SpeedDream: World's fastest sailboat?

the thing that intigues me is this;

How do these monos with flying keels maintain a stable equilibrium? You see, normally as the boat heels the righting moment increases as the keel becomes closer to horizontal... with these flying keel ideas ive seen floating around the net, as the boat heels the keel gets higher and thus further away from horizontal and therefore the boats righting moment DECREASES... its a very unstable design... the only way i can see it working on a large yacht, would be with some kind of gyroscope monitored automatic control to keep the keel horizontal at all times as the boat changes heel thru gusts and lulls... or a rediculous amount of sail trimming...

AS the keel would be constantly moving and adjusting itself, considerable power would be needed to power the hydraulic movements over a long period of time like an ocean crossing etc...

A multihull flying a hull, is basically the same design scenario as mono with a flying keel when you think about it... except with a multi, you have a narrower hull in the water and much more overall beam for righting moment and better shroud angles to stay the mast...

 

Collin: these people probably hope to make money out of this endeavour, the last thing they are going to do is publish their research for their competition to study!

Groper: I think it has been quite a while since serious ocean racing boats were designed for stability. Think fly-by-wire in aircraft; that's what these boats are all about, with constant crew activity to maintain the racing edge. Sailing in a stable condition equates to loafing along and wasting time for these guys. You nailed it with "ridiculous amount of sail trimming" . . .

However there is a bit of positive stability in the system with the keel horizontal to windward there would be a buoyancy change between wet and dry and the DSS horizontal to leeward would change lift near the surface so at speed it could be a stable self-maintaining system. That is, until a gust hits . . . but that’s normal for all sailing.

 

i can understand them not wanting to put all of their information out there, but it does exist, right? They aren't pulling these speed numbers out of thin air are they?

 

As if they'd do a thing like that. as if . . . hmm . . .

 

Quote "Okay, now where's the research that leads to people making these claims about this boat? There has to be research behind this boat....so where is it?"
Probably they do have very little "solid" data.

There is almost nothing for sail boats. A bit more has been published for ships on foils, but the useful papers are covered by secret defense or are very privately owned. A bunch of theoretical papers of not real great use, or even very discouraging. We can remark that some ships have been made and no one has been a true success. Or very complex and expensive to build and maintain (Boeing), or no outstanding results (like the Hong Kong-Macao ferries, but very comfortable). After 40 knots, foils are very difficult to design (cavitation...) and compromises are almost impossible. Hydroptere, the most successful big sail foiler in term s of speed is not an ocean racer, and needs a lot of wind (ie HP) to have the foils working.

It's probably extrapolation from the very little existing data added with a lot of faith or auto-persuasion. Also a marketing technique (I call that the snake oil discourse).

I've seen that with many NA before; Britton Chance in the America's Cup, Gilles Vaton with the Charles Heidseick IV with numerous impossible claims, some proas, and many other NA (one britton I do not remember his name has a great palmares). Piver was also a specialist of the thing. Internet is full of similar claims.

The big big problem it's a mono and it's almost sure that monos are not the best platform for a ocean sailing foiler. Just physics and some basic calculations. Very refined calculation do not change the fact: not suitable for sail boats.

 

60' Monofoiler

There is a guy in Australia building a self-righting 30' foiling keelboat right now. I'm 100% convinced that a monohull foiler with movable ballast has the best potential for beating equivalent sized multihulls in the ocean. Among the many surprises with the tiny Moth foiler besides it incredible speed is it's ability to handle really rough conditions. I think a properly designed self-righting monohull foiler could stay up on foils at higher speed than a multi could in certain conditions. The thread I posted earlier has detailed design elements of such a boat.

 

Sail and hull performance can be predicted fairly accurately these days even for extreme departures from the "norm" and scow sailing hulls, DSS and canting keels are demonstrated realities. What remains to be demonstrated in any reasonably new design is how the whole thing comes together and stands up to real conditions. A great deal depends on the skipper and crew in such cases. I'm not sure if building and sailing the thing is what you mean by solid research - sounds more like rality check to me.

The concept needs a reality check, I'd agree with that . . . but I think we've done all the knocking that is called for, unless there is something new and specific anyone objects to in this concept.

 

Doug
It was relatively easy to extrapolate from a 20 feet catamaran to a 60 feet one. The Jet Service Cats by Gilles Ollier beginning of the 80ties gave the path. They are displacement slim hulls, and use similar rigging. After it was just engineering problems for handling the power.
The modern tris (after 1985) were an extrapolation of the data obtained from the maxi cats. Always slim displacement hulls. The amas began to grow until flying exactly like a cat, but with better rigidity and better passage of the waves. The boats became good all around, whatever the sea state and the wind, and with the engineering improving more and more reliable.
So the NA could go over the 60 feet to 90-100 feet without big insoluble problems. Again direct extrapolation.
Foilers are not so easy to extrapolate. The 1980ties foilers (Cantreau, PCA, Heidsieck etc...) lost foot in front of the cats and tris because of the FOILS. How to design a foil able to work well in a wide range of speeds and overcome the 40 knots barrier without going to ventilated foils, variable camber, slots and other complicated systems? A very difficult task.
The proof is the Hydroptere; it took a lot of years and more than 20 million dollars to get the speed record. But the boat is very limited in the conditions of sea and weather. Under the optimal speed of wind it's slower than a classical tri and it's a pain in light weather, over the optimal it's a danger. The foils used for the speed record are useless out of their relatively small optimal range. The boat has to use ballasts.
The fact is that Hydroptere never entered the 60 feet regatta circuit, nor made any oceanic race (even short ones in the Channel or Mediterranean). It's not for lack of money. The French sponsors poured money during a long time ( and a lot!) until being fed up. All the specialists worked on, Dassault and Aerospaciale gave a lot of supercomputer and engineering hours, the Navy worked on, everybody worked on. You can't imagine the amount of brain juice. I hope the best for the new Swiss sponsors.

