The Blistering Speed of SailGP - Cherry Blossom Inc.

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The catamarans use wings, not sails, and hydrofoils help the boat fly over the water. It's like a fast video game, with consequences.

By Kimball Livingston

A generation ago, sailing would not, could not have made the short list of team sports played at highway speeds. The boats that most people race are considered fast at nine knots; screaming at 15. That's about 10 to 17 m.p.h.

Then came the F50 catamaran in 2019, with wings instead of sails and hydrofoils that lift the boats above the friction of the water, reaching speeds beyond 60 m.p.h., as they seemingly fly above the ocean. Indeed, the crew member helping make that happen is called the flight controller, who manipulates the elevations and angles of the left and right hydrofoils centered between bow and stern.

In SailGP lingo, the controller can fly the boat higher or lower. Higher is faster, but riskier because it also gets the boat closer to a nosedive.

The boats also require a new breed of helmsmen — they call themselves drivers — who direct the rapid-fire team choreography in which decisions must be made in fractions of a second.

The wing trimmer, a term from sail trimming days, shapes the wing — an airfoil — for speed and stability. Compared with fabric sails, a wing can provide more stability even while producing more speed. SailGP wings are built from carbon fiber with titanium fittings under a light plastic wrap. The old days of eyeballing sail shape are gone from these boats.

Data from racing and practicing is accumulated and analyzed to determine optimum wing shape for speed in different conditions, and the trimmer uses hydraulic controls to achieve the target settings.

With more moving parts than an airplane wing, an F50 wing has a larger menu of shape settings.

Given more wind, a sailboat tips over farther and farther until it spills wind out of the sails or loses control. Up to a point, SailGP catamarans just keep going faster. The British team hit a record 53.05 knots. or 61.05 m.p.h., during practice last summer.

"Compared to traditional boats, what is striking in SailGP is the complexity of the control systems," said Nathan Outteridge, a two-time Olympic medalist who drives for the Japanese team. "I should say that driving is pretty easy, until things go wrong."

Jason Waterhouse, an Olympic medalist who is flight controller for the Australian team, manages the hydrofoils that go up and down at precise angles with precise timing. Get it wrong, and the boat can nosedive.

"I have to have muscle memory," Waterhouse said about operating the buttons and dials. It's like a fast video game, with consequences.

Waterhouse also controls the rake, or angle, on the horizontal flaps on the two rudders the driver uses to steer. The flight controller contributes to level flight by dialing in as much as seven degrees of differential rake between the rudder flaps. The flap on the side being pushed down by the wind is angled to push up, and the flap on the opposite side is angled to push down.

"It adds an extra 300-400 kilos [650 to 900 pounds] of righting moment," Waterhouse said, referring to the forces working to keep the boat from tipping over.

Paul Campbell-James, the wing trimmer for the U.S. team, said that because much of the boat's hydraulic power was generated by a battery instead of by a crew member turning a grinding pedestal, his team had given that grinder a second job.

"We set up our forward-facing grinder to also be a tactician," Campbell-James said. The grinder spins the pedestal's handles to generate power for the hydraulics but also looks for wind shifts.

Wing shape on these boats has taken over most of the trim-in, trim-out of normal sail control, while contributing to level flight. The key is negative camber, shaping the upper wing to pull opposite to the lower wing, countering the forces trying to tip the boat over. Negative camber adds to the effect of the rudder flaps to make for level sailing. Old school it is not.

In turning maneuvers, the crew switches sides and Campbell-James crosses the boat first to take over driving duties before others follow him across. As they come, if he wobbles the helm, the motion could flick his teammates off the deck.

At the same time, he has to keep the boat level in a dynamic turn, press a foot button to raise a hydrofoil, respond as the wing loads up on the new side and hang on against "G-forces that are unbelievable because, remember, you might be going 50 knots. That's a lot going on."