SLIPPING OR CAVITATING 22' PONTOON

[jeff surles]

i have a 2004 suntracker with a mercury 115 optimax dfi,when i take off on the boat i go to wot throttle and start trimming the motor up until its at proper speed.the problem im having is at half trim the motor feels like its slipping or cavitating.i done some maintenance on the boat and while i was working on it i found i was only getting about 3/4 throttle so i made the adjustments to get it to wot throttle.i took the boat out and now i cant hardly trim up at all before it starts feeling like its slipping or cavitating.but when this happens i surely loose speed..also my pontoon is a 22' also the prop is 13 3/4x15 three blade
THANKS FOR ANY HELP

 

[ahicks]

I'd suggest you have a look at the engine trim position while it's still on the trailer. Set it where the prop shaft is about parallel with the bottom of the pontoons. Then, note where the trim gauge is indicating. Now, you'll have a reference point in the back of your head. Going out/up much further than parallel isn't going to gain much (your GPS can be used to confirm), and going too far up/out beyond parallel is certainly going to cause cavitation.

Regarding correct prop, it's going to depend on what rpm you're turning vs, what you should be. In a perfect world your prop should let your engine turn at max. suggested rpm when loaded with your most "usual" load.

 

[bruceb58]

I have a 2006 Sun Tracker with a Mercury 90. I also find that I can't trim very much at all before it cavitates. Just the nature of these I think.

 

[MaPaHa]

Is this a new boat to you or have you had it a while? Is the problem new?

 

[jeff surles]

it got worse when i adjusted it to wot.i used to be able to trim to halfway now i cant trim much at all

 

[jeff surles]

i also read that a 4 blade prop works alot better on pontoons....what do you guys think?

 

[jeff surles]

thanks ahicks i see where you are coming from on the being in to parallel.so much past parallel theres no advantage if im understanding you correctly

 

[Jeep Man]

Jeff, do you have a "pontoon"prop, that is one with a wider blade and a bit of cupping on the outer edge? The cupping can reduce prop ventilation. A four blade prop will give you better hole shot and better reverse control but I don't see how it will help with ventilation.
If you go with a four blade, reduce your pitch by 1 to maintain the same rpm at WOT. Have you investigated the possibility of a spun prop (slippage at the prop hub)? To check for this draw a line across the inner and outer section of the prop. If the line moves after giving it a run, you have a spun prop and will need replacing. I have an '08 Suntracker with a 60 and have not had any ventilation issues and currently using a four blade.

 

[jeff surles]

I don't know that it's a pontoon prop . I know that it's a solas replacement for the oem prop for that motor.as you said JEEP MAN since it got worse after I got more throttle it could be slipping

 

[BigDfromTN]

i also read that a 4 blade prop works alot better on pontoons....what do you guys think?

I went to a 4 blade last year and have not looked back.
I was having problems with the original 3 blade "slipping" at times. Leading edge was nicked up here and there. Tried a couple 3 blades and was not happy. Had prop guy order me a 4 blade after reading others having good success with them. Very happy. No more slip unless I trim up too high which is normal.

Get a good prop shop that will let you use a prop and return it if not right. Worth every penny you pay. If you buy a prop and even have to pay to ship it back... You have spent more than the local guy will charge. And they will normally work with you to get you happy. Just my .02

 

[jeff surles]

THANKS ALOT FOR THAT INFO BIGD