OK, I think I can agree on maybe two fronts.
I like uni directional rudders, but you are saying that the board is a board and is not replacing the rudders and is helping the rest of the boat by taking the leeway issue away from them and so letting other parts do their job better.
So, your not really suggesting cambered rudders and no board, or cambered rudders and cambered board.
So this is a bit of a new idea, I am not thinking the addition of one board directly amidships would be too much of an addition to include, if it would make a significant bit of improved performance.
So I guess it would go OK with stern rudder down and board down, front ruder lifted.. This should balance ?
And when does the board come up, at a beam reach and beyond?
Doug
On Wednesday, 27 March 2019 08:15:25 PM AWST, Rick Willoughby rickwill@bigpond.net.au [harryproa] <harryproa@yahoogroups.com.au> wrote:
No - I do not agree. The bidirectional board is gives better windward performance than unidirectional rudders. The bidirectional board is better than rotating rudders because the rudders are symmetrical foils so will be less efficient at generating lift than the board designed for a narrow range close to zero AoA. We aimed for 3mm radius on the edges of the board and achieved close to that. The unidirectional rudders were built at a boat yard and actually have thicker trailing edges thicker than that. It is not unusual for unidirectional rudders with a 500 chord having a trailing edge with larger radius than 3mm.
Rick
On 27 Mar 2019, at 10:31 pm, '.' eruttan@yahoo.com [harryproa] <harryproa@yahoogroups.com.au> wrote:But, you agree, not as good as unidirectional rudders could be.
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Posted by: Doug Haines <doha720@yahoo.co.uk>
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