Speed Dream 27 Prototype

I do maintain my assertions. Multis are better suited to oceanic racing than monohulls for the technical explanation I already gave.

Yes Dough, I have read it. . Veal heel is very nice on small boats, I began it with my first Fireball 40 years ago, and became a rather good one practicer with my monodromic 15 feet proa. Great fun and rather precarious situation.

I know also pretty well the Mirabaud XL, the most successful monofoiler outside the 14 feet. Has a speed record of about 24 knots at Weymouth, has won several races on the Geneva Lake -where the races are very competitive- and they do veal heal all the time.
Yes you do it on a light boat, with moderate wind and flat water with three 20 years racing sail experienced guys who are more agile than gibbons in the Indonesian rain forest. The assistance boat is not far, there is no danger.

But with a 60 feet in an ocean race...Can you make that during 2000 NM? Solitary forget it. Maybe 75 220 pounds "monkeys" sleeping by turns?
Where do you get the energy for the fast sliding ballasts, instantaneous canting keel, filling water ballasts (when you're flying several meters above water...), hydraulic or electric servos coupled with the gyros, plus computers etc...Because you are in a very instable situation similar to a modern fighter driven by computer and fly by wire...How many Kw for all that?

I do remark that monofoilers seem to stay around the 20-25 knots mark. The explanation is rather simple. If they want to fly soon, they need profiles with flaps down and a high Cz, after accelerating the flaps go up and you obtain the designed profile. Nothing very new...ok but the problem resides in the profile and the invariance of the submerged surface; such a profile as needed on the monofoilers to fly soon won't go very fast. It will begin to have a big Cx around 25-35 knots, and to cavitate and stall at 40 knots.
Look to most of the motor foilers, their speed is about 40 knots. It's not an hazard. It's physics and compromises.
To go further you need profiles very peculiar, and/or controlled ventilation. And the instability go further. Profiles have not a wide domain of use; most have a ratio of 3 to 1 (max speed/stall speed), with hypersustentation 4 to 1 at best 5 to 1. If it's a STOL it won't go fast, if it goes fast it needs a 1 mile track.
Look at a Boeing's wing while landing; that looks complicated and it's very complicated. Try to transpose that on a monofoiler, the surface of its under water wing is invariant and you need a ratio of 5 to 1...no other way than slots and ventilation with compressed air for fighting cavitation. If the wing stalls (dynamic stalls are very brutal, ask Chuck Yeager) it's the big splash, like jumping from a motorcycle at 60 mph.

That is the Achilles tendon of all the foilers, and even the faster motor foiler the Boeing built patrol boat (70 knots) suffered heavily of that. Plus complication and reliability problems.

When the wind is scarce you have all this drag under the hull. No way to get rid off. A trimaran with additional foils has not these problems...
The faster ferries (more than 50 knots) are catamarans with repliable small foils...there are good reasons.

 

Speed

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Ilan, thanks for reading the 60 footer specs.
1) A minor point: you did not do Veal Heel on your Fireball or proa. Thats one of the biggest misconceptions around: only a monofoiler with just two foils(or a bi-foiler with power foils-see previous sketch) can do Veal Heel-it is not just windward heel. It is windward heel where the center of gravity of the hull + crew moves substantially to windward. For Veal Heel the hull itself must move to windward substantially.
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2) You're right-the 60' monofoiler probably wouldn't be sailed single handed and it would require very fast movable ballast in addition to some sort of sonar/radar to spot objects ahead and just under the surface. Hydroptere has been developing a system to do that but so far it is not working.
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3) Actually, the Moth peak speed is 31.4 knots(36mph) so far-but no monofoiler with just 2 foils has yet been configured strictly for top speed.
When Hydroptere was configured for max speed her peak was 61 knots(70.15 mph). Hydroptere's surface piercing foils lend themselves very well to having different sections along the span.
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4) On a 60' monofoiler things like variable geometry foils could be tried , if necessary. Thats already being done on the PI foiler in Switzerland.
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5) The 60 footer could be done with retractable foils-like Hydroptere and Hydroptere.ch.

