Can I use "short" shaft o/b on "long" shaft transom?

[Shelby Ladner]

I have a 2000 model Johnson 25HP short shaft and I am trying to use it on a "Tracker" Grizzly 1448 aluminum john boat. The transom measures 21" inside and my a/v plate is approx. 3" above keel. It looks like I could lower engine 3" and tiller arm will clear. Could I use a T-H Marine Mini Jacker and reverse mount to lower my outboard 3"? Any suggestions would be appreciated! Thanks

 

[Silvertip]

Re: Can I use "short" shaft o/b on "long" shaft transom?

I do believe that's why they make both long and short shaft motors. If the prop isn't in the water you don't go anywhere. Once the boat is on plane the water is even with the bottom of the boat so the prop tips would likely be a couple inches out of the water. Don't think that will work. But why even ask. Try it and move the motor down if you can.

 

[mars bar]

Re: Can I use "short" shaft o/b on "long" shaft transom?

I think the less motor that's in the water the less handling you'll have and remember the water intake.

 

[coolguy147]

Re: Can I use "short" shaft o/b on "long" shaft transom?

the water intake is the most important part. better to have a long shaft motor on a short shaft boat.

 

[trendsetter240]

Re: Can I use "short" shaft o/b on "long" shaft transom?

I have a 2000 model Johnson 25HP short shaft and I am trying to use it on a "Tracker" Grizzly 1448 aluminum john boat. The transom measures 21" inside and my a/v plate is approx. 3" above keel. It looks like I could lower engine 3" and tiller arm will clear. Could I use a T-H Marine Mini Jacker and reverse mount to lower my outboard 3"? Any suggestions would be appreciated! Thanks

Yes it will work up until you try to plane. Displacement speeds will be fine but the moment your hull starts planing the engine will ventilate and you will go nowhere.

How do I know? Because I've tried it.

 

[Shelby Ladner]

Re: Can I use "short" shaft o/b on "long" shaft transom?

You are correct Trendsetter240. Once boat starts to plane prop spins out. What I was contemplating was purchasing a mini jacker (for raising o/b when using long shaft on short transom) and inverting to lower mine. I guess other options would be to either cut down transom or swap motors.

 

[DJ]

Re: Can I use "short" shaft o/b on "long" shaft transom?

Short answer-NOPE!

 

[McBoatin]

Re: Can I use "short" shaft o/b on "long" shaft transom?

I have gotten away with a short shaft on a 17.5inch transom (i know odd, a 1968 Landau Mod-V)

I used it on the river and at low speeds it would work great. at speed when it was about to plane the motor would get air around the prop and it caused poor power and the boat kinda shifted back and forth. You have a longer transom I think. It is not desirable but as long as water is pumping through the motor you will be fine at lower speeds. I never made it up the river as fast but I usually wasnt trying.

On the other hand I used a longshaft most of the time. It sat too low in the water, which is not good for rivers. I couldnt find a happy medium.

What i would have done is cut down my transom 2inches. I would not recommend it thought and after some research never did it.