Sounds great, Dick, but
how can he eliminate "all" prop walk. I don't think the various "P" factors (forgive a flyer's terminology refering to prop effects) can be eliminated, though their effects may be diminished greatly. Such things as asymetrical thrust of the downturning blade, torque, gyroscopic effects remain. In a twin screw power boat, and in twin aircraft, you get the best results by using counter-rotating engine directions to cancel them out (not all use them though). Can't do this in a sailboat though, unfortunately. Once you get enough water moving past the rudder, though, naturally these forces become relatively slight.