New pontoon problems

[glrichards]

Well I got a new pontoon and a new set of problems
It has a 115 4 stroke merc that only turns 3200 rpms with 8 people on board 3400 with 2 on board. The prop is 13.5X15 the toon is 24ft 8ft wide and with a full tank of fuel and gear is about 2600 lbs. The Dealer says that is the prop that they put on all the new toons and haven't had many problems but will work with me to get this resolved. He has contacted Mercury and is sending a new prop that they recomend.
The other problem is tounge weight 140 lbs. the toon full of fuel on the trailer weigh 3500 lbs
I moved it forward 5 inches and only picked up 40 lbs to 180 I can move it 4 more inches or should I move the axels to the rear to pick up more tounge weight.

 

[rrhodes]

Re: New pontoon problems

In my mind the trailer is a no brainer. Make the dealer fix the rigging. If you bought her new you should not have to do anything. As far as the prop goes. You are over propped but have you tried trimming the motor up to get the rpm's up a bit?

I would think a 13p would be the right prop but the math says 11p unless your 15p is cupped.

 

[sumcat1]

Re: New pontoon problems

Tip! Check tachometer setting. They have a switch on the back for different engines. My new pontoon with 60hp Bigfoot would only turn 5100rpm. Dealer said four strokes run that way. After the bull I checked the tach and found it set wrong.

 

[SunTrackerPB21]

Re: New pontoon problems

My new pontoon with 60hp Bigfoot would only turn 5100rpm. Dealer said four strokes run that way. After the bull I checked the tach and found it set wrong.

My '04 21' Suntracker (~1785 lbs) is running an '05 Merc BigFoot 60 (2 stroke). WOT with only 2 aboard is 5000 rpm. Moves out pretty good..
Drops to 4800 with 4 aboard.

 

[glrichards]

Re: New pontoon problems

The dealer called today the prop should be here tomorrow. Still don't know dia. or pitch but is a mercury prop that the mercury folks say will do it.
I would take it back to the dealer but they are in grand rapids mn almost 900 miles away. Bought it there because it was about 6000.00 less than I could buy around here. Have bought 2 pontoons there and saved a ton of money.
I am retired and plenty of time to travel and don't have any money but plenty of time.

 

[quantico]

Re: New pontoon problems

I would think the ideal prop pitch to be about 10...... for that application. you are way over propped and that is not good for the engine.

 

[glrichards]

Re: New pontoon problems

The dealer sent a new prop to replace the 13.5 x15 he sent me a merc black max 14x13 will take it out tomorrow and try it out. Don't think it willbe much different. All the prop wizards and people on iboats say a14x11 or a 14x10 wewill see what happens and post back.
Checked the tach to make sure it was set right it is on 6 that is what faria said thet is the correct setting.

 

[rrhodes]

Re: New pontoon problems

Remember to trim up until your prop loses it's bite and then drop just enough to stop cavitation. That should give you your best performance and RPM. I am running a similiar setup and pull 5800 rpm on a 13p prop.

 

[glrichards]

Re: New pontoon problems

Took the new toon out with the new 14X13 prop the increased to 4200 from 3200 and speed to 19.25 gps. Will start looking for a new prop monday going to try to find a 14X10 to bring it up to operating rpm over 5700. the old prop was a 13.50X15 and only turned 3200.I tried different settings on thtrim but didn't seem to make any differance.

 

[glrichards]

Re: New pontoon problems

After a lot of help from this forum and a new prop and finding the motor was running on 3 cylinders things are working out.

put on a 14X11 quicksilver prop pluged in the pencil coil ( now running on 4 cylinders) motor turns 6375 rpms and go's 27.7 mph with alight load and 10 gallons of gas.

Thanks to all for your help.

 

[Silvertip]

Re: New pontoon problems

When rpm are way off the last thing one should be looking at is a new prop and the dealer should have suggested this as well. As you found out, changing props cannot compensate for a poorly running engine. I don't mean to be critical but it amazes me that people can't tell when an engine is missing on one or cylinders. Those engines always sound funny, shake as though they are stuggling, and it should be obvious there is an issue.