my statement was in respone to the secondary posting that said understanding
wing arifoils was 3/4 of understanding sail airfoils.

no, the keel has not a thing to do with understanding how a sail works.
nothing.

it does have something to do with how a sailboat works, but not a thing on
how
a sail works.


You are correct.

But the initial posting was :"I'm trying to understand how a boat can
sail against the wind."

Understanding the sail as airfoil is not 100% of the answer. One must
also consider the effect of the keel.

Jack

_________________________________________________ _
Jack Dale
Swiftsure Sailing Academy
Director/ISPA and CYA Instructor
http://www.swiftsuresailing.com
Phone: 1 (877) 470-SAIL (toll free)
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