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

[@ufukozbir649]

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

[@SailingTipsCa]

Glad you liked the contents AND format!!!

[@ccrider8483]

When I read the title of this video in the thumbnail, I said to myself, it is simply because foiling boats are not seaworthy. This video did an excellent job of going into detail without being preachy or boring.

[@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.

[@SailingTipsCa]

Yes that was amazing and they didn’t wipe out! I bet they celebrated after emptying their drawers afterwards!

[@dimonstrdima]

Is this speed of French sailgp was in a long range like 500M or 1 km? No. It was like in a moment, a peak speed. Anyway its a huge and significant step forward. Great job.

[@jman414999]

in that race they stayed over 90kph for most of the race. amazing to watch

[@dimonstrdima]

@@jman414999 yeah, and they have no brakes )

[@markkurtis8637]

It wasn't long ago they said they thought 60mph was obtainable. Now they've surpassed that so... Exciting. Real exciting stuff.

[@burkelong4376]

Great breakdown of the foil/non-foil debate.

[@SailingTipsCa]

Thanks! I think foils are amazing, but there is quite a bit of nuance to their effectiveness.

[@ChainsawFPV]

Those FPV shots were great!

[@SailingTipsCa]

Glad you liked it!

[@russ549]

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

[@SailingTipsCa]

Sailing is such a cool sport in so many ways!!!

[@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!

[@SailingTipsCa]

I think they’re pretty amazing too - thanks for watching!

[@thethirdman225]

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.

[@SailingTipsCa]

Thanks for the update on INEOS! And you might enjoy my video on Sailrocket 2! How Did Vestas Sailrocket 2 Smash the Sailing Speed Record?!?! kzbin.info/www/bejne/gWTQYWltaJZ1h7s

[@ClassVtony]

Thanks makes me feel much better about my trimaran without foils

[@SailingTipsCa]

Yes I could add foils to my F-82R but they would add a considerable amount of weight which would slow the boat down and I would only benefit from them a small fraction of the time with the prevailing conditions around here!

[@mattcero1]

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

[@SailingTipsCa]

Cool - glad you liked it! The cavitation is a major issue at higher speeds! Check out how Sailrocket overcame it: How Did Vestas Sailrocket 2 Smash the Sailing Speed Record?!?! kzbin.info/www/bejne/gWTQYWltaJZ1h7s

[@chipsterb4946]

The original Windsurfer daggerboard started cavitating at about 12-15 knots. One second you were flying (relatively) and the next the board rolled up on a rail and dumped you.

[@joeyc8546]

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

[@SailingTipsCa]

Yes they already use the controls described in this video for stability, foiling height etc: How Do You Control a Foiling Boat?!?!? kzbin.info/www/bejne/npLIp5Ztlrysgpo What nobody has done yet is dynamically change the foil shape sufficiently to switch from sub-cavitation to super-cavitation speeds. The engineering challenge with this is that water is about 800 times more dense than air, so the foil is much smaller and under much higher loads than airplane wings which change shape.

[@antc5010]

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.

[@SailingTipsCa]

Yes IDEC Sport truly had a very lucky run with a very brave skipper and crew! You could see the differences between the foiling and non-foiling boats in the last Route du Rhum however those were relatively moderate conditions compared to the Southern Ocean. There’s no question the foiling boats will take the records at some point but it’s still interesting that it’s taken this long! Have you seen this video about overcoming cavitation? How Did Vestas Sailrocket 2 Smash the Sailing Speed Record?!?! kzbin.info/www/bejne/gWTQYWltaJZ1h7s

[@antc5010]

Thanks ... very interesting and it supports comment from Martin Fischer who is on the Luna Rossa team and also designs foils for Starboard. He confirms that you can design foils to go fast 0 - 35 kts, but need a totally different design to exceed 35 and up to 50 kts, but is then slower in the lower range. Without the specific setup of Sailrocket 2 foil cavitation at around 50kts is an issue for conventional foils and rigs. I certainly do not want to be on a windsurf foil board when the foil breaks loose at 50 kts! @@SailingTipsCa

[@SailingTipsCa]

@@antc5010 It would be really cool to have foils that could change shape as speed increases like airplane wings but the loads are much higher on foils so a bit more of an engineering challenge!

[@rcpmac]

Question. If at around 50 mph water vaporizes, the how does a propeller function when it’s rotating contact surface is traveling at speeds many times faster than that? Isn’t it a matter of foil shape?

[@SailingTipsCa]

Yes it’s precisely a matter of foil shape - foils that are efficient at less than 50 knots are generally not tolerant of cavitation, and foils that are tolerant of cavitation tend to be inefficient at less than 50 knots. Check out this video on a comparison of the shapes: How Did Vestas Sailrocket 2 Smash the Sailing Speed Record?!?! kzbin.info/www/bejne/gWTQYWltaJZ1h7s

[@delawariand9860]

Great video!

[@SailingTipsCa]

Thanks - glad you liked it!

[@Femboy.jax.]

Hey i know the imoca 60s are smashing records right now as semi foilers could we get a part 2 to the video or an update

[@SailingTipsCa]

Good question!!! The IMOCAs are currently smashing singlehanded monohull records for distance covered in 24 hours, and have also surpassed the Comanche monohull record I referenced in this video, but they’re still a few hundred nautical miles per day short of the 24 hour records set by non-foiling multihulls. Here’s a listing of records of various categories: www.sailspeedrecords.com/24-hour-distance

[@kwittnebel]

The only reason foilers do not hold all the records is that they have not been around as long as conventional boats and therefore they are much fewer in number and have not had as many opportunities to break the records. IDEC holds the RTW record for pretty much one reason: Francois Joyon is an animal, knows how to keep a boat light, and got into a fantastic low pressure moving at 35kt across the Indian Ocean that they were able to remain inside. So the weather system was moving precisely at the maximum speed the boat was able to maintain for eight or nine days, and they demolished the Indian Ocean record in the process. Crewed, with seven guys and the best weather router and skipper in the world. Then a few months later, Francois Gabart took MACIF, a fully foiling trimaran, around the world in 42 days - just missing the fully crewed non-foiling record set by IDEC, but at a much higher average speed, ALONE. Great skipper, great router, but he was only one guy. So foils basically allowed him to maintain much higher average speeds than Joyon did with a fully crewed non-foiling boat, even though Gabart was alone and sleeping much of the time with autopilot driving. Joyon's average speed throught the water was just over 22 knots. Gabart's was 27 knots. There is a certain amount of luck in the weather patterns in these RTW attempts also; IDEC sailed only 26,412 miles, where Gabart traveled 27,859. Gabart's singlehanded foiler would have won handily given similar course distance. Joyon himself suggests that the boat to beat his RTW fully crewed will likely be a foiler capable of sustained 45kt speeds: www.sailingworld.com/qa-with-idec-sport-skipper-francis-joyon/

[@SailingTipsCa]

I totally agree with you that foiling boats will eventually hold more records and that IDEC Sport currently holds the round the world record because 1) Francis Joyon is an animal and 2) they had amazing weather! I also agree that Francois Gabart's solo effort a few months later was totally amazing! A few questions though: I thought Francis Joyon's average speed for the entire race was 26.85 knots (en.wikipedia.org/wiki/IDEC_Sport), how did you get 22 knots?. I also didn't think MACIF was fully foiling in 2017 though (kzbin.info/www/bejne/bIaTfn6NZpl6Y6s) as it got a massive refit and was re-launched as a full-foiler in 2018 (kzbin.info/www/bejne/p166pIR3bdp4bbs). I could be wrong though...

[@kwittnebel]

@@SailingTipsCa 22 kt is over the theoretical course. 26 was Idec through the water. Still a single dude on a foiler outpaced them. And it was fully foiling. That is how he did it despite sailing over a thousand more miles than a fully crewed boat. Without foils it would not have been possible. He put up nearly the same 24h numbers as a boat with 6-7 guys on it.

[@SailingTipsCa]

@@kwittnebel Gotcha. Francois also would have benefitted from not having to carry the weight of 6 crew and provisions for 50 days which can be substantial!

