Volume I, Number 4


Design Program Update
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Tank Testing Program Underway

    Tank Testing
    Tank testing hull model.
The second phase of the extensive AmericaOne model-testing program began October 1 in the towing tank at the Naval Surface Warfare Center in West Bethesda, Maryland. Two 25-foot boat models were used in a series of tests conducted over a period of a week.

These tests provide the AmericaOne Design Team with additional information and insight regarding the performance of each design in the presence of the air-water, free-surface interface. This is an important element of sailing performance that cannot be modeled in a wind tunnel.

"The America's Cup is a sport that is dependent upon technology," says Paul Cayard, AmericaOne skipper and CEO. "To win you have to find the fastest boat, and with our testing program underway, we hope to accomplish just that. Literally, 10,000 different boat shapes must be tested with models. The data we acquired in July from the wind tunnel tests will serve as a baseline for the models."

The towing tank tests determine the total hydrodynamic resistance of the hulls as they are driven down the tank attached to a towing carriage. The forces and moments between the model and carriage are measured with load cells to determine the total lift, drag and heeling moments. In addition, the characteristics of the waves created as the one-third-scale models are towed the length of the tank are analyzed to determine the component of resistance associated with the wave-making characteristics of each hull.

Following the tests, the towing tank data are extrapolated to full-scale hydrodynamic performance data. These data then are used in a Velocity Prediction Program (VPP). The VPP is a computer-modeling environment used by the Design Team to predict the full-scale sailing performance of numerous design configurations in various wind speeds and angles.

"Tank testing is essential," explains Frank DeBord, president of Houston, Texas-based Scientific Marine Services, Inc. (SMS), the marine engineering firm supervising the tank testing program. "It's the closest thing to understanding the physics of a boat that you can get."

Since its inception in 1990, SMS has been involved in America's Cup boat design programs, and the firm's principals have America's Cup experience dating back to the 1970s. DeBord gained his first America's Cup experience conducting tank tests for the 12-meter Enterprise in 1977. In 1992, he was a member of the Stars & Stripes design team, and he completed special projects for the Partnership for America's Cup Technology (PACT). During the 1995 America's Cup, he was responsible for the experimental programs conducted by oneAustralia.

"The difference between the final two teams competing for the America's Cup will be in the design of the boat," DeBord adds. "The design team with the most complete understanding of the forces acting on the hull and appendages of the boat will typically fare the best. AmericaOne realizes it needs to win the design and technology battle and that's why we're here at the towing tank so early."

SMS senior engineer Claudio Fassardi directly oversees the AmericaOne wind tunnel and towing tank testing programs, He conducted America's Cup class model tests for design programs, including the Partnership for America's Cup Technology (PACT) in 1992 and Team Dennis Conner in 1995.


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