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SHIP GLOSARYAbaft. Aft of; toward the stern from a designated location. Accommodation ladder. A portable inclined ladder hinged to a platform attached to the edge of a ship, or at the sill of a shell entry port, and which can be positioned to provide access between ship and small craft or shore. Adjustable pitch propeller. A propeller in which the individual blades are fastened to the hub in such a way that they can, on occasion, be twisted, or removed and replaced. Admeasurement. (See registered tonnage.) Advance. The theoretical linear distance a screw propeller would move forward were it working within a nut. Also the linear transfer of forward distance effected by a vessel after starting the hard-over turning maneuver. Aft. Toward, at, or near the stern. Afterbody. That portion of a ship's hull abaft amidships. Afterpeak. The compartment in the stern, abaft the aftermost watertight bulkhead. After perpendicular. (See length between perpendiculars.) Air cushion vehicle. A vessel that uses powerful fans to inject air beneath itself, which provides vertical support allowing the craft to move with little friction over the surface. Air port. A hinged glass window generally circular, in the ship's side or deckhouse, for light and ventilation; also called porthole, portlight or side scuttle. All-hatch ship. A vessel in which most of the deck over the cargo holds is cut away for hatches. Alternator. (See generator.) Amidships. In the vicinity of the midlength of a ship as distinguished from the ends. Technically it is exactly half way between the forward and the after perpendiculars. Also a helm order to indicate the rudder is to be put on the centerline. Anchor. A heavy forging or casting so shaped as to grip the sea bottom, and by means of a cable or rope, hold a ship or other floating structure in a desired position regardless of wind and current. Anode. An electrode carrying a positive charge. Apparent wind. The direction from which the air impinges on a boat in motion. Appendages. The portions of a vessel extending beyond the main hull outline including such items as rudder, shafting, struts, bossings, and bilge keels. Arc welding. (See electric arc welding.) Armature. The metallic skeleton of a ferro cement hull. Athwartship. Across the ship, at right angles to the fore-and-aft centerline.

Automation. Automatic, rather than human, control systems. Auxiliary machinery. All machinery other than that required for main propulsion. Balanced rudder. A steering foil in which the turning stock is located close to the foil's center of lateral pressure. Bale cubic. The cubic capacity of a cargo hold measured to the inside of the frames or cargo battens and underside of deck beams. Ballast. Any solid or liquid weight placed in a ship to increase the draft, to change the trim, or to regulate the stability. Ballast tank. A watertight enclosure that may be used to carry water ballast. Bar keel. A longitudinal appendage, rectangular in section, running along the bottom of the ship, usually on the centerline. Baseline. A fore-and-aft reference line. On large vessels it is at the upper surface of the flat plate keel at the centerline. Vertical dimensions are measured from a horizontal plane through the baseline, often called the molded baseline. Battens. (See cargo battens.) Beam, cant. Deck beams aft radially disposed and extending from the transom beam to the cant frame heads at the deck edge. Beam, deck. An athwartship horizontal structural member, usually a rolled shape, supporting a deck or flat. Beam knee. (See knee, beam.) Beam, molded. The maximum breadth of the hull measured between the inboard surfaces of the side shell plating. Beams, cant. Deck supports at aft end, arranged in a fan-like pattern. Beam seas. A train of waves approaching a vessel directly from one side. Beam, transom. (See transom beam.) Bearding line. The intersection of the inside surface of the shell plating and the stem or sternpost. Below. Indicative of a location below deck. Bending moment. The product of a weight acting at a distance from the support. Bermuda sail. Same as jib headed or Marconi sail. Berth. Where a ship is docked or tied up; also a place to sleep aboard; a bunk or bed. Between decks. (See 'tween decks.) Bevel. The angle between the flanges of a frame or other member. (When greater than a right angle, open bevel, when less, closed or shut); also, to chamfer.

