“You have to understand the aerodynamic principles well and how to apply them,” Mr. Drummond said. “If you have the skills to design an airplane, you have the skills to design a yacht. Now we could have a good crack at a windmill.”
Load-shifting can be done with more traditional sails, too, by changing their shape, which is accomplished in part by having a flexible mast. But even with technology — one system uses image-recognition equipment to “read” lines on the sails to see if they match prescribed curvatures — shape-changing is difficult. It is easier with a solid wing.
Alinghi 5 uses traditional sails, but that is not to say it is any less innovative than BMW Oracle’s boat. It has a flexible mast, one that is nearly 200 feet tall, and some of the biggest sails anywhere. Like most advanced racing sails, they are a sandwich of polyester film sheets with a filling of carbon fibers providing strength. The fibers are laid out in radial lines calculated to match the loads, and where the fibers come together in areas of maximum stress the sail has a distinct look, as if it has been dusted with ashes.
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