Prop Slipping

[Trey Smith]

I have a 14 Alumacraft with a 25hp Johnson. It runs fine on calm water or going up river but in choppy water or going down river it will run full throttle for 15 seconds to a minute and then the engine will rev up and lose speed. Drop back down and take off it will do the same thing. I tried lowering the motor but it killed my speed and wouldn't let me plane out. Any suggestions?

 

[Mark42]

Re: Prop Slipping

The hub is probably spun. Time for a new prop.

 

[steelespike]

Re: Prop Slipping

I would guess the prop is worn not performing up to factory specs.
Props do wear especially in silty or cloudy water.In severe conditions the diameter can even be reduced.
Is the bottom of the boat clean and smooth? Any dents or irregularities
could be introducing air into the prop path.The antivent plate(just above the prop) should be about even with the bottom of the boat.

 

[Trey Smith]

Re: Prop Slipping

No dents in bottom of boat, pulled the prop off today and all the splines looked good and so did the the rubber around the prop was good also. I did noticed my transom had some play in it I replaced the board so it has no play in it would that have something to do with my problem? Thanks for all your responses.

 

[steelespike]

Re: Prop Slipping

If the transom is now taller the motor could be too high.
Is the anti vent plate(just above the prop)about even with the bottom?
What year is the motor?

 

[Trey Smith]

Re: Prop Slipping

I ran my boat today, the motor only slipped once and I lowered the motor and it never slipped again I must have had it a little too high. I saw the fins in bass pro and walmart that you mount on the anti vent plate do they make a difference on a small motor like mine? Thanks for all the help.