[@JoeOvercoat]

That’s great for racing but is the risk of pitch polling because it cavitated and stalled the wings worth it for someone who just wants to go fast? That is, without drowning.

[@karlw7764]

@@SailingTipsCa true, but there is no way he was able to sail his boat to the same percent of its potential as a singlehander that a crew of 7 did with Joyon. And even 7 was considered shorthanded for Idec. Stamm talked about being on the wheel for two hours where the speed never dipped below 42kt; to drive it that hard they needed 7 guys because you are fried after just an hour or two sailing right on the edge of capsize the whole time. So Macif was clearly a much faster boat.

[@brianmgrim]

What’s the Vestas Sailrocket 2 considered? Not a foiling sailboat?

[@SailingTipsCa]

I was thinking of boats that can actually sail a course, and the Sailrocket can only sail on one tack, but a good idea for another video!

[@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.

[@SailingTipsCa]

The main point I was trying to make in the video is that foils provide the greatest benefit in moderate conditions and that benefit diminishes in light and heavy conditions. For example, most long distance skippers including Charles Caudrelier on Gitana typically don't press their foiling boats faster than ~40 knots due to the cavitation limits of their foils. For long-distance work they typically pick foils that work well at boat speeds ranging from 15-40 knots, but much less well above and below this. Breaking even the 24 hour distance record would require sustained speeds well above 45 knots, which is approaching super-cavitating foil territory (like Vestas Sailrocket) however foils that work at these speeds require a substantially different design and are very inefficient at lower speeds. For more info on super-cavitating foils check out the Vestas Sailrocket video: kzbin.info/www/bejne/gWTQYWltaJZ1h7s

[@tomweston3239]

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.

[@SailingTipsCa]

And windsurfing or kitesurfing on a foil is absolutely the best bang for the buck in terms of performance versus investment!!!

[@Str8representing]

@@SailingTipsCa how & why?

[@SailingTipsCa]

@@Str8representing The previous sailing speed record (prior to Sailrocket) was held by a kite surfer. It’s just much less expensive to put together a foiling kite package because it’s much smaller, lower loads, less materials required, but you get wet!

[@victorhauk5973]

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.

[@SailingTipsCa]

The reference to the sound barrier was more that “supercavitating” foils require an entirely different foil design, much like supersonic aircraft require an entirely different design to their subsonic counterparts.

[@surfcello]

Great video, but I'm not yet entirely convinced by your explanation. Cavitation occurs when the pressure locally gets to below the boiling point of the water, so the water spontaneously turns gaseous, and this can cause stalling of a foil. I understand that this becomes more and more likely at higher speeds for a given angle of attack and foil curvature. But do you have any explanation for this magical number of 50 knots? Couldn't one simply use a slimmer foil profile and a lower angle of attack at higher speeds? Or is this not possible due to structural limitations? Also I assume you meant "sound barrier" in a figurative way? I see no physical resemblance to the challenge of breaching the sound barrier in aircraft.

[@thamiordragonheart8682]

if you try and use a flat plate, you get a separation bubble over the leading edge that would probably start cavitation. I'm going to guess that 50kts just happens to be around the speed where you can't make the airfoil any thinner without it starting to act like a flat plate, so making it thinner doesn't really help delay cavitation anymore. And that is where other things like supercritical foils start to come in.

[@SailingTipsCa]

You also need a certain amount of lift to get the boat out of the water, which creates a certain amount of high and low pressure areas on the foil, regardless of thickness. If you make the foil bigger (i.e. more surface area) to distribute the load and reduce pressure gradients you also get more drag, which means you can't get to 50 knots in the first place. So the foil needs to be small enough to reduce drag, but that also increases the pressure. Water also behaves strangely around its state boundaries, for example you add pressure to ice and it changes back to water, which makes it slippery, other substances don't do that. All of that said I suspect the 50 knots is approximate and can float up and down depending on any number of variables, but it appears to be an observed practical limit.

[@SailingTipsCa]

Regarding the sound barrier part, yes it was figurative in that it's a physical speed barrier that requires a conscious engineering solution to exceed it. The physical phenomenon are entirely different though, as you noted!

[@eagleeyeproductions2317]

Great summary and explanation.

[@SailingTipsCa]

Thanks - glad you enjoyed it!

[@tommytar222]

It might sound stupid. But why do the crew need to get soaked in water when sailing. Are there other ideas or options, or is it how it is.

[@SailingTipsCa]

it’s a great question! Lots of the latest Ultime and IMOCA designs have good crew protection from the elements. Alex Thomson’s 2020 Hugo Boss design was even designed for him to spend most of the time sailing the boat from inside so he only needed foul weather gear a few times a day for inspections. The worst boats IMHO are the Volvo Ocean racing designs which have boatloads of water constantly pouring through the cockpits. I’ll take an Ultime or IMOCA over that any day!

[@guwhl]

The recent achievements in the ongoing Ocean Race with around 640nm in 24h show the potential of foiling monohulls.😮

[@SailingTipsCa]

Yes the IMOCAs are becoming blazing fast and probably easier to sail than a multihull too because they just get knocked over and spill wind when overpowered.

[@glenncosford3207]

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.

[@SailingTipsCa]

Yes that was a huge accomplishment!!! The underlying message in this video is to say that foiling is not a panacea to solve all speed-related problems due to limitations introduced by cavitation, rough seas etc. It can provide remarkable performance in some conditions, but it’s fascinating to note that the world records for circumnavigation are still held by non-foiling boats!

[@gerhardkutt1748]

Limitation is around 55kts. Then it depends if the foils are set up for super cavitation or not. Foil Cavitation sets in at that speed and the foils will disintegrate relatively quickly - especially if they are made of composites and not designed for super cavitation. We have blown carbon foils before at high speeds.

[@SailingTipsCa]

Yes my Vestas Sailrocket video (kzbin.info/www/bejne/gWTQYWltaJZ1h7s) goes into more depth about cavitation and foil designs to overcome it.

[@michaelmccluskey2044]

High end composites should be better at handling cavitation than metals, since they have both much higher yield strength and fatigue toughness than metals. The issue presumably isn't that the foils are composite, but rather that they're just not designed to handle cavitation (with the priority instead to make them lighter).

[@abarratt8869]

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.

[@SailingTipsCa]

Hydroptere was certainly one the pioneers in the field! I think bubbles is one of the techniques they use for “supercavitating” torpedo designs, so quite possibly an application here too!

[@KasperiVonSchrowe]

50 kts is a barrier where typical flow dynamics don't apply anymore. Practically the problem is more ventilation than cavitation, but nevertheless the result is similar: the foil loses lift and drag increases dramatically. Practical solution could be to design ventilating foils in similar ways than with with surface propellers. The air should be directed into separating zones in low pressure side and the flow would be separated from the foil controlled. The only issue is that the ventilating foil works poorly in lower speeds. But in that case 50 kts is not a barrier anymore.

[@SailingTipsCa]

Ventilation and cavitation both take place when a gas (e.g. air, water vapour) disrupts the laminar flow of water over the foil, and as you noted the effects are similar. Ventilation can take place at much lower speeds and is a common problem with transom-hung rudders on sport boats and smaller multihulls when surface air gets sucked down the foil. The typical solution is to install a fence on the foil to keep surface air from being sucked down. L'Hydroptere has visible fences on its lifting foils to prevent ventilation. Cavitation adds to the potential problems at higher speeds (e.g. above 50 knots) so you need a different foil design. Vestas Sailrocket used a wedge-shaped ventilating foil to hit 65 knots, but it's not really a sailboat in the traditional sense because it can only sail in a straight line and on a single tack. Here are some descriptions of their foil solution to overcome cavitation, and as you noted these foils don't work well at lower speeds: www.realisedesign.co.uk/uk-product-design-blog/fastest-boat-sailrocket-sailing-speed-record/ www.sailrocket.com/node/288 www.sail-world.com/Australia/Sailrocket-2-attempts-a-new-World-Speed-Sailing-Record/-91009

[@CorePathway]

The real problem is that people keep assuming a boat’s pronouns.

[@SailingTipsCa]

@@CorePathway I know - I wish boats would announce their pronouns like people have started doing in Zoom meetings lately!

