The mast of a sailing vessel is a tall spar, or arrangement of spars, erected more or less vertically on the centre-line of a ship or boat. Its purposes include carrying sails, spars, and derricks, giving necessary height to a navigation light, look-out position, signal yard, control position, radio aerial or signal lamp. Large ships have several masts, with the size and configuration depending on the style of ship. Nearly all sailing masts are guyed.
Three-masted training ship Mersey
Main topgallant mast
This photo of the full-rigged ship Balclutha, shows the fore-mast, main-mast and mizzen-mast, as well as all the ship's standing and running rigging. The Balclutha is berthed in San Francisco, and is open to the public.
Roman two-masted ship, its foremast showing a typically strong forward rake
A sailing ship is a sea-going vessel that uses sails mounted on masts to harness the power of wind and propel the vessel. There is a variety of sail plans that propel sailing ships, employing square-rigged or fore-and-aft sails. Some ships carry square sails on each mast—the brig and full-rigged ship, said to be "ship-rigged" when there are three or more masts. Others carry only fore-and-aft sails on each mast, for instance some schooners. Still others employ a combination of square and fore-and-aft sails, including the barque, barquentine, and brigantine.
A barque—a three-masted sailing ship with square sails on the first two masts (fore and main) and fore-and-aft sails on the mizzenmast
Fijian voyaging outrigger boat with a crab claw sail, an example of a typical Austronesian vessel with outriggers and a fore-and-aft sail
A carved stone relief panel showing a Borobudur ship (Austronesian) from 8th century Java, depicted with outriggers and fore-and-aft tanja sails
Chinese junk Keying with a center-mounted rudder post, c. 1848