Pontoon Ventilation Problem

[TrenchFisherman]

Just got a used pontoon this year and have really been enjoying it but have had some issues as well. I believe my boat has a ventilation problem because at times I can drive along and it will be running fine and then with a wind change or start going over larger waves the boat will start to over rev and then I will have to back off until the prop can get grip again. The reason why I think it is ventilation rather than cavitation is because I do not see my cavitation plate while on plane which i know is a problem but also because the prop has pock marks all over the face of the blades. I went to a few prop websites and used there prop finder tool and they said I should be using a 14 or 15. Well I went down to the dock and looked at my prop and I have this prop, 4877342A4515P, which is already a 15 inch so now I am not sure if a larger prop is even possible. It is a 2003 Mercury 90hp 2 stroke engine on a 23 foot pontoon boat. If you guys have any advice that would be great!

 

[steelespike]

You don't feel cavitation.
What is the wot rpm and gps speed? Assuming these numbers are normal I think going to a 4 blade prop with as much diameter that you can find
should solve your problem. Consider the Mercury Spitfire in the same pitch if your rpm is good.or a Solas Amita in a 4 blade.
You may have to drop an inch with the Solas.

 

[Sea Rider]

Who said you need to have an exposed AV plate while toon is on plane on calm water, what you need to do is lower engine till water flow passes slight under upper water deflector plate with engine trimmed at 90? on transom. Once dialed at that sweet height will have better performance on choppy, wavy, water cond than before with much better prop grip & thrust. A matter to try it out. If can't lower engine on transom, it's a different story..

Happy Boating