[@oldfrend]

surprised cavitation happens at such low speed considering propellers spin much faster than that. maybe the should make the foils out of high heat lightweight metal like titanium instead of carbon. i'm sure the added weight would be more than offset by the ability to foil at any speed.

[@SailingTipsCa]

Not sure if you’ve seen this video (How Did Vestas Sailrocket 2 Smash the Sailing Speed Record?!?! kzbin.info/www/bejne/gWTQYWltaJZ1h7s) but it’s definitely possible to design foils and propellers that work just fine at speeds greater than 50 knots, but the challenge is having them work well BOTH below and above 50 knots of blade speed. Propellers are generally designed to work well above that at the expense of poor efficiency below that.

[@terrysullivan1992]

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

[@SailingTipsCa]

Glad it made sense!

[@helmutdiez4306]

Thank you gut working out these factors.

[@SailingTipsCa]

The America’s Cup and SailGP sailors make it look so easy that we don’t realize the complexity involved!

[@bradclifton5248]

French sail Gp Boat hit 99.9km. That's over 53knots but, no records have been officially attempted.

[@kwittnebel]

Instantaneous speeds are sort of meaningless when speaking of speed records. It is always average speed over a set distance. And there are very specific criteria for the accuracy of the GPS used, etc. which must be verified by the organizing authority. To average 68 or whatever it did, Sailrocket probably had peak speeds of 75.

[@SailingTipsCa]

Yes, that must have been exhilarating in front of their home crowd in Saint Tropez, while also being terrifying at the same time! Their foils must have been cavitating like crazy, but luckily they must have sustained enough lift to maintain control of the boat and not wipe out completely like L'Hydroptere did after hitting 56 knots briefly. The SailGP boats can get away with pushing hard in these events because 1) their foils only need to last the duration of a race which is about 15 minutes and 2) there are rescuers standing by in the event things go upside-down.

[@kwittnebel]

@@SailingTipsCa Hydroptere had no active control on the mainfoils. Cavitation had nothing to do with its capsize. Duration of the racing has nothing to do with anything. Obviously foils need to last the entire racing season, and they do.

[@SailingTipsCa]

@@kwittnebel L'hydroptere had a foil design that cleverly decreased the foil area as the boat was lifted out of the water. I don't know the specifics of what exactly caused their capsize but their foils certainly would have been cavitating. I disagree that the duration of the racing is irrelevant - you need to back off at certain times in longer races to preserve the boat and ensure it lasts until the finish, not just the foils but everything!!! Even Alex Thomson backs off at times! Maybe you and Francis Joyon don't but most do! 😉

[@kwittnebel]

@@SailingTipsCa The F50 guys drive the boat hard all the time. They have plenty of time to refinish the foils if they start to get pitted from cavitation. They are not thinking at all about cavitation during a race. The IMOCA boats don't go fast enough under any circumstance for foil cavitation to be an issue. Joyon talks a lot about backing off; he has capsized and talks about how having capsized helps him know where the edge is and where to back off in heavy air. Thomson is retired last I heard.

[@Humungojerry]

would it be possible to somehow switch normal lifting foils for supercavitating foils when up to speed, to push well beyond 50 knots?

[@SailingTipsCa]

I think that’s the question! The mechanisms would be somewhat complex and would add weight to the boat, so it would be a tradeoff as with all things sailing!

[@rickemmet1104]

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.

[@SailingTipsCa]

Thanks! I think the apparent ease by which the highly skilled crews in the America's Cup and SailGP foil (over relatively short distances) diminishes the immense feat that full foiling actually is! For longer distance racing you really need more "set and forget" systems to enable the crew to adequately rest.

[@rickemmet1104]

@@SailingTipsCa Yeah, and think about the great racing sailors that capsize non-foiling multis. This is much harder than people think.

[@SailingTipsCa]

@@rickemmet1104 Yes even sailing a non-foiling multi at the edge of it's performance envelope over longer distances is a big challenge. I touch on this as one of the reasons larger monos have been very successful in the Race to Alaska (R2AK) compared to theoretically faster multis in the video "Race to Alaska (R2AK) Best Boat": kzbin.info/www/bejne/p6vHoYGFoJeirsU

[@rickemmet1104]

@@SailingTipsCa Great, thanks for the link, I'll watch that one too!

[@thamiordragonheart8682]

@@SailingTipsCa I think one of the odd issues for ocean foiling that a lot of people don't think of is just that foils basically stop helping when the peak to trough wave height approaches the maximum foiling ride height. Once you start wave piercing a full foiler isn't going to be much if any faster than a partial foiler because of the skin friction and impact from the waves. then you do also have the roll/heel angle stability issue, which is MUCH more complicated than for an aircraft because the sails are adding moments that are large, unpredictable, and completely independent of the foils. I think the biggest challenge is that all the tricks to gain passive roll stability on aircraft rely on sideslip to generate the restoring moment, which doesn't work very well when the sails produce a huge rolling moment for a comparatively small sideslip. This reveals yet another advantage of partial foilers in ocean races, they have just enough buoyancy left over in foiling mode to have a passively stable heel angle. roll stabilization in software only works when you have both the port and starboard foils in the water with independent control so you can use them like ailerons, but that would reduce your righting moment by a lot. I think pitch stability isn't much of a problem anymore since the boats don't seem to pitchpole very often the way the first couple generations of high-performance foilers did. GIven that the rudder foils at least on the AC75s seem to be generating lift from what I've seen instead of downforce like a traditional aircraft tail, I suspect the pitch stability is mostly in software like a fighter jet as opposed to passive stability. You would probably need to go for a 3 surface design to get passive stability without giving up speed.

[@therealzilch]

Fascinating and well explained. Subscribed.

[@SailingTipsCa]

Thanks - glad it made sense!

[@howardsimpson489]

Interesting that cavitation becomes really problematic at only 50 knots. Perhaps variable hydrofoil cross-sections similar to exiting research on aerofoils may help. Submerged torpedoes can travel at those speeds, the increased hydrostatic pressure would decrease cavitation.

[@SailingTipsCa]

There are definitely “supercavitating” designs for foils, rudders, torpedoes, but those are quite different and very inefficient at lower speeds. Kind of how a supersonic jet looks quite different and is also very inefficient at lower speeds.

[@glennboyd939]

I was told by a sailor that top speed depends on a ratio that takes into account waterline length, therefore cats and trimarans have a big edge. But if U take the boat out of the water with a foil, how does this ratio still apply?

[@SailingTipsCa]

Yes the so-called “hull speed” of a displacement boat is approximately 1.34 x the square root of the waterline in feet, so a longer boat generally goes faster. This is much more prevalent in displacement monohulls and somewhat “disappears” in 1) planing boats that get up on top of the water 2) boats like multihulls with long skinny hulls more than 8 times longer than they are wide and 3) boats with foils where the hull isn’t in the water at all.

[@russellmoore1533]

No mention of Sail Rocket 2? It holds the record at 65.45 kts.

[@SailingTipsCa]

Yes that’s another video! How Did Vestas Sailrocket 2 Smash the Sailing Speed Record?!?! kzbin.info/www/bejne/gWTQYWltaJZ1h7s

[@MartinMoe42]

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 ;-)

[@SailingTipsCa]

Yes in retrospect I should have made the Vestas Sailrocket 2 video at the same time and linked them together... My rationale at the time for not including Sailrocket 2 in this video was that I was focusing on boats that can sail an arbitrary course (e.g. multiple points of sail, both tacks) which Sailrocket 2 can't. Still Sailrocket 2 was an absolutely astonishing achievement, and certainly the first "boat" to surpass the cavitation barrier and enter it by a substantial amount, and not just edging into it...

[@MartinMoe42]

@@SailingTipsCa Fully understood, and they seem to have abandoned the offshore option. Maybe Mr. Larsen is getting old and afraid? ;-)

[@quchen]

You are absolutely right @@MartinMoe42. He gave a talk at my company’s conference back in 2016, including some videos of Sailrocket becoming a vertical rocket and coming down hard, requiring pretty much a full rebuild. He also said he would never enter that thing again once the record is broken, but also said »if someone else breaks my record who knows what’ll happen« with a cheeky smile. So who knows :-D

[@trouts4444]

@@SailingTipsCa Great video explained a lot to me. Thank you.

