Marine

Two radically new kiteboats hope to smash the world speed sailing record

Two radically new kiteboats ho...
Syroco's #1 challenge is to design a supercavitating hydrofoil that won't produce shuddering instability
Syroco's #1 challenge is to design a supercavitating hydrofoil that won't produce shuddering instability
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Syroco's #1 challenge is to design a supercavitating hydrofoil that won't produce shuddering instability
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Syroco's #1 challenge is to design a supercavitating hydrofoil that won't produce shuddering instability
The Syroco Speedcraft is a weightless boat design balancing forces between a huge sail and a single hydrofoil
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The Syroco Speedcraft is a weightless boat design balancing forces between a huge sail and a single hydrofoil
The SP80 from EPFL University uses a trimaran design and will stay on the water rather than rising above it
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The SP80 from EPFL University uses a trimaran design and will stay on the water rather than rising above it
Both boats are targeting 80 knots to smash the current world speed sailing record
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Both boats are targeting 80 knots to smash the current world speed sailing record
View gallery - 4 images

Two teams, Switzerland's SP80 and France's Syroco, are taking aim at the world speed sailing record in 2022, with a pair of thoroughly remarkable kiteboats that both teams believe can smash previous records, targeting top speeds up to 80 knots (92 mph/148 km/h).

The standing world speed sailing record was set in 2012 by Australia's Paul Larsen, who recorded a crazy 65.37 knots (75.23 mph/121.06 km/h) aboard the Vestas Sailrocket II, an inclined-rig hydrofoil designed in Britain. The video of the record run makes compelling viewing; 75 miles an hour over the surface of the water looks pretty damn hairy even on the beautifully flat sea Larsen was working with.

But Larsen was using a sail on a mast, and two teams now believe they'll smash that record using kites instead. Why kites? Well, when you start generating huge power from a sail attached to a mast that's joined to the hull of your boat, you don't just get lateral force to work with; the boat also wants to roll. The higher the power, the greater the roll moment. So even enormous, wide catamaran designs can sometimes tip over and capsize.

Kites are much harder to control – and this will be a key challenge for both contenders – but roll can be completely designed out of the equation, letting kiteboats harness significantly more power. Let's meet the contending designs.

The SP80, from Switzerland's EPFL University

Both boats are targeting 80 knots to smash the current world speed sailing record
Both boats are targeting 80 knots to smash the current world speed sailing record

Where many quick sailboats "fly" up out of the water on hydrofoils, the EPFL team's SP80 boat is designed to stay in contact with the water. There are two reasons for that. First, the team plans to take it up to speeds where flipping over is a genuine and dangerous possibility if the wind gets under it and lifts the front. Secondly, the phenomenon of cavitation – water boiling into vapor as it passes quickly over the foils – causes so much drag and instability that hydrofoiling boats are more or less limited to around 100 km/h (62 mph).

Thus, it'll be a trimaran, shaped like some sort of future high-speed VTOL aircraft. It'll be 8 m (26.2 ft) long, and its two outriggers give it a "wingspan" of 6 m (19.7 ft) for stability.

The SP80 from EPFL University uses a trimaran design and will stay on the water rather than rising above it
The SP80 from EPFL University uses a trimaran design and will stay on the water rather than rising above it

Its large kite is attached low and to the rear of the boat, and there's a specially curved foil in the water on the other side to balance against the huge power the kite will generate. For this, the team has used a triangular-sectioned "ventilating" shape designed to carve an air pocket into the water behind it as it moves through the water at high speed, eliminating the instability of cavitation caused by a traditional foil shape.

These will perform poorly at slower speeds, but unlike regular foils, they impose no theoretical speed limit on the boat. They're proven in high-speed motorboats capable of doing up to 350 km/h (217 mph). Getting the SP80 up and running could be a team effort; the rules of speed sailing allow the team to launch the kite from a motorboat or a floating platform.

The team has profiled the SP80 in a series of five short videos, starting with the one below.

SP80 Explained | Episode 1: Who are we?

The Speedcraft, from France's Syroco

The Syroco Speedcraft is a weightless boat design balancing forces between a huge sail and a single hydrofoil
The Syroco Speedcraft is a weightless boat design balancing forces between a huge sail and a single hydrofoil

Syroco's approach is entirely different, and it looks completely bonkers. It's a "weightless boat" that looks a bit like a speared fish flying along over the water. One side of that spear are the lines leading to the kite, and the other, directly opposite, is a thin wing leading down to a submerged hydrofoil.

The hydrofoil opposes the pull of the kite, holding itself in the water and handling steering duties, and the design looks remarkably simple; Syroco says the cabin itself is not particularly necessary to the design, other than as a place to put the people in to control the thing.

It might look simple, but the Speedcraft runs a hydrofoil. As speeds increase, the foil will start pulling hard against the kite, creating a high-pressure zone on one side of the foil and a very low-pressure zone on the other. When the pressure gets low enough, the water around it will start to vaporize. Yep, cavitation – the speed limiter on all previous hydrofoils.

Syroco is counting on it. "We won't even try to avoid cavitation," writes the team. "Instead, we work to make it steady. We need to achieve a supercavitating regime." The idea here is to create a homogenous pressure field near the surface of the foil, which will form a stable pocket of vapor that doesn't close up and create shocks and vibrations until a point well behind the foil.

The team is bringing some monster computing power to bear on the problem. In the first round of computational fluid dynamics simulations, the team took a standard cavitation foil designed by NASA in the 1950s, and modified it into 400 different designs. Each of these was run through some nine hours of simulations on a specially designed HPC system with 9,216 processing cores. The result: a design the team believe will perform 50 percent better than the original.

This forms the starting point; from here the team believes the geometry can be optimized to improve performance by another 50 percent. Check out a video of the Speedcraft below.

Syroco concept preview - ST EN

The plans from here

Both team have prototyped their designs, and have run tests on the water. Both have started building their final boats. And both plan to make their assault on the world speed sailing record in 2022 – although Syroco appears to be aiming for mid-year, while the SP80 team is looking more toward the end of the year.

Both designs are highly innovative, with impressive teams and solid resources backing them. This will be fun! Who's your pick to be fastest?

Sources: SP80, Syroco

View gallery - 4 images
6 comments
6 comments
Robert Craigs
My main reservation would be what happens if it hits rough water? If the hydrofoil entered the air I would expect serious trouble. → I suppose if you are only interested in setting a record, you could just pick your water conditions well.
Grunchy
Good luck to both teams! Impressive technology, I hope you achieve your goals.
jerryd
Now that is radical!!! Interesting take on the cavitation problem.
Bob Stuart
It is nice to see things reduced to their basics and optimized. What are the lift/drag numbers for the supercavitating foils?
Demosthenes
These record attempts are so important for the future of the planet, that everything else must take a back seat. A huge step forward for future CO2-free mobility on the water.
christopher
Double the foil area will halve the potential cavitation... just keep doing that until it's gone... doesn't sound like such a difficult problem to solve.