Prop help for a 21ft pontoon

[Carbkid]

I have a 1990 28hp johnson model#J28ESLESM on 21ft pontton that I just aquired and I feel that it has the wrong prop on it. Prop is a 9X10. Seems to cavitate no matter were the pin is set on the transom.

Thanks

 

[Sea Rider]

Being a 26 year oldie prop, probably already having a spun hub. By pin you mean the trim pin located at middle engine, rear of transom right ? You could have bad transom/engine height match for engine to cavitate/aereate, could be sitting too high on transom.

Happy Boating

 

[SeaDooSam]

Finding the right prop is a legitimate science! It is very complicated as well. Is your prop in good condition? Or does it have some dings and dents? My advice would be to find a local prop shop who is experienced and will let you try different props and return them of need be. I was surprised that I found one near me!