[@Sugarsail1]

Interestingly, Alexander Graham Bell way back in the 1800s did a rough calculation that the fastest a sailboat could ever be able to sail was about 50 knots. So far his rough estimate has proven correct.

[@SailingTipsCa]

Wow that’s very interesting!!!

[@duderino1950]

But I’m guessing he was thinking monohull on the water and had no possible way to predict or conceive of the physics of foiling.

[@liamgriffin3196]

so just asking on the trimarans they can already rase and lower the foils so why not take it a step further and have sets of foils that can be lowered to be used when needed or raised out of the way for instance you could have one larger set for lighter winds one smaller set for the light winds and a set like the sail rocket's for the ultra heigh winds. for rudders it would be more difficult for the ultra heigh winds but just like the A class catamarans one rudder set would do almost all the weather but idk for the ultra heigh speeds. or would this idea just violate the class rules.

[@SailingTipsCa]

Being able to change out foils while underway would be really cool! I don’t know of any class rules that allow that though…

[@liamgriffin3196]

@@SailingTipsCa but are there any class rules that ban it? edit: I am not being cocky I am genuinely curious

[@SailingTipsCa]

It depends on the class. Some class rules require all boats to use the same foils to keep the costs down and most classes limit the types of control inputs to the foils.

[@johnmiranda2307]

Most informative! Thank you

[@SailingTipsCa]

Glad you liked it!

[@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.

[@SailingTipsCa]

Yes and they’ve done that already with Vestas Sailrocket, but those foils are inefficient at lower speeds: How Did Vestas Sailrocket 2 Smash the Sailing Speed Record?!?! kzbin.info/www/bejne/gWTQYWltaJZ1h7s

[@michaelgeraghty3989]

The LA - Honolulu Transpac used to take 7 to 10 days for monohulls and around 5 days for catamarans and trimarans. At 37.5 KT average speed one of these boats could do it in 3 days.

[@SailingTipsCa]

Yes Lending Club 2 (formerly Groupama 3, Banque Populaire VII) sailed from Los Angeles to Honolulu in 3 days, 18 hours back in 2015!!! Not part of a Transpac Race per se but still amazing!!!

[@sailingaqualibra4848]

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.

[@SailingTipsCa]

Yes high averages speeds are the key! IDEC Sport managed 8091,73 miles in 10 days in the Indian and Southern Oceans, maintaining an average of 809 miles per day, with top speeds ranging from 38-44 knots.

[@pforce9]

Even in drag racing, ET beats top speed all the time. I sailed on a boat with averaging knot meters one time. Those things make your mistakes at the helm obvious. On my own boat, I constantly reminded my crew that, 0.25 knot over ten hours is 2.50 miles.

[@chrislatchem1854]

The foilers in The Ocean Race, now hold the 24 hr record for monohulls.

[@SailingTipsCa]

Yes the IMOCAs truly are the pinnacle of monohull design! Still a few hundred miles per 24 hours behind the non-foiling Ultime trimaran record holders though…I think those will be tough records to break!

[@bobhoven3959]

Verry nice explaining 💙👍👋

[@SailingTipsCa]

Glad you liked it!!!

[@djayberry]

Wonder if an adjustable telescopic foil would work

[@SailingTipsCa]

Yes a foil that can change shape to deal with different speeds would be cool! The problem is that they are quite small and heavily loaded (e.g. compared to airplane wings) so it’s quite an engineering challenge.

[@djayberry]

@@SailingTipsCa im imaging a telescopic foil with a hydraulic cylinder inside of it to make it longer or shorter im no expert but that seems like it would help set how high up they need

[@SailingTipsCa]

@@djayberry Gotcha! They can already adjust the depth of the foil in the water, plus either the angle of attack of the foil, or a flap on the trailing edge to control ride height. Here’s a video I did on foiling sail controls: How Do You Control a Foiling Boat?!?!? kzbin.info/www/bejne/npLIp5Ztlrysgpo

[@wardy89]

the biggest problem with the round the word record is that IDEC had incredibly favourable weather and conditions for large portions of their circumnavigation, especially the southern ocean leg, which means to have a realistic change of breaking the record your decent of the atlantic has to be very fast and you can't hold anything back which as we have seen in several attempts since can often result it breaking your boat.

[@SailingTipsCa]

Yes IDEC had amazing weather and Francis Joyon! Gitana 17 knew their only chance to beat it was to make faster transits of the Atlantic, which they did on the way down, but their boat also broke. It’s going to be a tough record to break!

[@wardy89]

@@SailingTipsCa yes Francis Joyon is a bit of a wizard when it comes to multihull sailing and you never want to bet against him!

[@Warwick3511]

@@SailingTipsCa yes and they all pick their weather to leave in unlike a race where you have a fixed start time.

[@jonathanwetherell3609]

Thanks very much for this insight.

[@SailingTipsCa]

Glad it was helpful!

[@scr5051]

Greetings Froom colombia south America great channel

[@SailingTipsCa]

Hola amigo! Glad you’re enjoying the channel!

[@Saltfly]

Variable size foils for adjustment on the go. Piece of cake.

[@SailingTipsCa]

Just like an airplane wing, but with a fraction of the size and much higher loads!!!

[@majormegapix]

Informative presintation. I had pondered the question of why foiled boats don't hold long-distance records given their speed. The fragility and complexity certainly explain why with some of the horrendous conditions in extended heavy weather sailing. Cavitation helps explain the longevity of the foils. I remember reading that the SS United States, which broke the Blue Riband record in 1952 at almost 36 knots, had the paint abraded off the bow below the waterline due to cavitation.

[@SailingTipsCa]

Yes foils have lots of practical limitations! The SS United States is also a great example of how long skinny hulls help overcome the wave resistance inherent in displacement boats, which is the same concept which helps multihulls go fast as described in this video: Why Are Trimarans So Fast?!?! kzbin.info/www/bejne/fanHdJapdsmCjK8

[@karlw7764]

Gabarts RTW boat and all the recent trimaran records are foiling boats. The route du rhum record just fell also to a foiling trimaran. The reason imocas are not very fast with foils is that they are too heavy because rules require them to be self righting. Still they are making some progress.

[@SailingTipsCa]

@@karlw7764 I think it’s just a matter of time before the foilers take the distance records, but they will do it based on higher average speeds and not higher top speeds. The recent RdR record was also in perfect foiling conditions!!!

[@tonycrabtree3416]

I miss the America's Cup 12 meter boats. These news boats are great for drags races, but lack the feel of sailorship. At least to me. Nice informative video.

[@SailingTipsCa]

The 12 meters were definitely much more relatable to most sailors out there. The new generation of foilers require a significantly different skill set which is hard for most people to wrap their minds around. Glad you liked the video!

[@skenzyme81]

Eventually, hydrofoils will need the sort of control surfaces aircraft have to manage cavitation. Slats and flaps on hydrofoils are just a topic of research and simulation for now.

[@SailingTipsCa]

Yes shape-changing control surfaces would be cool, like airplanes have. The challenge here is that water is ~800 times more dense than air, so the loads are higher and the foil itself much smaller than an airplane wing, so harder to fit all the gadgets inside.

[@marvreimer4948]

boundary layer transition theory. WSU has water tunnels and wind tunnels thanks to my neighbor donations. Many aerospace engineers in our yacht club which race. We had women's world windsurfer champ, I raced Hobie Cat world's. The speed limit is drag. Ice boats go well over 100 mph. My topspeed was in a small cruising sloop at the edge of a tornado on the lake. It blew a pontoon boat past us like a news paper blowing on a sidewalk. Killed them all. The sloop was planning like a Laser. We were dealing with rag and glue kevlar composites 40 years ago.

[@fixento]

SailGP In 2022, the France SailGP Team set the SailGP speed record at 53.96 knots (99.94 km/h, 62.10 mph).

[@kajwelin6886]

Very nice and intresting videos, thank you. I was about to comment the F50:s speed record in St.Tropez, 99,9 km/h (53,9 kn) but there was smart comments below about it.

