Why don't assymetric fins have winglets?

winglets on fins mostly don't work because the pitch angle of the board is not stable enough.
a winglet which is out of proper alignment will have a lot of drag.

on speed or most windsurfer fins winglets don't make sense anyway, because at higher speeds the the lift coefficient is very low and so the induced drag is quite low as a result.

winglets are not the optimum solution to reduce induced drag if you don't have any span restrictions. on planes they are often used to squeeze more lift from a wing without needing a new wing design and also for directional stability.

www.mh-aerotools.de/airfoils/winglets.htm

cheers
Boogie

Awesome, thanks for the link Boogie, very interesting

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C3 said...

, because at higher speeds the the lift coefficient is very low and so the induced drag is quite low as a result.

winglets are not the optimum solution to reduce induced drag if you don't have any span restrictions. on planes they are often used to squeeze more lift from a wing without needing a new wing design and also for directional stability.

Boogie
www.C3-fins.com

Usually a planes wing span is restricted due to physical restrictions at boarding gates etc. Having a wing tip gives an effective increase in aspect ratio without increasing the span. Increased AR gives a higher L/D ratio at higher angles of attack.