frame that is bent to fit around the boss in the way of a stern tube or shaft.
FRAME LINES :
Molded lines of a vessel as laid out on the mold loft floor for each frame,
showing the form and position of the frames.
FRAME SPACING :
The fore-and-aft distances between frames, heel to heel.
The vertical distance from the waterline to the top of the weather deck at side.
FREEING PORTS :
Holes in the lower portion of a bulwark, which allow deck wash to drain off into
the sea. Some freeing ports have swinging gates which allow water to drain off
but which are automatically closed by sea-water pressure.
FURNACED PLATE :
A plate that requires heating in order to shape it as required.
Strips of timber, metal, or boards fastened to frames, joists, etc., in order to
bring their faces to the required shape or level, for attachment of sheathing,
ceiling, floor, etc.
FUTTOCKS : The pieces of timber of which a frame in a wood ship is composed. Starting at
the keel they are called the first futtock, second futtock, third futtock, and
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A spar to which the top of a fore-and-aft sail is attached. It is usually fitted
with a jaw at the mast end to clasp the mast.
GAGE, DRAFT :
An installation comprising a graduated glass tube, connected at the bottom end
with the sea and with the top end open to the air, on which the draft of the
vessel is shown by the level of water in the tube.
The space on a vessel in which the food is prepared and cooked.
The process of coating one metal with another, ordinarily applied to the coating
of iron or steel with zinc. The chief purpose of galvanizing is to prevent
GANGBOARD, GANGPLANK :
A term applied to boards or a movable platform used in transferring passengers
or cargo from a vessel to or from a dock.
The term applied to a place of exit from a vessel. Gangways are fitted in the
sides of a vessel in the shape of ports requiring means of closure or may be
movable portions of bulwarks or railing on the weather decks.
GANTLINE or GIRTLINE :
A rope reeving through a single block aloft and used for hoisting or lowering
rigging, drying clothing and hammocks, etc.
The strakes of outside plating next to the keel. These strakes act in
conjunction with the keel and are usually thicker than the other bottom strakes.
Packing materials, by which air, water, oil, or steam tightness is secured in
such places as on doors, hatches, steam cylinders, manhole covers, or in valves,
between the flanges of pipes, etc. Such materials as rubber, canvas, asbestos,
paper, sheet lead and copper, soft iron, and commercial products are extensively
A comprehensive term in general use on shipboard signifying the total of all
implements, apparatus, mechanism, machinery, etc., appertaining to and employed
in the performance of any given operation, as "cleaning gear," "steering gear,"
"anchor gear," etc.
A term applied to wheels provided with teeth that mesh, engage, or gear with
similar teeth on other wheels in such manner that motion given one wheel will be
imparted to the other.
A metal fitting to hold a member in place or press two members together, to
afford a wearing or bearing surface, or to provide a means of taking up wear.
A device by which a ship's compass, chronometer, etc., is suspended so as to
remain in a constant horizontal position irrespective of the rolling or pitching
of the vessel. It consists of two concentric brass hoops or rings whose
diameters are pivoted at right angles to each other on knife-edge bearings.
On ships this term is used to define a structural member which provides support
for more closely spaced members, such as beams, frames, stiffeners, etc., which
are at right angles to it and which either rest upon it or are attached to its
web. It may be longitudinal or transverse, continuous or intercoastal, and is
usually supported by bulkheads and stanchions. The term is also used to
designate the longitudinal members in the double bottom.
The distance measured on any frame line, from the intersection of the upper deck
with the side, around the body of the vessel to the corresponding point on the
A swivelling fitting on the keel or mast end of a boom for connecting the boom
to the mast. Also called a Pacific iron.
GRAB, HAND :
A metal bar fastened to a bulkhead, house side, or elsewhere, to provide means
of steadying a person when the ship rolls or pitches.
An implement having from four to six hooks or prongs, usually four, arranged in
a circular manner around one end of a shank having a ring at its other end. Used
as an anchor for small boats, for recovering small articles dropped overboard,
to hook on to lines, and for similar purposes. Also known as a Grappling Hook.
A structure of wood or metal bars so arranged as to give a support or footing
over an opening, while still providing spaces between the members for the
passage of light and the circulation of air.
The sharp forward end of the dished keel on which the stem is fixed. A curved
piece of timber joining the forward end of the keel and the lower end of the
cutwater. A lashing, chain, or the like, used to secure small boats in the
chocks and in sea position in the davits.
A wreath or ring of rope. Fibre, usually soaked in red lead or some such
substance, and used under the heads and nuts of bolts to secure tightness. A
worked eye in canvas.
A general term for all anchors, cables, ropes, etc., used in the operation of
mooring and unmooring a ship.
Timbers fixed to the ground and extending fore and aft under the hull on each
side of the keel, to form a broad surface track on which the ship is
end-launched. "Groundways" for a side launching embody similar basic features.
Lugs cast or forged on the stern post for the purpose of hanging and hinging the
rudder. Each is bored to form a bearing for a rudder pintle and is usually
bushed with lignum vitae or white bearing metal.
A term applied to the line where a weather deck stringer intersects the shell.
The upper edge of the side of an open boat.
GUNWALE BAR :
A term applied to the bar connecting a stringer plate on a weather deck to the
GUSSET PLATE :
A bracket plate lying in a horizontal, or nearly horizontal, plane. The term is
often applied to bracket plates.
GUTTER EDGE :
A bar laid across a hatchway to support the hatch cover.
Wire or hemp ropes or chains to support booms, davits, etc., laterally, employed
in pairs. Guys to booms that carry sails are also known as backropes.
A small auxiliary drum usually fitted on one or both ends of a winch or
windlass. The usual method of hauling in or slacking off on ropes with the aid
of a gypsy is to take one or more turns with the bight of the rope around the
drum and to take in or pay out the slack of the free end.
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HALF-BREADTH PLAN : A plan or top view of one-half of a ship divided by the middle vertical plane.
It shows the waterlines, cross section lines, bow and buttock lines, and
diagonal lines of the ship's form projected on the horizontal base plane of the
HALF MODEL : A model of one-half of a ship divided along the middle vertical plane.
HALYARDS : Light lines used in hoisting signals, flags, etc. Also applied to the ropes used
in hoisting gaffs, sails, or yards.
HAMPER, TOP HAMPER : Articles of outfit, especially spars, rigging, etc., above the deck, which,
while ordinarily indispensable, may become in certain emergencies both a source
of danger and an inconvenience.
HARD PATCH :
A plate riveted over another plate to cover a hole or break.
HARPINGS; HARPINS :
The fore parts of the wales of a vessel which encompass her bows and are
fastened to the stem, thickened to withstand plunging. The ribbands bent around
a vessel under construction to which the cant frames are temporarily secured to
hold them in their proper position.
HATCH, HATCHWAY :
An opening in a deck through which cargo may be handled, machinery or boilers
installed or removed, and access obtained to the decks and holds below. Hatch is
properly a cover to a hatchway but is often used as a synonym for hatchway.
HATCH BAR :
A term applied to flat bars used for securing and locking hatch covers. A bar
over the hatch for rigging a tackle.
HATCH BATTENS :
A term applied to flat bars used to fasten and make tight the edges of the
tarpaulins that are placed over hatches. The batten and the edge of the
tarpaulin are wedged tightly in closely-spaced cleats.
HATCH BEAMS :
A term applied to the portable beams fitted to the coamings for the purpose of
supporting the hatch covers.
HATCH, BOOBY :
An access hatchway leading from the weather deck to the quarters. A small
companion which is readily removable in one piece. A wooden, hoodlike covering
for a hatchway, fitted with a sliding top.
HATCH CARRIER :
The supports which are attached to the inside of the coaming to take the ends of
the hatch beams.
HATCH CLEATS :
A term applied to the clips attached to the outside of the hatch coaming for the
purpose of holding the hatch battens and wedges which fasten the edges of the
HATCH COVERS or HATCHES :
Covers for closing the hatchway, in cargo ships usually made of wood planks in
sections that can be handled by the crew. In naval ship, steel hatch covers are
used. The wood cover is made tight against rain and the sea by stretching one or
more tarpaulins over them, secured at the edges by the hatch battens.
HATCH RESTS :
A term applied to the shelf fitted inside and just below the top of the coaming
for the purpose of supporting the hatch covers.
HATCHWAY TRUNK :
A term applied to the space between a lower deck hatchway and the hatchway or
hatchways immediately above it when enclosed by a casing. A trunk may be either
watertight or nonwatertight.
The hawse hole; also the part of a ship's bow in which the hawse holes for the
anchor chains are located.
HAWSE BAG :
A conical-shaped canvas bag, stuffed with sawdust, oakum, or similar material,
and fitted with a lanyard at apex and base, used for closing the hawse pipes
around the chain to prevent shipping water through the pipes; also called a
"jackass", "hawse plug", or "hawse block".
HAWSE BOLSTER :
A timber or metal bossing at the ends of a hawse pipe to ease the cable over the
edges and to take the wear.
HAWSE HOLE :
A hole in the bow through which a cable or chain passes.
HAWSE PIPES :
Tubes leading the anchor chain from the deck on which the windlass is located
down and forward through the vessel's bow plating.
A large rope or a cable used in warping, towing, and mooring.
HEAD LEDGE :
A term applied to the forward or after end coaming of a hatch, more frequently
used in connection with wood coamings.
HEAD OF A SHIP :
The fore end of a ship which was formerly fitted up for the accommodation of the
crew. A term applied to a toilet on board of a ship. A ship is trimmed by the
head when drawing more water forward and less aft than contemplated in her
HEAVE : To haul; to cast or hurl; as, to heave the
lead, to heave a line, The alternate rising and falling of a vessel in a seaway.
HEAVING LINE : A small line thrown to an approaching vessel, or a dock as a
HEEL: The convex intersecting point or corner of the web and flange of a bar.
The inclination of a ship to one side, caused by wind or wave action or by
shifting weights on board.