[@SailingTipsCa]

I think the F50s are amazing boats! The have tons of sensors and there is a lot more knowledge about foiling than in the 2013 America's Cup, where they had to introduce wind speed limits to ensure the boats didn't go too fast and lose control. I bet the F50 ground crews fit the exact wings and foils to enable the crews to "safely" sail as fast as possible in the prevailing conditions.

[@josepedro8968]

The first big sail boat with foils was not hydroptere. The first, with the vision and genius of Eric Tabarly, was Paul Ricard. In the 70's. Bought the book "The Atlantic Record" by that time or in 1980..can't remember, was a teen, started to sail in 76, a kid.

[@SailingTipsCa]

Cool - how fast did they manage to get going?

[@josepedro8968]

@@SailingTipsCa Are you joke, ignorant or just stupid...? Grow up sissy...

[@user-bf7vy3ub9c]

Well put: “50knots is like the the sound barrier limit for foils”

[@SailingTipsCa]

Figuratively of course, in that it's a physical speed barrier that requires special design considerations and engineering to surpass. The physical phenomena are different, but it's a good analogy in that supersonic jets require special engineering and are not particularly efficient at subsonic speeds.

[@drakkhenn42]

Engineers knows how to design a foil to push the cavitation limit at high speed. But this mean your foil will be even less efficient in light wind (that's also why it's easier on short race to go faster than 55 knots if such a boat is designed - Syrocco?-). Ultimate class is working a lot on aerodynamics and, from what I know, a lot on a new foil (tip part of the mid hull) that will be in "reverse" (dragging the boat down to the sea where other foil lift) to enable more power to be transmitted form the sails. Next race (Route du Rhum) they should be even faster.

[@SailingTipsCa]

Yes the challenge is figuring out how to get good moderate AND high speed performance out of foils - solutions for one or the other are known. Looking forward to seeing what they come up with for the Route de Rhum!

[@drakkhenn42]

@@SailingTipsCa Normally, SVR Lazartigue should win, I did a visit at Lorient of Banque Pop... that was crazy !!! :D talk about this after the Route du Rhum ... wait and see !

[@SailingTipsCa]

@@drakkhenn42 These are amazing boats - the French definitely take offshore multihulling to the next level - looking forward to the race! Note to others that SVR Lazartigue is the former MACIF on which Francois Gabart broke the singlehanded circumnavigation record.

[@drakkhenn42]

@@SailingTipsCa We have a long tradition on multi hull "first one" by Tabarly. You talk about the hydopter on your video, that was nice, but, too much drag. The real game changer come from the America's Cup, and (has you named it :D) it's really the US who brought that amazing idea of tip on the foil on sailing boat. What an idea ! :D We are waiting for you on the ocean, not on the bay area "swimming pool" ! :D When will build your first ultim ??? :D If by any chance you sail on western part of France, or you are around, let me know. I will ask to a couple of friend to organise an Ultim Class visit :D

[@SailingTipsCa]

@@drakkhenn42 I think the Kiwis also played a major role and were the first to achieve full foiling in AC72. I'm on the West Coast of Canada so not much Ultime action around here, unfortunately! I sail a Farrier-designed F-82R which is smaller, slower, more cost-effective, and more practical!

[@niklasxl]

so is the future of the fastest boats ones with variable size foils that can be removed from the water fully when winds are to high or low? :D a nice engineering challenge

[@SailingTipsCa]

Quite possibly! Airplanes can quite literally change the size and shape of their wings to maximize lift and efficiency at different speeds, so why not foils?!?!? The engineering challenge is that airplane wings are comparatively large so there’s room to put things inside them, while foils are quite small and the loads comparatively high, on a PSI basis that is!!!

[@niklasxl]

@@SailingTipsCa oh yeah i did not even think about flaps and slats in this context :D do you know if multi element wings behave similarly in hydrodynamically as airodynamically? and yeah the pressures on the hydrofoils must be massive probably 100s of bars at the leading edge while the trailing edge is almost at a vacuum if it cavitates

[@SailingTipsCa]

@@niklasxl I’m not a hydrodynamics expert but I do know that 1) sailing and aeronautical applications both use NACA profiles (e.g. 0012 is commonly used for helicopter blades and sailing rudders and daggerboards) 2) some smaller foiling boats control lift with trailing edge slats on their main foils 3) some larger boats either use trailing edge slats on T-foil rudders or move the entire foil case/cassette to change the angle of attack of the foil. So there are certainly many similarities between air and water, the latter being much denser.

[@billhanna8838]

@@SailingTipsCa It used to be a thing in high aspect keels with trim tabs Etc mainly for up wind performance in older keel boats in th e 80s .

[@ben3989]

It seems so much harder to make variable lift foils as hydrofoils. The density of the water just seems extreme relative to air.

[@dkchen]

I could be wrong, but isn't staying on foils pretty difficult in general. And expecting to do it for the whole trip is just too much to ask for a boat crew.

[@SailingTipsCa]

I agree - I think it’s much harder than most people think because the pros make it look easy!

[@roberts.wilson1848]

There's a new design already that fixes caviatation of the foils. The design needs to be like a kammback of a vehicle (citroen c4 coupe) rather than teardrop shape all the way. The air trapped after the foil seems to solve the problems of the cavitation and speeds of 50kn have been done Also these long distance records depend A LOT on the weather. As we have been shown by the comanche world record behind the scenes, they used to the maximum (or close to it) the weather patterns and receiving the most benefits, plotting a route for that particular need. So it isn't about hydrofoil vs nonfoil, a lot of other factors lead to world record times.

[@stingtheweimaraner]

Yes we talk about “supercavitating” foil design in this video: How Did Vestas Sailrocket 2 Smash the Sailing Speed Record?!?! kzbin.info/www/bejne/gWTQYWltaJZ1h7s The Jules Verne (around the world) record attempts also try to pick the best weather window. And in those exceptional weather windows the difference between foiling and non-foiling boats diminishes significantly.

[@SailingTipsCa]

I made this video because lots of people automatically believe that boats with foils are always faster in all conditions, which isn't necessarily true! Sting pointed to one of our videos on foil designs that can go faster, but those designs are inefficient at lower speed, just like supersonic aircraft are inefficient at lower speed.

[@streetsailor]

And then there's Sailrocket at 65.45 knots over 500 meters! Peak speed 68 knots. Must have been some crazy hydrodynamics happening around her single foil.

[@SailingTipsCa]

Yeah they used a special ventilating foil design to enable them to break through the cavitation barrier around 50 knots. Maybe a good topic for another video!

[@Warwick3511]

Another thing to remember it was also optimized to sail in one direction and had to be towed back for each run. To sail off shore you need to sail on both tacks.

[@SailingTipsCa]

@@Warwick3511 Exactly - not the most convenient! Here’s a recent vid on Sailrocket: How Did Vestas Sailrocket 2 Smash the Sailing Speed Record?!?! kzbin.info/www/bejne/gWTQYWltaJZ1h7s

[@Warwick3511]

@@SailingTipsCa I was following their channel when they were going for the record at the time.

[@SailingTipsCa]

@@Warwick3511 That was a pretty exciting time!

[@helmutdiez4306]

GREAT REPORT THX A LOT

[@SailingTipsCa]

Great - glad you liked it!!!

[@Paul-ou1rx]

Interesting. Not a boat owner but I was under the impression that the foiling boats were practically an entirely new class because "regular boats" could never compete with them.

[@SailingTipsCa]

Yes foils offer advantages in some but not all conditions! The Australian OMR rating system doesn’t change a boat’s handicap for having foils and you’d think the foiling boats would win all the time but they don’t!

[@Warwick3511]

foilers have been around for some time but were foil stabilized. there was williwaw around the early 70s the could get air borne, then there was paul ricard by Eric Tabarly that had small floats and foils to assist in righting.

[@AngusMcIntyre]

The answer to cavitation appears to be 'super cavitating' foils, as pioneered by vestas sailrocket 2

[@SailingTipsCa]

Yes, except that “super cavitating foils’ are much less efficient at speeds under 50 knots! How Did Vestas Sailrocket 2 Smash the Sailing Speed Record?!?! kzbin.info/www/bejne/gWTQYWltaJZ1h7s

[@gregepp3082]

I randomly get to be your first comment. Cool vid on a topic I had not considered. Thanks for putting this together.

