D&H: abbreviation for "dangerous and hazardous" cargo.

Dangerous cargo: all substances of an inflammable nature which are liable to spontaneous combustion either in themselves or when stowed adjacent to other substances and, when mixed with air, are liable to generate explosive gases or produce suffocation or poisoning or tainting of foodstuffs. 

Dangerous liquids: liquids giving off inflammable vapors. 

Davits: two radial cranes on a ship which hold the lifeboats. They are constructed in such a way as to lower and lift the lifeboats the easiest way possible and are also unobstructed in case of an emergency.

DCA: dredging contractors of america.

DDC: destination delivery charge, based on container size, that is applied in many tariffs to cargo. It covers crane lifts off the vessel, drayage of the container within the terminal and gate fees at the terminal operation.

Deadfreight factor: percentage of a ship's carrying capacity that is not utilized.

Deadweight: a common measure of ship carrying capacity or the number of tons of cargo, stores and bunkers that a vessel can transport. It is the difference between the number of tons of water a vessel displaces "light" and the number of tons it displaces "when submerged to the 'deep load  line'." a vessel's cargo capacity is less than its total deadweight tonnage. The difference in weight between a vessel when it is fully loaded and when it is empty (in general transportation terms, the net) measured by the water it displaces. This is the most common, and useful, measurement for  shipping as it measures cargo capacity.

Deadweight cargo: a long ton of cargo that can be stowed in less than 40 cubic feet.

Deck gang: this includes the officers and seamen who comprise the deck department aboard ship. The gang may also be referred to as the deck crew, deck department, or just deck.

Deckhand: seaman who works on the deck of a ship and remains in the wheelhouse attending to the orders of the duty officers during navigation and maneuvering. He also comes under the direct orders of the bosun.

Deck house: a small super-structure on the top deck of a vessel, which contains the helm and other navigational instruments.

Deck log: also called the captain's log. It includes a full nautical record of a ship's voyage, written up at the end of each watch by the deck officer on watch. 

Deck officer: as distinguished from engineer officer, refers to all officers who assist the master in navigating the vessel when at sea, and supervise the handling of cargo when in port.

Deep sea trades: the traffic routes of both cargo and passenger vessels which are regularly engaged on the high seas or on long voyages.

Deep stowage: any bulk, bagged or other type of cargo stowed in single hold ships.

Demurrage: a fee levied by the shipping company upon the port or supplier for not loading or unloading the vessel by a specified date agreed upon by contract. This fee is usually, assessed upon a daily basis after the deadline.

Density: the weight of cargo per cubic foot or other unit.

Disabled ship: when a ship is unable to sail efficiently or in a seaworthy state as a result of engine trouble, lack of officers or crew, damage to the hull or ship's gear.

Discharges: an essential document for officers and seamen as it serves an official certificate confirming sea experience in the employment for which he was engaged.

Displacement: the weight, in tons of 2,240 pounds, of the vessel and its contents. It is calculated by dividing the volume of water displaced in cubic feet by 35, the average density of sea water.

Dod: department of defense.

Domestic offshore trades: domestic shipping routes serving alaska and non-continental u.s. states and territories.

Dot: department of transportation.

Double bottom: general term for all watertight spaces contained between the outside bottom plating, the tank top and the margin plate. The double bottoms are sub-divided into a number of separate tanks, which may contain boiler feed water, drinking water, fuel oil, ballast, etc.

Draft: the depth of a ship in the water. The vertical distance between the waterline and the keel, in the u.s. expressed in feet, elsewhere in meters.

Drayage: charge made for local hauling by dray or truck. 

Dry-bulk container: a container constructed to carry grain, powder and other free-flowing solids in bulk. This container is used in conjunction with a tilt chassis or platform. 

Dry cargo: merchandise other than liquid carried in bulk. 

Dry cargo ship: vessel which carriers all merchandise, excluding liquid in bulk.

Dry dock: an enclosed basin into which a ship is taken for underwater cleaning and repairing. It is fitted with water tight entrance gates which when closed permit the dock to be pumped dry.

Dual purpose ship: specially constructed ship able to carry different types of cargoes such as ore and/or oil.

Dumping: attempting to import merchandise into a country at a price less than the fair market value, usually through subsidy by exporting country.

Dunnage: a term applied to loose wood or other material used in a ship's hold for the protection of cargo.

DWT: deadweight tons.