HEEL PIECE, HEEL BAR : A bar that serves as a connecting piece between two bars
which butt end-to-end. The flange of the heel bar is reversed from those of the
bars it connects.
The term applied to the tiller, wheel, or steering gear, and also the rudder.
A scrub broom for scraping a ship's bottom under water.
HOG FRAME :
A fore-and-aft frame, forming a truss for the main frames of a vessel to prevent
A term applied to the distortion of a vessel's hull when her ends drop below
their normal position relative to her midship portion.
HOG SHEER :
The sheer curve of the deck on a vessel, constructed so that the middle is
higher than the ends.
To raise or elevate by manpower or by the employment of mechanical appliances;
any device employed for lifting weights.
The space or compartment between the lowermost deck and the bottom of the ship,
or top of the inner bottom if one is fitted. The space below decks allotted for
the stowage of cargo.
HOLD BEAMS :
Beams in a hold similar to deck beams but having no decking or planking on them.
Close up; snugly in place; as, to drive home a bolt.
A shelter over a companionway, scuttle, etc. It is generally built of canvas
spread over an iron frame. It may also be constructed of light metal plating.
A term applied to those plates placed at the extreme forward or after ends of a
HOODING END :
The endmost plate of a complete strake. The hooding-ends fit into the stem or
Setting the frames of a vessel square to the keel after the proper inclination
to the vertical due to the declivity of the keel has been given.
HORSE TIMBER :
The after longitudinal strength member (often called counter timber) fastening
the shaft log or keel and the transom knee together. A small boat term.
(In naval architecture). Calking planking with oakum with a large maul or beetle
and wedge-shaped iron.
A term applied to an enclosure partially or wholly worked around fittings or
equipment. That portion of the mast below the surface of the weather deck.
Applied to topmasts, that portion overlapping the mast below.
The framework of a vessel, together with all decks, deck houses, and the inside
and outside plating or planking, but exclusive of masts, yards, rigging, and all
outfit or equipment.
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Toward the center; within the vessel's shell and below the weather decks.
INBOARD PROFILE : A plan representing a longitudinal section through the center of the ship,
showing deck heights, transverse bulkheads, assignment of space, machinery,
etc., located on the center plane or between the center and the shell of the far
INITIAL STABILITY : The stability of a vessel in the upright position or at small angles of
inclination. It is usually represented by the metacentric height.
INNER BOTTOM : A term applied to the inner skin or tank top plating. The plating over the
INTERCOSTAL : Occurring between ribs, frames, etc., The term is broadly applied, where two
members of a ship intersect, to the one that is cut.
ISHERWOOD SYSTEM : A system of building ships which employs close spaced, relatively light,
longitudinal main framing supported on widespread transverse members of
comparatively great strength instead of transverse main framing.
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JACK LADDER : A ladder with wooden steps and side ropes.
JACK ROD : A term applied to a pipe or rod to which the edges of awnings or weather cloths
JACKSTAFF : Flagpole at the bow of a ship.
JACOB'S LADDER : A ladder having either fiber or wire rope or chain sides with wood or metal
rungs attached at regular intervals. One end is usually fitted with sister hooks
or shackles for hooking on.
JOGGLED : A term applied where a plate or bar is offset in the way of a lapped joint. The
object of the joggle is to permit a close fit of the attached member without the
use of liners under alternate strakes of plating.
JOINT, BUTT : A term applied where a connection between two pieces of material is made by
brining their ends or edges together (no overlap) and by welding alone, or by
welding, riveting, or bolting each to a strip of strap that overlaps both
JOINT, LAPPED : A term applied where a connection between two pieces of material is made by
overlapping the end or edge of one over the end or edge of the other and by
fastening the same by bolts, rivets, or welding.
JOURNAL : That portion of a shaft or other revolving member which transmits weight
directly to and is in immediate contact with the bearing in which it turns.
JURY : A term applied to temporary structures, such as masts, rudders, etc. used in an
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KEEL : A center-line strength member running fore and aft along the bottom of a ship
and often referred to as the backbone. It is composed either of long bars or
timbers scarfed at their ends or by flat plates connected together by riveting
KEEL, BILGE : A fin fitted on the bottom of a ship at the turn of the bilge to reduce rolling.
It commonly consists of a plate running fore and aft and attached to the shell
plating by angle bars. It materially helps in steadying a ship and does not add
much to the resistance to propulsion when properly located.
KEEL, BLOCKS : Heavy timber blocks piled one above the other on which the keel of a vessel is
supported when being built, or when she is in a dry dock. They are placed under
the keel from bow to stern and a sufficient distance apart to allow working
KEEL, DOCKING : In dry docking, the weight of a ship is carried almost entirely on the keel and
bilge blocks. The keel and keelson provide the means of distributing the
pressure on the center line, and docking keels composed of doubling strips of
plate or a heavier plate or built-up girders are sometimes fitted on the bottom
at a distance from the center line corresponding to the best position for the
bilge block. The docking keels are fitted in the fore and aft direction,
generally parallel or nearly so to the keel.
KEELSON, VERTICAL CENTER : The lower middle-line girder which, in conjunction with a flat plate keel on the
bottom and a rider plate on top, forms the principal fore-and-aft strength
member in the bottom of a ship. In addition to its importance as a "backbone" or
longitudinal strength member, it serves to distribute and equalize the pressure
on the transverse frames and bottom of the ship when grounding or docking
occurs. In steel ships this keelson usually consists of a vertical plate with
two angles running along the top and two along the bottom. The girder, however,
may be made up of various combinations of plates and shapes. This member should
continue as far forward and aft as possible. Usually called the Vertical Keel.
KENTLEDGE : Pig iron used either as temporary or permanent ballast or as a weight for
inclining a vessel.
KERF : The slit made by the cut of a saw. Also the channel burned out by a cutting
KING POST : A strong vertical post used to support a derrick boom. See Samson Post.
KNEE : A block of wood having a natural angular shape or one cut to a bracket shape and
used to fasten and strengthen the corners of deck openings and the intersections
of timbers, and to connect deck beams to the frames of wood vessels. The term is
also applied to the ends of steel deck beams that are split, having one leg
turned down and a piece of plate fitted between the split portion, thus forming
a bracket or knee.
KNOT : A unit of speed, equaling one nautical mile (6,080.20 feet) an hour, as when a
ship goes ten nautical miles per hour, her speed is ten knots.
KNUCKLE : An abrupt change in direction of the plating, frames, keel, deck, or other
structure of a vessel.
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LADDER : A framework consisting of two parallel sides, connected by bars or steps which
are spaced at intervals suitable for ascending or descending. On shipboard the
term ladder is also applied to staircases and to other contrivances used in
ascending or descending to or from a higher or lower level.
LADDER, ACCOMMODATION : A staircase suspended over the side of a vessel from a gangway to a point near
the water to provide easy access to the deck from a small boat alongside.
LADDER, COMPANION : A staircase fitted as a means of access from a deck to the quarters.
LADDER, SEA : Rungs secured to the side of a vessel to form a ladder from the weather deck to
LAGGING : A term applied to the insulating material that is fitted on the outside of
boilers, piping, etc.
LANDING, LANDING EDGE : That portion of the edge or
end of a plate over which another plate laps. The covered-up edge
LANYARD : The present use of this term is generally limited to a piece of rope or line
having one end free and the other attached to any object for the purpose of
either near or remote control.
LAP : A term applied to the distance that one piece of material is laid over another;
the amount of overlap, as in a lapped joint.
LAPSTRAKE : A term applied to boats built on the clinker system in which the strakes overlap
each other. The top strake always laps on the outside of the strake beneath.
LAUNCH : A term applied to a small power or motor boat. See launching.
LAUNCHING : A term applied to the operation of transferring a vessel from the building ways
into the water. End launching and side launching methods are employed; the
former method is used when the vessel is built at an angle, usually at right
angles, to the waterfront and the vessel is launched stern first, while in side
launching the vessel is built parallel to the waterfront and launched sidewise.
In preparing for an end launching, usually groundways, made of heavy timbers are
laid with an inclination of about 1/2" and 5/8" to the foot parallel to the
center line of the ship one on either side of the keel, and spaced about
one-third of the beam of the vessel apart. These groundways run the length of
the vessel and for some distance out under the water. On top of the groundways
are placed the sliding ways, also heavy timbers, and between these two ways is
placed a coating of launching grease. The sliding ways are prevented from
sliding on the greased groundways by a trigger or similar device and dog or
dagger shores. Cradles are built up to fit the form of the vessel, and between
the sliding ways and the cradle, wedges are driven and the weight of the ship
thus transferred from the building blocks to the sliding ways. After the
building blocks and shores are removed, the trigger is released and gravity
causes the vessel to slide down the inclined ways. In some cases hydraulic jacks
are set at the upper end of the groundways to exert pressure on the sliding ways
to assist in overcoming initial friction along the ways. A similar procedure is
followed in the case of side launchings, except that more than two groundways
are usually used, depending on the length of the ship, and the inclination of
the ways is steeper.
LAYING OFF : A term applied to the work done by a loftsman in laying off the ship's lines to
full size in the mold loft and making templates therefrom. Also known as laying
LAYING OUT : Placing the necessary instructions on plates and shapes for shearing, planing,
punching, bending, flanging, beveling, rolling, etc., from templates made in the
mold loft or taken from the ship.
LEADING EDGE : That edge of a propeller blade which cuts the water when the screw is revolving
in the ahead direction. That edge of a rudder, diving plane, or strut arm which
faces toward the bow of the ship.
LENGTH BETWEEN PERPENDICULARS : The length of a ship measured from the forward side of the stem to the aft side
of the stern post at the height of the designed water line. In naval practice,
the total length on the designed water line.
LENGTH OVER ALL : The length of a ship measured from the foremost point of the stem to the
aftermost part of the stern.
LIFT A TEMPLATE : To construct a template to the same size and shape as the part of the ship
involved, from either the mold loft lines or from the ship itself, from which
laying out of material for fabrication may be performed.
