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Why we have chosen the rigs we have and how to get the best out of them
Small boat rigs Little Auk The rig on the Little Auk is a boomless standing lugsail. It is an attractive looking rig, and is certainly easily distinguishable from the standard "bermudan" sail that is so common in any marina.Keep it Simple For Little Auk though, a major design criteria was simplicity, and for that, this rig is hard to beat. Simpler still would be a single mast and a triangular "leg'o'mutton" sail with no boom, but to get enough sail area, the mast would have to be a lot longer than the boat, which would make carrying, storage and transporting the boat on land, awkward. Having no boom there are only two spars (mast and yard) and two adjustment ropes. One of course, is the mainsheet and the other is attached to the tack (the lower, leading corner). This tack attachment is very important, and should be hauled in so that the sail sets with no creases in it. The tension is determined by wind strength, and is hard to get wrong since the sail will crease if it is too tight or too slack. Don't sheet to the centreline! The sail has no boom, so the positioning of the sheet leads is very important. Many boomless sails (particularly on small boats, or mizzens for larger craft), are sheeted to the centreline of the boat. This considerably reduces the drive that the sail can deliver since the bottom trailing corner is curving up to windward and acting as a very effective brake. On the Little Auk, the sheet leads are positioned to give optimum sail shape in the close hauled (upwind) position. This position was found partly by calculation, and partly by trial and error on the prototype. The disadvantage of boomless sails is that they loose their shape as soon as the sheets are let out, unless the sheet lead is moved along the radius from the mast, which requires a very wide boat (or a multihull). On the Little Auk, we consider this loss of downwind performance acceptable, since the area presented to the wind is still fairly substantial owing to the boat and crew. It would be possible to convert her to a balanced lug rig, with a boom, like Kittiwake, so long as there was not too much sail in front of the mast (less than 1/5th of foot length), as this would reduce her weather helm too much. The disadvantage of doing so are the addition of the boom to hit people, and the extra spar to store when rowing, in an already small boat. Razorbill has a single sprit-boomed gunter rig identical to that on Storm Petrel (except for size) The Great Auk's rig is a larger version of that on Kittiwake. The Opsrey rig is again a larger version of Little Auk's |