I'm using a Merc 9.9 as a kicker/trolling motor and it moves my 24' boat at 6mph or so wide open. It has the standard 2 plade prop. Can I change to a 3 blade like sailboaters use and improve the speed. There is no tach on the Merc but the RPMs sound low. What is the rule of pitch/dia if I can use another prop? Anybody out there with insight?
