Software speeds design of America's Cup challenger

San Francisco--Thanks to CAD and finite element analysis, engineers for America True, the San Francisco Yacht Club challenge for America's Cup 2000 already have a good idea how their design will perform in water tests that get underway in June 1999. They've been using Structural Dynamics Research Corp.'s (SDRC; Milford, OH) I-DEAS software to develop and test different versions of the design for the America's Cup challenger.

"We started by coming up with a generic hull and then designed various pieces for it," says Phil Kaiko, lead designer. Using the software's "replace" feature, engineers produced about 100 versions of the boat, creating 3D models automatically. "Then we do a bending analysis to get the stiffness, " Kaiko says. "Normally, if we wanted a second geometry it would take several days of re-modeling, but we are doing it automatically."

The ability to devise several versions of a design until you get the best one is important in any engineering project. When designing America's Cup racing boats, it's critical.

Race officials changed the design rules for the more-than-100-year-old competition after the 1983 season. Boats now can be longer, lighter, and use different materials in the hulls. In effect, says Kaiko, the boat becomes a testing platform for several new ideas.

While the specifications allow the use of a variety of materials, Kaiko says America True will use carbon fiber skins in a honeycomb core. Actual hull skins will be more than 1 1/4-inch thick. The boat will weigh between 50,000 and 60,000 lb, in keeping with the rules. Of the total weight, about 40,000 lb of it is lead in the keel to keep the boat from overturning.

Engineers follow a formula to get the boat's exact dimensions that combine length, displacement, and sail area. Tradeoffs are allowed. For example, want a longer boat? Use less sail area.

"I-DEAS is the cornerstone for our design," says Kaiko. "We use it to create a 3D solid model. We can then access the history tree of the model and replace any branch with new geometry. The process is simple and automatic."

Kaiko says the integration of I-DEAS CAD with I-DEAS FEA, and with fluid dynamics and machining tools, speeds the design process.

Speed is important in the design of the boat as well as the race. Boat designers have a two-year window to get all their work done. They started the design in October 1997. The construction phase goes from November 1998 to May 1999. Then, from June to September 1999, the crew will go to sea trials. They start racing in October 1999. The America's Cup competition is in 2000 in Auckland, New Zealand.

The America True team got much of its design-related data from the America3 team that won the America's Cup in 1992. "We have some design ideas for America True that are really unconventional, and thanks to the software we've been able to create prototypes rapidly, then turn around data to make design changes quickly," says Kaiko. "We already have 50 drawings we know we'll need, and as we develop the structure the software will automatically update those drawings."

Sometime this month, construction will get underway for America True, the San Francisco Yacht Club's entry in the year 2000 America's Cup.