25 hp Yamaha cavitation problem

[fishwalton]

Ever since I hit a log going full speed there has been a cavitation or slipage problem with my 2006 25 hp Yamaha 2 cyl. As I fish the river the motor was not locked down just in case I did hit something, etc. The motor kicked up and reved up really high before I could get it shut down. Now at full speed there is a cavitation or some kind of slipping problem. It's like the prop loses it's grip and motor wants to rev up slightly. It's worse in slight chop but still have the problem on smooth water. Back off throttle slightly and the problem goes away.

Replaced the prop.with OEM 9 x 9 7/8 but problem still exist. Now using 9 x 11 prop and it's not as bad because the RPM's are reduced a bit. Prop when accident happened was a rebuilt. The 9 x 11 is also a rebuild. Could the hub be slipping just a tad at speed?

One mechanic advised it could be the rev limiter was damaged. This is a little over $300 plus labor. No way to know for sure without replacing but if that is not the problem I don't think the part can be returned.

I'm trying to minimize my repair cost as the bux are a bit tight. Any ideas on how to solve this problem?

[99yam40]

you can mark the hub and prop to see if it is moving/slipping
But slipping hub should be when there is a lot of force on it during planing not at the top RPMs while just running along

Might look for other damage to lower unit or bottom of boat.
Is it possible you damaged the transom and changed the angle the motor sits, coming up that hard could have done some type of damage

[fishwalton]

knock

I forgot to mention after I hit the log the next few trips there was a rather pronounced knock when motor in top speed. Very noticable. When I backed off the throttle it went away. I hear the knock but at a lesser loudness just every now and then when at speed but not as bad as right after the accident.