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, Windsurfing, windsurfer, or Kitesurfing, kitesurfer), on ''ice'' (iceboat) or on ''land'' (Land sa ...

vessel. * On a

square rig Square rig is a generic type of sail plan, sail and rigging arrangement in which a sailing ship, sailing vessel's primary driving sails are carried on horizontal spar (sailing), spars that are perpendicular (or wikt:square#Adjective, square) to t ...

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 ship rig with sails set mainly in the median plane 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. (In extremely heavy weather, the mainsail may be lowered, and a much smaller trysail hoisted in its place). Historical fore-and-aft rigs used a four-sided gaff rigged mainsail, sometimes setting a gaff topsail 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 catamaran () (informally, a "cat") is a watercraft with two parallel hull (watercraft), hulls of equal size. The wide distance between a catamaran's hulls imparts stability through resistance to rolling and overturning; no ballast is requi ...

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 Bermuda rig, Bermudian rig, or Marconi rig is a type of sailing rig that uses a triangular sail set abaft (behind) the mast. It is the typical configuration for most modern sailboats. Whilst commonly seen in sloop-rigged vessels, Bermuda rig is ...

uses a triangular mainsail aft of the mast, closely coordinated with a jib for sailing upwind. A large overlapping jib or

genoa Genoa ( ; ; ) is a city in and the capital of the Italian region of Liguria, and the sixth-largest city in Italy. As of 2025, 563,947 people live within the city's administrative limits. While its metropolitan city has 818,651 inhabitan ...

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 Point of sail#Reaching, reach (wind at 90° to the course) to Point of sail#Running downwind, downwind (course in the same direction as the wind). Spinna ...

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 Nathanael Greene Herreshoff'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 A bolt rope (Variants: "bolt-rope" and "boltrope", French: ''ralingue'', Spanish: ''relinga'', Old Norse: *''rár-línk'', comprising ''rár'' genitive of ''rá'' "rope" and ''línk'' "edge of a sail "), is the rope that is sewn at the edges of the ...

, 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