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There’s more than one way ...

Fifty knots has been as elusive for sailors as the four-minute mile was for runners and the sound barrier for pilots, but Paul Larsen and Malcolm Barnsley say SailRocket is ready to clock that speed and make history.

Fifty knots has been as elusive for sailors as the four-minute mile was for runners and the sound barrier for pilots, but Paul Larsen and Malcolm Barnsley say SailRocket is ready to clock that speed and make history.

Not a proa or catamaran or monohull or sailboard or kitesurfer, SailRocket is its own animal. “It is totally unique,” says Barnsley, 50, its British designer. “I believe it is the best way to do 50 knots.”

Australian Larsen, the project manager and skipper, took SailRocket to Walvis Bay, Namibia in southwest Africa in early March to challenge the sailing speed record of 48.7 knots set by boardsailor Finian Maynard in 2005. On April 9 the 33-foot sailboat posted its best speed yet — 38.3 knots — and did it with one of the two small planing surfaces that it rides on damaged. “The back one ripped off at the start of the run, leaving a very jagged surface,” says Barnsley, speaking to Soundings from his home in Southampton, England. “The back was sinking in and dragging very badly. By all calculations we should never have gone 38 knots, but we did.”

He says independently corroborated speed predictions suggest that SailRocket will reach 2.6 times wind speed at 20 knots, which means it could set a new record with just more than 19 knots of wind. But judging from its performance with a damaged hull, Barnsley believes SailRocket’s predicted speed is way too conservative. “We may do a lot more than 50 knots,” he says, presuming all goes well.

In its first run on Walvis Bay, SailRocket went into a spin at 34 knots, snapping the mast of its new solid-wing sail — a result of not balancing the wing and hydrofoil quite right, Barnsley says. Larsen suspended racing for two weeks to repair the damage. The speedster went back into the shop April 9 to rebuild the aft planing surface and again April 24 to replace the forward one, which also was deteriorating. Both were strengthened to better handle a small chop on the bay.

Barnsley says SailRocket doesn’t like waves of any size. A 2-inch chop reduces speed 6 knots. “Six-inch waves, forget it,” he says. “We wouldn’t ever try to sail the boat in that. It would kill it dead.”

SailRocket’s design is so radically different than any other sailboat challenging the 50-knot barrier that Barnsley isn’t sure what genus it falls into. “We need to invent a name for the concept,” he says.

Spidery and sleek, SailRocket is designed to have no heeling moment, which is the main limitation to most designs going faster, and a source of control problems at high speeds. Conventional sailboats counteract heeling with weight, which causes drag. SailRocket’s pencil-thin 33-foot carbon-fiber sandwich hull rides on tiny planing surfaces fore and aft, each about the size of a paperback book.

Barnsley, a senior test engineer for Vestas, which manufactures huge composite-construction blades for wind generators, eliminates heel by putting a solid-wing sail out on a crossbeam that extends 25 feet out from the bow. The wing is canted inward at the same angle as an inward- canting hydrofoil, or wing, that extends down into the water, also at the bow. Barnsley says the purpose of this hydrofoil isn’t to lift the boat out of the water. (SailRocket planes.) Its purpose is to counteract the heeling moment of the sail.

When the 22-square-meter wing sail, hydrofoil and crossbeam are all properly balanced geometrically, there is no heeling moment, Barnsley says, so all the energy from the wind goes into pushing the boat forward, not over on its side. SailRocket has two rudders: a standard sea rudder, which the pilot uses at speeds up to about 40 knots, and an air rudder, which works like an aircraft’s tail rudder and is deployed at 40 knots after retracting the sea rudder.

Barnsley says when properly balanced SailRocket is naturally stable. “There really shouldn’t be a need for the pilot to do anything once he hits the start gate,” he says. “He only has to go for 20 seconds.”

The team chose Walvis Bay to challenge the record because of the favorable conditions there for speed runs. Barnsley says the wind is the right strength (18 to 22 knots) and blows from the right direction relative to the 500-meter course 80 percent of the time from March into May. The course is set up 15 to 20 meters off a low, flat, treeless spit of beach, and because the wind usually blows off the beach it has no dead spots and, in the beach’s lee, chop is minimized. Best wind is 20 degrees abaft SailRocket’s beam, a slightly broad reach, Barnsley says.

The designer says he is “100 percent confident” that SailRocket will break the world record. He also is quite sure it can break 50 knots so long as ventilation — air getting sucked down around the planing surfaces — doesn’t become a problem and cause drag. “We’ve not seen any evidence of that so far,” he says.

Theoretical predictions say that the boat can sail 55 knots in 22 knots of wind, but at 53 knots, cavitation — tiny bubbles of water caused by the high pressure around the foil — is sure to kick in and cause drag. SailRocket’s foil is designed to suppress cavitation, Barnsley says. “If the cavitation is relatively mild, we could find ourselves doing 55 knots,” he says.

Larsen, however, won’t be reaching for that speed until he is ready. He will crank the speed up slowly in successive runs, testing the balance, testing his control — and tweaking, tweaking, tweaking. “We are very much aware that one big crunch could be the end of this project, so we want to be very careful,” Barnsley says.