Prop for 25' pontoon

[elake]

Hello all, hoping you can help me out with figuring out the best prop for my pontoon. Yesterday I replaced my prop on my 1985 25' pontoon with an aluminum 10 1/2'' X 11'' prop. I seem to be having a problem with the engine revving up after hitting 5mph. I was pointed to this forum from the engine repair forum to ask the experts on a prop size for my pontoon and make sure the pitch is right. There may be a ventilation or cavialation proplem going on and I'm trying to figure if the prop would be related. From what I can tell the old prop was original on the boat and I replaced it with a duplicate. Any advice is much appreciated!!!

Almost forgot, it's a 30hp Johnson pushing the 25' tooner.

 

[steelespike]

Re: Prop for 25' pontoon

Not an expert but::Is 10 1/2 X 11 the same as the old prop? It seems to me an 11 in pitch is at the high end for that application.You may need to go down in pitch.You need to borrow a tach so you know what rpm you are running. Usually the dealer will help with a tach and let you try props if you are intending to buy one.If the rpm is too low at wot it can damage the motor.Is all else the same.Did you change the trim?Try trimming in one notch. was the old prop aluminum?Generally a stainless prop is less likely to ventilate.If the old prop was cupped and the new isn't it may ventilate.