Patent ID: 7461609

Claim:
A wing-type sail system, comprising: a substantially rigid main wing-type sail for extending generally in a vertical plane; means for supporting said main wing-type sail for pivoting movement about a substantially vertical axis; first and second secondary airfoils mounted to said main wing-type sail so that said secondary airfoils are spaced outwardly from said plane of said main wing-type sail on opposite sides thereof, said first and second secondary airfoils being located in positions spaced outwardly from sides of said main wing-type sail and rearwardly of a trailing edge thereof; and means for selectively pivoting said secondary airfoils in first and second directions relative to said plane of said main wing-type sail, so that said secondary airfoils react with wind passing thereover to exert a force tending to pivot said wing-type sail in first and second directions about said vertical axis.