DAVY JONES’ LOCKER - The bottom of the sea.

DAYBEACON - An unlit fixed structure which has a dayboard for daytime identification.

DEAD AHEAD - Directly ahead.

DEAD ASTERN - Directly aft.

DEADRISE - The design angle between the keel and horizontal.

DECK - A cover over a compartment or hull. (top surface of the boat/yacht/ship)

DELTA - Letter Din the Marine Radio Alphabet.

DINGHY - A small open boat. A dinghy is often used as a tender for a yacht.

DISPLACEMENT - The weight of water displaced by a floating vessel, thus, a marine vessel's weight.

DISPLACEMENT HULL - A type of hull that plows through the water, displacing a weight of water equal to its own weight, even when full power is added.

DOCK - A protected water area in which vessels are moored.The term is often used to denote a pier or a wharf.

DOLPHIN - A group of piles driven close together and bound with wire cables into a single structure.

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

DRAFT - The depth of water a marine vessel draws.