Vapor Control Valve

Voyage Data Recorder

Video Display Terminal. An input and display device which includes a keyboard and a screen and allows a human to communicate with a computer.

Visual Display Unit

A rain gauge or array of rain gauges designed to measure the inclination and direction of falling rain.

A line drawn to indicate both the direction and magnitude of a force, such as leeway or a current.

Any quantity, such as force velocity, or acceleration, which has both magnitude and direction at each point in space, as opposed to scalar which has magnitude only. Such a quantity may be represented geometrically by an arrow of length proportional to its ...

SAID [sic] of the wind when it changes. Also, to slack a cable and let it run out. (See PAY.) To veer and haul, is to haul and slack alternately on a rope, as in warping, until the vessel or boat gets headway.

To slack off or move off; also said of a change of direction of wind, when the wind shifts to a different direction.

A shifting of the wind direction, opposite of backing. Clockwise in the northern hemisphere, counter-clockwise in the southern hemisphere.

A clockwise change in wind direction. Veering winds with height are indicative of warm air advection (WAA).

Vessel Experience Factor

Also VMG. Actual boat speed after adjusting for such factors as current and leeway.

A component of a heating or ventilation appliance used to conduct fresh air into, or waste air or combustion gases out of, an appliance or interior space.

A device mounted in the vent connector that closes the vent when the heating unit is not firing. This traps heat inside the heating system and house rather than letting it draft up and out the vent system.

A tube in which combustion gases from a combustion appliance are vented out of the appliance to the outdoors.

A type of combustion heating appliance in which the combustion gases are vented to the outside, either with a fan (forced) or by natural convection.

A container designed with openings in the side and/or end walls to permit the ingress of outside air when the doors are closed.

The process of moving air (changing) into and out of an interior space either by natural or mechanically induced (forced) means.

That portion of supply air that is drawn from outside, plus any recirculated air that has been treated to maintain a desired air quality.