If Iam cruising along in my sib when its a bit rough the engine sounds noisy after going over a wave .
As the boat lifts and the motor revs a little higher its as if an air bubble has formed around the exhaust and the exhaust note is louder from then on until
I stop and get going again .
Once on the plane again its fine for a while until the motor revs a little over a wave and its noisy again. until i stop or turn
I don't seem to lose any power .
Iam sure an air pocket is forming behind the exhaust outlet ,
Main concern is that it may be causing some damage to the engine . Water is pumping fine when it happens there is no change in the outlet stream .
If the tale tale is still doing its job then you are getting the water around your engine that it needs. So as biggles says, sounds like you should be fine.