LIFTING : Transferring marks and measurements from a drawing, model, etc., to a plate or
other object, by templates or other means.
LIGHT, PORT : An opening in a ship's side, provided with a glazed lid or cover.
LIGHTENING HOLE : A hole cut out of any structural member, as in the web, where very little loss
of strength will occur. These holes reduce the weight and in many cases serve as
access holes. This condition is particularly true in floor plates and
longitudinals in double bottoms.
LIGHTER : A full-bodied, heavily-built craft, usually not self-propelled, used in bringing
merchandise or cargo alongside or in transferring same from a vessel.
LIMBER CHAINS : Chains passing through the limber holes of a vessel, by which they may be
cleaned of dirt.
LIMBER HOLE : A hole or slot in a frame or plate for the purpose of preventing water from
collecting. Most frequently found in floor plates just above the frames and near
the center line of the ship.
LINE : A general term for a rope of any size used for various purposes: small cords
such as long line, lead line, or small stuff as marlin, ratline, houseline, etc.
LINER : A piece of metal used for the purpose of filling up a space between a bar and a
plate or between two plates; a filler.
LINES : The plans of a ship that show its form. From the lines drawn full size on the
mold loft floor are made templates for the various parts of the hull.
LIST : The deviation of a vessel from the upright position due to bilging, shifting of
cargo, or other cause.
LOAD LINE : The line on the "lines plan" of a ship representing the intersection of the
ship's form with the plane of the water's surface when the vessel is floating
with her designed load on board. Also applied to the actual intersection of the
surface of the water with a vessel's side.
LOCK NUT : A thin nut which is turned down over the regular nut on a bolt to lock the
regular nut against turning off. Also applied to a thin nut placed on a pipe to
hold packing at a joint or used on both sides of a bulkhead through which a pipe
passes to secure tightness.
LOCKER : A storage compartment on a ship.
LOFTSMAN : A man who lays off the ship's lines to full size in the mold loft and makes
LONGITUDINALS : A term applied to the fore-and-aft girders in the bottom of a ship. These
girders are usually made up from plates and shapes and are sometimes intercostal
and sometimes continuous.
LOUVER : A small opening to permit the passage of air for the purpose of ventilation,
which may be partially or completely closed by the operation of overlapping
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MAGAZINE : Spaces or compartments devoted to the stowage of ammunition. Often specifically
applied to compartments for the stowage of powder as a distinction from shell
MAIN BODY : The hull proper, without the deck houses, etc.
MAIN DECK : The principal deck of the hull, usually the highest extending from stem to stern
and providing strength to the main hull.
MANGER : A term applied to the manger-like space immediately forward of the manger plate
which is fitted just abaft the hawse pipes to prevent water entering through the
pipes from running aft over the deck.
MANHOLE : A round or oval hole cut in decks, tanks, boilers, etc. for the purpose of
MANIFOLD : A casting or chest containing several valves. Suction or discharge pipes from or
to the various compartment, tanks, and pumps are led to it, making it possible
for a pump to draw from or deliver to any one of several compartments.
MANTLET PLATE : A thin plate for the protection
of personnel, fitted over bolt or rivet heads to act as a screen to prevent the
heads flying about when the structure is subjected to impact.
MARGIN PLANK : A plank forming the boundary or margin of the deck planking.
MARGIN PLATE : The outer boundary of the inner bottom, connecting it to the shell plating at
MARINE RAILWAY : See drydock, railway.
MARLINE SPIKE : A pointed iron or steel tool used to separate the strands in splicing rope, and
as a lever in marling or putting on seizings. The wire rope spike has a flat,
rounded end and the manila rope spike has a sharp point.
MARLIN : A double-threaded, left-handed tarred cord, about 1/8" diameter, made of a good
grade of American hemp.
MAST : A long pole of steel or wood, usually circular in section, one or more of which
are usually located, in an upright position, on the center line of a ship.
Originally intended for carrying sails, they are now used more as supports for
the rigging, cargo and boat-handling gear and wireless equipment.
MAST COLLAR : A piece of wood or a steel shape formed into a ring and fitted around the mast
hole in a deck.
MAST HOUNDS : The upper portion of the mast at which the outrigger or trestle trees are
fitted. Also applied to that portion at which the hound band for attaching the
shrouds is fitted on masts without outrigger or trestle trees.
MAST PARTNERS : A term applied to wood planking or steel plating worked around a mast hole to
give side support to the mast.
MAST STEP : A term applied to the foundation on which a mast is erected.
MAST TABLE : See Boom Table.
MESSROOM : A space or compartment where members of the crew eat their meals; a dining room.
A dining room in which officers eat their meals is called a wardroom messroom.
MIDDLE BODY:That portion of the ship adjacent to the midship section. When it has a uniform
cross section throughout, its length its waterlines being parallel to the
centreline, it is called the parallel middle body.
MIDSHIP BEAM : A deck beam of the transverse frame located at the midpoint between the forward
and after perpendiculars. Also applicable to the transverse dimension of the
hull at the same point.
MIDSHIP FRAME : The frame located at the midpoint between the perpendiculars.
MIDSHIP SECTION : The vertical transverse section located at the midpoint between the forward and
after perpendiculars. Usually this is the largest section of the ship in area.
Also, applied to a drawing showing the contour of the midship frame upon which
is depicted all the structural members at that point with information as to
their size and longitudinal extent.
MIDSHIPS : Same as Amidships.
MITRED : Cut to an angle of 45 degrees or two pieces joined to make a right angle.
MOCK UP : To build up of wood or light material to scale or full size a portion of the
ship before actual fabrication of the steel work. Used to study arrangement,
methods of fabrication, workability, etc.
MOLD : A pattern or template. Also a shape of metal or wood over or in which an object
may be hammered or pressed to fit.
MOLDED LINE : A datum line from which is determined the exact location of the various parts of
a ship. It may be horizontal and straight as the molded base line, or curved as
a molded deck line or a molded frame line. These lines are determined in the
design of a vessel and adhered to throughout the construction. Molded lines are
those laid down in the mold loft.
MOLDED EDGE : The edge of a ship's frame which comes in contact with the skin, and is
represented in the drawings.
MOLD LOFT : A space used for laying down the lines of a vessel to actual size and making
templates therefrom for laying out the structural work entering into the hull.
MOORING : A term applied to the operation of anchoring a vessel in a harbor, securing her
to a mooring buoy, or to a wharf or dock by means of chains or ropes.
MOORING LINES : The chains or ropes used to tie up a ship.
MOORING PIPE : An opening through which mooring lines pass.
MORTISE : A hole cut in any material to receive the end or tenon of another piece.
MOTORSHIP : A ship driven by some form of internal combustion engine. Not generally applied
to small boats driven by gasoline engines which are usually called motorboats.
MULLION : The vertical bar dividing the lights in a window.
MUSHROOM VENTILATOR : A ventilator whose top is shaped like a mushroom and fitted with baffle plates
so as to permit the passage of air and prevent the entrance of rain or spray.
Located on or above a weather deck to furnish ventilation to compartments below
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NAUTICAL MILE : See knot.
NIBBING PLANK : A margin plank that is notched to take the ends of regular deck planks and
insure good calking of the joint.
NIGGERHEAD : A small auxiliary drum on a winch. See Gypsy.
NIPPLE : A piece of pipe having an outside thread at both ends for use in making pipe
connections. Various names are applied to different lengths, as close, short,
NORMALIZE : To heat steel to a temperature slightly above the critical point and then allow
it to cool slowly in air.
NORMAN PIN : A metal pin fitted in a towing post or bitt for belaying the line.
NOSING : The part of a stair tread which projects beyond the face of the riser.
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OAKUM : A substance made from soft vegetable fiber such as hemp and jute impregnated
with pine tar. It is principally used for calking the planking on wood decks of
steel vessels and for calking all the planking on wood ships where
watertightness is desired. It is also for calking around pipes.
OFFSETS : A term used by draftsmen and loftsmen for the coordinates in ship curves. Also
applied to joggles in plates and shapes of structural shapes.
OGEE : A molding with a concave and convex outline like an S.
OILTIGHT : Having the property of resisting the passage of oil.
OLD MAN : A heavy bar of iron or steel bent in the form of a Z used to hold a portable
drill. One leg is bolted or clamped to the work to be drilled and the drill head
is placed under the other leg which holds down the drill to its work.
ON BOARD : On or in a ship; aboard.
ON DECK : On the weather deck, in the open air.
ORLOP DECK : The term formerly applied to the lowest deck in a ship; now practically
OUTBOARD : Away from the center toward the outside; outside the hull.
OUTBOARD PROFILE : A plan showing the longitudinal exterior of the starboard side of a vessel,
together with all deck erections, stacks, masts, yards, rigging, rails, etc.
OVERBOARD : Outside, over the side of a ship into the water.
OVERHANG : That portion of a vessel's bow or stern which projects beyond a perpendicular at
OVERHAUL : To repair or put in proper condition for operation; to overtake or close up the
distance between one ship and another ship moving in the same direction.
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PACKING : A general term applied to a yielding material employed to effect a tight joint,
also called gasket material.
PAD EYE : A fitting having one or more eyes integral with a plate or base to provide ample
means of securing and to distribute the strain over a wide area. The eyes may be
either "worked" or "shackle." Also known as lug pads, hoisting pads, etc.
PAINTER : A length of rope secured at the bow of a small boat for use in towing or for
making it fast. Called also a bow-fast.
PALM : The fluke, or more exactly, the flat inner surface of the fluke of an anchor; a sailmaker's protector for the hand, used when sewing canvas; a flat surface at
the end of a strut or stanchion for attachment to plating, beams, or other
PANTING : The pulsation in and out of the bow and stern plating as the ship alternately
rises and plunges deep into the water.
PANTING BEAMS : The transverse beams that tie the panting frames together.
PANTING FRAMES : The frames in the fore peak, usually extra heavy to withstand the panting action
of the shell plating.
