The alternating motion of a boat, leaning alternately to port and starboard; the motion of a boat about its fore-and-aft axis.

A pair of additional backstays temporarily rigged to provide extra support to the masts of square rigged vessels when sailing downwind.

A vessel's position determined by observation and navigational data.

A strong tropical revolving storm of force 12 or higher. In the northern hemisphere hurricanes revolve in a clockwise direction. In the southern hemisphere these storms revolve counterclockwise and are known as typhoons.

A mechanical barometer used to measure air pressure for warnings of changing weather.

: Regular ship shaped vessel, production ship. Positioned by anchors or dynamic positioning. Has its own propulsion machinery.

A gas produced by many fruits and vegetables that accelerates the ripening and aging processes.

Anchor cable is caught around the fluke or an object is caught around the anchor .

The largest circle which can be inscribed on a sphere by a plane that cuts through the center of the sphere. On the earth, the equator is a great circle, as are all the meridians of longitude which pass through both poles. The shortest distance between tw ...

Any object used to increase the drag of a boat and slow her down. Typically shaped like a parachute or cone opened underwater, drogues decrease a boat's speed in heavy weather. Also see sea anchor.

To keep close.

Pieces of plank bolted to the outer end of the bowsprit, to reeve the foretopmast stays through.

An old method of cleaning a vessels bottom by burning off weed, barnacles or other growth while the vessel was in dry dock or careened. Breaming was also known as graving.

A device which operates compressors in sequence according to a programmed schedule.

A short piece of line spliced into the end of the clapper by which the bell is struck. Traditionally it is finished off with a double wall knot crowned in its end.

A sound signal device (not necessarily mechanically operated).

Amount of time for a compressor to complete one cycle.

To approach something from upwind

Temperature at which condesation first occurs and moisture is formed.

see Watch