Cavitation...I think....

[Pedrode]

First experience of what I believe was cavitation today. Accelerating to go on the plane and revs suddenly climbed while boat seemed to stall in the water. Initially thought it was an engine fault but after a while everything reverted to normal. Had the boat for 4 years now, engine set up never touched, and never had this issue - maybe the way it was loaded, very light with one passenger up front?? Or do the sea conditions sometimes cause this (very light chop today)?

[willk]

Couple of possibilities (there will be more):

1. You hit a lump of seaweed or other debris - wrapped around the leg and caused odd turbulence resulting in cavitation.

2. The bushing on your prop is goosed.

[Pedrode]

Thanks willk. I usually find that when there are a number of possibilities, it's the expensive one that turns out to be the right answer. I hadn't considered the bushes...mind you I would have thought that I would have experienced similar issues for the rest of the run but the boat accelerated and planed absolutely fine after the initial 'incident'.

[jyasaki]

It's actually ventilation (pulling surface air into the prop.)

Can be caused by a lot of things; most common is having the motor trimmed up and hitting a swell in such a way that causes the level at the transom to recede.

See if it happens again before you worry too much about it.

jky

[Pedrode]

All running as normal today. Decided it was bad loading. Had the wife too far forward.