Spun Prop or just grass?

I took my 17' Glastron with Evinrude 150 O/B with 14 1/4X21 prop, out to the lake today for its first run this year. When I got to the lake I noticed that it was VERY grassy. I mean it was awful. But I figured I'd try anyway. Got under way and went about 3/4 throttle to get on plane. Same as I've always done. The bow picked up then all of a sudden it felt like the boat slowed and the RPM's shot up. Backed off and tried again. Same thing. I did manage to get on plane at one point and it ran fine while on plane. Once I dropped off plane, so the kids could see an alligato,r I never could get back on plane. I tilted the motor up expecting to see the prop covered in grass, but nothing. I've never hit anything (that I know of) and it ran fine last year. Prop looks ok. SO , could excess grass cause a prop to "slip" or am I looking at a spun prop?

Re: Spun Prop or just grass?

It's hard to say, but put some marks(felt tip marker or similar) on the prop and on the hub, run it down the river and back...if it's spun the marks won't line up.....then you can have prop repaired or replace it. Good Luck!

Re: Spun Prop or just grass?

I pulled the prop and knocked the hub out of it. Its a hard plastic hub and everything looks fine. No scars on the keyways, cracks or anything. I'll try marking the hub and prop next time i go out. I would never have thought thick grass would cause this big of a problem.

Re: Spun Prop or just grass?

Maybe that grass is causing the prop to catch air and ventilate?...might be the issue!

Re: Spun Prop or just grass?

Whats your tach saying? rpms...

Re: Spun Prop or just grass?

Yeah Robert, I think that is what's happening. When I throttle up it gets to about 2800-3000 RPM's then shoots to 4500-5000 like its not in gear. It idels around ok, just will not get on plane. I think next time I go out I'll try another lake. Thanks alot guys.

Re: Spun Prop or just grass?

Check your trim, Make sure the motor is trimming all the way down. If it's not, that's your problem.

Re: Spun Prop or just grass?

Does seem like maybe a hub.Weeds could shut down forward motion. and even cause overheat from lack of water.
Bad weeds you would have some left on the prop.
You can shed weeds by reversing preferably in a clear area.
Sometimes so bad you have to remove by hand.