Slot effect?

[brieninidaho]

As a racer I have just finished reading "The Art and Science of Sails" with excerpts from Arvel Gentry and understand the concept of opposed circulation flows by the headsail and main resulting in a slowing of flow in the slot, results in increased upwash for the headsail and the slight detrimental effect of downwash to the main.
It is apparent that to achieve maximum benifit from the combination of sails that the slot must be tuned for optimum slot effect resulting in maximum increased flow/velocity/lift to the lee of the headsail.
With steady state conditions (wind, water, etc.) there should be optimum sail shapes, heading in relation to the wind, angle of heel, AND a optimized slot. This means that the angle of attack of the headsail and the main must be set in relation to each other to achieve an optimal slot effect.
I am trying to understand the visual clues one might see/feel to judge an optimum slot effect with maximum leeward headsail flow/lift.
Currently I have luff tells on the genoa and leech tells on the main. I was thinking of adding a leech tell to the genoa and wondering if a leeward tell on the main would help me understand the slot flow better and help in optimizing the slot. If a main leeward tell would be helpful what would be an optimal placement (mid sail aft of max draft, forward of max draft, at max draft???).

I understand that there is more to boat speed than trimming the slot (i.e. a balanced helm with optimum heel), but I am concerned that without the slot "tuned" that I am missing out on maximum headsail lift.

Any help in this is regard greatly appreciated. I hope that this is not a misuse of this forum.

Thanks
Brien

[brian eiland]

Originally Posted by brieninidaho

As a racer I have just finished reading "The Art and Science of Sails" with excerpts from Arvel Gentry and understand the concept of opposed circulation flows by the headsail and main resulting in a slowing of flow in the slot, results in increased upwash for the headsail and the slight detrimental effect of downwash to the main.......
Any help in this is regard greatly appreciated. I hope that this is not a misuse of this forum.

Thanks
Brien

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Don't have a lot of time right now to add additional comments, but I might suggest you look back thru other discussions of this subject matter in previous post such as "sail aerodynamics" at <http://boatdesign.net/forums/showthread.php?t=457&page=1&pp=15>