is the motor going on the same boat?
since its a 30hp, it makes it a little simpler.
A bigger prop pitch will pop you out of the water faster and lose some RPM's while a smaller one will give you a higher WOT aslo giving you higher RPMS.. If you have a service manual handy it might help..I don't know if its the same for all motors but you figure a 500-600 rpm difference with each prop up or down grade.
FYI, not a stupid question... I just went through a whole prop ordeal. some people find, finding the right prop as an art form.
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