Nautical Glossary


Beam: The width of a ship.

Boat: A small, open craft without any deck.

Bow: The front end of a vessel.

Buoyancy: This is a vessel's ability to stay afloat.

Centre-line: An imaginary line which runs down the middle of the ship from the bow to the stern.

Draught: This is the depth of water required to float a vessel.

Hull: The outer body of a vessel.

Keel: This is the lowest length-ways timber upon which the framework of the rest of the vessel is built. In short, it is the "backbone" of a boat.

Knots: This is the unit of measurement for gauging a vessel's speed at sea - 1 knot = 1.85 km/hour.

Latitude: This is a means of determining how far north or south of the Equator a vessel is. Imaginary lines of latitude are used in this process. The Equator is 0º. All other lines of latitude run parallel to the Equator up to 90º at the North Pole and to 90º at the South Pole. When you have worked out your latitude and longitude together you can determine a vessel's exact position.

Log: A permanent record of the day-to-day progress of a vessel, including all events which occurred, the vessel's speed and any other related matters.

Longitude: Lines of Longitude commence at the North Pole and run to the South pole. They are all of equal length and are furthest apart at the Equator. They are used on maps and charts to determine distance in degrees east or west of the Greenwich Meridian which is at 0º.

Navigation: Navigation is the science of plotting a vessel's route from one position to the next in the least amount of time and with the maximum safety.

Port: The left-hand side of a vessel, looking forward.

Prau: This boat, used by Wallace and to be used by Tim Severin, is "a fast, sharp-ended rowing or sailing-boat widely used in Malayan water and once popular with Malayan pirates. The prau is long and narrow, rugged with one or two fore-and-aft sails. Modern praus are usually open and relatively small. In earlier times they were decked and up to 60 feet or 18 metres long." (Encyclopaedia Britannica, Vol. 9, p.668 2c.)

The Alfred Wallace, Tim Severin's prau, will be 48 feet long and built according to a native design using hand tools. Colin Mudie, the naval architect who has assisted Tim Severin with earlier projects, has provided the plans for this new prau which has been built in the Kei Islands. A quarter rudder will steer the vessel which is powered by a rectangular sail hung on a bipod mast.

Rudder: A flat wooden (sometimes metal) piece attached to the vessel's stern post which enables the boat to be steered.

Starboard: The right-hand side of a vessel, looking forward.

Stern: The back of a ship.

Tacking: This is the name given to the zig-zag course which is steered in order to make progress against the wind.