The tris are already very fast all around WITHOUT foils. A 100 feet tri has easily the 35-38 knots mark in the best condition and has already a potential of 700 NM/day. They can be built light and strong with a good security.
The foils arrive as bonus. The turbo. With the actual foils 40-42 knots and 900 NM/day. That works. It's reliable (a circumnavigation without big problem) and the security is good. No need of big ballast and if the foil fails it's not a mortal wound. The 40-42 knots correspond to the speed of the cavitation problem. A bigger reynolds helps a lot, but the profile becomes more specialized...
That's the problem...2 sets of foils, medium and high speed? automatic flaps? induced ventilation of a medium speed foil "transforming" it in a high speed no cavitation foiler?(probably the solution of the Hydroptere in world speed record configuration) The problem has been thought since more than 50 years...
But the base is already fast...it's just improvement (easy to say, hard to obtain).

For the mono is a different problem. At equal size no mono, with ballast, canting keel and tutti quanti is unable to see the stern of a tri in oceanic races. Maybe is a very light breeze. In a ocean crossing there are days of difference in the 60feet.

So if not flying the mono is desperately slow. Worst if without foils the mono is good for downwind, upwind it will be a dog. What percentage of flying conditions have you in a several days race? Thats the problem.

The other problem is the rigging. A foiler do not heel, so the rigging has to be made to withstand the stresses on a relatively narrow platform. The compression on the mast is enormous. On a 14 or 35 feet is not a problem. On a 100 feet it's a very big problem.
I won't talk of rotating mast, size of spreaders, mobile rigging etc.
The tris now are so wide and so stiff that the mast can be rotating without spreaders!!! simple because the rigging is on so wide platform.
The mobile lest (the skipper) on a 14 feet weights more than twice the "naked" boat, has excellent sensors, a good computer to analyze the sensations and very good fast servos to take care of the tiller and the sheet.
On a 35 feet with 5 young healthy guys it's manageable. The ballast and the 5 guys represent an apreciable % of the displacement. On a 100 feet...
There is a big amount of work, and some extraordinaire inventions before getting a mono able to win over a multihull, without or with foils.

 

60' monofoiler vs 60' trimaran

Great comments , Ilan. You know if you look at my thread on a 60' mono you'll see that there is no reason the monofoiler can't be very wide. And a bi-foiler arrangement is well suited to this. It will take ,as you say, lots of money and invention but I think(as I show in the other thread) it is possible.
Your comments are very well thought out-thanks.
PS- a monofoiler does heel-by design- up to 30 degrees to windward which results in a substantial increase in RM-30-40% as shown by Moths using "VeelHeel"(which is not just windward heel).

 

Ilan: I see your point, which is very clearly explained. Multihull design is a great way to gain lots of RM without excessive weight, and once flying only one skinny hull is wet so there can be LESS wetted area than a comparable mono. Of course, ouside of performance multis have other problems so there will never be any shortage of monos, but that's another topic altogether.

Also, I hadn't fully appreciated the limitations of foils with regard to range of operating conditions.

Doug: What is the solution? For an aircraft where stalling sets the lower limit the ratio of maximum to minimum speed is less than for a boat where there is no lower limit. What is the solution? For military aircraft variable sweep wings has improved matters: So are we evolving towards variable sweep foils?

In my earlier experiments with a sailng kayak, where the narrow cockpit eliminates hiking, I solved the problem of limited righting moment by using a Bruce Foil and a mast canted to one side, which is similar in some ways to Veel heel. The SpeedRocket takes that concept to the max but I was there years before . . . and the Bruce foil has about double the leeway of a conventional keel so it's limited when sailing upwind.

 

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AK, a hydrodynamist would have to anwser that. However, I'd say that anything is on the table-see the foils in the picture below for the PI 28-telescoping foils. There are some limitations with foils speed wise but I'm fairly confident that a monohull foiler could stay on foils in rougher conditions than a multihull foiler-time will tell-and no question about a properly designed monohull foiler being faster than an equivalent length "foil assist" multihull.

 

Well, at least boat design isn't becoming boring the way all my various and variegated jobs eventually all did - I seemed to spend most of my professional life fleeing from boredom . . .

 

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The lucky people are the sailors: they get to try all this stuff first hand-terror and all....

 

I could be wrong but It seems to me that the number of hulls is irrelevant. Its kites that will more than likely change the game. Rather than weight to windward and lift to leeward it will be lateral resistance that will be the primary area of concern.

 

Why would kites be the answer?