wrasse

I'm experiencing hull vibration and noise when coming on plane on my single engine 454 donzi. Once on plane it goes away. It feels like it's coming from the bottom of the hull and makes this "woo" "woo" cyclic shuddering sound and goes away if I throttle back or once I get on plane. Turning is no problem, no vibration at all. Just when under load when coming on plane.
My mechanic says my prob checks out ok and the u-joints/gimble bearings are new.
I come on plane with drives in and tabs down never exceeding more than 3000 rpm.

Any ideas? Is this prop cavitation?

BadDog

Is this a new problem or new to you boat? Might try swapping props out, rule the simple things out.

bouncedcheque

had same problem - proved to be an unbalanced prop. Darren at Houston Prop straightened her up and I drove away like new.

mats

I once had a small hit on one of the prop blades.This caused the prop to go slightly out of balance and it vibrated at certain rpms.