Bilge. Intersection of bottom and side. May be rounded or angular as in a chine form hull. The lower parts of holds, tanks and machinery spaces where bilge water may accumulate. Bilge and ballast system. A system of piping generally located in the holds or lower compartments of a ship and connected to pumps. This system is used for pumping overboard accumulations of water in holds and compartments, and also for filling or emptying ballast tanks. Bilge bracket. A vertical transverse flat plate welded to the tank top or margin plate and to the frame in the area of the bilge. Bilge diagonal. An imaginary sloping plane whose location is shown on the body plan of a lines drawing, and whose true shape is shown, usually, below the half-breadth plan. Bilge keel. A long longitudinal fin fitted at the turn of the bilge to reduce rolling. Bilge strake. Course of shell plates at the bilge. Bilge water. Stagnant water collected in the lower parts of a vessel. Billboard. A sloping plate above the rake or gunwale of a vessel having low freeboard, on which an anchor is stowed and from which it can be released for use. Binnacle. A stand or box for holding and illuminating a compass Bitter end. The inboard end of a ship's anchoring cable which is secured in the chain locker. Bitt, mooring. Short metal column (usually two) extending up from a base plate attached to the deck for the purpose of securing and belaying ropes, hawsers, etc. used to secure a ship to a pier or tugboat. Also called a bollard. Bitumastic. An elastic bituminous cement used in place of paint to protect steel. Blade area ratio. That proportion of the propeller disk occupied by the blades. Bleeder. A small cock, valve, or plug to drain off small quantities of fluids from a container or piping system. Block coefficient. The ratio of the underwater volume of a ship to the volume of a rectangular block, the dimensions of which are the length, draft and beam. The relationship is expressed as a decimal. Body plan. A drawing consisting of two half transverse elevations or end views of a ship, both having a common vertical centerline, 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 waterlines, the buttock lines, and the diagonal lines. Bollard. (See bitt, mooring.) Bolster. (See hawsepipe.) Bonjean curves. A set of curves, each of which represents a plot of the cumulative area of a station on the lines plan, from the base line to any point above it. Booby hatch. An access hatch in a weather deck, protected by a hood from sea and weather. Also called a companionway.

Boom. A long round spar hinged at its lower end, usually to a mast, and supported by a wire rope or tackle from aloft to the upper end of the boom. Cargo, stores, etc, are lifted by tackle leading from the upper end of the boom. Also the spar at the bottom of a fore and aft sail. Boom crutch. A term applied to a light structure built up from a deck to support the free end of a boom when it is not in use. Also called a boom rest. Boom table. A stout small platform usually attached to a mast to support the hinged heel bearings of booms and to provide proper working clearances when a number of booms are installed on or around one mast. Also called a mast table. Boottop, or boottopping. The outer surface of the shell plating between light and load waterlines. Bossing or boss. The curved swelling outboard portion of ship's shell plating that surrounds and supports the propeller shaft. Boundary layer. The body of water that is dragged along with a vessel because of friction. Bow. The forward end of a ship. Bower anchor. An anchor carried at the bow. Box girder. A large structural beam composed of four plates arranged in a rectangular configuration in cross section. Bracket. A plate used to connect rigidly two or more structural parts, such as deck beam to frame, or bulkhead stiffener to the deck or tank top (usually triangular in shape). Brake horsepower. The power delivered by a diesel engine before entering any reduction gear. Braking flaps. Hinged plates, usually attached to a rudder, that can be swung out so as to help stop a ship's forward motion. Breadth, molded. (See beam, molded.) Break. The end of a partial superstructure such as a poop, bridge or forecastle where it drops to the deck below. Breakwater. Inclined bulwark-like structure on a weather deck to deflect sea water coming over the bow and moving aft. Breasthook. A triangular plate bracket joining port and starboard side stringers at the stem. Breast line. A mooring rope oriented at about a right angle to the length of the ship. Bridge. A superstructure at or near a ship's mid-length. Bridge, flying. The platform forming the top of the pilothouse. Bridge house. A term applied to an erection fitted on the upper or superstructure deck of a ship. The officers' quarters, staterooms and accommodations are usually located in the bridge house and the pilothouse is located above it. Bridge, navigating. The conning station or command post of a ship.

Brittle fracture. A tensile failure that acts with such abruptness that the failed material does not "neck down." Broach. To be turned ninety degrees off course. Broken stowage. The spaces between and around cargo packages, including dunnage, and spaces not usable because of structural interferences. Brow. A water shed