Pontoon motor size advice

[BASSBOAT21]

24 foot party barge by tracker---rated up to 120 hp----could i go higher and what size shaft do i need for motor--20 or 25 in---looking to stay with the older type motors cant afford anything newer--any advice

 

[BobGinCO]

Re: Pontoon motor size advice

Go with a 120. Do not go higher. It MAY be illegal in your state, your insurance company may not cover you if you do, and if you're ever in a boating accident, they will crucify you.

Oh, and a pontoon typically does NOT need a long shaft. Mine is 20"

 

[BASSBOAT21]

Re: Pontoon motor size advice

Thank u great advice

 

[Silvertip]

Re: Pontoon motor size advice

20 inch shaft IS a long shaft. 15 inch is a short shaft. 25 inch is an Xtra long shaft so yes -- you need a long shaft.

 

[MaPaHa]

Re: Pontoon motor size advice

I would research which of the older motors are rated at the crankshaft and when they started rating at the prop. Depending on who you ask, there can be as much as a 10% difference with the ones rated at the crankshaft being lower. You could put on an older 120 that’s really around 110 in todays standards. Here some other thoughts on what it sounds like you want to do.

You are right on the bubble of a boat that you can ski behind but it will have to be tweaked to the max to hit 30 mph or so. I catch it from all sides because I’m trying to get 3 or so more mph but my alternative is spending a bunch of money to get into the next class of boats. I like to ski around 30 or so and I can tell the difference between 26 and 30 on skies. You should have enough speed to tube ok but turning is always a problem with a pontoon unless you have a water glide or strakes on the toons.

If you’re looking for top performance and don’t want to push the legal limit then I would ask the motor guys to comment on which of the older 120 motors are stronger (over 120 but still rated at 120) and make sure to get one rated at the prop if you want the max power for a given motor.

You can improve the boat performance for not a lot of money. The easiest thing to do is polish the toons really good. Find a way to get to the bottom side of the toons where they sit on the bunks on the trailer. You can also skin the underside to keep the water spray from hitting the joists and causing drag. A good SS prop of the right type and pitch can do wonders. These could be worth a few mph. I run a nice 4 blade with exhaust ports drilled in it and it has a holeshot and acceleration like crazy but probably costs me a mph or two on top end compared to a performance 3 blade. Talk to a good prop person that can figure speed and slippage with a given motor and explain what you want to achieve. Power Tech is who I use. Try a prop or two and get some data before buying a new one.

That’s a lot of horsepower so I would make sure the back of the boat is solid and braced well and not a Mickey Mouse motor pod waiting for an accident to happen. Also, double check you’re steering cable. I run a no-feedback helm and cable which is very solid.

Those are my safety and performance tips for starters.

 

[WTX Desert Boater]

Re: Pontoon motor size advice

I have a 2006 20' Sylvan. 60hp motor with a 20' shaft. Max the boat is rated for is a 90hp motor.... Wish I had one....

 

[steelespike]

Re: Pontoon motor size advice

You don't see anyone saying:: "I wish I had less horsepower"
Get the biggest motor you can afford that the boat is rated for.
Besides ample power The motor will be loafing when running at the speeds of lesser motors.
Do keep in mind a 120 hp will go through about 12 gallons per hour at wot.

 

[BobGinCO]

Re: Pontoon motor size advice

Do keep in mind a 120 hp will go through about 12 gallons per hour at wot.

Wow, I can't imagine staying at WOT for a full hour. That would be 22 miles of lake!

 

[calvinator]

Re: Pontoon motor size advice

x2 on the horsepower rating on older motors (btw, I'm repowering my toon with an older motor).

For me, I was looking at older Mercury motors. The 90 and 100 hp units were crank HP rated. Roughly a 15% difference in prop rating means those motors are 75-85 hp motors. Might not be enough grunt.

I was looking at the 115 and 135 Merc motors. Then I ran across a mint 150HP Merc and I just bought it yesterday!. I won't have it on my boat for another month, but my thoughts are this is a 130HP motor. My boat and transom are rated for 125HP.

Also, I found a prop guide for my motor and Mercury recommends running a 11"-13" pitch prop for pontoon. With that prop, my max RPM can only get to 5300RPM vs. 5800RPM with a higher pitcher prop. The lower RPMS means less horsepower, so my 150HP (130 prop rated) has less horsepower with a 13" pitch prop (guessing 115Hp?). But that low pitch prop will be all low end torque and that is what I need for my 'toon.

OK, lots of "art" into my calculations, but the point, at least for me, is to not skimp on the horsepower for the older motors. They were crank rated and then when you prop them right for a pontoon, you lose top end RPM, which is lower horsepower anyways.

 

[Turner7619]

Dont mean to hijack but I was wondering how a 86 johnson 115 would work on my 18 ft bass buggy?

 

[GA_Boater]

Dont mean to hijack but I was wondering how a 86 johnson 115 would work on my 18 ft bass buggy?

You did mean to hijack or you would have started a thread of your own. And to add insult, you aren't even close to being on topic with the OP's question.

Closed.