[@SailingTipsCa]

Cool - glad it made sense! It’s hard to know how the idea in my head will translate through the video to other people!

[@billhanna8838]

@@SailingTipsCa Very nicely , Simply translated to the average sailor or non sailor , Well done

[@MrWilliamSchlegel]

what about Flying Nikka which has been built to break records (I think)?

[@SailingTipsCa]

The interesting thing about Flying Nikka is that she's a monohull like the AC75s, but I don't see anything with her design though that would address the cavitation problems at ~50 knots. So if she breaks records it would likely be due to her ability to maintain higher average speeds in moderate wind conditions.

[@ryanpeart2108]

Well reasoned.

[@SailingTipsCa]

Thanks - glad it made sense!

[@Pad.Rick.]

Very interesting! Thanks 👍

[@SailingTipsCa]

Thanks - glad you liked it!

[@RiceCookerJunior]

I recommend to Watch the Vendée Globe race, a solo race around the globe. Last time was in 2021. Hugo boss skipper has damaged his boat (again). But on the top 4, it was boats with foils. It is a phantastic race. Next time in 2025.

[@SailingTipsCa]

Looking forward to seeing how the latest designs perform! I’ve done a couple of videos on Alex Thomson’s 2016 design, which is still the second fastest IMOCA to circumnavigate, even with a broken foil for 2/3 of the race, and more than five days faster than the winner in 2020/21!!!

[@RiceCookerJunior]

@@SailingTipsCa Why are you promoting not to build foil sailing boats? They are faster (IMOCA or the 60 foot multi-hull boat). They have beaten records on all long distances. But you have to stay a bit reasonable (not like Alex 2 years ago). OK, foils are facing the issue of cavitation at high speed. But is it because they are sailing with a foil or they are sailing fast? Is there a kind of theoretical limit, considering the mechanical equations?

[@SailingTipsCa]

@@RiceCookerJunior I think foiling boats are really cool, but there are also lots of practical limitations, which is what I’m trying to help people understand. They provide higher average speeds in moderate conditions, but add weight and drag to the boat in light conditions, and cavitate in heavy conditions.

[@aanii2878]

It's so amazing that they circumnavigated on a sailboat in 41 days.

[@SailingTipsCa]

I know it’s a crazy pace!!!

[@pforce9]

So all they have to do is solve the cavitation problem and make adjustable foils and they can go faster?

[@SailingTipsCa]

If you use an airplane analogy, a subsonic jetliner uses wings with flaps to increase chord, camber, and size for low-speed takeoff and landing, while maintaining high-speed efficiency. And supersonic planes need different wings altogether. If you could somehow create a morphing foil that does all of this, plus the control systems to operate it, then yes!

[@pforce9]

@@SailingTipsCa The Russian rocket torpedo may have some of the answers to raising the upper limit of raw speed. Maybe use a ram scoop to collect high pressure water and channel it to bleed it over the leading edge of the foils to create a laminar flow.

[@SailingTipsCa]

@@pforce9 I think the various components of technology exist, especially in military applications as you’ve noted, it’s “just” a matter of putting it together in a civilian package without the benefit of a military budget!

[@mrl22222]

@@SailingTipsCa perhaps this is an application where "shape memory" materials can come in. Under certain circumstances it could be deformed (even elongated) and then return to it's original shape later.

[@SailingTipsCa]

@@mrl22222 That’s an interesting idea!

[@sergiokroff4321]

Dear Fellows, for me the reason why a Mono-Hull Sail is faster than a Trimaran Sail in this case, is becaouse the Resultant Net Force among the Sail Lift and the Hull Drag that puch the Sail Boat Forward (Squeezing the Hull) is greater in the Mono-Hull Rgds

[@SailingTipsCa]

You should check out this video: Why Are Trimarans So Fast?!?!? kzbin.info/www/bejne/fanHdJapdsmCjK8

[@sergiokroff4321]

@@SailingTipsCa It’s True, although the length among them isn’t the only parameter to consider, is also the displacement among others measures and my previous comment was more related with none foil sail vessels for oceanic ride, maybe because I have in mind an oceanic carbon fiber catamaran than around 2000 broken in heavy seas but with foils it could be different. Therefore, back to the foils sail boats for long distance oceanic ride and the comparison among mono hull and trimaran foil vessels , there is 2 facts in summary that play a significant role on their performance : 1 is the directional stability and the 2 is the wave galloping (pitch), on the first, mono hull have a distribution among the foils close to the center line its mean more like an Arrow Shape its mean highest directional stability to maintain an specific trajectory and in the trimaran the distance among the foils are more like a soap casing shape pushed in the pool, its mean doesn’t have much directional stability to hold an specific constant trajectory of the vessel without a dynamic steering wheel , in other hand the distributed weight of the trimaran allow to induce a greater lift force than a mono hull for the same wind velocity, foil designing etc. and for the 2, the mono hull in heavy seas its more capable to absorb the incoming waves, for the hull geometry and for 1 and a trimaran hull when its consider the distance among the hull´s with the encounter wave velocity and buoyancy distribution the pitch response isn’t necessarily synchronize, inducing further directional instability and galloping effects, which however in a regime of high speed over the waves isn’t necessarily a significant factor, hence in summary, for me a way to improve a trimaran foil performance sail vessel for oceanic ride, it’s to have an extended research to determinate the best hull´s foil distribution that allow the highest directional stability and second the foils must have a dynamic angle of attack control in order to maintain the lift force accordingly with the incoming waves (e.g. pegasus-class hydrofoils patrol boats) its mean for long oceanic ride a trimaran foil will require more level of engineering complexity than a trimaran foil for bay ride. Rgds and Cheers !

[@SailingTipsCa]

@@sergiokroff4321 Yes offshore foiling has far more complexities than in protected waters! Dynamic controls to react to the waves would be cool and I’m not aware of any offshore foiling boats that do that.

[@sergiokroff4321]

@@SailingTipsCa Actually Foiling Sail Vessels are realtiviily New, perhaps in the future some companies will eventually do a research on this topics . Regds

[@dannydavis8889]

You forgot to mention the problem with the apparent wind changing to such a degree that fast boats can't get close to the true wind.

[@SailingTipsCa]

Yes fast boats definitely "bend" the apparent wind angle far forward of the true wind angle. Even our F-82R trimaran, which is fast compared to most boats but certainly not these foiling monster, can "bend" the apparent wind forward by up to 90 degrees e.g. a TWA of 150 can look like an AWA of 60. This "bending" becomes less pronounced as the wind moves forward, and a good tight sheeting angle means we can still point as high as a fast racing monohull, but it's often faster in terms of VMG to crack off a few degrees as this substantially increases boat speed.

[@dannydavis8889]

@@SailingTipsCa Thank you for the info. Appreciate it.

[@Cbob64]

Regarding IMOCA, they are not full foiling boat (i.e. Hugo BOSS )as today, lifting rudders are forbidden.

[@SailingTipsCa]

Probably for good reason - full foiling boats are inherently very unstable so I think that would be a handful for a solo sailor in the Southern Ocean!

[@Cbob64]

@@SailingTipsCa Foiling Ultims are safer than old ORMA 60 & MOD70 trimaran.

[@SailingTipsCa]

@@Cbob64 Yes they are and I think that’s more a factor of them getting the overall dimensions right, as the non-foiling versions e.g. IDEC Sport are also safer than the ORMA 60 & MOD70 designs.

[@Cbob64]

@@SailingTipsCa Also : during gust, foiling trimaran accelerate and generate more lift. Regular boat are plawing the water surface... kzbin.info/www/bejne/hqWampaPibSco5I (personal video) - you can see the hull "working" the water surface... until the crash.

