Originally Posted by Chikokishi
Designing/building a small sailboat. I need 100-110 square feet of sail for her.
Ok I'll bite, but I detect a serious lack of experience in sailing.
Go read this: SA / D Ratio
Now, how did you come up with 100 sq. ft.? Better to start with a good figure for displacement (yes, this is tricky) and then work out how much sail you want. Err on the side of more (up to a SA/D of 20 or so) but design to be able to shorten sail. Also depends on intended use - windy places or light wind places.