Hi all new here and need help...lol

[littlehoe]

Hey all, I just bought a new xcursion pontoon boat, its a x23rfc so a 23 footer, I put a new 115 yammy outboard on it. When the dealership gave me the boat it had a 15 aluminum prop on her and I took her out for the maiden voyage, well after warming up the engine with some cruising I went to test full throttle as I was told by the dealership and whoa, It pinned the tach at over 7000 rpm. So I pulled her back fast and next day went back to dealership. They gave me a 17 and 19 pitch prop to try. Well the 17 hit about 6800 rpm and the 19 hits 6200 rpm. Speed wise the boat hits 20mph right away and then stays there. I can cruise at 5500 rpm in any of those props at 20 mph and any more throttle over that causes the boat to just rev higher and sounds like a cavatation or ventilation at the back. They told me I should see close to 30 mph with the boat. Anyways, boat was at the dealer for the last 2 weeks and I just picked it up and they told me everything tests fine and the boat is perfect on land...lol... So now I am taking it back to the lake with a 13 x 19 prop just to use it this weekend and then I will be bringing the service guy with me next week for a ride.

The dealership says the motor is in the right position as compared to the other boats they have sold like mine and they have no idea. at one point almost sounding like they thought I was lying because they said there was no way I should be able to spin out a 19 pitch prop on that boat and motor combo.

Oh and it didn't matter if it was 2 people on the boat or 5 and a dog with a full livewell. it hit 20mph and that was all she had before cavatation/ventilation sounding.

Any help will be greatly appreciated.... oh all of those props I have tried are aluminums too...

 

[Georgesalmon]

Re: Hi all new here and need help...lol

Sounds like a decent dealership. Gave you three props to try and sending a service tech for a ride next week? Just let them fix it.

 

[Silvertip]

Re: Hi all new here and need help...lol

Sounds to me like the motor needs to be mounted lower and a 19P seems like way too much pitch for a pontoon. If ventilation is the problem (and apparently it is) then swapping props is not likely going to fix the issue. Motors on pontoons run in very turbulent water so the motor needs to be set down to get a good bite. Yamaha also has a four blade "pontoon-specific" prop that should be used.

 

[littlehoe]

Re: Hi all new here and need help...lol

Hey again, well the dealership says the motor is in line with all the other similar boats to mine for mounting depth and the such and they say its all tip top on land. Basically they told me they don't know whats wrong which is why I was asking for some opinions from everyone to maybe help the dealership figure it out too... Anyways we ran the boat this weekend with the 13 x 19 aluminum prop and it ran great, still only 20 mph but pulled 2 tubes with adults behind the boat no problem until we had to turn a corner and then the motor got bogged down some with that 19 prop and we would lose speed but still had a blast. Hopefully this week I can get the service guy out to the lake with me to figure it out...

Here is a video of it, I don't know if this will help any but maybe you will see something i am missing. You really see how easy it jumps from 5500 to 6100 or so rpms.



Here are a couple pictures of the motor at about 5500-6000 rpm looks like its in the water good to me but I really don't know lol.

 

[littlehoe]

Re: Hi all new here and need help...lol

after looking at those pics again I am having second thoughts that they were taken when the motor was a wot or near that... I have a video that shows the engine at running speeds... once it uploads I will post it...

 

[littlehoe]

Re: Hi all new here and need help...lol

here is that video...

 

[jestor68]

Re: Hi all new here and need help...lol

A lot of pontoon users report that installing the DoelFin hydrofoil reduces or pretty much eliminates ventilation(they call it cavitation).

It'll only cost you $40 to find out. It will appear a lot smaller on your motor.