[@SailingTipsCa]

@@Cbob64 Cool video - looks like fun!!! Yes multihulls in archmedian (non-foiling) mode only have so much buoyancy whereby foilers can generate more lift as they go faster…until they reach the point of cavitation…

[@w8stral]

No, that is NOT the main reason. #1 reason is that they are UNSTABLE for the same reason a canard aircraft is unstable(roughly speaking). The wave motion increases angle of attack, causing the foil to stall, post max amplitude of wave, crashing the hull at HIGH speed causing a pitch pole. The lifting rudder in the rear can try to counter this moment, but all it really does is dump the entire hull lower to the waves in the same direction of the pitch pole to begin with so the ONLY solution is for a pilot, be it human or computer to anticipate the amplitude and hope and pray you do not have cross waves nor do you have a Big peak wave from cross wave direction so the dumb computer( be it human or not) cannot see this and dumps the boat. Why America's cup races especially are in closed waters for the hydrofoils and never in open ocean. It is why the America's cup always has one guy staring at a computer screen trying to keep the boats foiling. #2 reason you gave and that is Cavitation, though even this is not exactly true as all it really means is one needs a different hydrofoil for this speed regime, just as a supersonic aircraft has a completely different airfoil required for supersonic flight compared to subsonic. With the only problem being the hydrofoil is working in non compressible fluids and an aircraft is not. So, you have to cheat by usually introducing air in front of the foil lowering density. If you think about it, every speedboats and many ships propellers are supersonic. It would not be difficult to add different hydrofoils to these boats... Just takes $$$ and competency in learning to drop the higher speed foil when appropriate. In short, the problem is applied engineering COST for bragging rights with no real world application. So, no one making these around the world boats gives a damn about technical realities, rather they are just trying to be slightly faster than the next billionaires largesse dumped onto a captain for bragging rights. So, currently for bragging rights it is partial foiling. Maybe in another decade a billionaires bragging rights will require true hydrofoiling to be 1knt faster. Military is not really interested as stealth(subs) is more important than speed or being so blatantly obvious no one can mistake you for a warships presence. And if a military DID go towards hydrofoils they can get most of the benefits by using super long lifting bodies instead of a hydrofoil, but outside the presentation material here.

[@SailingTipsCa]

Yes, foiling boats are incredibly unstable, and the penalty for getting it wrong in larger boats is capsize which is very expensive. You basically need some kind of fly-by-wire computer system like fighter jets which is also very expensive. Smaller foiling dinghies tend to use a mechanical wand sensor on the water surface to control foil height, which is much cheaper and more accessible to the masses, but you can't really cross ocean with those. And yes, there are super-cavitating foil designs that would enable these boats to go faster (e.g. Vestas Sailrocket) but like supersonic aircraft they are not very efficient at subsonic speeds, so as you noted the foils would have to be changed out at a certain speed which presents some interesting engineering and cost challenges! Maybe a good topic for another video!

[@tomaslotuyo4425]

So, if multi hulls don't perform well offshore and don't break long distance records, what about François Gabart's round the World solo record : 42 days ?

[@SailingTipsCa]

His achievement was totally amazing! But non-foiling boats still hold the 24 hour distance records, as well as the overall around the world record. Foiling boats beak records by achieving higher average speeds in moderate conditions, but their advantage is diminished in higher and lower winds - that’s what I was trying to say in the video.

[@Dewidewi-dt8ox]

Lautan adalah tol terbesar tanpa hambatan. Sebenarnya say a ingin mengarahkan rancangan lebih me laut dimana bisa jadi lahan luas untuk hidup

[@SailingTipsCa]

Google Translate: “The ocean is the largest unimpeded highway. Actually I want to direct the design more towards the sea where it can be a large area for living.” Yes the ocean is a huge place with lots of potential for lots of things!

[@kirilcavdarov965]

Will someone make an ekranoplane evolution of these great boats? Maybe impossible but, sure would be neat.

[@SailingTipsCa]

I'm sure the designers of Ultime's take ground effect into account with their beam designs etcetera but I'm not sure if they do it just for controlling the boat and reducing wind resistance or for actual lift. If it did "fly" like an ekranoplan you'd still need some kind of foil in the water to pull it back down, like Vestas Sailrocket in this video: How Did Vestas Sailrocket 2 Smash the Sailing Speed Record?!?! kzbin.info/www/bejne/gWTQYWltaJZ1h7s

[@weatheranddarkness]

@@SailingTipsCa Interesting you mention Sailrocket 2 here because the lower portion of its wing would actually see a degree of ground effect lift, not a significant factor and that lift primarily served just to raise the leeward sponson. One craft that does claim to use ground effect and also uses hydrofoils is Regent Seaglider. I expect the contribution of ground effect there too is minimal, but being designed to run low it will see efficiency gains. The foils primarily serve to help in transition phases.

[@SailingTipsCa]

@@weatheranddarkness I recall reading that Sailrocket 2’s beam connecting the main fuselage and wing also has some aerodynamic properties and also operates in ground effect, and I think helps control the height of the wing, although I must admit I don’t recall the specifics. I’ll check out the Regent Seaglider!

[@weatheranddarkness]

@@SailingTipsCa the beam was a bit more neutral but ya, contributed some of the lift to unload the sponson.

[@kailaniandi]

They break parts and then some records

[@SailingTipsCa]

Yup I think that’s pretty common!!!

[@yachticus]

I am not sure if the author has seen the AC or Sail GP yachts - they both knock these two out of the park

[@SailingTipsCa]

Yes the AC and SailGP boats are impressive, but they all share the same ~50 knot cavitation limit. The AC and SailGP boats also typically sail on closed courses on protected waters during daylight hours. Check out this video of Jimmy Spithill (of AC and SailGP fame) on board an ocean-going Ultime trimaran going 47 knots in the middle of the night on autopilot! www.sail-world.com/news/210276/Americas-Cup-champion-flies-offshore-Video

[@GarretKrampe]

over 50 kn you need ski/skids with dampers much like a snow mobile.

[@SailingTipsCa]

That would make a great video!

[@GarretKrampe]

@@SailingTipsCa Even Rudders and keels cavitate at these speeds so it's a whole different ball game . I assume that you have watched the latest record holder ? On the purpose-built Vestas Sailrocket 2, Paul Larsen (AUS) in 2012 set the outright sailing speed record of 65.45 knots (75.3 mph) on the 500-metre course. In 2022, France SailGP Team posted the fastest time ever in an F50, hitting 54 knots (62 mph) during a race. one of the latest methods being trailed is using a large diameter spinning disc to lower the differential velocity between the water and the rudder.

[@SailingTipsCa]

@@GarretKrampeYes I did another video “How Did Vestas Sailrocket 2 Smash the Sailing Speed Record?!?!”kzbin.info/www/bejne/gWTQYWltaJZ1h7s That explains how they did it. I hadn’t heard about the spinning disc method - interesting!

[@GarretKrampe]

@@SailingTipsCa Yes I have written to the designers in UK and asked if they want to make a legitimate attempt ay an 80+ Kn run . The spinning discs and powered aerofoils are of my own designs. But food for thought . Yes "supersonic" "air foils" are required over 50 Kn basically knife edges. RE numbers are ~9-10 x that of the foil in air so take a plane design and /10 (size chord area etc). I'll take a look at your Denmark Turbines (Vestas) UK designed and built and Aussie piloted video.

[@SailingTipsCa]

@@GarretKrampe Very cool!!! I hope the UK design team explores your offer to collaborate!

[@Cbob64]

These Utlim 32 boats are beast, way more interesting than AC boats.

[@SailingTipsCa]

I agree the Ultims are amazing! There’s a cool video of Jimmy Spithill on Macif and even he thinks it’s pretty intense! kzbin.info/www/bejne/hWOze4SgbLJ0b9E

[@Cbob64]

@@SailingTipsCa I also suggest this one kzbin.info/www/bejne/iqDYlGuwg9mer5o&ab_channel=TeamActual At time 00:15:00 facing the waves. Hard!

[@ВалерийХарченко-ш5д]

Something is wrong. At the start of the Ocean Race from Alicante, the speed of the Volvo65 was 14 knots, and on hydrofoils, in the same place - 34! It's not 20%. Что-то не так. На старте океанской гонки из Аликанте, скорость Вольво65 была 14 узлов, а на подводных крыльях, там же - 34! Это никак не 20%.

