Not sure about Metal Boats but that is bad low on a glass boat. Will say this, when you raise the motor RPM's should go up so you are still in the prop market. I have been playing with mine and have it almost where I want it. Noticed it lost it's bite a couple of times in the rollers on Sardis Saturday, gonna drop it a quarter of an inch and start looking for a prop.
Good luck, that ride is sweet!!