A mainsail is a sail rigged on the main mast of a

sailing Sailing employs the wind—acting on sails, wingsails or kites—to propel a craft on the surface of the ''water'' (sailing ship, sailboat, raft, windsurfer, or kitesurfer), on ''ice'' (iceboat) or on ''land'' (land yacht) over a chosen cour ...

vessel. * On a

square rig Square rig is a generic type of sail and rigging arrangement in which the primary driving sails are carried on horizontal spars which are perpendicular, or square, to the keel of the vessel and to the masts. These spars are called ''yards'' and ...

ged vessel, it is the lowest and largest sail on the main mast. * On a

fore-and-aft rig A fore-and-aft rig is a sailing vessel rigged mainly with sails set along the line of the keel, rather than perpendicular to it as on a square rigged vessel. Description Fore-and-aft rigged sails include staysails, Bermuda rigged sails, g ...

ged vessel, it is the sail rigged aft of the main mast. The sail's foot is normally attached to a

boom Boom may refer to: Objects * Boom (containment), a temporary floating barrier used to contain an oil spill * Boom (navigational barrier), an obstacle used to control or block marine navigation * Boom (sailing), a sailboat part * Boom (windsurfi ...

. (In extremely heavy weather, the mainsail may be lowered, and a much smaller

trysail A trysail (also known as a spencer) is a small triangular or square fore-and-aft rigged sail hoisted in place of a larger mainsail when winds are very high. The trysail provides enough thrust to maintain control of the ship, e.g. to avoid ship ...

hoisted in its place). Historical fore-and-aft rigs used a four-sided

gaff rig Gaff rig is a sailing rig (configuration of sails, mast and stays) in which the sail is four-cornered, fore-and-aft rigged, controlled at its peak and, usually, its entire head by a spar (pole) called the ''gaff''. Because of the size and shap ...

ged mainsail, sometimes setting a gaff

topsail A topsail ("tops'l") is a sail set above another sail; on square-rigged vessels further sails may be set above topsails. Square rig On a square rigged vessel, a topsail is a typically trapezoidal shaped sail rigged above the course sail and ...

above it. Whereas once the mainsail was typically the largest sail, today the mainsail may be smaller than the jib or genoa; Prout

catamarans A Formula 16 beachable catamaran Powered catamaran passenger ferry at Salem, Massachusetts, United States A catamaran () (informally, a "cat") is a multi-hulled watercraft featuring two parallel hulls of equal size. It is a geometry-stab ...

typically have a mainmast stepped further aft than in a standard sloop, so that the mainsail is much smaller than the foresail.

Bermuda rig

The modern

Bermuda rig A Bermuda rig, Bermudian rig, or Marconi rig is a configuration of Mast (sailing), mast and rigging for a type of sailboat and is the typical configuration for most modern sailboats. This configuration was developed in Bermuda in the 1600s; the t ...

uses a triangular mainsail aft of the mast, closely coordinated with a

jib A jib is a triangular sail that sets ahead of the foremast of a sailing vessel. Its tack is fixed to the bowsprit, to the bows, or to the deck between the bowsprit and the foremost mast. Jibs and spinnakers are the two main types of headsail ...

for sailing upwind. A large overlapping jib or

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is often larger than the mainsail. In downwind conditions (with the wind behind the boat) a

spinnaker A spinnaker is a sail designed specifically for sailing off the wind on courses between a reach (wind at 90° to the course) to downwind (course in the same direction as the wind). Spinnakers are constructed of lightweight fabric, usually n ...

replaces the jib. Some mainsails are "full-batten" mainsails, meaning the

batten A batten is most commonly a strip of solid material, historically wood but can also be of plastic, metal, or fiberglass. Battens are variously used in construction, sailing, and other fields. In the lighting industry, battens refer to linea ...

extends all the way from the mast to the leach of a sail. A partial batten extends from the leech partway to the mast. Battens enable the mainsail to project farther away from the mast. However, there is some cost associated with the battens themselves, "batten pockets" need to be sewn into the sail, and "batten cars" may be needed to allow the sail to be raised and lowered. Before

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's invention of sail tracks and slides in the 1880s, mainsails were limited in height. Traditional mainsails were held against the mast by hoops that went the full way around the mast. This meant a traditional mainsail could be raised no higher than the first point a rope or wire was required to keep the mast upright. Further mainsail area (and height) was obtained by adopting a gaff rig. A mainsail may be fixed to the boom via slugs, cars, or a bolt-rope, or may be "loose-footed," meaning it is only attached at the tack and clew.

References

{{Sail Types, state=expanded Sailing rigs and rigging

Bermuda rig

See also

References