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Banner image, Nomenclature of Naval Vessels

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S T U V W X  Y  Z


Toward the stern of a ship; back; behind; back of; further aft than.
At right angles to the keel.
On or in a ship.
Side by side; over against; opposite to.
Stairs slung at the gangway, leading down the vessel's side to a point near the water, for ship access from small boats.
Near the stern; toward the stern.
That portion of a ship's body aft of the midship section.
Frames aft of amidships, or frames near the stern of the ship.
The aftermost tank or compartment forward of the stern post.
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 ship.
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.
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.
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 from within.
In the top or upper rigging; on the yards; above the decks.
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.
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 power.
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.
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.
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.
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.
Same as angle bar.
A bar of angle-shaped section used as a stiffener and for attachment of one plate or shape to another.
A structural shape having a bulb on one flange of the angle, used as a frame, beam, or stiffener.
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 oiltight joint. See Stapling.
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.
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 immersed.
A reinforcing timber bolted to the after side of the stem.
The principal axis member, or spindle, of a machine by which a motion of revolution is transmitted.
Sometimes used in lieu of "hogging".
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.
Signifying position, in the rear of or abaft the stern; as regards motion, the opposite of going ahead; backwards.
Across, from side to side, transverse, across the line of a vessel's course.
Reaching across a vessel, from side to side.
Various winches, pumps, motors, engines, etc., required on a ship, as distinguished from main propulsive machinery (boilers and engines on a steam installation).
A rooflike canopy of canvas suspended above a vessel's decks, bridges, etc., for protection against sun and weather.


Used for the same purpose but on the opposite side to a bosom bar.
A portable back support nicely designed and fitted on the after side of the stern thwart in a small motor or row boat.
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.
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.
A rudder with its axis between the forward and after edge.
A piece of timber from 4" to 10" square.
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 submarines.
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.
Sea water, confined to double bottom tanks, peak tanks, and other designated compartments, for use in obtaining satisfactory draft, trim, or stability.
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.
A light wood; a South American raft made of light wood.
A craft of full body and heavy construction designed for the carriage of cargo but having no machinery for self-propulsion.
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."
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.
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 them.
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.
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.
The extreme width of a ship. Also an athwartship or longitudinal member of the ship's structure supporting the deck.
A bracket between a frame or stiffener and the end of a beam; a beam arm.
A line showing the points of intersection between the top edge of the beam and the molded frame line, also called "molded deck line".
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.
A beam made from a flat plate, with the flange bent at right angles as by an angle-bending machine.
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.
A term applied to foundations, particularly those having vertical web plates as principal members. The vertical web plates of foundations are also called bearers.
A block on or in which a journal rotates; a bearing-block.
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.
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.
Underneath the surf the water. Underneath a deck or decks.
A large machine used to give curvature to plates by passage in contact with three rolls.
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.
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.
The space between any two, not necessarily adjacent, decks. Frequently expressed as "Tween Decks."
A term for a plane having any other angle than 90 degrees to a given reference plane. Also, a small tool similarl to a try square except that the blade is adjustable to taking bevels.
A term applied where one flange of a bar is bent to form an acute angle with the other flange.
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.
A cock or valve with a bent outlet; strictly, the bent outlet.
A loop or bend in a rope; strictly, any part between the two ends may be termed the bight.
The rounded portion of a vessel's shell which connects the bottom with side. To open a vessel's lower body to the sea.
The curved shell plates that fit the bilge.
The lowest portion of a ship inside the hull, considering the inner bottom where fitted as the bottom hull limit.
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.
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 vessel.
The inboard end of a vessel's anchor chain which is made fast in the chain locker.
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.
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.
A small cock, valve, or plug to drain off small quantities of fluids from a container or system.
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".
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 code.
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.
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.
A block having two sheaves of different diameters placed in the same plane one above the other.
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 obstructions.
A mechanical device used to supply air under low pressure for artificial ventilation and forced draft, usually of the centrifugal type.
The act of going on board a ship.
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.
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.
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.
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.
A compartment in the hold, in the middle or after section of a vessel, where the boilers are placed.
See "bits".
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 temporary foundation.
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.
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".
Curves of areas of transverse sections of a ship. The curves of the moments of these areas above the base line are sometimes included.
A cover used to guide and enclose the tail end of a valve spindle.
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 facilitate access.
A term applied to a spar used in handling cargo, or to which the lower edge of a fore-and-aft sail is attached.
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.
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.
A portable, heavy duty tool, used for boring, counter boring, reboring, facing, grooving, etc., where true alignment is of primary importance.
The inside of an angle bar.
An angle fitted inside another.
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.
The curved, swelling portion of the ship's underwater hull around the propeller shaft.
The plate that covers the boss.
That portion of a vessel's shell between the keel and the lower turn of the bilge.
A term applied to the bottom shell plating in a double bottom ship.
That part of the shell plating which is below the water line. More specifically, the immersed shell plating from bilge to bilge.
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.
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.
A spar projecting forward over the bow for the purpose of holding the lower ends of the head sails.
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.
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.
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.
The joining of certain metals by the use of a hard solder.
The maximum breadth measured over plating or planking, including beading or fenders.
The greatest breadth of the vessel measured from heel of frame on one side to heel of frame on other side.
Measured amidships at its greatest breadth to outside of plating.
The point at which the partial decks known as the forecastle and poop are discontinued.
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.
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 together.
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.
A term applied to an erection or superstructure fitted about amidship on the upper deck of a ship.
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.
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.
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 watershed.
A distortion, such as a bulge; to become distorted; to bend out of its own plane.
Generally, but not exclusively, applied to various devices used to prevent water from entering turret gun ports, hawse and chain pipes, etc.
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.
An inclined launching berth where the ship is built.
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.
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.
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 peak tank.
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.
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.
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.
A partition or enclosure bulkhead, used largely in store rooms, shops, etc., made of wire mesh panels.
A machine, usually hydraulic or electric, for bending bars, shapes or plates while cold.
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.
A brace extending from the deck to a point near the top of the bulwark, to keep it rigid.
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, etc.
A built-in berth or bed.
A compartment used for stowage of coal or oil fuel.
Ability to float; the supporting effort exerted by a liquid (usually water) upon the surface of a body, wholly or partially immersed in it.
The floating or buoyant power of the unsubmerged portion of the hull of a vessel. Usually referred to a specific condition of loading.
The carrying capacity of a vessel expressed in long tons.
Men who operate gas torches for burning plates and shapes to proper sizes for assembly into the structure.
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.
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.
The rounded-in overhanging part on each side of the stern in front of the rudder, merging underneath in the run.
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".
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.


