pontoon cavitates at wot HELP!!!!!!!!!!!

[tommytoon]

i have a 1988 21' crest pontoon with a 75 horse mercury longshaft motor, the prop i was told by the previous owner was for pontoons. the pitch or numbers on prop are 2832-13 and at wot i am at 4100rpm and begin to cavitate. mercury said i should be at 5000 to 5500 rpm with said motor. the motor is as low as it can go because of the transom and the power trim pin is at its last hole so trim is all the way down,no chance of adjustment because i get instant cavitation. i even checked to make sure the prop nut or rubber inside isnt spinning and its not. ANY SUGGESTIONS WOULD BE HELPFUL AND THANKS IN ADVANCE tommytoon

ps would a cavitation plate help????

 

[Old Screwball]

Re: pontoon cavitates at wot HELP!!!!!!!!!!!

I kinda just went through that problem. I got a 15 pitch stainless re-hubbed for my 75hp Merc thinking it would do better than the 13 pitch that came on the motor. (Bought boat and motor new) BAD 15 stainless caveatted (slipped) at 4000rpm. Took it off and put an aluminum 17 pitch on. Worked great, no slip, but topped out at 4200rpm. I think I really need a 15 pitch aluminum. Have the 13 at the 'Prop Dr." now getting re-pitched. Should give me a WOT of 5000 and top speed around 24mph, based on the other props performance. Won't be back to the river for 3 weeks, I'll post them.

Good Luck.

 

[tommytoon]

Re: pontoon cavitates at wot HELP!!!!!!!!!!!

thanks for your input mr. screwball i might have to try that, please let me know how that works for you

tommytoon