[@SailingTipsCa]

The 20% figure came from two different references - designers of Ultimes and IMOCAs. It's an average figure and in some cases it will be more, and in other cases less! For example for Ultimes in 30 knots of wind the difference will be much less than 20%, in more moderate conditions it will be more, and in light (i.e. non-foiling) conditions it will be less again.

[@Maybe1Someday]

Fastest sailing circumnavigation is a big gamble on the weather also

[@SailingTipsCa]

Yes the weather is really key, and Francis Joyon and IDEC had pretty much a perfect weather window!

[@antontromp3879]

Why dont they Dimple the foils like a golf ball to avoid cavitation?

[@SailingTipsCa]

Maybe some fluid dynamics engineers can speak to that, however they have added tubercles (like on whale fins) to rudders to maintain laminar flow and prevent stalls: biekerboats.com/project/rudder-tubercles/

[@tomainsworth5656]

the dimples delay boundary layer separation on the golf ball a little. however, the flow environment is so extreme in the cavitation regime that you have to let the flow detach otherwise bad things happen, like wildly unstable flow

[@SailingTipsCa]

@@tomainsworth5656 Yes there are some cavitation clips in the video How Did Vestas Sailrocket 2 Smash the Sailing Speed Record?!?! kzbin.info/www/bejne/gWTQYWltaJZ1h7s It looks like the wedge foil does a decent job of creating “controlled” flow separation.

[@Sailor376also]

My question would be, How well do foils handle 3 to 5 meter seas? Open water, well developed rollers, would be the easiest that could be expected. And yet. I don't think a foil would consistently handle a large swell. Cup races are normally on sheltered water,, chop or 1 meter,, maybe 2 meters. And then you get right into durability. Water is hard.

[@SailingTipsCa]

Yes the point of this video was to help people understand how hard this really is! Multihulls are very sensitive to sea state even before you add foils! It really comes down to the shape and period of the waves along with the point of sail, so you'd have to take all of that into account to find the best velocity-made-good (VMG).

[@GG-zh6yp]

just a matter of time until foils become more sea-state friendly......

[@SailingTipsCa]

Yes imagine if they could auto-extend in conjunction with the waves! There would still be a limit though…

[@GG-zh6yp]

@@SailingTipsCa yes but you get the feeling we are just starting on this foil journey. given the car sailinging speed record is 200+ kph... the boats have plenty of catching up to do.

[@GG-zh6yp]

@@SailingTipsCa yep, the concepts are endless and exciting.....

[@SailingTipsCa]

@@GG-zh6yp Yes this is just the beginning of the journey. And the fact that the foiling IMOCAs are now so fast even against non-foiling multihulls is pretty exciting!

[@domenicozagari2443]

AT THAT SPEED THEY CAN STEER WITH AIR RUDDERS.

[@SailingTipsCa]

Like an airplane!!!

[@domenicozagari2443]

@@SailingTipsCa Yes :)

[@franmcgowan4068]

Vestas Sailrocket 2 121kph...

[@SailingTipsCa]

Yup I did a video on that: How Did Vestas Sailrocket 2 Smash the Sailing Speed Record?!?! kzbin.info/www/bejne/gWTQYWltaJZ1h7s

[@jcbtiller]

Im here from a story about a kid building a boat to circumnavigate his new world. So cheers mate, your video apparently was great research / inspiration for a really good author.

[@SailingTipsCa]

The KZbin algorithm works in fascinating ways - thanks for watching!

[@alamos8]

But of all that is true, why they keep doing these foiling designs for offshore racing? I mean, all the Ultims trimatans have foils that can elevate the hull avobe water given the conditions, not only Gitana 17. If they were so sure that it is sooo much difficult to beat existing record, why not to just make non foiling trimarans, and optimize all they can in all aspects, just with no foils? If they keep pushing on the foil thing, it must be because the engineers see more potential there than in a normal (and presumable cheaper and stronger) design. Even the 24h record holder has gone to foils, and I can imagine that was made not to reduce her performance, and we ate talking here about long distance offshore racers.

[@SailingTipsCa]

Yes all the.Ultimes now have foils of some kind because they do offer significant advantages in moderates winds, like those encountered in more temperate and equatorial latitudes, and that’s where the engineers and designers feel non-foiling designs are still leaving something on the table.. But to your point, I personally know of two 8-10M trimarans with lifting foils and the owners of them do say there are more effective ways to improve boat speed, like canting rigs and rotating wing masts. The Australian OMR rating system also doesn’t rate foils (i.e. you can add foils to your boat with no rating change) and yet the foiling boats aren’t stealing the podium. There is a foiling kit available for my F-82R, but it adds about 10% to the weight of the boat, which is significant when I can feel a performance difference with the weight of each additional crew member. So my point with this video was that foiling is hard, and not always faster, contrary to what lots of people think, and initially myself included!

[@FromJunkToJanha]

Vestas sail-rocket gets around the 50 knot limit by using cavitation to be part of the foil...

[@SailingTipsCa]

Yes I have a video on that too! I think it’s technically ventilation using air sucked down from the surface… How Did Vestas Sailrocket 2 Smash the Sailing Speed Record?!?! kzbin.info/www/bejne/gWTQYWltaJZ1h7s

[@michaelgarrow3239]

Geez you could get from San Diego to Hawaii in 2-3 days! 😳

[@SailingTipsCa]

Yes the Transpac record from LA to Hawaii is 3 days, 8 hours, 9 seconds, set by Lending Club 2, which happens to be the same boat as IDEC Sport (which also holds the round the world record) but with different stickers on it!

[@eumeis]

Hey Dude, nice channel. I do educational sailing content myself as well and i like the way you present your info. I recently started to fiddle with editing more seriously and im suspicious a low level soundtrack on the background does wonders to increase retention. I suggest you try it out

[@SailingTipsCa]

Thanks! I've tried background music in a few videos and have mixed feelings about it. I totally agree that if done well it can enhance the video, but I've also seen feedback (mostly on other channels) that the content is great but ditch the music. Also in my case about 40% of SailingTips.Ca viewers are from non-English speaking countries (e.g. Germany, Italy, France) so I'm wary that music might mess with the transcription/subtitles they use, or otherwise interfere with their understanding of the content. Finally, there are also trolls out there who scour KZbin for alleged copyright violations, report your videos, and approach the artist as a broker claiming "see how many copyright violations we found with your music". Then by the time you've demonstrated to KZbin and the "broker" that you actually have the rights to use the music KZbin has stopped promoting your video. So there can definitely be value but also lots of pitfalls! Do you have experience/suggestions with how you manage any of these issues?

[@davidwild66]

The enemy of foiling must be extra weight in the boat, and boats sailing long distance must have to carry extra weight by way of supplies for a long journey.

[@SailingTipsCa]

Yes every pound added needs to be lifted! Water makers provide a means to get drinking water from the sea which helps a lot!

[@davidwild66]

@@SailingTipsCa ...and the French are lifting kilograms, so that must be even harder🤣

[@SailingTipsCa]

@@davidwild66 LOL exactly!!!

[@tankeater]

Drag and friction... That's simply it... thanks for the explanation that a 3rd grader would give.

[@SailingTipsCa]

Yup, good thing I scraped through 3rd grade!!! Hopefully the 2nd graders can learn something…

[@tankeater]

@@SailingTipsCa doubtful

[@SkyPilot54]

Toys of the super rich , Time for a revolution

[@SailingTipsCa]

Big boat foiling is not unlike most major sports franchises: The owners/financers are super rich, a few of the key players (e.g. skippers) make a good living, many others on the team make a working living. Small boat foiling is much more accessible to the masses: You can buy a used foiling dinghy (e.g. UFO, WASZP) for about the price of a good bicycle.

[@SpaceCrete]

I knew there was a reason I didn't have a foiling boat.

[@SailingTipsCa]

There is a foiling kit available for my F-82R trimaran, but it adds about 10% to the weight of the boat, which is significant when I can feel a performance loss from the weight of each additional crew member! The stakes are also much higher for failure without massive budgets. Therefore the most accessible way to foil for most people is a dinghy like a UFO, WASZP, or Moth.

[@SpaceCrete]

@@SailingTipsCa In a roundabout way I was just admitting to being a cheapskate.

[@SailingTipsCa]

@@SpaceCrete LOL or a normal person!