88 evenrude spl bass prop on a pontoon?

[Crest2588spl/kevin]

I bought a 25 ft pontoon with a 88 evinrude spl that has a 14x13 prop on it , my max rpm is around 3100 rpm at aprox 17 mph. i moved the engine up one hole to get about 3300 rpm and 20 mph but starts to cup ,or suck air! so im gonna have to go back to flush..Top hole.. This engine runs absolutely Great but i no i will hurt it if i continue this load at wot. the prop i have looks to be a bass boat prop kinda pointy on the ends 3 ear 14x13, I need some direction to make i guess a drastic change in my set up. My boat is a older heavy pontoon at 25ft great condition but i dont really no what to do as far getting the rpm's up and perhaps speed or control... im kinda thinking 13x13 4 blade but i had to ask the fellow boating community for some input...Thanks so much !!! Kevin and Alisha
it is a production stock/aluminum prop

 

[82rude]

First id verify that the tac is good.Next id would try a 9 pitch because you have a small motor on a heavy fair size pontoon.My buddy has a 250 4 stroke merc on his 26 footer.Im not a pontoon person maybe somebody else will chime in but maybe its just too much boat for too little motor to expect much atall??

 

[SkiDad]

you gotta go down in pitch and you need to look at a pontoon specific prop. You really need to get those rpm's up to around 5000.

 

[Sea Rider]

If it's a little motor on a heavy toon, don't expect a wow speed out of it, just dial a proper prop for motor to run at near max wot revs as usually loaded and be happy with whatever speed dialed. Take some cold ones to compensate..

Happy Boating