I have a 1980 Crestliner 18' fishhawk tiller with 1982 50hp Mariner. I do not know what my max RPM is on this motor. I did not find any pitch on the existing prop. (I do see on it, "Michigan" and "M" and 3 GUP) according to GPS I am getting up to approx 18-20 knots with 2 people in boat. I...
