Gaff rig[1] is asailing rig (configuration of sails, mast and stays) in which thesail is four-cornered,fore-and-aft rigged, controlled at itspeak and, usually, its entirehead by aspar (pole) called thegaff. Because of the size and shape of the sail, a gaff rig will have runningbackstays rather than permanent backstays.
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 equivalentBermuda rig for a given hull design.[2]
A sail hoisted from a gaff is called agaff-rigged (or, less commonly,gaff rigged orgaffrigged)sail.[3]
Gaff rig remains the most popularfore-aft rig forschooner andbarquentine mainsails[citation needed] and othercourse sails, andspanker sails on asquare rigged vessel are always gaff rigged. On other rigs, particularly thesloop,ketch andyawl, gaff rigged sails were once common but have now been largely replaced by theBermuda rig sail,[4] which, in addition to being simpler than the gaff rig, usually allows vessels to sail closer to the direction from which the wind is blowing (i.e. "closer to the wind").[citation needed]
The gaff is hoisted by twohalyards:
Additionally, agaff 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 theaft-most sail, so are typically only found on schooners or ketches, and then only on the foresail or mainsail.[citation needed]
A triangular fore-and-aft sail called a jib-headedtopsail may be carried between the gaff and themast.[7]
Gunter-rigged boats are similar, smaller vessels on which a spar (commonly, 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.
Thespritsail is another rig with a four-sidedfore-aft sail. Unlike the gaff rig where thehead hangs from a spar along its edge, this rig supports theleech of the sail by means of a spar named asprit. The forward end of the sprit is attached to themast but bisects the face of the sail, with the after end of the sprit attaching to thepeak and/or theclew of the sail.
For a given sail area a gaff rig has a shorter mast than aBermudan rig. In short-ended craft with full body, heavy displacement and moderateballast ratio, it is difficult to set enough sail area in the Bermudan rig without a mast of excessive height and acentre of effort (CE) too high for the limitedstability of thehull.[8] Because of its lowaspect ratio, the gaff rig is less prone tostalling if oversheeted than something taller and narrower.[9]
Whilstreaching, the CE being set further back, will encourage a small craft to bear up into the wind, i.e. strongweather 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 popularsailplan for small craft.[citation needed] 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.[citation needed] The usual adjustments to mast rake, or even bowsprit length may be made to a gaffer with persistent heavy weather (or lee) helm.
On a gaff-rigged vessel, any heading where the wind is within 20 degrees of dead aft is considered arun.[10] Whenrunning with a gaff rig, the CE of the mainsail may actually be overboard of the hull, in a stiff wind the craft may want tobroach. Running goose winged with a balloon staysail poled out to windward will balance the CE; Nick Skeates circumnavigatedWylo II with this configuration.[11]In light winds, or when racing, awatersail may also be set.
Since 1972, theSydney Amateur Sailing Club has regularly hosted a Gaffers Day for any classic sailing boat that can "hoist a spar". Up to 90 vessels from around Australia take part in sailing on Sydney Harbour in a practical demonstration of the skills and technology used in the nautical past.[12]
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