The blazing speed of SailGP
A generation ago, sailing could not have been on the shortlist of team sports practiced at highway speeds. The boats most people sail on are considered to be nine knot fast; scream at 15. It’s about 10 to 17 mph
Then came the F50 catamaran in 2019, with fenders instead of sails and hydrofoils that lift the boats above the friction of the water, reaching speeds above 60 mph, as they apparently fly above the ocean. This is because the crew member helping to make this happen is called the flight controller, who manipulates the elevations and angles of the left and right hydrofoils centered between the bow and stern.
In SailGP parlance, the controller can make the boat fly higher or lower. Higher is faster, but riskier as it also brings the boat closer to a nose-down.
Boats also need a new breed of coxswain – they call themselves pilots – who lead the rapid-fire team choreography in which decisions have to be made in fractions of a second.
The wing trimmer, a term of sail tuning days, shapes the wing – an airfoil – for speed and stability. Compared to fabric sails, a wing can offer more stability while producing more speed. SailGP wings are constructed of carbon fiber with titanium fittings under a lightweight plastic wrap. The old days of the eyeball shaped sails are gone from these boats.
Race and training data is accumulated and analyzed to determine the optimum kite shape for speed under different conditions, and the trimmer uses hydraulic controls to achieve target settings.
With more moving parts than an airplane wing, an F50 wing has a larger menu of shape settings.
With more wind, a sailboat tilts farther and farther until it knocks the wind off the sails or loses control. Up to a point, SailGP catamarans continue to go faster. The British team hit a record 53.05 knots. or 61.05 mph, when practicing last summer.
“Compared to traditional boats, what is striking about SailGP is the complexity of the control systems,” said Nathan Outteridge, two-time Olympic medalist who pilots for the Japanese team. “I have to say the driving is pretty easy, until things go wrong.”
Jason Waterhouse, Olympic medalist and flight controller for the Australian team, manages the hydrofoils that rise and fall at precise angles with precise timing. If you are wrong, the boat may nose down.
“I must have muscle memory,” Waterhouse said of using the buttons and dials. It’s like a fast-paced video game, with consequences.
Waterhouse also controls the tilt, or angle, of the horizontal flaps of the two rudders that the driver uses to steer. The flight controller contributes to level flight by dialing up to seven degrees of differential bank between the rudder flaps. The shutter on the side pushed down by the wind is tilted to push up, and the shutter on the opposite side is tilted to push down.
“It adds 300-400 extra kilos [650 to 900 pounds] of righting moment, ”Waterhouse said, referring to the forces that work to keep the boat from tipping over.
Paul Campbell-James, the US team’s wing trimmer, said that since much of the boat’s hydraulic power is generated by a battery rather than a crew member turning a grinding stand, his team had entrusted this crusher with a second job.
“We configured our forward facing rectifier to be a tactician as well,” said Campbell-James. The chipper rotates the pedestal handles to generate power for the hydraulics, but also looks for changes in wind.
The wing shape on these boats took over most of the trim and output settings of normal sail control, while also contributing to level flight. The key is negative camber, shaping the upper wing to pull away from the lower wing, countering the forces that attempt to tip the boat. The negative camber adds to the effect of the rudder flaps to allow level navigation. The old school is not.
In turning maneuvers, the crew changes sides and Campbell-James crosses the boat first to take over steering duties before others follow. As they arrive, if he wobbles the bar, the move could knock his teammates off the bridge.
At the same time, he has to keep the boat level in a dynamic turn, press a foot button to lift a hydrofoil, react when the kite loads from the new side and hold on to the “G forces which are incredible because that, remember, you might be going at 50 knots. There is a lot going on.