> as if it was a plane wing. This is how nearly all sailing works. Excepting the case of sailing directly downwind, the curve of the sail works like a wing,

> as if it was a plane wing. This is how nearly all sailing works. Excepting the case of sailing directly downwind, the curve of the sail works like a wing, and the keel provides something to "push" against - the effective "lift" (if it were a wing) drives you forward. This is why you can sail into the wind at all...