PARAVANE : The paravane is a special type of water kite which, when towed with wire rope
from a fitting on the forefoot of a vessel, operates to ride out from the ship's
side and deflect mines which are moored in the path of the vessel, and to cut
them adrift so that they will rise to the surface where they may be seen and
PARCELLING : Narrow strips of canvas which are tarred and wound around ropes, following the
lay and overlapping in order to shed water. The parcelling is applied after
worming, preparatory to serving.
PARTNERS : Similar pieces of steel plate, angles, or wood timbers used to strengthen and
support the mast where it passes through a deck, or placed between deck beams
under machinery bed plates for added support.
PAULIN : A term applied to a pliable canvas hatch cover, and also to pieces of canvas
used as a shelter for workmen or as a cover for deck equipment.
PAWL : A term applied to a short piece of metal so hinged as to engage in teeth
or depressions of a revolving mechanism for the purpose of preventing recoil.
Fitted to capstans, windlasses, etc. Also called Pall.
PAYING : The operation of filling the seams of a wood deck, after the calking has been
inserted, with pitch, marine glue, etc. Also applied to the operation of
slackening away on a rope or chain.
PEAK, FORE AND AFTER : The space at the extreme bow or stern of a vessel below the decks.
PEAK TANK : Compartments at the extreme fore and aft ends of the ship for any use either as
void spaces or as trimming tanks. When used for the latter purpose, water is
introduced to change the trim of the vessel.
PEEN : To round off or shape an object, smoothing out burrs and rough edges.
PEEN : The lesser head of a hammer, and is termed ball when it is spherical, cross when
in the form of a rounded edge ridge at right angles to the axis of the handle,
and straight when like a ridge in the plane of the handle.
PELICAN HOOK : A type of quick releasing hook used at the lower end of shrouds, on boat grips,
and in similar work where fast work may be necessary.
PELORUS : A navigational instrument, similar to a binnacle and mariner's compass, but
without a magnetic needle, used in taking bearings, especially when the object
to be sighted is not visible from the ship's compass. Also known as a Dumb
PERIOD OF ROLL : The time occupied in performing one double oscillation or roll of a vessel as
from port to starboard and back to port.
PERISCOPE : An instrument used for observing objects from a point below the object lens. It
consists of a tube fitted with an object lens at the top, an eye piece at the
bottom and a pair of prisms or mirrors which change the direction of the line of
sight. Mounted in such a manner that it may be rotated to cover all or a part of
the horizon or sky and fitted with a scale graduated to permit of taking
bearings, it is used by submarines to take observations when submerged.
PILLAR : A vertical member or column giving support to a deck. Also called a stanchion.
PILOT HOUSE : A house designed for navigational purposes. It is usually located forward of the
midship section and so constructed as to command an unobstructed view in all
directions except directly aft along the center line of the vessel where the
smokestack usually interferes.
PIN, BELAYING : A small iron or tough wood pin, made with a head, shoulder, and shank. It is
fitted in holes in a rail and is used in belaying or making fast the hauling
parts of light running gear, signal halyards, etc.
PINTLES : A term applied to the pins or bolts which hinge the rudder to the gudgeons on
the stern post.
PITCH : A term applied to the distance a propeller will advance during one revolution,
the distance between the centers of the teeth of a gear wheel, the axial advance
of one convolution of the thread on a screw, the spacing of rivets, etc. Also
applied to pine tar, asphalt and coal pitch used in paying seams of a deck.
PITCHING : The alternate rising and falling motion of a vessel's bow in a nearly vertical
plane as she meets the crests and troughs of the waves.
PITTING : The localized corrosion of iron and steel in spots, usually caused by
irregularities in surface finish, and resulting in small indentations or pits.
PIVOTING POINT : That point during the progress of a launching at which the moment of buoyancy
about the fore poppet equals the moment of the vessel's weight. At this point
the stern begins to lift and the vessel pivots about the fore poppet.
PLAN : A drawing prepared for use in building a ship.
PLANKING : Wood covering for decks, etc. The shell of wood boats.
PLATFORM : A partial deck.
PLATING, SHELL : The plating forming the outer skin of a vessel. In addition to constituting a
watertight envelope to the hull, it contributes largely to the strength of the
PLIMSOLL MARK : A mark painted on the sides of vessel designating the depth to which the vessel
may, under the maritime laws, be loaded in different bodies of water during
various seasons of the year.
POLARITY : The property possessed by electrified bodies by which they exert forces in
opposite directions. The current in an electrical circuit passes from the
positive to the negative pole.
PONTOON : A scow-shaped boat used in connection with engineering and military operations
such as transporting men and equipment, bridge construction, supports for
temporary bridges, salvage work, etc. Also applied to cylindrical air and
watertight tanks or floats used in salvage operations.
POOP : The structure or raised deck at the after end of a vessel.
POPPETS : Those pieces of timber which are fixed perpendicularly between the ship's bottom
and the bilgeways at the foremost and aftermost parts of the ship, to support it
when being launched. They are parts of the cradle.
PORT : The left-hand side of a ship when looking from aft forward. Also an opening.
PORT, AIR : See air port.
PORT FLANGE : See watershed.
PORT GANGWAY : An opening in the side plating, planking, or bulwark for the purpose of
providing access through which people may board or leave the ship or through
which cargo may be handled.
PORTHOLE : See air port.
PORT LID : See deadlight.
PROOF STRAIN : The test load applied to anchors, chains, or other parts, fittings, or structure
to demonstrate proper design and construction and satisfactory material.
PROOF STRENGTH : The proof strength of a material, part, or structure is the strength which it
has been proved by tests to possess.
PROPELLER : A propulsive device consisting of a boss or hub carrying radial blades, from two
to four in number. The rear or driving faces of the blades form portions of an
approximately helical surface, the axis of which is the center line of the
PROPELLER ARCH : The arched section of the stern frame above the propeller.
PROPELLER GUARD : A framework fitted somewhat below the deck line on narrow, high-speed vessels
with large screws so designed as to overhang and thus protect, the tips of the
PROPELLER THRUST : The effort delivered by a propeller in pushing a vessel ahead.
PROPORTIONAL LIMIT : The stress within which stresses and deformations are directly proportional.
Within this limit, on removing stress, there is no permanent set.
PROW : An archaic term for the bow of a ship.
PUDDENING, PUDDING : Pads constructed of old rope, canvas, oakum, etc., sometimes leather covered, in
any desired shape and size and used to prevent chafing of boats, rigging, etc.,
on the stem of a boat to lessen the force of a shock.
PUNCH : A machine for punching holes in plates and shapes.
PUNCH, PRICK : A small punch used to transfer the holes from the template to the plate. Also
called a "center punch".
PUNT : A flat bottom boat with square ends, used in painting and cleaning a vessel's
sides when in port.
PURCHASE : Any mechanical advantage which increases the power applied.
PYROTECHNICS : Flares, rockets, powder, etc., used for giving signals or for illumination, more
generally used as distress signals.
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QUADRANT : A reflecting hand navigational instrument constructed on the same principle as
the sextant but measuring angles up to 90 degrees only. Also known as an octant.
One-fourth of the circumference of a circle. A fitting in the shape of a sector
of a circle secured to the rudder stock and through which the steering leads
turn the rudder. The rim is provided with two grooves to take the steering
chains or ropes and is of sufficient length of arc so that the leads are
tangential to the rim at all rudder angles.
QUARTER : The upper part of a vessel's sides near the stern; also portions of the vessel's
sides about midway between the stem and midlength and between midlength and the
stern. The part of a yard just outside the slings.
QUARTERMAN : An underforeman, a term generally restricted to navy yards.
QUARTERS : Living spaces for passengers or personnel. It includes staterooms, dining
salons, mess rooms, lounging places, passages connected with the foregoing,
etc.; individual stations for personnel for fire or boat drill, etc.
QUAY : An artificial wall or bank, usually of stone, made toward the sea or at the side
of a harbor or river for convenience in loading and unloading vessels.
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RABBET : A groove, depression, or offset in a member into which the end or edge of
another member is fitted, generally so that the two surfaces are flush. A rabbet
in the stem or keel would take the ends or edges of the planking or shell
RACKING : Deformation of the section of a ship, generally applied to a transverse section,
so that one set of diagonals in the plane of action is shortened while those at
right angles thereto are lengthened.
RADIO ROOM : A room, usually sound-proofed, used for sending and receiving radio messages.
RAFT, LIFE : A frame work fitted with air chambers to support a number of people in case of
accidents. Carried on deck and light enough to be handled without mechanical
RAIL : The upper edge of the bulwarks. Also applied to the tiers of guard rods running
between the top rail and the deck where bulwarks are not fitted.
RAKE : A term applied to the fore and aft inclination from the vertical of a mast,
smokestack, stempost, etc.
RALLY : The action of gangs of men uniting in driving wedges between the cradle and the
sliding ways preparatory to launching or similar activities.
RANGE, GALLEY : The stove, situated in the galley, which is used to cook the food. The heat may
be generated by coal, fuel oil, or electricity.
RAT GUARD : A dished, circular piece of metal made in two parts and fitted closely on
hawsers and lines to prevent rats boarding or leaving a ship while at a dock or
wharf. The concave side is placed toward the shore to prevent boarding, and the
guard is reversed to prevent rats leaving the ship.
RATLINES : Short lengths of ratline stuff secured to the shrouds parallel to the waterline
and serving as ladder rungs for the crew to ascend or descend.
REAMING : Enlarging a hole by the means of revolving in it a cylindrical slightly tapered
tool with cutting edges running along its sides.
REDUCTION GEAR : An arrangement of shafts and gears such that the number of revolutions of the
output shaft is less than of the input shaft--generally used between a motor or
a steam turbine shaft and the propeller shaft.
REEVING : The act of passing the end of a rope or chain through an opening, as passing a
rope through a block.
REVERSE FRAME : An angle bar or other shape riveted to the inner edge of a transverse frame to
RIBBAND : A fore-and-after strip or heavy batten used to support the transverse frames
temporarily after erection.