Pictures: Veal Heel(not just windward heel-hull moves to windward), Pi28 variable geometry foils.
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So what do you call it if a catamaran with foils outboard of the hulls lifts its windward foils so only two foils are in the water?

 

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It depends. Was it designed to sail on two foils(like Oracle)? Hydroptere has been photographed sailing on just two foils but it mostly sails on three foils and it was designed to sail on three foils. 2,3,4 foil multifoiler. Bi-foil multifoiler IF it just has 2 foils and is designed to sail on 2 foils.
I guess.

 

Hydroptere isn't a catamaran. Yes. I'm talking about something similar to the America's Cup yachts, but with the foils outboard the hulls. Wouldn't that be the closest multihull analog to your veal-heeled moth?

 

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Oracle has sailed on two foils many times but with the lee hull in the water.
Rocker, the C-Class foiler claims to have "Veal Heeled" but I disagree because the boat did not physically move the hulls to weather. But there was a slight net increase in RM so it's a close call on Rocker( picture 2 below).
I think that real Veal Heel as a distinct technique (resulting in a 40% or so increase in RM)is probably limited to 2 foil monofoilers with or without buoyancy pods/power foils with angles of heel to windward of 20-30 degrees.
SYZ has foils mounted outboard (pictures 3 & 4):

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SpeedDream

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A catamaran heeled over. Not Veal Heel because the boat CG is to leeward of its "normal" position. Analogous to a "normal" cat flying a hull.


SpeedDream website: http://www.mxspeeddream.com/main.html

 

Speed Dream

Here's great pix:

 

No question that's a beautiful rig, and no question Vlad knows how to design an exciting looking hull. But I'd be more convinced of his ability to get the hull right if he'd cut his teeth in development class racing. Here are photos of the latest TP52 from Marcelino Botin and the Class 40 Mare from Samuel Manuard. Botin is the winningest designer of TP52s, and Mare is arguably the fastest boat in Class 40 racing. I suppose the latter has some things in common with SpeedDream, but SpeedDream is a pretty radical - I think too radical - departure from the boats that are out there winning races IMHO. I understand the principle: take a boat like Mare that is designed to an overall length restriction and replace the sprit with an extended bow without moving the boat's center-of-gravity forward much. If he had just done that it would have been an interesting experiment, but I think it's too wedge shaped, and I think the step is a mistake.

 

How can you compare boats designed within tight rules with one designed outside of all rules?

 

I can compare them because they sail in the same ocean. How can you say whether an idea is right or wrong if you don't compare it to something? The two rules I cite are pretty open with respect to hull shape, differing from each other largely in that one allows water ballast and the other doesn't (and has tighter controls on displacement).

BTW I think my Classic Moth is too wedge shaped as well (photos in my gallery). It should have a wider deck and BMAX should be farther forward.

 

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Rather than comparing it to a 52 and 40 footer it might be better to compare it with other 27 footers. Unfair comparisons tell us nothing.
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Have you seen this? MX-Next:

 

The fact that they sail in the same ocean using the same principles with similar size, shape & layout all sound like good reasons to compare.

They have slightly different goals (one is a fast racing boat with rules, one is a fast boat without need to worry about winning races) but the "fast boat" part is again a reason to compare.

I am sure that both used many of the same input info (proven fast sails, successful foil concepts, etc.) to achieve their "fast boat" goal.

Comparing can be very useful in finding flaws with choices. Finding these flaws can lead to advances in the future.

Size differences do matter, but we can try to factor this into the comparisons.

Compare away (just be sure to note the limitations of the comparisons)

 

Yup. It's interesting, it doesn't have a step, and I wonder what top dinghy sailors will make of it. I would like to see it get built. Should it be compared to other boats of same LOA or would you suggest some other measure of comparability? Perhaps something with a comparable rig and sail area? I still think it could be made better by moving BMAX forward (as could my boat).

 

Comparing the MX-Next to other boats would probably involve looking at : (more here: http://www.boatdesign.net/forums/sailboats/mx-next-new-dinghy-design-44329.html )
1) Singlehanders about the same length,
2) Singlehanders with about the same SA,
3) Singlehanders with about the same numbers,
4) Singlehanders around the same price.