Engineering news
But their boats have as much in common with planes as traditional seafaring vessels, and they owe part of their success to the wits of the engineers who work on them.
Impromptu fleets of boats are a common sight in the lead-up to the competition, with one team’s boat being tailed by others trying to take photographs of any engineering innovations so they don’t get caught out.
Professional Engineering spoke to David Durocher, an engineer at Altair, an engineering firm which worked with the Artemis Racing team on their entry into this year’s competition. The team, who made it to the final qualifying rounds, also feature in a short film, Surface to Air, which highlights the engineering challenges of maximising speed on the high seas.
“These boats are a mechanical engineer’s dream,” Durocher says. “And, the improved performance from America’ s Cup 34 to America’s Cup 35 is amazing. It’s a testament to what we can do today with the right application of engineering fundamentals, high-end materials and components, very sophisticated tools and a brilliant team at the wheel. Nothing drives innovation like observing the other team’s boat is clipping along just a little faster than yours. It’s the ultimate motivator.”
Altair’s involvement in the America’s Cup dates back to the 1990s, when they introduced a software tool called OptiStruct. “It’s the perfect tool for designing the structures of these boats,” explains Durocher. “In brief, it allows you to develop minimum mass structures purely based on package space, design loads and physics of the problem. Typically it beats an existing design by 20 percent. Total mass and mass distribution in these boats is very important.”
For this year’s competition, Altair were brought in at the very start of the process to design more efficient structures. They paid particular attention to creating a detailed structural model of the daggerboard, a part of the boat which protrudes from the hull like a fin. Because these boats are designed to minimize drag, this is often the only part of the vessel that actually touches the water.
“One big challenge is the development of a daggerboard that does well across a wide range of wind speeds,” says Durocher. “Here you’re balancing lift and drag as the daggerboard bends, twists and changes behavior under hydrodynamic loading. It’s not a single design point that you’re after. Ideally, it’s a design that can adapt well across a large range.”
The engineering work doesn’t finish when the race starts. There are constant tweaks and improvements to keep up with the other teams, as well as the challenge of detecting and making repairs. “Some of these are obvious, like holes in hulls and delaminating carbon,” says Durocher. “Others are identified only via nondestructive testing.”
Repairs are challenging. “During the races, the challenge is compounded with an extreme time component. Frequently this can be overnight when you have three races one day, three the next. Maybe you can afford to make repairs in between. But, what can you accomplish overnight and ensure you don’t degrade boat performance significantly?”
Simulators have been “fundamental” to the challenge. “Leveraging simulation is a huge advantage for developing designs much faster than via traditional physical trial and error approaches," says Durocher. "When you have a structure like the daggerboard that takes months to manufacture and costs hundreds of thousands of dollars, you have to start thinking about ways to evaluate ideas that don’t require large amounts of physical prototypes. I expect each team is heavily leveraging simulation and high end hardware to crank through the computations as fast as possible. You see this across all industries and anywhere a highly-engineered design is needed.”
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