The pitch of your wheel ( prop ) is a pretty critical issue. As boats don't have transmissions the owner needs to find one ( prop ) that will make their engine run at its recommended WOT range. Anything lower - in your case - and you will be straining the motor. Anything faster and you'll see little pieces start to fly off of it.
As a general rule of thumb for every 1 degree or inch of pitch change you will see your RPM's change by 200.
Again, verify your WOT rpm's for that motor and go from there.
We could probably get into cupped wheels, S.S. , aluminum etc. Just stick with what you have and modify your pitch.