RIBS : A term applied to the transverse frames of a boat.
RIDE : To float in a buoyant manner while being towed or lying at anchor.
RIDER PLATE : A continuous flat plate attached to the top of a center line vertical keel in a
horizontal position. Its under side is attached to the floors, and when an inner
bottom is fitted, it forms the center strake.
RIGGING : A term used collectively for all the ropes and chains employed to support the
masts, yards, and booms of a vessel, and to operate the movable parts of same.
RISE OF BOTTOM : See deadrise.
RISER : The upright board of a stair. A pipe extending vertically and having side
RISINGS : The fore and aft stringers inside a small boat, secured to the frames, and on
which the thwarts rest.
RIVET : A metal pin used for connecting two or more pieces of material by inserting it
into holes punched or drilled in the pieces and upsetting one or both ends. The
end that bears a finished shape is called the head and the end upon which some
operation is performed after its insertion is called the point. Small rivets are
"driven cold," i.e., without heating, and large ones are heated so that points
may be formed by hammering.
RIVETING : The art of fastening two pieces of material together by means of rivets.
RIVETING, CHAIN : A term applied to an arrangement of the rivets in adjoining rows where the
center of the rivets are opposite each other and on a line perpendicular to the
RIVETING, STAGGERED or ZIG-ZAG : A term applied to an arrangement of the rivets in adjoining rows where the
rivets in alternate rows are one-half the pitch or spacing ahead of those in the
RIVETS, LINE OF : A term applied to a continuous line of rivets whose centers fall on a line
perpendicular to the joint.
RIVETS, ROW OF : A term applied to a continuous row of rivets whose centers fall on a line
parallel to the joint. Joints made by one row of rivets are known as
single-riveted joints; by two rows, as double-riveted joints; by three rows, as
treble-riveted joints; by four rows, as quadruple-riveted joints; etc.
ROLL : Motion of the ship from side to side, alternately
raising and lowering each side of the deck. The oscillating motion of a vessel
from side to side due to ground swell, heavy sea, or other causes.
ROLLING CHOCKS : Same as keel, bilge.
ROPE : The product resulting from twisting a fibrous material, such as manila,
hemp, flax, cotton, coir, etc., into yarns or threads which in turn are twisted
into strands and several of these are laid up together. Fiber rope is designated
as to size by its circumference. Wire rope is made of iron, steel, or bronze
wires, with and without a fiber core or heart, twisted like yarns to form
strands which are laid up to form the rope. Wire rope is designated as to size
both by its diameter and by its circumference.
ROPE LAY : The direction in which a rope is twisted up.
ROPE, RIDGE : A rope running through the eyes at the heads of the awning stanchions to which
the edge of an awning is hauled out and stopped. The term "center ridge rope" is
applied to the rope supporting the center of an awning.
ROPE WORMING : Filling in the contlines of a rope with marline. The marline should run with the
lay of the rope.
ROSES : Perforated metal plates, fitted over the outside of injection sea cocks to
prevent entrance of foreign substances to the ship's pumps and piping system.
ROWLOCK : A U-shaped fitting with a shank or a socket which is attached to the gunwale of
a boat and used as a fulcrum for oars in rowing, sculling, or steering.
RUBBING STRIP : A plate riveted to the bottom of the keel to afford protection in docking and
grounding. A strip fastened to the face of a fender or to the shell plating
where contact is likely to occur.
RUDDER : A device used in steering or maneuvering a vessel. The most common type consists
of a flat slab of metal or wood, hinged at the forward end to the stern or
rudder post. When made of metal, it may be built up from plates, shapes, and
castings, with or without wood filling, or it may be a casting. The rudder is
attached to a vertical shaft called the rudder stock, by which it is turned from
side to side.
RUDDER, BALANCED : A rudder having the leading edge of a whole or a part of its area forward of the
center line of the rudder stock, thus advancing the center of pressure of the
water on the rudder and reducing the torque.
RUDDER BANDS : The bands that are placed on each side of a rudder to help brace it and tie it
into the pintles.
RUDDER CHAINS : The chains whereby a rudder is sometimes fastened to the stern. They are
shackled to the rudder by bolts just above the water line, and hang slack enough
to permit free motion of the rudder. They are used as a precaution against
losing a rudder at sea. These chains are also called "rudder pendants".
RUDDER FRAME : A term applied to a vertical main piece and the arms that project from it which
form the frame of the rudder. It may be a casting, a forging, or a weldment.
RUDDER PINTLES : See pintles.
RUDDER POST : See Stern post.
RUDDER STOCK : A vertical shaft having a rudder attached to its lower end and having a yoke,
quadrant, or tiller fitted to its upper portion by which it may be turned.
RUDDER STOPS : Fittings attached to the ship structure or to shoulders on the rudder post to
limit the swing of the rudder.
RUDDER TRUNK : A watertight casing fitted around a rudder stock between the counter shell
plating and a platform or deck, usually fitted with a stuffing box at the upper
RUDDER, UNDERHUNG : A rudder that is not hinged to or stepped on the stern post, but is supported
entirely by the rudder stock and the rudder stock bearings.
RUN : The underwater portion of a vessel aft of the midship section or flat of the
bottom. That portion of the after hull that tapers to the stern post.
RUNNING RIGGING : Ropes which are hauled upon at times in order to handle and adjust sails, yards,
cargo, etc., as distinguished from standing rigging which is fixed in place.
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SAFETY TREADS : A special nonslipping metal plate fitted to the deck at the foot of a ladder or
stairway and often fitted on the upper surface of the steps of ladders and
stairs. Steps made of safety treads are called safety steps.
SAGGING : The deformation or yielding caused when the middle portion of a structure or
ship settles or sinks below its designed or accustomed position. The reverse of
SAIL TRACKS : A device fitted on the after side of a mast in which slides, secured to the
forward edge of a fore-and-aft sail, travel up and down the mast as the sail is
hoisted or lowered; used in lieu of mast hoops.
SAMSON POST : A strong vertical post that supports cargo booms. See king posts.
SCANTLINGS : A term applied to the dimensions of the frames, girders, plating, etc., that
enter into a ship's structure.
SCARF : An end connection made between two pieces of material by tapering them so that
they will fit together in a joint of the same breadth and depth as the pieces.
SCREEN BULKHEAD :A light bulkhead used as a shelter from an excess of heat, cold, or light, or to
conceal something from sight.
SCRIEVE BOARD : A large board made of soft, clear, planed lumber, sometimes a section of the
mold loft floor, on which a full-sized body plan of a ship is drawn. The lines
were formerly cut in by the use of a scriving knife, which made a small U-shaped
groove, to prevent them from being obliterated. Pencil lines have taken the
place of cutting to a large extent. It is used in making templates of frames,
beams, floors, etc., and in taking off dimensions. It is sanded smooth after it
has served its purpose.
SCUPPER PIPE : A pipe conducting the water from a deck scupper to a position where it is
SCUPPERS : Drains from decks to carry off accumulations of rain water or sea water. The
scuppers are placed in the gutters or waterways on open decks and in corners of
enclosed decks, and connect to pipes leading overboard.
SCUTTLE : A small opening, usually circular in shape and generally fitted in decks to
provide access. Often termed escape scuttles, and when fitted with means whereby
the covers can be removed quickly to permit exit, are called quick acting
SCUTTLE BUTT : The designation for a container of the supply of drinking water for the use of
SEA CHEST : An arrangement for supplying sea water to condensers and pumps, and for
discharging waste water from the ship to the sea. It is a cast fitting or a
built-up structure located below the waterline of the vessel and having means
for attachment of the piping. Suction sea chests are fitted with strainers or
SEA COCK, SEA CONNECTION : A sea valve secured to the plating of the vessel below the waterline for use in
flooding tanks, magazines, etc., to supply water to pumps, and for similar
SEAM : A term applied to an edge joint.
SEAMSTRAP : A term applied to a strip of plate serving as a connecting strap between the
butted edges of plating. Strap connections at the ends are called buttstraps.
SEARCHLIGHT : A powerful electric lamp placed at the focus of a mirror, which projects the
light in abeam of parallel rays.
SET IRON : A bar of soft iron used on the bending slab as a form to which to bend frames
into the desired shape.
SERVE : To wrap any small stuff tightly around a rope which has been previously wormed
and parcelled. Very small ropes are not wormed.
SET, PERMANENT SET : The permanent deformation resulting from the stressing of an elastic material
beyond its elastic limit.
SETSCREW : A machine screw with either a slotted or a square head used to hold a part in
SET UP : To tighten the nut on a bolt or stud; to bring the shrouds of a mast to a
uniform and proper tension by adjusting the rigging screws or the lanyards
through the dead eyes.
SHACKLE BOLT : A pin or bolt that passes through both eyes of a shackle and completes the link.
The bolt may be secured by a pin through each end, or a pin through one end and
through the eye, or by having one end and one eye threaded or one end headed and
a pin through the other.
SHAFT, SHAFTING : The cylindrical forging, solid or tubular, used for transmission of rotary
motion from the source of power, the engine, to the propellers.
SHAFT ANGLE : The angle between the center line of the shaft and the center line of the ship
is the horizontal angle and the angle between the center line of the shaft and
either the base line or the designed waterline is the vertical angle.
SHAFT ALLEY : A watertight passage, housing the propeller shafting from the engine room to the
bulkhead at which the stern tube commences. It provides access to the shafting
and its bearings and also prevents any damage to the same from the cargo in the
spaces through which it passes.
SHAFT COUPLING : The means of joining together two sections of a shaft, usually by means of bolts
through flanges on the ends of the sections of the shafts.
SHAFT PIPE : See Stern Tube.
SHAFT STRUT : A term applied to a bracket supporting the outboard after end of the propeller
shaft and the propeller in twin or multiple-screwed vessels having propeller
shafts fitted off the center line. It usually consists of a hub or boss, fitted
with a bushing, to form a bearing for the shaft, and two streamlined arms
connecting it to the side of the ship. The inboard ends of the arms are fitted
with palms for attachment to the shell or to interior framing.
