prop aeriates bad

[jchale333]

I have a 24' pontoon with a 50hp Merc. With any weight on front and over half throttle prop aeriates badly and sends RPM`s to the moon. I have to stop and start again over and over. I didnt have this problem until last fall when i had to replace the trim tab because the other one was apparently left loose from factory and fell off,,thats the only thing i have done to the engine. If everyone rides in the back it does ok but with a few people its uncomfortable.

Anyone know if the trim tab adjustment may cause this,,,doesnt seem so but I learn something everyday. Any ideas,,,thanks in advance

 

[Dhadley]

Re: prop aeriates bad

There are pontoon specific props. What prop do you have? What shape is it in?

 

[Jeep Man]

Re: prop aeriates bad

Assuming that the motor is a long shaft, what brand, what year of boat, what size tubes, and, is the motor at it's lowest setting?

 

[jchale333]

Re: prop aeriates bad

Assuming that the motor is a long shaft, what brand, what year of boat, what size tubes, and, is the motor at it's lowest setting?

Its a 50 hp Mercury 2004 Suntracker 24 foot Party Barge, Not sure what the tube size is what ever is standard. Motor is at its lowest setting.
I bought it new didnt have a problem till i replace that trim tab last year.

 

[jchale333]

Re: prop aeriates bad

There are pontoon specific props. What prop do you have? What shape is it in?

The prop is i believe a 13 X 22 and is the prop that came with the Suntracker 24 ft party barge package on the 50 hp Merc I bought it new. The prop is good,,paint isnt even chipped off.

 

[lmuss53]

Re: prop aeriates bad

That seems like WAY to much prop pitch for that boat, I would think you'd be in the 11, 13, 15 pitch range with a 24 footer and 50 hp. I had a 50 on my 19 footer until recently and had a 13 on it.

If you take the trim tab back off does the problem go away? If so do you need the trim tab? If you can cure the problem by undoing the recent fix I would do that. The trim tab may be creating some interuption in the water flow that now makes the steep prop cavitate.

If you get this working I'd be real interested to hear what your full throttle RPM reading is, because I bet if that is a 22 pitch prop it is not letting you run in the recommended RPM range for your 50. You do not want to run that 50 lugged down to 3500 or 4000 RPM at full throttle.