Prop pitch for 150xp crossflow on pontoon

[Blue316]

I know this is a subject that will get a lot of different answers but that is the point.
Am in the process of repowering the 24' pontoon as well as adding new pontoon logs. Biggest question is which prop is gonna be the happy medium.
This motor came with a 14 1/4" x 26 SS prop and went ahead and had that cleaned up and rebushed. That however was for a bass boat that would crack 55 regularly. Now that it's going on a pontoon which would be the ideal prop for it....and would this one even be worth trying?... suggestions and thoughts welcome!!

 

[racerone]

A 15" pitch would be a good starting point.----Is the motor in good shape?----For reference in the future do a compression test.----Post the actual values here.

 

[Scott Danforth]

not even worth trying on a poontoon. you will probably be in the 18" range with a high-thrust style prop.

 

[Blue316]

A 15" pitch would be a good starting point.----Is the motor in good shape?----For reference in the future do a compression test.----Post the actual values here.

The motor is being rebuilt from bare block so the compression will be like new.

 

[racerone]

Sorry---I guess I missed the " rebuilt " part in post #1.

 

[tphoyt]

Install a tac if you don’t have one already and give it some break in time before trying to figure out the best prop. Jmo

 

[flyingscott]

Prop it to run to 5500 rpm wide open and be happy

 

[Blue316]

Prop it to run to 5500 rpm wide open and be happy

That is the goal. Have to just figure out the correct pitch first, tried the wrong pitch on a different outboard before and it robbed me of almost 1000 rpm and nearly 5-6mph.

 

[Texasmark]

I have no toon experience but isn't a 150 a bit much for a toon even if its 24' long? I'm guessing 150 would be workable on a tri-toon, but a toon? Never heard of nor ran across that much hp on a toon.

 

[racerone]

There are lots of toons with monster motors.

 

[Blue316]

Ive seen plenty of toons with that size and bigger motors. This just happens to be the one I found for a good price. During the motors teardown I talked to a retired marina owner and was told it has been done plenty of times just gotta reinforce the transom and move a little of the weight out of the back.

I mean hell look at the size of the outboards that come standard on bass boats now. Some are more than twice that hp and bass boats are only around 17-20 feet long.

 

[Scott Danforth]

Ive seen plenty of toons with that size and bigger motors. This just happens to be the one I found for a good price. During the motors teardown I talked to a retired marina owner and was told it has been done plenty of times just gotta reinforce the transom and move a little of the weight out of the back.

I mean hell look at the size of the outboards that come standard on bass boats now. Some are more than twice that hp and bass boats are only around 17-20 feet long.

Exceeding the manufacturer rating means you are on your own legally. If an event occurs you will be in your own

While there are pontoons with 700 to 1200hp. They were designed and tested as such from the factory.

 

[Texasmark]

Exceeding the manufacturer rating means you are on your own legally. If an event occurs you will be in your own

While there are pontoons with 700 to 1200hp. They were designed and tested as such from the factory.

Really! Boy am I in the dark on toons.

 

[Scott Danforth]

Really! Boy am I in the dark on toons.

Twin 450Rs

 

[Blue316]

Exceeding the manufacturer rating means you are on your own legally. If an event occurs you will be in your own

While there are pontoons with 700 to 1200hp. They were designed and tested as such from the factory.

Yep that's the plan.

Anyways to get back on track, so far the suggestions are between 15-18 pitch. Any other suggestions?

 

[Scott Danforth]

Anyways to get back on track, so far the suggestions are between 15-18 pitch. Any other suggestions?

pick one....... test to make sure the RPM is within range...... go up/down from there.

 

[Texasmark]

Twin 450Rs

View attachment 390463

Well obviously that's not a run of the mill common toon so all bets are off! Looks more like "boys and their toys".

 

[JohnSz]

My 22' pontoon with 150 Merc came stock with an Enertia 15.6" X 13P prop. Don't know your gear ratio, but most pontoons run with a 11P - 15P props. Too many variables to think you will get it perfect on the first guess. As others have said you are going to have to pick one to test with. Get you motor height dialed in, etc, and go from there.