KissCut-new Swiss Foiler

[Doug Lord]

Thanks Terry, it is a very innovative solution to the idea of using hydrofoils on a cat.
To the best of my knowledge it is the first cat to use fewer than three foils and is significant for that reason alone. But it has tremendous potential especially in "foil assist" where the foils don't necessarily lift the whole boat clear of the water-but significantly reduces drag. I don't know the details of how Arnie and the designer have made the center module work but if it actually works smoothly and is not too heavy I think the
system is quite an advance. The ability to fully retract the foils is really a good by-product of the system. With the module over to one side the RM of the boat is substantial and Arnie says it has flown 100% in that configuration.

[ancient kayaker]

I'm not so sure: if the cemter module is light moving it will have little effect on RM; easier to move the meat.

[Doug Lord]

Originally Posted by ancient kayaker

I'm not so sure: if the cemter module is light moving it will have little effect on RM; easier to move the meat.

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Terry, the reason the center module can have a large effect on RM is that by moving it to leeward the center of lift of the foils becomes quite separated from the boats CG creating a righting arm and -if the boat flies a fairly large RM. The crew in the weather hull adds to it as you point out.
If the boat was to 100% fly with the module centered there would be zero righting moment created by the weight of the boat-the only RM in that case would be that created by the distance to weather the crew is from the center of lift of the foils.
One of the foil assist options is to leave the module centered and set the adjustable wand for an altitude that reflects the windward hull just clearing the water. According to Arnie this set up gets the thing to fly the windward hull before it would normally AND the wand will cause the foils to pull down as well as up- adding to RM if the wind increases and maintaining the boat at a set angle of heel. The foils pull down or up depending on wind strength.
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There is more to this thing than meets the eye at first glance.....

[bistros]

Originally Posted by Doug Lord

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Terry, the reason the center module can have a large effect on RM is that by moving it to leeward the center of lift of the foils becomes quite separated from the boats CG creating a righting arm and -if the boat flies a fairly large RM. The crew in the weather hull adds to it as you point out.
If the boat was to 100% fly with the module centered there would be zero righting moment created by the weight of the boat-the only RM in that case would be that created by the distance to weather the crew is from the center of lift of the foils.
One of the foil assist options is to leave the module centered and set the adjustable wand for an altitude that reflects the windward hull just clearing the water. According to Arnie this set up gets the thing to fly the windward hull before it would normally AND the wand will cause the foils to pull down as well as up- adding to RM if the wind increases and maintaining the boat at a set angle of heel. The foils pull down or up depending on wind strength.
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There is more to this thing than meets the eye at first glance.....

And it broke catastrophically the first time he tried to lift both hulls out of the water with the module to leeward. These aren't trival forces you are playing with, and the stiction in loaded system of this type has got to be huge.

I know that some folks are absolutely in love with complex solutions to simple problems, but Terry's reference to moving the meat is the simplest solution. There's more to meat than the first glance of your eye.

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Bill

[Doug Lord]

From Arnie Duckworth:

"this boat is an ambitious development project with little precedent to draw from. i am satisfied with our success so far but setbacks can still be expected. obviously i will make everything stronger but also refine some of the mechanisms. the new lift foil will be asymmetric and have a greater range of flap angle. the sails have been re-cut and the rig is being re-evaluated to better control sail shape. "
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Whether the foils were fixed in the center or on the movable module to leeward the crew would have to move. The problem is with the foils fixed in the center position the weight of the boat does not contribute to RM. With the sliding module the weight of the boat contributes to RM as in a "normal" cat. The center position is an excellent "foil assist" configuration but the highest performance will be with the module as far to leeward as possible.

[Gary Baigent]

Yes, the system theoretically could work (and I would be the last to damn an original project because of breakages) - but surely there is a simpler way to lift a catamaran .... like angled foils through the hulls. But at the moment: "Okay, we've lee foiled our way into the lead, let's tack, crank that foil assembly across to the middle, you blokes, or what about the windward side? it will be better there on the next board, mumble, mumble, decision, grind, grind, heavens! the loads are high and now it's jammed and the whole fleet has passed us by - and we're stuck in irons with the foil in the platform middle. Hey, that foil assembly has got real weighty with all the epoxy and carbon reinforcements, Arnie, you sure you didn't use polyester resin?."

[Doug Lord]

Originally Posted by Gary Baigent

Yes, the system theoretically could work (and I would be the last to damn an original project because of breakages) - but surely there is a simpler way to lift a catamaran .... like angled foils through the hulls. ."

