recommended prop

[Fishhawk1980]

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 think it was reading knots. any idea what pitch is recommended?

 

[WillyBWright]

Re: recommended prop

I would say an 11 pitch. Only testing would tell for sure, but 11 should be well within the ballpark.