Mizzen topgallant mast

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 sail, spars, and derricks, and 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.

Until the mid-19th century all vessels' masts were made of wood formed from a single or several pieces of timber which typically consisted of the trunk of a conifer tree. From the 16th century, vessels were often built of a size requiring masts taller and thicker than could be made from single tree trunks. On these larger vessels, to achieve the required height, the masts were built from up to four sections (also called masts), known in order of rising height above the decks as the lower, top, topgallant and royal masts. Giving the lower sections sufficient thickness necessitated building them up from separate pieces of wood. Such a section was known as a made mast, as opposed to sections formed from single pieces of timber, which were known as pole masts.

For square-sail carrying ship, the masts, given their standard names in bow to stern (front to back) order, are:

Some names given to masts in ships carrying other types of rig (where the naming is less standardised) are:

Most types of vessels with two masts are supposed to have a main-mast and a smaller mizzen-mast, although both brigs and two-masted schooners carry a fore-mast and a main-mast instead. On a two-masted vessel with the main-mast forward and a much smaller second mast, such as a ketch, or particularly a yawl, the terms mizzen and jigger are synonymous.

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