Replace 20" with 25" issues?

JWhit

Petty Officer 2nd Class
Joined
Mar 29, 2010
Messages
130
I have an older motor that needs to be replaced, it's got a 20" shaft. Have found a good used motor that is 25" shaft, can this be used and what are the risks? I assume that it may sit lower than the pontoons, slight angle issue? Thanks
 

EGlideRider

Lieutenant Junior Grade
Joined
Dec 14, 2008
Messages
1,000
Re: Replace 20" with 25" issues?

What size boat and motor? I don't think you'll have a problem.

You should be able to raise the new motor. Examine the mounting holes in the new motor to determine how much.

Good luck
 

JWhit

Petty Officer 2nd Class
Joined
Mar 29, 2010
Messages
130
Re: Replace 20" with 25" issues?

24 foot pontoon, current motor is 77 johnson 140, (new) is late 80's force 125
 

EGlideRider

Lieutenant Junior Grade
Joined
Dec 14, 2008
Messages
1,000
Re: Replace 20" with 25" issues?

Mmmm. Lots of horses.... In the early 80's, I had a 24 footer with a 140 and it would outrun everything on the lake.

I still don't think you'll have a problem. If you were happy with the old setup, I would try to raise the new motor close to the 5 inch difference and then lower it if you get any ventilation.

The only disadvantages of going too low are a little more parasitic drag and an increased chance of hitting underwater obstructions.
 

JWhit

Petty Officer 2nd Class
Joined
Mar 29, 2010
Messages
130
Re: Replace 20" with 25" issues?

thanks for the advice, if i can get it running well i think i'll throw it on there. i'll just be careful in shallow water to tilt it up
 
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