Shipbuilding Terms and Phrases
The following pages are a glossary of shipbuilding terms from United States Shipping Board Emergency Fleet Corporation publication The Building of a Wooden Ship by Charles G. Davis (1918), a long out-of-print book. These definitions will be very handy when reading the works of such authors as Davis, Howard I. Chapelle, V.R. Grimwood, and others I will reference in this blog. In some cases, I have added further clarification to a definition in the form of editor’s notes. These are in italic, contained in parentheses, and attribute the modern author of the clarification.
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DAGGER: a piece of timber that faces into the poppets of a cradle or launching way, and crosses diagonally under the keel at the bow, holding the two parallel timbers of the launching cradle from spreading. Note: the word “dagger” seems to apply to any timber, plank or knee which is framed in aslant or diagonally.
DAGGER KNEES: are used in place of hanging knees. The arm against the side of the vessel is brought up aslant to the under side of the connecting beam. In merchant ships they are used in the lower hold, and are placed in this position to allow as much storage room as possible. Note: Any straight hanging knees not perpendicular to the face of the beam to which they are attached are generally called “dagger knees.”
DAP: shallow groove cut in the face of a timber; groove cut in the outside face of the vessel’s frame, to receive or hold steel strapping.
DASHER OR DRIVER BLOCK: small block attached to the end of the after gaff or spanker gaff, used for reeving the ensign halyards. Most steamers do not carry this after or spanker gaff.
DAVIT GUY: a small guy rope secured to the extreme outer end of a davit used to secure the davit in a desired position, generally at a right angle to the keel.
DAVITS: the fixed wooden timbers, iron or steel forgings which can be swung or topped over the side of a vessel, and from which life or other boats are suspended; a small frame used for catting the anchor, handling accommodation ladder or hoisting ammunition from the magazine; “boat davit,” “cargo davit,” “accommodation ladder davit,” “magazine davit.”
DEADEYE: a small circular hardwood block without sheave, containing three or more holes pierced through the least thickness, and with a score or groove cut around the outside of the big circumference to receive a strop or grommet. It was formerly part of the rigging used for securing the shrouds to the chain-plates and setting shrouds taut. Turnbuckles have now generally replaced deadeyes for this work.
DEAD-FLAT: the middle of the length of a ship where the frames are similar with flat floors, sometimes called the “square body.” From the first dead-flat frame forward to the last dead-flat frame aft they are sometimes marked by the framer thus: yS
DEAD-LIGHT: thick glass windows fitted in the portholes of a vessel.
DEAD-RISE: the inclination or angle that the bottom of a vessel makes from the horizontal, measured from the horizontal at the half or molded breadth.
DEAD-ROPE: a rope that is securely fastened at each end and does not reeve through any block or pass over any sheave.
DEAD-WATER: the eddy to be seen in the water under the stern when a ship is moving forward.
DEAD-WEIGHT CAPACITY (DEAD-WEIGHT CARGO, DEAD- WEIGHT TONNAGE): the total displacement of a ship represents the weight actually supported by the water, and may be divided into two sections: Section 1 is the light-weight of the ship. Section 2 is the dead-weight tonnage. Section 1 may be divided into two parts, viz.: hull, which consists of steel, wood and fittings; machinery, which consists of engines, boilers and auxiliaries. The dead-weight capacity, therefore, consists of cargo, spare gear, crew and effects, passengers, baggage, coal in bunkers, coal on fire bars, fresh water, reserve feed water, provisions, sanitary salt water, water ballast, bilge water, stores, etc.
As the ordinary expression for dead-weight includes coal, feed water, consumable stores, the length of a voyage and the quantity of these items necessary for that voyage will have a material effect on the total amount of cargo the vessel can carry, so that sometimes dead-weight cargo is spoken of as a more definite indication of the actual earning capacity of the vessel.
The dead-weight cargo capacity is the capacity of the vessel when fully loaded and provided with all fuel, etc., for actual cargo-carrying.
DEAD-WOOD: a mass of timber built up on the keel at the bow and stern of a ship. The dead-wood supports the cant-frames, bracing and stiffening the stem and stern-posts.
DECK: the part of the vessel corresponding to the floor of a building.
DECK-BEAM: a member running athwartship under and supporting a deck.
DECK BULL’S-EYE: dead-lights; the thick pieces of glass fitted flush and watertight into the deck to allow light in the hold or compartment.
DECK ERECTION: the cabins, houses or superstructure, as erected above the upper deck.
DECK-PIPE: a term usually applied to the hole in the deck through which the anchor chain or cable leads from the chain-locker to the windlass.
DECK-TACKLE: a double purchase used for handling heavy weights or cargo on deck.
DEPTH OF HOLD (DEPTH IN HOLD): the vertical height between the floor and main deck; the upper deck in Ferris type of ship.
