If you can average 2kt or 3kt more than your opposition on a certain point of sail, it represents a huge gain over the course of a race.’ ‘We were able to achieve a flatter sail without an unstable leech. ‘We could eventually absorb about 90 per cent of the extra midgirth we needed to demonstrate by means of that front-end panel,’ adds designer Daniel Fong, who also has an extensive offshore, grand prix and America’s Cup CV. When the sail was flying the airflow would suck this unwanted sail area around to the leeward side where it lay flush and quiet, leaving the rest of the sail to do its work as efficiently as possible. In a reversal of convention they met the 75 per cent mid-girth requirement by pushing the extra ‘girth’ to the leading edge and in front of the natural load line instead of the leech. They dispensed with a luff cable altogether and replaced it with three full-luff vertical carbon-Technora panels supporting a genoa-type sail plan. Two years ago Doyle took a very different approach. ‘The whole game has been to push the 75 per cent rule as far as you can, trying to find a balance between how much shape you put in the sail against how much leech instability you are prepared to accept,’ says Doyle designer and special projects specialist Justin Ferris, whose offshore racing CV includes multiple Volvo campaigns. As the apparent wind moved forward the trimmers would crank up the luff load and sheet on hard, leaving the excess leech material either flapping away, adding drag and fast degrading an expensive sail, or tamed with an over-tensioned leech-line acting like a handbrake. The most common solution has been an ugly duckling compromise of a genoa-type shape supported on an integral composite luff cable, but with superfluous material along the leech to achieve the 75 per cent mid-girth target. The advantages of a sail able to achieve both purposes, but still be measured as a spinnaker, are most obvious when you look at relative sail areas: the largest rated jib area for a Maxi72, for example, is about 130m 2, as opposed to the 500m 2 area that most teams measure with as a maximum spinnaker area.įor years, and at great expense, sailmakers have looked for ways to achieve the full multi-purpose potential of Code Zero sails within the constraints of the spinnaker definition. The challenge was to achieve a sail with the area of a spinnaker and able to be used for heavy-air running, yet flat enough to operate like a masthead genoa at relatively tight angles in lighter airs. Other offshore racing classes have similar constraints. Under IRC, for example, the definition of a spinnaker demands that the mid-girth measurement is at least 75 per cent of the foot length. Also thought provoking is comparing Momo’s sailing angle with Proteus to weather… racing with a headsailĪs is often the case, class and rating rules often lagged behind the pace of technical development, leaving sailmakers and competitors to adopt clumsy work-arounds to extract the available performance within outdated regulations.Īlmost from the time that asymmetrical spinnakers became mainstream, the name of the game has been to design flatter and flatter sails – until they came up hard against limits imposed by the rating rules. The three individual luff ‘lens’ groups are visible on this Code Zero – the combined effect being to allow the luff profile to project significantly to weather with no blowback of surplus material. Main picture: the Maxi72 Momo on the way to becoming 2017 world champion at the Maxi Worlds in Porto Cervo.
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