SHAKES : Splits or checks in timbers which usually cause a separation of the wood between
annular rings. A ring shake is an opening between annular rings; a through shake
is an opening which extends between two faces of a timber.
SHAPE : A bar of constant cross section such as a channel, T-bar, angle bar, etc.,
either rolled or extruded.
SHAPING : Cutting, bending, and forming a structural member.
SHEARS : Large machines for cutting plates or shapes.
SHEAR LEGS : A rig for handling heavy weights, consisting of an A-frame of timber or steel
with the top overhanging the base, having the lower ends fixed or pivoted and
the top ends held either by fixed stays or by topping lifts which permit change
of slope of the legs. Tackles are secured at the top of the frame through which
the hoisting rope or cable is run. Sometimes called sheers.
SHEATHING : A term applied to the wood planking fitted over a steel deck, to the planking
fitted over the underwater portion of a steel hull, and to the copper or alloy
sheets with which the bottom of a wood ship, or a steel ship sheathed with wood,
SHEAVE : A wood or metal disk, having a groove around its cylindrical surface to permit a
rope or chain to run over it without slipping off and a bushing for bearing on
the pin or bolt on which it revolves.
SHEAVE HOLES : A term applied to apertures in masts, booms, and spars in which sheaves are
SHEER : The longitudinal curve of a vessel's rails, decks, etc. the usual reference
being to the ship's side; however, in the case of a deck having a camber, its
center line may also have a sheer. The amount by which the height of the weather
deck at the after or forward perpendicular exceeds that at its lowest point.
SHEER PLAN : A side elevation of the ship's form.
SHEER STRAKE : The topmost continuous strake of the shell plating, usually made thicker than
the side plating below it.
SHELF : A wood ship term applied to the fore and aft timber that is fastened to the
frames to form a support for the ends of the beams. See clamp.
SHELL EXPANSION : A plan showing the shapes, sizes, and weights of all plates comprising the shell
plating, and details of the connections.
SHELL LANDINGS : Points marked on the frames to show where the edges of the shell plates are to
SHELTER DECK : A term applied to a deck fitted from stem to stern on a relatively light
SHIFT OF BUTTS : An arrangement of butts in longitudinal or transverse structural members whereby
the butts of adjacent members are located a specified distance from one another,
measured in the line of the members.
SHIM : (In naval architecture). A piece of wood or iron let into a slack place in a
frame, plank, or plate to fill out a fair surface or line. Also applied to thin
layers of metal or other material used to true up a bed plate or machine or
inserted in bearings to permit adjustment after wear of the bearing.
SHIPSHAPE : A nautical term used to signify that the whole vessel, or the portion under
discussion, is neat in appearance and in good order.
SHOAL : A small of timber or plank placed under the heel of a shore.
SHORES : Pieces of timber placed in a vertical or inclined position to support some part
of a ship, or the ship itself, during construction or while in dry dock.
SHORE, SPUR or SIDE : A piece of timber placed in a nearly horizontal position with one end against
the side of the ship and the other against the side of a dry dock or dock to
keep the vessel at a desired distance from the face of the dock.
SHROUD : A principal member of the standing rigging, consisting of hemp or wire ropes
which extend from or near a masthead to the vessel's side, or to the rim of a
top, to afford lateral support for the mast.
SICK BAY : A name applied to the space on board a ship where members of the crew and
passengers are given medical service and includes the dispensary, operating
room, wards, etc.
SIDE PLATING : A term applied to the plating above the bilge in the main body of a vessel. Also
to the sides of deck houses, or to the vertical sides of enclosed plated
SIDING OF A FRAME : The fore and aft dimension of a frame.
SISTER HOOK : A hook made in halves and set on eyes facing each other in such a manner that it
may be made to function as a link.
SKEG : The extreme after part of the keel of a vessel, the portion that supports the
rudder post and stern post.
SKIN : The term usually applied to the outside planking or plating forming the
watertight envelope over the framework. It is also applied to the inner bottom
plating when it is called an inner skin.
SKYLIGHT : An erection built on a deck, having glass lights in its top and fitted over an
opening in the deck for the purpose of admitting light and air to a compartment
SLACK : The opposite of taut; not fully extended as applied to a rope; to "slack away"
means to pay out a rope or cable by carefully releasing the tension while still
retaining control; to "slack off" means to ease up, or lessen the degree of
SLEEPERS : Timbers placed upon the ground or on top of piling to support the cribbing,
keel, and bilge blocks.
SLEEVE : A casing, usually of brass, fitted over line or other shafting for protection
against wear or corrosion, or as a bearing surface.
SLIDING WAYS : See launching.
SLING : A length of chain or rope employed in handling weights with a crane or davit.
The rods, chains, or ropes attached near the bow and stern of a small boat into
which the davit or crane tackle is hooked. The chain or rope supporting the yard
at the masthead.
SLIP : The difference between the pitch of a propeller, or the mean circumference of a
paddle wheel, and the advance of the ship through the water corresponding to one
revolution. An inclined launching berth. A space between two piers for berthing
SLIPWAY or BERTH : The space in a shipyard where a foundation for launching ways and keel blocks
exists and which is occupied by a ship while under construction. The term berth
is more properly applied to the space a ship occupies pier or at an anchorage.
SLUICE : An opening in the lower part of a bulkhead fitted with a sliding watertight
gate, or small door, having an operating rod extending to the upper deck or
decks. It is used to permit liquid in one compartment to flow into the adjoining
SLUSH : Grease, formerly obtained from the meat boiled in the coppers, used for
lubrication and for slushing the spars after scraping them.
SMOKESTACK : A metal chimney or passage through which the smoke and gases are led from the
uptakes to the open air.
SNUBBING : Drawing in the waterlines and diagonals of a vessel abruptly at their ends. The
checking of a vessel's headway by means of an anchor and a short cable. The
checking of a line or cable from running out by taking a turn about a cleat,
bitts, or similar fitting.
SNY : To twist a plate into an uneven warped shape on a mold.
SOFT PATCH : A temporary plate put on over a break or hole and secured with tap bolts. It is
made watertight with a gasket such as canvas saturated in red lead.
SOLE PLATE : A plate fitted to the top of a foundation to which the base of a machine is
bolted. Also a small plate fitted at the end of a stanchion.
SOUNDING PIPE : A vertical pipe in an oil or water tank, used to guide a sounding device when
measuring the depth of liquid in the tank. Also called a Sounding Tube.
SOUNDNESS OF STEEL CASTINGS : Absence in a casting of cavities or blow holes formed by air bubbles.
SPAN : The distance between any two similar members, as the span of the frames. The
length of a member between its supports, as the span of a girder. A rope whose
ends are both made fast some distance apart, the bight having attached to it a
topping lift, tackle, etc. A line connecting two davit heads so that when one
davit is turned the other follows.
SPANNER : A form of open-head wrench for use with special fittings whose character is such
as to preclude the use of the ordinary type of wrench.
SPAR : A term applied to a pole serving as a mast, boom, gaff, yard, bowsprit, etc.
Spars are made of both steel and wood.
SPECIFIC GRAVITY : The ratio of the weight of a given volume of any substance to the weight of an
equal volume of distilled water. Since the distilled water weighs approximately
62.4 pounds per cubic foot, any substance, a cubic foot of which weighs less
that this, has a specific gravity of less than one, and will float on water. Any
substance of greater weight per cubic foot has a specific gravity of more than
one and will sink. Specific gravity of gases is based in a like manner on the
weight of air.
SPECTACLE FRAME : A single casting containing the bearings for and furnishing support for the ends
of the propeller shafts in a twin screw vessel. The shell plating is worked
outboard so as to enclose the shafts and is attached at the after end to the
spectacle frame. Used in place of shaft struts.
SPIKE : A stout metal pin headed on one end and pointed at the other, made of either
square or round bar, and used for securing heavy planks and timbers together.
SPILING : The curve of a plate or strake as it narrows to a point.
SPLICE : A method of uniting the ends of two ropes by first unlayering the strands, then
interweaving them so as to form a continuous rope.
SPOT FACE : To finish off the surface around a bolt hole in a plane normal to the axis of
the hole to provide a neat seat for the nut of washer.
SPRING : The deviation from a straight line or the amount of curvature of a sheer line,
deck line, beam camber, etc., an elastic body or device which recovers its
original shape when released after being distorted.
SPROCKET, SPROCKET WHEEL : A wheel on whose periphery are teeth or cogs designed to engage with the links
of a pitch or sprocket chain through which motion is transmitted to a second
SQUATTING : The increase in trim by the stern assumed by a vessel when running at high speed
over that existing when she is at rest.
STABILITY : The tendency which a vessel has to return to the upright position after the
removal of an external force which inclined her away from that position. To have
stability, a vessel must be in a state of stable equilibrium.
STABILITY, RANGE OF : The number of degrees through which a vessel rolls or lists before losing
STAGE : A floor or platform of planks supporting workmen during the construction or the
cleaning and painting of a vessel, located either inside or outside the vessel.
STAGING : Upright supports, fastened together with horizontal and diagonal braces forming
supports for planks which form a working platform or stage.
STAGGER : To zigzag rivet holes in adjacent rows.
STANCHIONS : Short columns or supports for decks, hand rails, etc. Stanchions are made of
pipe, steel shapes, or rods, according to the location and purpose they serve.
STANDING RIGGING : Rigging that is permanently secured
and that is not hauled upon, as shrouds, stays, etc
STAPLING : Plates or angles fitted closely around or against continuous members passing
through a watertight or oiltight member and caulked or welded to maintain the
water or oil tightness of the structure.
STARBOARD : The right-hand side of the ship when looking from aft forward. Opposite to port.
STATEROOM : A private room or cabin for the accommodation of passengers or officers.
STAYS : The ropes, whether hemp or wire, that support the lower masts, topmasts,
top-gallant masts, etc. in a fore and aft direction.
