Damage control team - A group of crew members trained for fighting flooding in the vessel
Datum .1 - The most probable position of a search target at a given time
Datum .2 - The plane of reference to which all data as to the depth on charts are referenced
Derelict - Vessel still afloat, abandoned at sea
Destination - Port for which a vessel is bound

Disabled - A vessel damaged or impaired in such a manner as to be incapable of proceeding on its voyage
Disembark (to) - To go from a vessel
Distress alert (GMDSS) - A radio signal from a distressed vessel automatically directed to an MRCC giving position, identification, course and speed of the vessel as well as the nature of distress
Distress/ Here - the verbal exchange of information on radio from ship to shore Urgency traffic and/or ship to ship / aircraft about a distress / urgency situation as defined in the relevant ITU Radio Regulations
Draught (or draft) - Depth in water at which a vessel floats
Dragging (of anchor) - Moving of an anchor over the sea bottom involuntarily because it is no longer preventing the movement of the vessel
Dredging (of anchor) - Moving of an anchor over the sea bottom to control the movement of the vessel
Drifting - Being driven along by the wind, tide or current
Drop back (to) - To increase the distance from the vessel ahead by reducing one's own speed
DSC - Digital Selective Calling (in the GMDSS system)
Embark (to) - To go aboard a vessel
EPIRB - Emergency Position Indicating Radio Beacon
Escape route - A clearly marked way in the vessel which has to be followed in case of an emergency
Escort - Attending a vessel to be available in case of need, e.g. ice-breaker, tug, etc.
ETD - Estimated Time of Departure
Fathom - A measure of 6 feet
Fire patrol - A member of the watch going around the vessel at certain intervals so that an outbreak of fire may be promptly detected; mandatory in vessels carrying more than 36 passengers
Flooding - Major uncontrolled flow of seawater into the vessel
Fire monitor - Fixed foam/powder/water cannon shooting fire-extinguishing agents on tank deck, manifold etc.
Foul (of anchor) - Anchor has its own cable twisted around it or has fouled an obstruction
Foul (of propeller) - A line, wire, net, etc., is wound round the propeller
Full speed - Highest possible speed of a vessel
Fumes - Often harmful gas produced by fires, chemicals, fuel, etc.
General emergency alarm - A sound signal of seven short blasts and one prolonged blast given with the vessel’s sound system
Give way - To keep out of the way of another vessel
GMDSS - Global Maritime Distress and Safety System

(D) GPS - (Differential) Global (satellite) Positioning System
Half cardinal points - The four main points lying between the cardinal points: north east, south east, south west and north west
Hampered vessel - A vessel restricted by her ability to manoeuvre by the nature of her work
Hatchrails - Ropes supported by stanchions around an open hatch to prevent persons from falling into a hold
Heading - The horizontal direction of the vessel's bows at a given moment measured in degrees clockwise from north
Hoist Here - a cable used by helicopters for lifting or lowering persons in a pick-up operation