DERRICK: a mechanical device for hoisting heavy weights, cargo, etc.
DEVIL’S CLAW: a strong forked iron or steel hook to secure or “stopper” the anchor chain or cable, also called “chain stopper.”
DIMINISHING-POST: a tapering piece of plank, or timber, used to terminate the end of a strake which is not continuous from bow to stem, or used for some other similar purpose.
DISPLACEMENT: the amount of water displaced by a vessel. If the vessel is floating in still water, the weight of the water she displaces equals the weight of the vessel herself with all her machinery, equipment, stores, cargo, etc. The displacement of the vessel in cubic feet divided by 35 when floating in salt water, or by 36 when floating in fresh water, will give the total weight of the vessel, etc. in long tons of 2240 lbs.
DOG: a wooden or metal fitting used to secure doors, hatch covers, manhole covers, etc.; a wide iron or steel staple used by shipwrights.
DOG-SHORE: a small wooden brace or strut used for supporting the ship on the building ways until she is ready to launching.
DOLLY: a short iron or steel pin, temporarily driven into holes bored into the frame, planking or ceiling, used to brace jacks or other mechanical levers when forcing timbers or planks into position; a short, heavy bar of steel used to buck up rivets when riveting in place; a roller put under heavy objects in order to move them with little labor from place to place.
DOLLY-ROLLER: a small roller mounted on a wooden or metal frame and used to transport timber or heavy material from place to place.
DOPE: a term applied to a mixture of red lead and tallow, used for gunning a seam or crevice that develops or threatens to develop a leak.
DOUBLE ASSISTANT KEELSON: the keelson timbers which are alongside the outside and are fastened to the assistant keelson.
DOUBLE BLOCK: tackle-block that contains two sheaves.
DOUBLE BOTTOM: the compartment at the bottom of a steel or composite ship under the floor between frames and the ceiling and planking, or inner and outer bottoms. Used for ballast, tanks, storage of water, fuel, oil, etc.
DOUBLING: planking a ship’s bottom twice; sometimes done when ships are weak or when planking cannot be secured of sufficient thickness.
DOWEL: a short, round peg of wood, used for joining or securing two timbers, or planks, or other objects together.
DOWELLING: a method of joining two pieces together by tenants, dowels or coaking.
DOWNHAUL: a line attached to a fall, whip, purchase tackle, halyard, etc., which will not overhaul or lower of its own weight.
DRAFT (DRAUGHT): the depth to which a vessel sinks in water, especially when laden; the vertical distance from the bottom of the keel to the surface of the water. When a vessel is loaded, the term “loaded water draft” is used; when unloaded, the term “light water draft” is used. Also the drawing or design of the ship prepared by the naval architect, indicating the different parts and dimensions of the ship. From this drawing the ship is constructed
DRAFT-MARKS: the marks out or inscribed on the stem and rudder post which indicate the depth or distance from the bottom of each mark to the bottom of the keel. The inscribed marks are usually six inches high. By reading the height of the water on these marks you can determine the amount of water or draft that the vessel has.
DRIFT: a term applied to indicate where sheer is raised and rails cut off; the scroll pieces with which rails are sometimes ended, sometimes called “drift pieces”; the difference between the diameter of a mast and its hoop, or between the diameter of a hole and the treenail or bolt which is used; the length of a rope which is more than the part used; the amount of space between the two blocks in a purchase tackle.
DRIFT-PIN: a bolt used for backing out short or broken treenails or bolts.
DRIVER: the foremost fore-and-aft spur of the cradle, launching or bilge ways, the end of which is attached to the forward side of the bow poppet and is cleated or bolted to the ground ways.
DRUMHEAD: the top part of a capstan, formerly made of a semicircular piece of elm which framed together forming a circle, into which the capstan bars were fixed.
DRUXY (DRUXEY): a term indicating a certain state of decay in timber. When observed, generally shows white, spongy veins. One of the most deceptive of all defects.
DUBBING: the process of dressing the timbers or planking smooth with an adz.
DUMB-CHALDER: a metal cleat or block, bolted to the afterside of a rudder-post for the end of a rudder pintle to rest on. Its purpose is to relieve the gudgeon or rudder-braces of some of the weight of the rudder. In modeen vessels the weight is carried by a rudder bearer.
DUMP: a nail used in fastening planking to a timber frame, as distinguished from a bolt.
DUNNAGE: light material such as mats, thin boards or brushwood, stowed among or beneath the cargo of a vessel, to keep it from injury by chafing or to make the stowing compact, so the cargo will not shift in heavy weather when the vessel is rolling or pitching badly; any light or less valuable articles of cargo used for the same purpose. In ship-building waste or refuse wood is sometimes called “dunnage.”
DUTCHMAN: a piece of wood fitted into an imperfectly made seam; a shim.