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Team Dennis Conner's 1995 America's Cup Stars & Stripes: The Design Story

Background

The America's Cup Race is an international yacht race in which individual yacht crews compete for the right to represent their home countries in either a challenge or a defense of the event's trophy. Only crews from the country currently holding the America's Cup may compete in the defender races (for the Citizen's Cup), while any country may enter the challenger trials (for the Louis Vuitton Cup), with no limit on the number of boats per country. A series of trials among the challengers determines which crew will represent its country and meet the winner of the defender races. The challenger and defender then compete in a series of races for the America's Cup. The first contest for the prize, originally known as the 100 Guinea Cup or Queen's Cup, was sponsored by the Royal Yacht Squadron of Britain as part of an international exhibition in London in 1851.

Since 1958, the race has been run over a triangular 39-km (24-mi) course. Although the race is usually the best four of seven heats, occasionally other designations, such as the best two of three heats or the best five of nine heats, are assigned. The competitors in the race have a crew of 11. The crew members roles are Bowman, Sewerman, Mastman, Trimmers, Mainsheet Hand, Navigator, Tactician, and the Skipper.

In 1983, the Australia II defeated the United States entry, Liberty, for the first victory by a non-American boat in the race's history. Until 1983 American entries had successfully defended the cup 25 consecutive times. The 1988 contest, held off the coast of San Diego, California, was the first in which a catamaran, Dennis Conner's Stars & Stripes of the United States, was matched against a traditional single-hull yacht. After the catamaran won, New Zealand unsuccessfully contested the victory in court. In 1989 guidelines for the International America's Cup Class yachts were established, and ships up to 75 ft (22.86 m) became eligible. The 1992 competition, off San Diego was won by the United States entry, America³.

The 1995 Stars & Stripes Engineering Development Effort

Having lost the Cup the previous race season, Team Dennis Conner was anxious to regain it from America³.

The Team Dennis Conner design effort had been continuous since development of the new class of boat in 1989. The design team consisted of naval architects, structural engineers, aerodynamicists, computational fluid dynamics experts, computer analysts, and wind tunnel and towing tank engineers. The design team contributed extensively to the writing of the new International America's Cup Class Rule at the time, gaining a head-start in understanding of the Rule as well as helping to ensure the class remains a supreme technical challenge.

Team Dennis Conner Operations Manager Bill Trenkle oversaw the design and construction program. As Vice President of Dennis Conner Sports, he had been involved in the design, construction and commissioning of Conner's America's Cup yachts since 1987. He had been a member of Conner's America's Cup campaigns since 1980 and sailed as port tailer and on-board liaison to the design team.

Chris Todter was the Technical Director for Team Dennis Conner, the same position he held for the 1992 campaign. He had continued the Stars & Stripes design development non-stop since 1992. Todter brought with him ten years of America's Cup experience as a technical manager. Todter directed the design program, including research and development. He also assisted in the evaluation of data from on-the-water sailing to the design team.

Naval architect David R. Pedrick of Pedrick Yacht Designs was principal designer for the team in his seventh America's Cup campaign. His work with Conner began in 1987 as a principal designer for Conner's winning 12 Meter yacht Stars & Stripes and continued as a principal designer for Stars & Stripes '92. A strong research-oriented yacht design company, Pedrick has always been in the forefront of advanced technology. Pedrick's firm was the only yacht design company in the world with in-house VSAERO capability at the time, a key technology in aerospace computational fluid dynamics (CFD) applied to keel design. Pedrick and his associates, Thomas "T.J." Perrotti, Scott Ferguson and Sam Howell, were responsible for configuration analysis and lines generation for tank models and appendage models, layout and structural coordination, and extensive data analysis and simulation.

Many new tank test model components, including bulbs, keels and rudders at 1/5 scale and 1/3 scale, were fabricated by Modelwerks Inc. in Seattle, Washington. Modelwerks was a relatively new high-tech aerospace company founded by Stayne Hoff, Jay Paterson, and Jon Stamm. Their decades of experience in wind tunnel model design, fabrication, and test engineering was of great use to the TDC effort during the tank test model development program in 1993-1994. Principal technical interchanges were between T.J. Perrotti (then at Pedrick Yacht Design) and the Modelwerks staff, with Chris Todter of TDC facilitating as the integrator between his two vendors on opposite US coasts.

