Two navigational aids separated in distance so that they can be aligned to determine that a boat lies on a certain line. Transits can be used to determine a boat's position or guide it through a channel. Also called a range.

A device designed to remove solids, such as dirt, scale, rust and other contaminants from the air system.

Short period oscillation in level of enclosed, or partly enclosed, area of water when not due to the action of tide-raising forces.

Break horse power

To retire from a life at sea and settle ashore.

Term used in the days of sail to indicate the starboard of the two anchors carried at the bow of a ship. The anchor on the port side was known as the small bower (although they were the same size).

The power which is theoretically required to compress a gas under constant temperature, in a compressor free from losses, from a given inlet pressure to a given discharge pressure.

A control line that adjusts tension along the foot of the sail, pulling the clew away from the tack; used to maintain proper sail shape.

Same as not under command.

Sailor's name for the north star, Polaris, which for all practical purposes remains fixed above the north pole, bearing north from everywhere in the northern hemisphere, making it a true aid to navigation.

(1) The underside of the hull that sits in the water (2) The ocean floor

A course marked by buoys or ranges measuring one nautical mile. Measured miles are used to calibrate logs.

At or towards the stern or rear of a ship.

(1) The mast section next above the topmast and and below the royal mast. (2) The yard supported by that mast. (3) The third lowest square sail. It is stretched between the topgallant yard and the top yard.

The direction and speed of the wind as it appears to those on board, relative to the speed and direction of the boat; combination of the true wind and the wind caused by the boat's movement through the water.

When a vessel fills with water and sinks.

Are load carrying machine elements permitting some degree of motion in which the lubricant is air or some other gas.

A listing of a particular boat's steering deviation on each point of the compass

Said of a seaman who has retired from sea service.

The outside plating of a vessel.