Prop slipping?

[Genofish]

I have a 2003 2 stroke Yamaha 90hp that normally runs at WOT of 5500 at 34mph. Today the RPM hit 6000 on a sharp turn but dropped down after I reduced the speed. Since then the max rpm is about 4900 at 29mph, when I trim up to where I normaly run the rpm hits 6000. This is running straight, no turns. The prop has a rubber hub, could it be slipping?

[Moose-Hunter]

I have a 2003 2 stroke Yamaha 90hp that normally runs at WOT of 5500 at 34mph. Today the RPM hit 6000 on a sharp turn but dropped down after I reduced the speed. Since then the max rpm is about 4900 at 29mph, when I trim up to where I normaly run the rpm hits 6000. This is running straight, no turns. The prop has a rubber hub, could it be slipping?

From what you've described, it sounds like you cavitated the prop in the sharp corner, then when it "bit" may have spun the hub. But... The fact you could still run the prop at all after that has me baffled. Usually when the hub lets loose, the party is over. End of any propelled movement.

But you say you can still run the prop, eh? Hmmmm.....

How does the engine shift? Does it still go in and out of gear that same as before that sharp turn? Is there any binding? Any added "clunks"? Or.. Is it smoother?

[boatfixer]

The hub can be slipping and still have some bite. It will, however, get worse as time goes on. A few more runs and Im sure it wont even get up on plane.

To check for a spun hub, remove the prop and make a mark across the prop and the splined part of the hub. Reinstall and run it, remove it and look to see if the marks still line up.

[Moose-Hunter]

The hub can be slipping and still have some bite. It will, however, get worse as time goes on.