How two teams plan to smash the world sailing-speed record

Launched in 1869, the Cutty Sark was the fastest sailing ship of its time. These days the clipper is a London tourist attraction. In its prime, when it dashed across the world carrying tea from China and wool from Australia, it could reach a heady 17 knots (31.5kph, or 19.6mph). Modern racing yachts, employing radical designs based on 150 years of advances in aerodynamics and hydromechanics, go much faster. And even stranger craft are hoving into view, as part of an attempt to break the speed record for a sail-powered craft, which was set, in 2012, at 65 knots.

Speeds have been rising for years. In the 1970s, as hulls became narrower and slippier, racing yachts began to slice through water at more than 30 knots. In the 1980s daredevil windsurfers reached over 40 knots. They were overtaken in the 2000s by kitesurfers at more than 55 knots. The physical demands and risk of injury from balancing on a small board at such a pace, however, means that sailing vessels—of a sort—are back in the race.