Glossary: D

22 terms.

• Danger Angle
  A horizontal or vertical sextant angle that, when not exceeded, ensures a vessel remains clear of a coastal hazard.
• Dangerous Goods
  Cargo classified under the IMDG Code as posing risks to health, safety, property, or the environment during sea transport.
• Dead Reckoning
  Calculating current position using a known past position, then advancing it using speed, course, and elapsed time.
• Deadweight
  The total weight a vessel can carry including cargo, fuel, water, stores, and crew, measured in metric tonnes.
• Deck Cadet
  A trainee deck officer undertaking approved sea service under a maritime academy programme to qualify for an OOW certificate.
• Deck Cargo
  Cargo stowed on the open weather deck and exposed to the sea environment, requiring additional securing and weatherproofing.
• Deck Log
  The official daily record of the ship's position, weather, incidents, crew changes, and navigational events kept by deck officers.
• Deep Water Route
  A route within defined limits, surveyed and confirmed to have sufficient depth, designated for use by vessels requiring deep draught.
• Demurrage
  A penalty charge payable by the charterer when a vessel is kept at the loading or discharging berth beyond the agreed laytime.
• Designated Person Ashore
  The ISM Code-required company contact point with direct access to the highest management level, responsible for safety and pollution prevention oversight.
• Deviation
  The error in a magnetic compass caused by the ship's own magnetic field, varying with the vessel's heading.
• Deviation Card
  A tabulated record of a magnetic compass's deviation on successive headings, prepared after compass adjustment or swing.
• Digital Selective Calling
  A standard for transmitting pre-defined digital messages over VHF/MF/HF radio to initiate distress, urgency, or routine calls.
• Dispatch
  A payment made by the shipowner to the charterer for completing loading or discharging operations before the agreed laytime expires.
• Displacement
  The total mass of water displaced by a floating vessel, equal to the combined weight of the hull, machinery, cargo, and stores.
• Docking Survey
  An in-water or drydock inspection of the hull, rudder, propeller, and sea valves required by classification societies every two to five years.
• Document of Compliance
  A certificate issued to a shipping company confirming its Safety Management System meets ISM Code requirements.
• Draft
  The vertical distance between the keel and the waterline, determining the minimum water depth needed for safe navigation.
• Drydock
  A scheduled period when a vessel is taken out of service and placed in a dry facility for hull inspection, maintenance, and repairs.
• Dunnage
  Timber, mats, or other material placed under or between cargo to protect it from moisture, damage, and shifting.
• Dynamic Positioning
  A computer-controlled system that automatically maintains a vessel's position and heading using thrusters, without anchoring.
• Dynamic Positioning Operator
  A certificated officer qualified to operate and monitor a vessel's dynamic positioning system during offshore operations.