Hi Bob,
Using your approximate dimensions above for the tip chord, say 7.5", with 3/8" under the trailing edge you'll have about 2.9degrees of washout.

I've seen 2-3 degrees (washout) often mentioned in my web searches but I was hoping someone out there would have more experience &/or knowledge with respect to the Selig 'foils mentioned.

Looks like empiricism is the way forward...

Steve

P.S. S.W.A.G. ??? [sm=confused.gif]