Lbrought 1869, the Cutty Sark was the fastest sailing ship of its time. These days the clipper is a tourist attraction in London. At its peak, when it dashed around the world carrying tea from China and wool from Australia, it could reach 17 knots (31.5kph, or 19.6mph). Modern racing yachts, which use radical designs based on 150 years of development in aerodynamics and hydromechanics, are faster. And even stranger craft are watching, 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 increased over the years. In the 1970s, as hulls became narrower and sleeker, racing yachts began slicing through the water at more than 30 knots. In the 1980s, daredevil windsurfers reached over 40 knots. They were overtaken in the 2000s by kitesurfers at over 55 knots. The physical demands and risk of injury from balancing a small board at such speed, however, means that sailing ships are—sort of—back in the race.
The current record is set by Paul Larsen, an Australian. He used a strange catamaran called Vestas Sailrocket 2, that rises above the water on hydrofoils and is powered by a wing sail. These rigid structures, similar to a wing mounted vertically on the plane, use the wind more efficiently than fabric sails.
The record was set in a one-way run of 500 meters. To qualify, a craft must be able to float, have at least one person on board, be propelled only by wind and be in contact with water. The new contenders follow these rules, however, like Mr Larsen’s craft, neither look like an ordinary sailing boat. One, called SP80, has its origins in the Swiss Federal Institute of Technology Lausanne. Another is from Syroco, a marine-technology startup based in Marseille, France.
the SP80 (pictured) resembles a futuristic jet fighter. Instead of sails or winged sails, the ship was powered by a kite. At high speeds, only the front of the boat and the two pods on each side are in contact with the water, reducing drag. The pilot sits in the front of the cockpit and drives. The co-pilot, in the back seat, controls the kite. “At this high speed it is best to focus on only one important task,” said Laura Manon, one of the team. They have an established base in Leucate, on the coast of southern France, to prepare for a record attempt next year.
The Syroco also goes for a two-seater, though its craft is more unusual. It is also powered by a kite. The body of the boat is a torpedo-shaped room where the crew sits. As the kite pulls the compartment faster, it rises out of the sea and into the air, reducing drag as much as possible. Only a small hydrofoil remained in the water, anchoring the craft and stopping it from flying completely.
Alexandre Caizergues, one of the co-founders of Syroco (and the holder of many kitesurfing records), will be the pilot in charge. “We have two wings, one in the air and one in the water,” he said. Exactly how to control each is still being worked out with a scaled-down radio-controlled prototype before a final design is chosen.
One problem both teams face is a phenomenon known as “cavitation”. This happens because a rapidly moving surface—such as a hydrofoil or a propeller blade—creates an area of low pressure behind it. That allows steam bubbles to form, causing turbulence that can slow a boat and even damage its structure. Part of the secret sauce for both companies is designing hydrofoils that can handle the problem.
If all goes according to plan, the record may not only be broken, but crushed. Both teams are targeting a speed of 80 knots. And this faster technology may have other uses. Some experimental cargo ships have been fitted with wingsails to reduce fuel costs, and kite towing has also been tried. The return of air power to commercial shipping will mark a happy closing of the historical circle. But wing sails and kites may not look as good as Cutty Sark once done, with all 32 sails furled. ■