prop advice

[cemcrae53]

Finally got my 21' suntracker party barge with 85 hp merc all put together. Motor is running like a top thanks to I boats tuning threads and all the advice I have gotten from you pontoon guys.
Only issue I have now is ventilation (cavitation) coming out of the hole. I have to throttle
gradually to keep from peeling out (as my wife calls it) Boat has a 3 blade 13 pitch prop and
WOT is 4800 rpm. This is in lower part of suggested range. I was thinking a 4 blade might help
Any advice on this would be appreciated.

 

[Silvertip]

Re: prop advice

Is the motor mounted on the pod as low as it will go? If you replace the three blade with a four blade of the same pitch the WOT rpm will drop even more. You would need to drop pitch as well to get up higher in the rpm band. Mercury has a line of pontoon-specific props. These have large rounded blades that provide the "bite" pontoons need since the engine is operating in very turbulent water as it passes between the tubes.

 

[EGlideRider]

Re: prop advice

+1 for Silvertip.