Alberto Calderon was head designer for the team specializing in aerospace technology. Through his company, Advanced Aeromechanisms Corporation (AAC) of La Jolla, California, Calderon and his associates, Matt Brown, Associate Designer, and William Burns, Research Associate, contributed research in advanced aerodynamics, including wind tunnel and towing tank support and analysis. Founded in 1965, AAC had been engaged in aerospace research for more than 20 years and was well known for design consultant work for NASA, the Department of Defense, and the Concorde.

The team of associate designers Stephen Slaughter, Paul Miller, and David Dillon had been working full time since the 1992 campaign on development of a new hull structure. These advanced composites engineers were again providing leading edge structural concepts and design refinement. They worked with Newport Adhesives and Composites which provided additional technical expertise and supplied the pre-impregnated carbon fiber used for yacht construction.

Design research had been supported by General Motors Technical Center, Boeing Aircraft Company, Lockheed Space Systems, Analytical Methods Incorporated, and Cray Research. General Motors provided access to its immense wind tunnel for keel, bulb and sail design. Boeing contributed advanced aerodynamics technical expertise and software analysis toward the development of highly refined appendages (keel, bulb, and rudder) as well as sail development. Lockheed Space Systems contributed toward structural design. Analytical Methods was responsible for CFD analysis of hull shapes, and Cray Research supported both Boeing and Analytical Methods with extensive analysis time on Cray supercomputers, necessary to be able to process the monumental requirements of state of the art CFD codes.

To achieve the highest level of model testing, the towing tank facilities at the David Taylor Model Basin, belonging to the Navy and acknowledged as one of the world's best tanks, was used to test hulls and appendages. The team's own new state-of-the-art dynamometer and data acquisition system was utilized to compute drag and side force on the yacht models in smooth and rough-water testing.

Tank results were used to refine and validate design ideas that are developed with both Velocity Prediction Programs (VPP) and Computational Fluid Dynamics (CFD) computer codes. While the computer codes used for VPP and CFD work were technologically advanced, even today there will always still be a need to validate given concepts in the tank.

The 1995 Stars & Stripes was built at Eric Goetz Custom Boats in Bristol, Rhode Island. It was the first America's Cup yacht ever built off a mold that was cut by a computer-driven laser to achieve unprecedented accuracy.

The Racing

Stars and Stripes sea trials went well, and quickly the Dennis Conner team was racing in the Defender Series. Ultimately, TDC triumphed in that race series to win the Citizen's Cup, but the victory was one of a great crew and experience and not the fastest craft per se. From race observations, clearly the Young America design was the fastest of the American boats for the racing conditions being experienced. In an event first, Conner asked PACT '95 and the Young America team if he could have his race team (plus half of Young America's) compete against the winner of the Challenger Series using the Young America boat instead of Stars and Stripes, and he was allowed to do so.

The switch to Young America gave Conner's team less than a week to learn to sail the new boat, but that was less risky than sailing the slower Stars & Stripes against the swift Black Magic I. "Young America's deck layout is different, but we're getting used to it," said Trenkle. "It's like getting a new car and the knobs are not where you think they are."

The Challenger Series racing had been colorful. John Bertrand's 75' One Australia broke in two and sank in heavy wind and fierce waves on March 5, 1995, in the worst accident in the 144-year history of America's Cup racing. All 17 crewmembers were rescued as the $3 million yacht disappeared into the Pacific Ocean within two minutes (settling to an economically unrecoverable depth of 500 feet). The Challenger Series winner, Team New Zealand, who had two exceptionally fast boats, and who had managed their own campaign with singular focus, went on to defeat Team Dennis Conner / Young America in the America's Cup finals in five straight wins with their Black Magic I. It showed the power of having two good boats that could test and tune against each other during the trials.

America's Cup Race Results

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