36 terms starting with D.
- Damage Stability
Stability of a ship after one or more compartments are flooded; assessed deterministically (older rules) or probabilistically (SOLAS II-1 Reg. 6).
- Damaged Waterline
Equilibrium waterline after damage flooding; must remain below margin line / bulkhead deck for SOLAS compliance.
- Danger Angle
A horizontal or vertical sextant angle that, when not exceeded, ensures a vessel remains clear of a coastal hazard.
- Dangerous Goods (DG)
Cargo classified under the IMDG Code as posing risks to health, safety, property, or the environment during sea transport.
- Data Collection System (DCS)
IMO mandatory annual reporting of fuel oil consumption for ships >5,000 GT, used to support CII and EEXI.
- Dead Reckoning (DR)
Calculating current position using a known past position, then advancing it using speed, course, and elapsed time.
- Deadweight (DWT)
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 Cadet
Officer-in-training in the deck department, completing 12-18 months of supervised sea time toward CoC OOW Deck.
- 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.
- Deepwater Port
Port with sufficient draft (typically >= 14 m) to accept VLCC, ULCC, ULCV, and Capesize vessels.
- 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 (DPA)
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 (DSC)
A standard for transmitting pre-defined digital messages over VHF/MF/HF radio to initiate distress, urgency, or routine calls.
- Disbursement Account (DA)
Itemised statement from the port agent listing all charges incurred during a port call.
- 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.
- Diving Support Vessel (DSV)
Vessel built around a saturation diving system, typically with DP-3, ROVs, and large moonpool.
- 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 (DOC)
A certificate issued to a shipping company confirming its Safety Management System meets ISM Code requirements.
- Doppler Weather Radar
Ship-borne or shore-based weather radar that uses Doppler shift to estimate precipitation intensity and storm motion.
- Double Bottom
Twin layer of shell plating with the inner-bottom forming the cargo hold or tank floor; required on most cargo vessels for damage stability and ballast.
- Draft
The vertical distance between the keel and the waterline, determining the minimum water depth needed for safe navigation.
- Draught Marks (draught scale)
Numeric scale painted on the bow, mid, and stern of the ship indicating the depth of submergence at that point.
- drillship
Ship-shaped deepwater drilling unit with a central moonpool, drilling derrick, and DP-3 dynamic positioning for ultra-deepwater exploration and production drilling.
- Drillship
Mobile drilling unit built on a ship-shaped hull, typically DP-3, capable of drilling in ultra-deep water.
- Drydock
A scheduled period when a vessel is taken out of service and placed in a dry facility for hull inspection, maintenance, and repairs.
- Drydocking Frequency
Standard 5-yearly cycle with one intermediate drydocking allowed up to 7.5 years for certain ship types under in-water survey schemes.
- DSC (Digital Selective Calling)
Pre-formatted digital distress and safety calling technique transmitting identity, nature of distress, position, and time on dedicated watch-keeping frequencies.
- Dunnage
Timber, mats, or other material placed under or between cargo to protect it from moisture, damage, and shifting.
- Dynamic Positioning (DP)
A computer-controlled system that automatically maintains a vessel's position and heading using thrusters, without anchoring.
- Dynamic Positioning Operator (DPO)
A certificated officer qualified to operate and monitor a vessel's dynamic positioning system during offshore operations.