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Gaff rig is a sailing rig (configuration of sails) 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. The gaff enables a fore and aft sail to be four sided, rather than triangular. A gaff rig typically carries 25 percent more sail than an equivalent bermudian rig for a given hull design.
Gaff rig remains the most popular fore-aft rig for schooner and barquentine mainsails and other course sails, and spanker sails on a square rigged vessel are always gaff rigged. On other rigs, particularly the sloop, ketch and yawl, gaff rigged sails were once common but have now been largely replaced by the bermuda rig sail, which, in addition to being simpler than the gaff rig, usually allows boats to sail closer to the direction the wind is coming from.
The gaff is hoisted by two halyards:
- The throat halyard hoists the throat of the sail (the end closer to the mast) at the forward end of the gaff and bears the main weight of the sail and the tension of the luff.
- The peak halyard lifts aft end of the gaff and bears the leech tension. Small craft attach the peak halyard to the gaff with a wire span with eyes at both ends looped around the gaff and held in place with small wooden chocks, larger craft have more than one span. Peak halyards pull upwards, approaching the gaff at right angles.
Additionally, a gaff vang may be fitted. It is a line attached to the end of the gaff which prevents the gaff from sagging downwind. Gaff vangs are difficult to rig on the aft-most sail, so are typically only found on schooners or ketches, and then only on the foresail or mainsail.
Gunter-rigged boats are similar, smaller vessels on which a spar popularly but incorrectly called the gaff is raised until it is nearly vertical, parallel to the mast and close adjacent to it. Topsails are never carried on gunter rigs.
The Spritsail is another rig with a four-sided fore-aft sail. Unlike the gaff rig where the head hangs from a spar along its edge, this rig supports the leech of the sail by means of a spar named a sprit. The forward end of the sprit is attached to the mast but bisects the face of the sail, with the after end of the sprit attaching to the peak and/or the clew of the sail.
Sailing characteristics (small craft)
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For a given sail area a gaff rig has a shorter mast than a bermudian rig. In short-ended craft with full body, heavy displacement and moderate ballast ratio, it is difficult to set enough sail area in the bermudian rig without a mast of excessive height and a center of effort (CE) too high for the limited stability the hull. Because of it's low aspect ratio, the gaff rig is less prone to stalling if oversheeted than something taller and narrower.
- Reaching with Gaff Sails
Whilst reaching, the CE being set further back, will encourage a small craft to bear up into the wind, i.e. strong weather helm. The boat builder can compensate for this at design stage, e.g. by shifting the keel slightly aft, or having two jibs to counter the effect. The Gaff-Cutter, is in fact a very popular sailplan for small craft. The helmsman, can reduce weather helm significantly, simply by sheeting out the mainsail. Sheeting out may appear to create an inefficient belly in the sail, but it is often a pragmatic alternative to having a heavy helm. A swing keel lifted halfway is the perfect treatment for weather helm on a gaffer. The usual adjustments to mast rake, or even bowsprit length may be made to a gaffer with persistent heavy weather (or lee) helm.
- Running with Gaff Sails
On a gaff-rigged vessel, any heading where the wind is within 20 degrees of dead aft is considered a run. When Running with a gaff-rig, the CE of the mainsail may actually be overboard of the hull, in a stiff wind the craft may want to broach. Running goose winged with a balloon staysail poled out to windward will balance the CE, Nick Skeates circumnavigated Wylo II with this configuration. In light winds, or when racing, a watersail may also be set.
A near-vertical gaff allows this Gunter-rigged boat to carry a triangular sail that is similar to the Bermuda rig
Gaffelaar, by Johannes Christiaan Schotel, depicting both gaff and square-rigged boats
Gaff rigged yachts race on Sydney Harbour, circa 1900
Carmita, racing cutter
Victory Chimes, National Historic Landmark
The yacht of the VOC-Chamber of Rotterdam, by Jacob van Strij
- "The Gaff Rig Page". Retrieved 2008-10-05.
- Philips-Birt, Douglas (1954). Rigs and Rigging of Yachts. W&J Mackay & Co. Ltd. p. 176.
- "N-gram comparison of 'gaff-rigged', 'gaff rigged', 'gaffrigged', 1900–2008". Google books Ngram Viewer. Google Inc. Retrieved 17 February 2013.
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- Cunliffe, Tom (1992). Hand, Reef and Steer, Adlard Coles Nautical, London, page 12.
- Leather, John (2001). The Gaff Rig Handbook (second ed.). Woodenboat Books. p. 32. ISBN 0-937822-67-1.
- Leather, John (2001). The Gaff Rig Handbook (second ed.). Woodenboat Books. p. 33. ISBN 0-937822-67-1.
- Leather, John (2001). The Gaff Rig Handbook (second ed.). Woodenboat Books. p. 54. ISBN 0-937822-67-1.
- Philips-Birt, Douglas (1954). Rigs and Rigging of Yachts. W&J Mackay & Co. Ltd. pp. 47–48.
- Cunliffe, Tom (1992). Hand, Reef and Steer, Adlard Coles Nautical, London, page 15
- Cunliffe, Tom (1992). Hand, Reef and Steer, Adlard Coles Nautical, London, page 118
- Cunliffe, Tom (1992). Hand, Reef and Steer, Adlard Coles Nautical, London, page 120