STEALER : A strake of shell plating that does not extend completely to the bow or stern.
STEERING GEAR : A term applied to the steering wheels, leads, steering engine, and fittings by
which the rudder is turned.
STEM : The bow frame forming the apex of the intersection of the forward sides of a
ship. It is rigidly connected at lower end to the keel.
STERN : The after end of a vessel; the farthest distant part from the bow.
STERN FRAME : A large casting or forging attached to the after end of the keel to form the
ship's stern. Includes rudder post, propeller post, and aperture for the
propeller in single-screw vessels.
STERN PIPES : A round or oval casting, or frame, inserted in the bulwark plating at the stern
of the vessel through which the mooring hawser or warping lines are passed. Also
called Stern Chock.
STERN POST : The main vertical post in the stern frame upon which the rudder is hung. Also
called the Rudder Post.
STERN TUBE : The bearing supporting the propeller shaft where it emerges from the ship. It
consists of a hollow cast-iron or steel cylinder fitted with brass bushings,
which in turn are lined with lignum vitae, white metal, etc., bearing surfaces
upon which the propeller shaft, enclosed in a sleeve, rotates.
STIFF, STIFFNESS : The tendency of a vessel to remain in the upright position, or a measure of the
rapidity with which she returns to that position after having been inclined from
it by an external force.
STIFFENER : An angle bar, T-bar, channel, etc., used to stiffen plating of a bulkhead, etc.
STOCKS : A general term applied to the keel blocks, bilge blocks, and timbers upon which
a vessel is constructed.
STOP WATER : A term applied to canvas and red lead, or other suitable material, placed
between the facing surfaces of plates and shapes to stop the passage of oil or
water. Also applied to a wooden plug driven through a scarph joint between
timbers to insure water tightness.
STRAIN : The measure of the alteration of form which a solid body undergoes when under
the influence of a given stress.
STRAND : An element of a rope, consisting, in a fiber rope, of a number of rope yarns
twisted together and, in a wire rope, of a primary assemblage of wires.
STRAKE : A term applied to a continuous row or range of plates. The strakes of shell
plating are usually lettered, starting with A at the bottom row or garboard
STRAKE, BILGE : A term applied to a strake of outside plating running in the way of the bilge.
STRAKE, BOTTOM : Any strake of plating on the bottom of a ship that lies between the keel and the
STRENGTH MEMBER : Any plate or shape which contributes to the strength of the vessel. Some members
may be strength members when considering longitudinal strength but not when
considering transverse strength, and vice versa.
STRETCHERS : Athwartship, movable pieces against which the oarsmen brace their feet in
pulling a small boat.
STRESS : The intensity of the force which tends to alter the form of a solid body; also
the equal and opposite resistance offered by the body to a change of form.
STRINGER : A term applied to a fore-and-aft girder running along the side of a ship and
also to the outboard strake of plating on any deck. The side pieces of a ladder
or staircase into which the treads and risers are fastened.
STRINGER PLATES : A term applied to the outboard plates on any deck, or to the plates attached to
the top flanges of a tier of beams at the side of a vessel.
STRUM BOX : The enlarged terminal on the suction end of a pipe which forms a strainer to
prevent the entrance of material liable to choke the pipe. Also called Rose Box.
STRUT : A heavy arm or brace.
STUD: A bolt threaded on both ends, one end of which is screwed into a hole
drilled and tapped in the work, and is used where a through bolt cannot be
STUD LINK: Chain in which each link has a short distance piece (known as a stud)
worked at its mid-length at right angles with its major axis. This is done in
order to maintain the link shape.
STUDDING : The vertical timbers or framing of a wooden deck house, fitted between the sill
and the plate.
STUFFING BOX : A fitting designed to permit the free passage or revolution of a rod or a pipe
while controlling or preventing the passage by it of water, steam, etc.
SUBMARINE : Beneath the surface of the sea. A vessel which is capable of service both below
and on the surface of the water.
SUNK FORECASTLE, SUNK POOP : A forecastle or poop deck which is raised only a partial deck height above the
level of the upper or weather deck.
SUPERSTRUCTURE : A structure built above the uppermost complete deck; a pilot house, bridge,
galley house, etc.
SURGE: A vessel's transient motion along her fore and aft axis.
SWAGE: To bear or force down. An instrument having a groove
on its under side for the purpose of giving shape to any piece subjected to it
when the swage is struck by a hammer.
SWALLOW: A term applied to the oval or round opening in a chock or mooring ring.
SWASH BULKHEADS : Longitudinal or transverse nontight bulkheads fitted in a tank
to decrease the swashing action of the liquid contents. Their function is
greatest when the tanks are partially filled. Without them the unrestricted
action of the liquid against the sides of the tank would be severe. A plate
serving this purpose is called a swash plate.
SWAY: A vessel's motion from side to side.
SWIVEL: A special link constructed in two parts which revolve on each other,
used to prevent fouling due to turns or twists in chain, etc.
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TACKLE: Any combination of ropes and blocks that multiplies power. Also applied
to a single whip which does not multiply power but simply changes direction.
TAFF RAIL : The rail around the top of the bulwark or rail stanchions of the after end of
the weather deck, be it upper, main, raised, quarter, or poop.
TAIL SHAFT : The aft section of the shaft which receives the propeller.
TANKS : Compartments for liquids or gases. They may be formed by the ship's structure as
double bottom tanks, peak tanks, deep tanks, etc., or may be independent of the
ship's structure and installed on special supports.
TANK TOP : The plating laid on the bottom floors of a ship, which forms the top side of the
tank sections or double bottom.
TARPAULIN : A term formerly applied to a paulin which was usually tarred.
TAUT : The condition of a rope, wire, or chain when under sufficient tension to cause
it to assume a straight line, or to prevent sagging to any appreciable amount.
TEE BAR : A rolled or extruded structural shape having a cross section shaped like the
TELEGRAPH : An apparatus, either electrical or mechanical, for transmitting orders, as from
a ship's bridge to the engine room, steering gear room, or elsewhere about the
TELEMOTOR : A device for operating the valves of the steering engine from the pilot house by
means of either fluid pressure or electricity.
TEMPLATE : A mold or pattern made to the exact size of a piece of work that is to be laid
out or formed, and on which such information as the position of rivet holes,
size of laps, etc., is indicated.
TENON : The end of a piece of wood cut into the form of a rectangular prism, designed to
be set into a cavity or mortise of a like form in another piece.
TENSILE STRENGTH : The measure of a material's ability to withstand a tensile, or pulling stress
without rupture, usually measured in pounds or tons per square inch of cross
TEST HEAD : The head or height of a column of water
which will give a prescribed pressure on the vertical or horizontal sides of a
compartment or tank in order to test its tightness or strength or both.
THOLES : The pins in the gunwale of a boat which are used for oarlocks.
THREAD : The spiral part of a screw.
THWARTS : Boards extending across a rowboat just below the gunwale to stiffen the boat and
to provide seats.
TIE PLATE : A single fore-and-aft or diagonal course of plating attached to deck beams under
a wood deck to give extra strength.
TILLER : An arm attached to the rudder head for operating the rudder.
TOE : The edge of a flange on a bar.
TOGGLE PIN : A pin having a shoulder and an eye worked on one end, called the head, and whose
other end, called the point, has its extremity hinged in an unbalanced manner so
that after being placed through a hole, it forms a T-shaped locking device to
keep the pin from working out or being withdrawn without first bringing the
hinged portion into line with the shaft of the pin.
TONGUE AND GROOVE : The term applied to a plank or board which has one edge cut away to form a
projection, or tongue, and the opposite edge cut out to form a groove, the
tongue of one plank fitting into the groove of the adjoining plank.
TONNAGE, GROSS : The entire internal cubic capacity of a vessel expressed in "tons" taken at 100
cubic feet each. The peculiarities of design and construction of the various
types of vessels and their parts necessitate certain explanatory rulings in
connection with this term.
TONNAGE, NET : The internal cubic capacity of a vessel which remains after the capacities of
certain specified spaces have been conducted from the gross tonnage. Tonnage
should not be confused with displacement.
TOP BREADTH : The width of vessel measured across the shelter deck.
TOPPING LIFT : A rope or chain extending from the head of a boom or gaff to a mast, or to the
vessel's structure, for the purpose of supporting the weight of the boom or gaff
and its loads, and permitting the gaff or boom to be raised or lowered.
TOPSIDE : That portion of the side of the hull which is above the designed waterline. On
or above the weather deck.
TORQUE : The moment of a system of forces that causes rotation, as of a shaft or a rudder
TRANSOM : A seat or couch built at the side of a stateroom or cabin, having lockers
(transom lockers) or drawers underneath.
TRANSOM, TRANSOM BOARD : The board forming the stern of a square-ended row boat or small yacht.
TRANSOM FRAME : The last transverse frame of a ship's structure. The cant frames, usually normal
to the round of the stern, connect to it.
TRANSVERSE : At right angles to the ship's fore-and-aft center line.
TRANSVERSE FRAMES : Vertical athwartship members forming the ribs.
TREADS : The steps or horizontal portions of a ladder or staircase upon which the foot is
TREENAILS : Wooden pins employed instead of nails or spikes to secure the planking of a
wooden vessel to the frames.
TRIM : The arithmetic sum of the drafts forward and aft above and below the mean
water-line. The angle of trim is the angle between the plane of flotation and
the mean water-line plane. A vessel "trims by the head" or "trims by the stern"
when the vessel inclines forward or aft so that her plane of flotation is not
coincident with her mean water-line plane. See Drag.
TRIPPING BRACKETS : Flat bars or plates placed at various points on deck girders, stiffeners, or
beams as a reinforcement to prevent their free flanges from tipping.
TRUNK : A vertical or inclined shaft formed by bulkheads or casings, extending one or
more deck heights, around openings in the decks, through which access can be
obtained, cargo, stores, etc., handled, or ventilation provided without
disturbing or interfering with the contents or arrangements of the adjoining
TUMBLE HOME : The decreasing of a vessel's beam above the waterline as it approaches the rail.
