Motor height

[Liquid Asset]

Yes I meant 5000 rpms, typing on my phone lol. That motor was a 1983 4 cylinder 50 HP mercury. They didn't turn the rpms of a newer version.

My whole point of the example is that the Op's motor can be made to work. It simply needs to be in the proper rpm range. If his motor is running where it needs to be it doesn't matter what boats its on. The motor doesn't know weather it's on a 16' or 28' as long as it's propped to run at the recommend rpm.

[wwind3]

Yes I meant 5000 rpms, typing on my phone lol. That motor was a 1983 4 cylinder 50 HP mercury. They didn't turn the rpms of a newer version.

My whole point of the example is that the Op's motor can be made to work. It simply needs to be in the proper rpm range. If his motor is running where it needs to be it doesn't matter what boats its on. The motor doesn't know weather it's on a 16' or 28' as long as it's propped to run at the recommend rpm.

You may get the rpms but not the speed....you may get 5000rpms on a 28 ft boat--but you'll be lucky to get 10mph---and you will spin the hub out on your prop in short order. I can put a 9.8 hp Merc on my toon (world's fastest 9.8 btw) turning 5-6000 rpms and I wont get much speed. The only cure for his boat is horsepower--running half the rated HP is why he will never have any performance--it aint the prop--altho it will help some.

[jonboy2542]

I'll be honest, both seem like good points to me. I don't completely understand pontoons yet so I can really say. I am going to try the prop first, as it is the cheapest or find one to try if I'm lucky. But will this help with blowouts? As it sucks crossing down the river and all of a sudden a blowout, throttle down, back to normal, speed up, repeat.


Again thank you to all who help

[Marc K]

Yes I meant 5000 rpms, typing on my phone lol. That motor was a 1983 4 cylinder 50 HP mercury. They didn't turn the rpms of a newer version.

My whole point of the example is that the Op's motor can be made to work. It simply needs to be in the proper rpm range. If his motor is running where it needs to be it doesn't matter what boats its on. The motor doesn't know weather it's on a 16' or 28' as long as it's propped to run at the recommend rpm.

You may get the rpms but not the speed....you may get 5000rpms on a 28 ft boat--but you'll be lucky to get 10mph---and you will spin the hub out on your prop in short order. I can put a 9.8 hp Merc on my toon (world's fastest 9.8 btw) turning 5-6000 rpms and I wont get much speed. The only cure for his boat is horsepower--running half the rated HP is why he will never have any performance--it aint the prop--altho it will help some.

I would respectfully suggest that getting a prop that allows the motor to run in its design range when WOT would be the best starting point.

Marc

[wwind3]

I'll be honest, both seem like good points to me. I don't completely understand pontoons yet so I can really say. I am going to try the prop first, as it is the cheapest or find one to try if I'm lucky. But will this help with blowouts? As it sucks crossing down the river and all of a sudden a blowout, throttle down, back to normal, speed up, repeat.


Again thank you to all who help

Interesting re: the blowouts.. Does it happen in calm water?

[jonboy2542]

Yes in calm as well. It's confusing

[wwind3]

Yes in calm as well. It's confusing

when it happens do your rpms go way up? If so---your hub is spinning out.....mine did it at 3000---ran ok till then and then hub would slip. Tried a different prop? If it does it with a different prop I go back to water flow around prop is getting disturbed---like stalling a wing on an airplane...probably motor shaft is too long.....

[jonboy2542]

I wouldnt say the rpms go all the way up but they do go up some. Currently it will jump from 4000 to about 5000. I will more the hub next time I go out and check for slippage. If i do change the prop,I am thinking of going with a 4 blade. At the current time, I cant really afford another motor

[Liquid Asset]

If you are going to get a 4 blade Id recommend calling the help line at Michigan wheel. An online prop calculator is fine but with your situation needing to get up to the proper rpm first and then adding the additional variable of switching to a 4 blade it's more complicated. They were very helpful when I talked to them in the past.

[wwind3]

I wouldnt say the rpms go all the way up but they do go up some. Currently it will jump from 4000 to about 5000. I will more the hub next time I go out and check for slippage. If i do change the prop,I am thinking of going with a 4 blade. At the current time, I cant really afford another motor

A pontoon prop is under tremendous force trying to push the boat thru the water....all the time...like I said before--I've blown my hub out at least 2 times. Wont be noticeable till you get to a certain point.. Mine was around 3-3500rpm--then it would break loose and overrev. See if you can borrow a prop and try it. If it's the problem --relatively cheap fix. I'm running a 3 blade Merc SS and a 3-blade aluminum as a spare. Both will spin around 5800 rpm--if I overtrim a tad more--overrev alarm will go off. Never tried a 4 blade....good luck

[jonboy2542]

So I purchased a new prop and hub kit. I am going to try it on the water Friday. I will let you guys know what the verdict is

[onlybillhere]

i was out sunday on the river...ran at WOT no ventilation both upstream and down. Going upstream was more of a chore for the pontoon, it didn't help to have a pretty stiff head wind too. raising the motor was the best thing for it. It even stopped all the spray that was covering the motor and sun deck (that was really annoying).

I hope this fixes the issue with yours....i feel your frustration.

[wwind3]

So I purchased a new prop and hub kit. I am going to try it on the water Friday. I will let you guys know what the verdict is

[wwind3]

So I purchased a new prop and hub kit. I am going to try it on the water Friday. I will let you guys know what the verdict is

Any report yet?

[jonboy2542]

So I am a little late on testing things out due to the recent hurricane and a death in the family. Anyways.....


I ran into a problem; when I installed the new prop, i forgot the thrust washer and I ended up gashing the bearing carrier pretty bad and the prop. I replaced the bearing carrier after screwing up and decided to continue with the new prop even with the slight damage. It did run a little better I got around 19 to 20 mph gps. But there is a gap between the prop and bearing carrier so i believe that might have some restriction. I will yet again replace the prop but might try a different size.