Sailing Terms that Begin the Letter 'D'

Daggerboard: A type of centerboard that is removed vertically.

Davy Jones (Locker): An idiom for the bottom of the sea.

Daybeacon: An unlighted fixed structure which is equipped with a dayboard for daytime identification.

Dayboard: The daytime identifier of an aid to navigation presenting one of several standard shapes (square, triangle, rectangle) and colors (red, green, white, orange, yellow, or black).

Deadeye: A round wooden plank which serves a similar purpose to a block in the standing rigging of large sailing vessels.

Deadrise: The design angle between the keel (q.v.) and horizontal.

Decks: the structures forming the approximately horizontal surfaces in the ship's general structure. Unlike flats, they are a structural part of the ship.

Deck hand: A person whose job involves aiding the deck supervisor in (un)mooring, anchoring, maintenance, and general evolutions on deck.

Deck supervisor: The person in charge of all evolutions and maintenance on deck; sometimes split into two groups: forward deck supervisor, aft deck supervisor.

Deckhead: The under-side of the deck above. Sometimes paneled over to hide the pipe work. This paneling, like that lining the bottom and sides of the holds, is the ceiling.

Derrick: A lifting device composed of one mast or pole and a boom or jib which is hinged freely at the bottom.

Devil seam: The curved seam in the hull planking closest to the waterline when the ship is level. The seam between these two planks, set at a nominal right angle to each other, is the devil seam. This seam is particularly difficult to pay (and caulk) because there is little support in the direction of the compression created during caulking and expansion of the wood when wet. Hence, this seam "works" a lot. A sailor sealing this seam must first cause the ship to list (lean) toward the side opposite of the seam. This allows the sailor access to the seam by hanging below it, "between the Devil and the deep blue sea".

Devil to pay (or Devil to pay, and no pitch hot): 

"Paying" the Devil is sealing the devil seam. It is a difficult and unpleasant job (with no resources) because of the shape of the seam (closest to the waterline) and because you are positioned below the natural waterline.

Directional light: A light illuminating a sector or very narrow angle and intended to mark a direction to be followed. 

Disrate: To reduce in rank or rating; demote.

Dog watch: A short watch period, generally half the usual time (e.g. a two hour watch between two four hour ones). Such a watch might be included in order to slowly rotate the system over several days for fairness, or to allow both watches to eat their meals at approximately normal times.

Dolphin: A structure consisting of a number of piles driven into the seabed or riverbed in a circular pattern and drawn together with wire rope.

Downhaul: A line used to control either a mobile spar, or the shape of a sail.

Draft: The depth of a ship's keel below the waterline.

Draught: See draft.

Dressing down: Treating old sails with oil or wax to renew them, or a verbal reprimand.

Driver: The large sail flown from the mizzen gaff.

Driver-mast: The fifth mast of a six-masted barquentine or gaff schooner. It is preceded by the jigger mast and followed by the spanker mast. The sixth mast of the only seven-masted vessel, the gaff schooner Thomas W. Lawson, was normally called the pusher-mast.

Dunnage: Loose packing material used to protect a ship's cargo from damage during transport. Personal baggage.