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Scooby_simon View Drop Down
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    Posted: 24 May 07 at 1:31pm
Originally posted by English Dave

Incidentally, how would foiling tris such a the TriWave and the Rave fit into the handicapping equation. And if lifting foils take such craft outside the remit of SCHRS then what about stabilising foils such as on F16 rudders?

Over to you Scooby!

 

Hee hee, was wondering how long it would take someone to make that connection...

SCHRS does not do "porper" foilers like the TriWave.

For RM inducing devices such as opposing foils on rudders, I have a plan.  It's is in theory, possible to calc the RM developed based on speed, foil angle and area.
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Pascal View Drop Down
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Posts: 31 		Post Options Post Options   Quote Pascal Quote  Post ReplyReply Direct Link To This Post Posted: 24 May 07 at 2:02pm

Originally posted by English Dave

But because the rig is on the centre hull any increase in wind strength will depress the leeward float rather than lifting the centre hull. So the drag increases with the wind

This depends on the design of the tri. On a tri designed to fly the main hull, when it does so there's just one float in the water so it's pretty much like a cat. On a tri designed with a planing main hull, the crew would compensate the heeling by sitting out on the winward trampoline.

Originally posted by English Dave

You also have the problem of tacking. It's hard enough to get two long straight lines to turn a circle, let alone three. On cats you keep the weight on the "inside" hull as far as possible to help the outside one (which has further to go) skim across the water. At least that's the theory I work to.

Tacking a tri is actually more similar to tacking a monohull because the centreboard is under the main hull, so the boat pivots around it. The floats are also much smaller than the main hull, so they just follow.

Rgds,
Pascal



Edited by Pascal
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mrzen View Drop Down
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Posts: 19 		Post Options Post Options   Quote mrzen Quote  Post ReplyReply Direct Link To This Post Posted: 24 May 07 at 2:06pm
Originally posted by Pascal

This depends on the design of the tri. On a tri designed to fly the main hull, when it does so there's just one float in the water so it's pretty much like a cat. On a tri designed with a planing main hull, the crew would compensate the heeling by sitting out on the winward trampoline.


If this is the case, wouldn't a tri be closer to a planing monohull than a cat?


Edited by mrzen
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Pascal View Drop Down
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Posts: 31 		Post Options Post Options   Quote Pascal Quote  Post ReplyReply Direct Link To This Post Posted: 24 May 07 at 2:15pm
That's a difficult call... Maybe the tri could be compared to a skiff, with the floats replacing the trapeze?
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mrzen View Drop Down
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Posts: 19 		Post Options Post Options   Quote mrzen Quote  Post ReplyReply Direct Link To This Post Posted: 24 May 07 at 2:25pm
that's what i'd say - the righting force exerted by the float would be large, like a  couple of trapezers on the other side...

i would also argue that as heeling force increases, drag should reduce, as the weight on the main hull would drop. As a result, I would have thought that planing would be achieved at a slower speed...

Once planing, a skiff should then be able to achieve a higher speed as it would have less drag (as there is no stabilising float, just trapezeing sailors), however, you have to be a much better sailor to achieve a similar result...

interesting...
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Pascal View Drop Down
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Posts: 31 		Post Options Post Options   Quote Pascal Quote  Post ReplyReply Direct Link To This Post Posted: 01 Jul 07 at 1:53pm

First pictures from the sea trials:

I'll be bringing back the boat to Datchet in September. See you on the water!

Pascal
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