Dynamic stability

[Doug Lord]

Originally Posted by Bertil

Some things has happened with the so called lee-wing:
-A mailing between me and the inventor have been going on since I last wrote here. We also met at the Mets in Amsterdam last year where the inventor Hugh Welbourn showed a prototype.
-Hugh have tried it on a 27-footer with a leewing on one side. He have also tried ii on a 30-footer "Drinks Trolley" (see the net), and last spring a retrofit on a 38-footer.
-The results is closedhauled an increase in speed of app 5%, and when reaching 30-40%.
-The boat gets more stable in waves and feels as appr 30% bigger, and heeling 5-6% less. So it is very nice for cruising too.
-On the 38-footer the wing were mounted too near the bow of structural reasons and a new problem arised. When closehauled OK as expected, but when reeching the wing didn't work. It was disturbed by the bowwaves and did not work.
-My question to this forum is now:
Where to place the wing to avoid this?

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If I were you I'd ask Hugh Wellborn as PS suggested. Alternatively you could PM Vlad Murnikov who is using a very similar foil on his Speed Dream Prototype and is working with Wellbourn. Wellbourn has done the full size and tank testing necessary to answer your question-nobody here would have any better knowledge on this particular innovation. Good Luck!

PS- do you have any more info on the 38 footer-a link perhaps?

Speed Dream 35 Prototype

Hugh Welbourns's DSS 25

Dynamic Stability Systems-IMOCA approves!

[Bertil]

Sorry, but the problem comes from Hugh and he has not solved it. We need to have someone who knows how waves behave near the hull from hull out to app 2m.

[Doug Lord]

Originally Posted by Bertil

Sorry, but the problem comes from Hugh and he has not solved it. We need to have someone who knows how waves behave near the hull from hull out to app 2m.

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Is it a displacement hull?
UPDATE: I've found out that there is a problem with this boat but just so there is no confusion it is not a Welborn design-it is a retrofit. I'd be interested in more detail Bertil.

[Bertil]

It is an displacement hull. I have got some ideas of how to solve the problem and will count on it and will be back here on the forum when I,m ready.