The interior of a deck house, usually the space set aside for the use of officers and passengers.
A watertight structure used for raising sunken vessels by means of compressed air. Also the floating gate to close the entrance to a drydock.
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.
The operation of jamming material into the contact area to make a joint watertight or oiltight.
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.
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 arch.
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 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.
A frame the plane of which is not square to the keel.
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.
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 bars.
Merchandise or goods accepted for transportation by ship.
A heavy boom used in loading cargo. See "boom".
A large opening in the deck to permit loading of cargo.
A mat, usually square and made of manila rope, used to protect the deck covering while taking stores, etc., on board.
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.
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.
Short beams forming a portion of the framing about deck openings. Also called headers when they support the ends of interrupted deck beams.
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.
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.
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.
Planking fitted on top of the floors or double bottom in the cargo holds.
Thick strakes of planking fastened to the inside flanges or edges of the framing in the cargo holds.
The middle line of the ship from stem to stern as shown in any water line view.
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.
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.
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 waterline.
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.
The point in a sail or an immersed plane surface at which the resultant of the combined pressure forces acts.
The immersed longitudinal vertical middle plane of a vessel.
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.
Compartment in forward lower portion of ship in which anchor chain is stowed.
The iron-bound opening or section of pipe leading from the chain locker to the deck, through which the chain cable passes.
A bar or plate secured to the shell of a vessel to which the standing rigging is attached.
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.
A device used to secure the chain cable when riding at anchor, thereby relieving the strain on the windlass, and also for securing the anchor in the housing position in the hawsepipe.
A bevel surface formed by cutting away the angle of two intersecting faces of a piece of material.
A small room adjacent to the bridge for charts and navigating instruments.
The line formed by the intersection of side and bottom in ships having straight or slightly curved frames.
The inserting of oakum or cotton between the plank edges of boats to secure watertightness. Also called calking.
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.
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 the member.
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.
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 strength.
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.
An instrument used for indicating the angle of roll or pitch of a vessel.
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.
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.
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.
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.
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.
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.
The frame worked around a manhole to stiffen the edges of the plating around the opening and to provide a support for the cover.
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 the valve.
A term used in connection with small boats to refer to an uncovered, sunken place or pit, usually for the accommodation of passengers.
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 tightness.
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.
A vessel designed for the carrying of coal, which may or may not be fitted with special appliances for coal handling.
A large mat used to close an aperture in a vessel's side resulting from a collision.
The cover over a 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.
A subdivision of space or room in a ship.
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.
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 commercial vessels.
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.
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.
A vessel with a metal frame and a wooden shell and decks.
A comprehensive term for all ropes of whatever size or kind on board a ship.
A solid key or wedge used to secure a wheel on a shaft or the like.
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.
That part of a ship's stern which overhangs the stern post, usually that part above the water line.
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.
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.
A rivet driven flush on one or both sides.
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 couplings.
A support of wood or metal shaped to fit the object which is stowed upon it.
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.
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.
The carriage on which the ship rests when being docked on a marine railway.
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.
Foundations of heavy blocks and timbers for supporting a vessel during the period of construction.
A temporary horizontal timber brace to hold a frame in position. Cross-spalls are replaced later by the deck beams.
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.
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.
A lookout station attached to or near the head of a mast.
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.
A term applied to a support for a boom. Also applied to the jaw of a boom or gaff.
A galley structure on deck; a small cabin.
The forward edge of the stem at or near the water line is called the cutwater.

25 August 2003