A device for furnishing fresh air to compartments below deck or exhausting foul air. Construction designed to lead air below decks. May have a cowl, which can be angled into or away from the wind; and may be constructed with baffles, so that water is not ...

An opening through which fresh air is supplied to a space or cabin.

A wooden or metal pipe used to supply or to exhaust air.

The swiveled opening at the top of a ventilator.

An enterprise in which there is a risk of loss.

A tube with a narrow throat (a constriction) that increases the velocity and lowers the pressure of the liquid passing through it, creating a partial vacuum immediately after the constriction in the tube. The vacuum created has a sucking effect, and a ven ...

A tube designed to measure the rate of flow of fluids. It consists of a tube having a constriction or throat at its midsection. The difference between the pressure measured at the inlet and at the throat is a function of the fluid velocity. Compare to Pit ...

A small, moveable graduated scale adjacent and parallel to the main scale of an instrument. It provides a means for interpolating between the graduations of the main scale.

General name for an instrument designed to measure the vertical component of the wind speed. See anemoclinometer.

The distance between the water level at chart datum and an overhead obstacle such as a bridge or power line.

The distance that an observer can see vertically into a surface-based obscuring phenomenon such as fog, rain, or snow. The distance estimate must be based upon ceiling balloon ascensions or ceiling light projector measurements.

A type of wind turbine in which the axis of rotation is perpendicular to the wind stream and the ground.

General term for an instrument which records the vertical electric current in the atmosphere.

A general term for a floating craft that carries passengers, cargo or both

The international carrier is obligated to make declarations of the ship's crew and contents at both the port of departure and arrival. The vessel manifest lists various details about each shipment by B/L number. Obviously, the B/L serves as the core sourc ...

Allows equipment and supplies arriving at one port to be loaded on a vessel, aircraft, etc., for its exclusive use and to be exported from the same port.

Vehicles Ferry.

Abbreviation for visual flight rules, but commonly used to refer to the relatively favorable weather and/or flight conditions to which these rules apply.

Virgin Islands, British

Very High Frequency. (30-300 MHz) Designate also the radio communication apparatus using this frequency. It reaches only slightly beyond the horizon, except in favourable circumstances where transmission up to several hundred miles are possible.