Opposite of flare.
TURNBUCKLES : Used to pull objects together. A link into whose opposite ends two threaded
bars, one left-handed, the other right-handed, are inserted.
TURRETS : Structures designed for the mounting and handling of the guns and accessories
(usually main battery guns) of a war vessel. Turrets are constructed so as to
revolve about a vertical axis usually be means of electrical or hydraulic
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UMBRELLA : A metal shield in the form of a frustrum of a cone, secured to the outer casing
of the smokestack over the air casing to keep out the weather.
UNSHIP : To remove anything from its accustomed or stowage place; to take apart.
UPPER DECK : Generally applied to the uppermost continuous weather deck.
UPPER WORKS : Superstructures or deck erections located on or above the weather deck.
Sometimes applied to the entire structure above the waterline.
UPTAKE : A sheet-metal conduit connecting the boiler smoke boy with the base of the
smokestack. It conveys the smoke and hot gases from the boiler to the stack and
is usually made with double walls, with an air space between to prevent
radiation of heat into adjacent spaces.
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VALVE : A mechanical device used for controlling or shutting off the passage of a fluid
or gas into or out of a container or through a pipe line.
VANE : A fly made of bunting and carried at the masthead or truck, which, being free to
rotate on a spindle, indicates the direction of the wind.
VANG : Ropes secured to the outer end of a cargo boom, the lower ends being fastened to
tackles secured to the deck, used for guiding and swinging and for holding the
boom in a desired position. Also applied to ropes secured to the after end of a
gaff and led to each side of the vessel to steady the gaff when the sail is not
VENTILATION : The process of providing fresh air to the various spaces and removing foul or
heated air, gases, etc., from them. This may be accomplished by natural draft or
by mechanical means.
VENTILATORS, BELL-MOUTHED or COWL : Terminals on open decks in the form of a 90-degree elbow with enlarged or
bell-shaped openings, so formed as to obtain an increase of air supply when
facing the wind and to increase the velocity of air down the ventilation pipe.
VISOR : A small inclined awning running around the pilot house over the windows or air
ports to exclude the glare of the sun or to prevent rain or spray from coming in
the openings when the glazed frames are dropped or opened. They may be of canvas
VOICE TUBE : A tube designed for the carriage of the human voice from one part of the ship to
another. In its simplest form the voice-tube system includes a speaking
connection between the pilot house and engine room only. In large war vessels
the system becomes very complicated. Voice tubes are generally made up to about
four inches in diameter and fitted with appropriate speaking and listening
terminals. Telephones have largely replaced them.
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WALES : The side planking on a wood ship lying between the bottom and the top-side
WARP : A light hawser or tow rope; to move a vessel along by means of lines or warps
secured to some fixed object.
WARDROOM : A room or space on shipboard set aside for use of the officers for social
purposes and also used as their mess or dining room.
WASH PLATES : Plates fitted fore and aft between floors to check the rush of bilge water from
side to side when the ship is rolling.
WATER LINE : A term used to describe a line drawn parallel to the molded base line and at a
certain height above it, as the 10-foot water line. It represents a plane
parallel to the surface of the water when the vessel is floating on an even
keel, i.e., without trim. In the body plan and the sheer plan it is a straight
line, but in the plan view of the lines it shows the contour of the hull line at
the given distance above the base line. Used also to describe the line of
intersection of the surface of the water with the hull of the ship at any draft
and any condition of trim.
WATERSHED : A fitting on the outside of the shell of a ship over an air port, a door, or a
window to prevent water which runs down the ship's side from entering the
opening. One over an air port is also called a Brow or a Port Flange.
WATERTIGHT COMPARTMENT : A space or compartment within a ship having its top, bottom, and sides
constructed in such a manner as to prevent the leakage of water into or from the
space unless the compartment is ruptured.
WATERWAY : A narrow channel along the edge of the deck for the collection and disposal of
water occurring on the deck.
WATERWAY BAR : An angle or flat bar attached to a deck stringer plate forming the inboard
boundary of a waterway and serving as an abutment for the wood deck planking.
WAYS : See launching
WEATHER DECK : A term applied to the upper, awning, shade, or shelter deck, or to the uppermost
continuous deck, exclusive of forecastle, bridge, or poop, that is exposed to
WEB : The vertical portion of a beam; the athwartship portion of a frame; the portion
of a girder between the flanges.
WEB FRAME : A built-up frame to provide extra strength consisting of a web plate with
flanges on its edges, placed several frame spaces apart, with the smaller,
regular frames in between.
WEB PLATES: A wide girder plate as in a web frame or hatch beam. Angle bars are usually
fitted on each edge.
WEDGES : Wood or metal pieces shaped in the form of a sharp V, used for driving up or for
separating work. They are used in launching to raise the vessel from the keel
blocks and thus transfer the load to the cradle and the sliding ways.
WELDING : For all welding definitions see "General Specifications for Inspection of
Material, Appendix VII, Welding, Part A, Section A-1, Welding Nomenclature and
Definitions," issued by the Navy Department.
WHIP : A term loosely applied to any tackle used for hoisting light weights and serves
to designate the use to which a tackle is put rather than to the method of
reeving the tackle.
WILDCAT : A special type of drum whose faces are so formed as
to fit the links of a chain of given size.
WEIGH ANCHOR: To raise the anchor. When it is aweigh it is
off the bottom.
WINCH : A hoisting or pulling machine fitted with a horizontal single or double
drum. A small drum is generally fitted on one or both ends of the shaft
supporting the hoisting drum. These small drums are called gypsies, niggerheads,
or winch heads. The hoisting drums either are fitted with a friction brake or
are directly keyed to the shaft. The driving power is usually steam or
electricity, but hand power is also used. A winch is used principally for the
purpose of handling, hoisting, and lowering cargo from a dock or lighter to the
hold of a ship and vice versa.
WINDLASS: An apparatus in which horizontal or vertical drums or gypsies and
wildcats are operated by means of a steam engine or motor for the purpose of
handling heavy anchor chains, hawsers, etc.
WIND-RODE: Caused to ride or drive by the wind in opposition to the course of the
tide; -- said of a vessel lying at anchor, with wind and tide opposed to each
WIND SCOOP: A scoop-shaped fitting of sheet metal which is placed in an open air
port with the open side forward for the purpose of catching air and forcing it
into a cabin, stateroom, or compartment.
WING, WINGING : A term used to designate structural members, compartments, sails, and objects on
a ship that are located a considerable distance off the fore-and-aft center
WORM, WORM SHAFT : A threaded shaft designed to engage the teeth of a wheel lying in the plane of
the shaft axis. This type of gear is used for the transmission of heavy loads at
WORMING : Filling the contlines of a rope with tarred small stuff preparatory to serving,
to give the rope a smoother surface and to aid in excluding moisture from the
interior of the rope.
WRENCH : A hand tool used to exert a twisting strain, such as setting up bolts, nuts,
WRINKLING : Slight corrugations or ridges and furrows in a flat plate due to the action of
compressive or shear forces.
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Yacht : a recreational
boat. It designates two rather different classes of watercraft, sailing and
power yachts. Yachts are differentiated from working ships mainly by their
leisure purpose, and are basically fancy houseboats. However, since the level of
luxury on larger yachts has seen an increasing trend, the use of the word yacht
to mean any sailing vessel has been diminishing and is more and more limited to
racing yachts or cruising yachts. Yacht lengths generally start at 32-35 feet
(10-11 m) and go up to hundreds of feet. A mega yacht generally refers to any
yacht (sail or power) above 100 ft (34 m) and a super yacht generally refers to
any yacht over 200 ft (70 m). This size is small in relation to typical cruise
liners and oil tankers.
Yankee : a fore-sail
flying above and forward of the jib, usually seen on bowsprit vessels
Yar or Yare (pronounced "yahr" :
(Said of a ship) quick to the helm; easily handled or maneuvered
Yard : 1. the
horizontal spar from which a square sail is suspended. Not to be mistaken for
yardarm. 2. the spar from which a quadrilateral fore-and-aft sail like a spanker
or lugsail is suspended. 3. an area where boats are built, stored or repaired. A term applied to a spar attached at its middle portion to a mast and running
athwartship across a vessel as a support for a square sail, signal halyards,
Yardarm : the very end
of a yard. Often mistaken for a "yard", which refers to the entire spar; as in
to hang "from the yardarm"
Yaw : A vessel's motion
rotating about the vertical axis, so the bow rotates from side to side. Compare
to Pitch, Roll, Headway, Sternway, Leeway, Drift, Surge, and Heave
YAWING: To turn from side to side on an uneven course.
YIELD POINT : The stress at which a piece of material under strain yields markedly, becoming
permanently distorted without increase of load.
YOKE : A frame or bar having its center portion bored and keyed or otherwise
constructed for attachment to the rudder stock. Steering leads to the steering
gear are connected to each end of the yoke for the purpose of turning the
rudder. Yoke lanyards are lines extending from the ends of the yoke to the stern
sheets of a small boat for use in steering.
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Zephyr : a gentle
breeze. The west wind.
Z-Twist : twisted rope
with a right-hand lay, the most common twist in rope; opposite of S-twist
Zodiak : a brand of
very popular inflatable and rigid inflatable boats (RIBs) used by SCUBA divers
because of their stability and ease of boarding from the water and as tenders by
much of the boating community
Zulu Time : the
difference between local time and Greenwich Meridian Time or Greenwich Mean Time
(GMT). Zulu time is sometimes denoted by the letter "Z", a reference to the
equivalent nautical time zone (GMT), which has been denoted by a Z since about
1950. Since the NATO phonetic alphabet and amateur radio word for Z is "Zulu",
UTC is sometimes known as Zulu time. This is especially true in aviation, where
Zulu is the universal standard. This ensures everyone, regardless of location is
using the same 24-hour clock, thus avoiding confusion when navigating between
time zones. See
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