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Simpler yes. With as wide an effective range for full flying and foil assist, no.
Unless ,of course, you've got it ,Gary?
There is no theoretically about it-the system works!
* easily retracted foils
* easily moved module
* multiple configurations available from foil assist to full flying-no other full flying cat configuration even comes close to this.
* 33% less foils than any other full flying catamaran

[ancient kayaker]

Agreed, it is a fascinating, even audacious concept, but it still doesn't blow my skirt up!

[Doug Lord]

Originally Posted by ancient kayaker

Agreed, it is a fascinating, even audacious concept, but it still doesn't blow my skirt up!

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What-you don't wear a mini skirt?? Ok, nevermind......

[Gary Baigent]

Doug, my man, what is a wide and effective range for full flying and foil assist? All foilers are in that state, blows a bit harder, flying, quieter winds, foil assist. Easily retracted foils, same again. Easy module shift, not so sure about that, mate, underway I mean. 33% less foil area, sounds a bit BS too. Also you're forgetting module drag in a seaway. How about weights with this complexity? All power to Arnie and his designer ... but I'm for simplicity.

[BWD]

um tink e meant a say 33% less number of foils.

PS kinda OT but: Luderitz update No.1 Vm 61.7 500m 53
and they only getting warmed up (tease tease...)

[Gary Baigent]

You are correct BWD, my misreading - but I still question the 33% figure - cat with conventional angled foils, leeward foil down, windward one up, plus rudder equals 2 foils immersed, the same as my foiler tri Flash Harry - I mean that's no more than a conventional monohull.

[bistros]

Originally Posted by Doug Lord

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Simpler yes. With as wide an effective range for full flying and foil assist, no.

I'd agree with this in theory. Not having witnessed it I could not reach a conclusion however. The design brief certainly has a wide and effective range. Not sure about the boat - this is the Internet after all.

Originally Posted by Doug Lord

Unless ,of course, you've got it ,Gary?
There is no theoretically about it-the system works!

Did you see this? Have you got pictures of the boat fully foiling? Didn't think so.

Originally Posted by Doug Lord

* easily retracted foils
* easily moved module
* multiple configurations available from foil assist to full flying-no other full flying cat configuration even comes close to this.
* 33% less foils than any other full flying catamaran

We don't know if the items Doug specifies as "easily" handled are - all we have is Internet reports to that effect, plus Doug's enthusiasm and rah-rah sis-boom-bah cheerleading. I can see how these items may be "easy" to move while under no load, but a loaded system with off axis loads due to a variety of different stressors is a different situation entirely. Lifting a loaded daggerboard while in motion is somewhat harder than doing so in a motionless boat at the dock.

This is an interesting experimental platform that shows a lot of innovation and novel approaches to the issues. Mr. Duckworth is quite honest in his assessment of it as an ongoing development project which is not complete. He seems far less content to claim complete success than Doug, although he is working towards his goals. I wish him the best!

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Bill

[ancient kayaker]

Bill: Good point about the Internet but my feeling is, it's real. I too have reservations about moving the center pod when supporting the weight of the boat under the dynamic conditions of foiling, I would expect mechanism design challenges, much physical work and probably control difficulty.

On the other hand, it would be relatively easy to move the pod with the boat either stationary or with foils raised. That would allow the mechanism to be much lighter, and a simple clamping arrangement could handle the forces on it when foiling.

For a straight course, constant wind and other conditions the pod's position could be preset as a coarse control, with the crew’s weight providing fine adjustment. Not very practical for general purpose sailing perhaps, but for straight-line speed, or occasional foiling, an acceptable compromise.

I have not been able to determine which of the above is the case so I emailed the designer and asked him what he intended.

[Doug Lord]

There is video of the boat flying from onboard. It is part of or accessible from the url's I already posted.
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Gary, comparing this boat to your boat: you carry around four foils-this thing just two. No catamaran having a total of just two foils has ever been produced before-to the best of my knowledge. And Gary no current catamaran has the facillity to control the angle of heel in light to heavy air automatically as does Happy Feet. No current catamaran has the abiility to 100% fly on just two foils(with only two foils on the boat) That is a wider range of foil assist and full foiling than any other current catamaran. I'm fairly sure that Kotaro Horiuchi did the first tri designed to be able to 100% fly on just two foils.

PS- one other thing Gary-the Decision 35 cats the Swiss (and others I guess) race have a fixed module down the centerline of the boat-no problem with water impact that I've heard.