Dew - As the surface of the earth cools at night, warm moist air near the ground is chilled and water vapour in the air condenses into droplets on the grass and other objects. Dew is particularly heavy on clear nights, when the earth cools rapidly. When a blanket of cloud insulates the earth, the cooling rate is slower.
Category: - Weather

Dew Point - The temperature to which air must be cooled to become saturated by the water vapour already present in the air.
Category: - Weather

DFO - Department of Fisheries and Oceans, Canada
Category: - Acronym

DFO - Department of Fisheries and Oceans, Canada (http://www.dfo-mpo.gc.ca/index.htm)
Category: - General

Digital Selective Calling - Digital Selective Calling is a synchronous system developed by the International Radio Consultative Committee (CCIR), used to establish contact with a station or group of stations automatically by means of radio.
Category: - Maritime

Direction Finder - radio; determines the direction of incoming radio waves
Category: - Maritime

Disabled - A situation wherein a vessel or aircraft afloat and not in distress or potential of distress, has lost all means of propulsion, steering or control to such a degree as to be incapable of proceeding to safety without assistance. "Désemparé"
Category: - Maritime - Risk

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.
Category: - Maritime - Risk

Disaggregate - To subdivide into component parts, such as examining a subset of data
Category: - Risk

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.
Category: - Maritime