i asked a prop question yesterday and didnt have enough info.. hope this will help ans my question. i have a 1984 cierra bayliner with an aq125a penta 270 outdrive i usually run at 4000 rpm at a speed of 20 mph sometimes not even. i would like to get a little better top end. i'm just not sure whats "healthy for the boat. right now the reason i'm changing the prop is i might have a spun hub.. prop engages at low rpms, as soon as i accelerate the motor winds out and the prop stops spinning.(hope it's a spun hub)..ps. would a "top end" prop be easier on the motor... also i dont know whats on there now help....