25 (4500# fin keel/spade rudder) has had a horizontal 12 hp Yanmar
retrofitted. It has an approx 13" 3 blade
fixed prop. Many onlookers have made no comment but the sailmaker
was aghast: he thought it would slow me down too much under sail.
I haven't had it in the water
yet so no idea of current
performance but I'd give up some speed to have some real power when I need it in tidal currents but how would I even begin to calculate the correctly sized prop?