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New tack to be tried for America's Cup

For the second straight contest, an MIT professor is assisting with the design of an America's Cup yacht. Professor of Ocean Engineering Paul D. Sclavounos is working with a syndicate that hopes to build the yacht that will defend the Cup in races to be held starting in the spring of 1995.

The syndicate known as PACT (Partnership for America's Cup Technology) is using a hydrodynamics computer package called SWAN (Ship Wave ANalysis) developed by Professor Sclavounos and his students over the last decade to arrive at what members hope is the most efficient hull design.

PACT, whose boat will be skippered by Kevin Mahaney, is competing for the right to represent the United States with Team Dennis Conner and other American would-be defenders who have not yet officially entered. (Bill Koch, an MIT alumnus, successfully defended the Cup in the 1992 races in 1992 with America3). Eight foreign syndicates from Australia, New Zealand, France, Spain and Japan are vying for the right to challenge the American boat next year.

SWAN, which Professor Sclavounos has used in designing other types of boats, produces a computer model of the flow of water around a ship's hull. Under terms of an agreement between him and PACT, only that syndicate will have the benefit of this latest tool of high-tech yacht design. "PACT's strategy is to base their advantage on SWAN-that's the card up their sleeve, if you will," he said.

SWAN will be used to evaluate the impact on performance of minute variations in hull shape. Because of the great skill of the sailors involved, "a difference of one percent in speed is enough to create a margin of victory of two minutes," Professor Sclavounos said. Winning margins are often shorter than that in America's Cup races, which last about three and a half hours, he added. In past competitions, boats have averaged about 9 knots (a bit more than 10 miles per hour) over a 27-mile course, he said.

PACT and the other syndicates will build models of various proposed boat designs and test them in large tanks around the country. Under the International America's Cup Class formula for boat dimensions (which replaced the old 12-meter rules in the 1980s), the yachts are expected to be about 70 feet long. The races to determine the American defender begin late next January off San Diego.

Partly because of a rule change limiting each syndicate to two boats, budgets for the expensive undertaking will be significantly lower than they were in 1992, Professor Sclavounos said. He estimated that each syndicate will spend about $20 million on preparations for this next contest, whereas they spent four to five times that amount in 1992. "It's a very laborious, very expensive process," he noted.

Since last summer, Professor Sclavounos and his colleagues have been using the MIT Cray supercomputer facility at the rate of about 200 CPU hours per month to evaluate candidate hull form designs. Cray Research is one of the sponsors of PACT, which existed as a research and development group three years ago but was not involved in the last America's Cup, he said. However, he himself used SWAN during the America3 design process to study the performance of the yacht hull in rough waters (PACT has not yet selected a name for its boat).

While the research of Professor Sclavounos and others is obviously aiding in designing an America's Cup yacht, the process operates the other way as well. The work "has pushed us in the direction of significant benefit to the rest of our research here," he said. "That's the fun and challenge of it-it pushes our level of expertise to its limits. It's been a very rewarding experience for us."

A version of this article appeared in the March 2, 1994 issue of MIT Tech Talk (Volume 38, Number 24).

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