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Old 10th December 2008, 04:06 PM   #11
andretsin
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I know this post stopped long time ago, but I would like to write my thoughts.
I also thought about the idea of a Serenity with hydrofoils. But when I think about that, my purpose is not to make the fastest board in any condition. That is not possible. For every condition there is a different design. For the ground there are wheels, and for the air there are wings. An airplane with wheels is slowlier than without them (that is why the hide them) and a car with wings would have too much surface (drag) (there are more reason why cars don't have wings :-) ).
A serenity with foils would be like a raceboard: slowlier than normal serenity in low winds but faster than planning boards, and faster than normal serenity in strong winds but slowlier than planning boards. But it would be the best overall wind conditions board (and spectacular).
It would need a folding hydrofoil to hide it in displacement mode to reduce drag (friction and induced), but this would make the board too complex and would brake with the main concept of windsurfing: simpliest sailing boat.
Gibbing and taking problems would be only a question of improving the design.
In my oppinion, I would put a normal "T" hydrofoil in the fin and some ski in the nose which would define the height and angle of flying, taking about 5% of the weight.
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Old 10th December 2008, 05:19 PM   #12
Jean-Marc
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Quote:
Originally Posted by andretsin View Post
A serenity with foils would be like a raceboard: slowlier than normal serenity in low winds but faster than planning boards, and faster than normal serenity in strong winds but slowlier than planning boards.
I doubt a hydrofoiled Serenity would be faster than a planing board. Below are the results of some drag racing I've made against a Bladerider (foiled moth) in light wind.

1) With a planing hull la HS105 + 11 m2 sail combo, we were equally fast side by side deep reaching in 7-12 knots wind range (typical Vmax 22-24 knots). However, as soon as I hit a 5 knots lull, I lost the planing while the Bladerider still continued at full speed hovering over his foils. I was stunned by the fact that the Bladerider has only a 8.0m2 main sail and weights around 45kg (compared to 20kg for the complete windsurfing gear). In low wind, the foils help a lot to reduce drag.

2) Another drag race in 1-5 knots of wind against the Bladerider, but this time on Serenity + 11 m2 sail combo. In 1-4 knots of wind, the Bladerider is really tippy and really slow while the Serenity is way faster, as long as the Bladerider cannot fly. She is faster than Serenity as soon as the Bladerider starts to fly over his foils in 6-7 knots wind, mainly because the Serenity's hull speed starts to top off at 12 knots in 7 knots wind. So, in ultra light wind, the foil is completely useless if you cannot make the hull fly.

That's all drag racing made so far for this year.

Cheers!

JM
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Old 10th December 2008, 05:35 PM   #13
andretsin
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I see i didn't explain it well enough. I mean that:
-In low winds (so low that is not possible to take off in hydrofoils and neigther planning in planning boards), hydrofoiled serenity would be slowlier than normal serenity (which don't have the wetted surface of hydrofoil) but would be faster than plannig board WHICH IS NOT PLANNING.
-In strong winds (flying in hydrofoils and planning), hydrofoiled serenity would be faster than non hydrofoiled serenity, but slowlier than planning board.
So, i agree with you and your experiments.
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Old 12th December 2008, 08:16 AM   #14
James
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Have any of y'all seen this video of the world's longest windsurfing board? It's a 9-man tandem, if I count right.

http://jimbodouglass.blogspot.com/20...ing-board.html

It obviously a displacement board, but it goes fast enough that they tow a waterski behind it towards the end of the video. Not the most practical watercraft ever, obviously.
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Old 22nd December 2010, 05:13 PM   #15
Aco
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Interesting info and suggestions in this (old) post from March 2008.

Having owned more than 10 SB boards and enthusiastically followed the SB innovations from Formula to the longboard revival with Serenity and Phantom, I have to admit I am surprised that Starboard ignores Hydrofoiling:
considering the obvious advantages of Moth over Formula in light winds Hydrofoils look like a revolution on a silver Plate.

Meantime, AHD has taken the opportunity to develop the first commercial windsurf hydrofoil system:
http://www.youtube.com/watch?v=9XtY3AHUKKo

It shows that in light winds foils are much more efficient than planing, allowing a 7.5m sail to be used in conditions where a 11m2 is necessary for Formula to work (!).
Now, imagine what would a 12.5m sail do on the Hydrofoil Setup...

I sincerely Hope that SB will consider developing a Hydrofoiled Windsurfing:
Serenity looks like "the one" for hydrofoils, combining speed in displacement and foiling modes!

Interesting suggestions to resolve the height problem with a front "ski" foil is presented in
http://www.star-board.com/forum/show...?t=1567&page=3

Some thoughts also under
http://www.star-board.com/forum/showthread.php?t=8526

Regards, Aco
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Old 22nd December 2010, 09:49 PM   #16
davide
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Quote:
Originally Posted by Aco View Post

Meantime, AHD has taken the opportunity to develop the first commercial windsurf hydrofoil system:
http://www.youtube.com/watch?v=9XtY3AHUKKo

It shows that in light winds foils are much more efficient than planing, allowing a 7.5m sail to be used in conditions where a 11m2 is necessary for Formula to work (!).
Now, imagine what would a 12.5m sail do on the Hydrofoil Setup...
The AHD is very interesting, but I wander how real is the claim that a hydrofoil with a recreational 7.5 (in a video from AHD they are using a Hot Sails Liquid, no cams) can be competitive with a formula with 10-12 sail, or at least give similar performance for the recreational sailor. If it really was it would be a real breakthrough in light air design. For the AHD the long foil is a bit of a concern: if you thought a 80cm formula fin was big that THING under the hull will require some real planning when going back to the beach!
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