Re: diameter
Generally if your prop is designed for your boat and application and your going brand for brand diameter is simply a function of the design.
If you were changing 4 bld to 4 bld same company the decrease in diameter "may" allow more rpm.When going from 3 to 4 usually you lose a little top end and rpm Simply more resistance in a 4.I believe usually you drop an inch in pitch when going to a 4.Disregarding any rpm issues.
