How Fast Can a Foiling Sailboat Actually Go?!?!?

Despite several years of foiling behind us now, most of the world’s sailing records are still held by non-foiling boats. But if foiling boats are so much faster, how come they haven’t broken more records? In this video we are going to explore why.

Foiling is when the hull of a boat is lifted out of the water by underwater wings called hydrofoils, like these International Moth dinghies which have been using full foiling since 2000. With the highest 10 second average for a Moth of 35.9 knots, it the fasted rated sailing dinghy in the world.

The first larger boat to use full foiling was L’Hydroptere, a French Experimental trimaran. She broke the sailing speed record in 2009 with speeds of 52.86 KT over 500M, and 50.17 KT over a nautical mile. She did briefly reach 56.3 KT, but not for long enough to qualify as a record, and lost control and capsized shortly afterward.

Since 2013 the America’s Cup and SailGP boats have also been full-foilers, but interestingly none of them have yet gone faster than L’Hydroptere.

In 2017 Gitana 17 was launched. She is the first ocean-going maxi trimaran designed from the ground up for full foiling, but in the five years she’s been sailing, she still hasn’t broken IDEC Sport’s non-foiling around-the-world record.

Some boats, like Alex Thomson’s 2016 Vendee Globe boat Hugo Boss are designed as partial-foilers, where the hull is still in the water much of the time, but the foils provide some lift and reduce pitching. In this footage Alex had broken his starboard foil off so his hull is fully in the water. But despite sailing 2/3 of the way around the world with a missing foil he still came in second, and ahead of foiling boats behind him.

So what’s the deal with foiling boats. Why don’t foiling boats like Gitana 17 hold more World Records? It’s because there are lots of practical and physical limitations associated with foiling, which we will discuss in this video, not the least of which is cavitation at around 50 knots.

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[ufukozbir]

I like this video very much; no unnecessary decoration. Straight to the point. thanks

[JKMediaCorp]

France's SailGP boat hit 99.9 kph briefly(just under 54 knots) a few weeks ago, and that is a new top speed record for that race series. They were seriously moving.

[russ]

I had a 1968 Columbia 22..learning to sail her was one of the coolest most eye opening experiences of my life...

[burkelong]

Great breakdown of the foil/non-foil debate.

[dogzer]

I've never even stepped on a sailboat but I find it amazing and particularly these type of foiling saiboats are quite a sight!

[thethirdman]

INEOS Britannia briefly got up to 55.6 knots in the Louis Vuitton Cup in Barcelona. That was on a bear away in 24 knots of wind and is an America’s Cup record…

Don’t forget Sailrocket 2‘s world 500 metre record of 65.45 knots, set on Walvis Bay in Namibia in 2012.

[mattcero]

Wow, I stumbled upon this, watched it and came out the other side smarter! Never knew about the cavitation of these. Thanks mate!

[ClassVtony]

Thanks makes me feel much better about my trimaran without foils

[sailingaqualibra]

Nice presentation on a very interesting topic. I think it's always been more important to establish high average speeds than ultimate, or fleeting, top speeds in distance ocean racing.

[antc]

The fundamental limit to foils is cavitation as you mentioned. However all high speed yachts are fundamentally fragile on ocean legs including IDEC Sport, which one could say had a lucky run. Current IMOCAs have successfully foiled the Southern Ocean without hitting objects in the water, and over 24 hrs Team Malizia managed 641.13 Nm to set the monohull record. Success with light weight racing yachts depends on a large dose of luck.

[rickemmet]

Great video, nice to see this being address seriously. Yeah, it's not safe foiling over long distances, the best helmsmen in the world crash their foiling multis on a regular basis. The Eagle 53 has had its T-foils installed, but they haven't put out a video on this new addition to the design. I suspect that the software required to make the boat foil safely hasn't yet been figured out.

[terrysullivan]

Thanks for the clear explanation. I've been wondering about this for a few years.

[tomweston]

I know from windsurfing, that we find foils just can't keep up at higher speeds. The gap's being closed but you can get to around 55knot on a fin, whereas 35 on a foil is around the limit with current tech (and that's not over any distance.) Foils are, however much, much quicker in turns and upwind which makes them way faster around a course in any conditions.

[victorhauk]

Cavitation is not anything like the sound barrier. Cavitation is the reduction of water pressure over the foil to the point that the water boils.

[joeyc]

Could they come up with an active system for managing the foil profiles to help with stability and cavitation issues?

[glenncosford]

Great video, but Dan and Greg Ketterman were the first to design and build Longshot which broke the world speed sailing record in early 90's which became the Hobie Trifoiler which was and I beleive is still the fastest production sail boat ever built in the early 90'. Just for context as they deserve some credit in relation to hydrofoiling.

[abarratt]

I once saw Hydroptere in the Solent, on a windy day. Very impressive, seeing her casually zipping along at such speed!

I'm wondering when someone will try blowing an air bubble film over a hydrofoil, from nozzles in its leading edge. That'd solve the cavitation problem.

[Chris.Davies]

Not sure, but I know that when the designers manage to introduce supercavitating foils we'll probably see another 10 to 15 knots added to the top speed.
DYOR.

[AnttiBrax]

The claim in the video that foils are mostly sub-optimal in long distance offshore racing due to varying weather conditions is just outright incorrect. Vendee Globe 2020 already had 4 foiling boats in the top 5. Would have been even more without equipment damage, which is something that will only improve as the technology matures. The reason why Jean Le Cam did so well is that he knew how hard to sail his boat while the foilers had to hold back, because there isn't enough experience yet in how hard they can be reliably pushed.

For long distance record attempts it's the same thing. Varying weather conditions have not mattered in RTW since Francois Joyon broke the record. Because everyone will need, foiling or not, the perfect ride to ever have a fighting chance against it. :)

And several of the recent RTW record attempts were foiled (pun intended) by flotsam while being clear ahead of IDEC.

[MartinMoe]

Amazing to do a video on this topic and not mention Paul Larsen and the Vestas Sailrocket program. In Vestas Sailrocket 2 they ventured into the realm of supercavitating foils and peaked with running a 500m course at 65.45 knots (121.21 km/h) with a 68.01 knots (125.95 km/h) peak.

There were some plans to take the program offshore but that has not come to fruition, yet.

On the other hand, I just realized that you have done a video on The Rocket before, I have even seen it. Too many sailing videos, not enough time and memory available ;-)