Mainsail

Sail rigged to the main mast of a sailing vessel
A square-rigged vessel

A mainsail is a sail rigged on the main mast of a sailing vessel.[1]

  • On a square rigged vessel, it is the lowest and largest sail on the main mast.
  • On a fore-and-aft rigged vessel, it is the sail rigged aft of the main mast. The sail's foot is normally attached to a boom.[1] (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 typically have a mainmast stepped further aft than in a standard sloop, so that the mainsail is much smaller than the foresail.[2]

Bermuda rig

The modern Bermuda rig uses a triangular mainsail aft of the mast, closely coordinated with a jib for sailing upwind. A large overlapping jib or genoa is often larger than the mainsail. In downwind conditions (with the wind behind the boat) a spinnaker replaces the jib.

Some mainsails are "full-batten" mainsails, meaning the batten 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.[3]

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, or may be "loose-footed," meaning it is only attached at the tack and clew.[4]

Mainsail on a Bermuda rig
  • Mainsail: 4 – batten 9 – reef diamonds Edges: 5 – Leech 6 – Luff 11 – Foot Corners: 1 – Head 10 – Tack 12 – Clew
    Mainsail: 4 – batten 9 – reef diamonds
    Edges: 5 – Leech 6 – Luff 11 – Foot
    Corners: 1 – Head 10 – Tack 12 – Clew
  • 1 – mainsail  2 – staysail  3 – spinnaker  4 – hull  5 – keel  6 – rudder  7 – skeg  8 – mast  9 – Spreader  10 – shroud  11 – sheet  12 – boom  13 - mast  14 – spinnaker pole  15 – backstay  16 – forestay  17 – boom vang 
    1 – mainsail Edit this on Wikidata 2 – staysail Edit this on Wikidata 3 – spinnaker Edit this on Wikidata
    4 – hull Edit this on Wikidata 5 – keel Edit this on Wikidata 6 – rudder Edit this on Wikidata 7 – skeg Edit this on Wikidata
    8 – mast Edit this on Wikidata 9 – Spreader Edit this on Wikidata 10 – shroud Edit this on Wikidata
    11 – sheet Edit this on Wikidata 12 – boom Edit this on Wikidata 13 - mast Edit this on Wikidata
    14 – spinnaker pole Edit this on Wikidata 15 – backstay Edit this on Wikidata
    16 – forestay Edit this on Wikidata 17 – boom vang Edit this on Wikidata

See also

References

  1. ^ a b Torrey, Owen C. Jr. (1965). Sails (Seamen's Bank for Savings ed.). New York: Palmer & Oliver. pp. 7–9.
  2. ^ Note: On some mast-aft rigs, the mainsail is dispensed with altogether, producing an unconventional sail plan that traditionalist find unattractive.
  3. ^ "Full Batten Mainsails by Andrew Dove 2007". August 2007.
  4. ^ Dickson, Dan. "Loose Foot vs. Attached Mainsail". Retrieved 27 March 2016.
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