Outboard Motor Shaft Length

[bowhunterfanatic]

I'm getting ready to finally bite the bullet and replace the outboard on my boat. The current outboard has a 20 inch shaft. I've found a smoking deal on a new Mercury but the problem is it's a 25 inch shaft. Is there any reason I can't just install it on a manual jack plate and raise it up 5 inches to essentially turn it into a 20 inch shaft? I can buy the outboard I've found plus a jack plate and have it installed for the same price as what everyone else has quoted me just the bare outboard cost. Saving $2,500+ seems like a no brainer if the jack plate will allow me to use the longer shafted outboard.

 

[GMONEY865]

I'm getting ready to finally bite the bullet and replace the outboard on my boat. The current outboard has a 20 inch shaft. I've found a smoking deal on a new Mercury but the problem is it's a 25 inch shaft. Is there any reason I can't just install it on a manual jack plate and raise it up 5 inches to essentially turn it into a 20 inch shaft? I can buy the outboard I've found plus a jack plate and have it installed for the same price as what everyone else has quoted me just the bare outboard cost. Saving $2,500+ seems like a no brainer if the jack plate will allow me to use the longer shafted outboard.

i would not advise doing this because you will be adding a lot of extra weight with the jack plate and the longer motor being heavier than a 20in model. plus you would not get any advantage with a jack plate being maxed out all the time.

what kind of boat and size motor is this going to be?

 

[bowhunterfanatic]

i would not advise doing this because you will be adding a lot of extra weight with the jack plate and the longer motor being heavier than a 20in model. plus you would not get any advantage with a jack plate being maxed out all the time.

what kind of boat and size motor is this going to be?

18 foot War Eagle. 115 4 stroke outboard. From what I can find the jack plate plus the longer shaft would add about 50 pounds, so definitely enough weight to make a difference. I'm not concerned about not gaining any performance as going a few MPH faster doesn't interest me.

 

[GMONEY865]

you could get your transom built up to 25in and then bolt the motor straight to the transom. the more setback you have with more weight will make the backend squat more than you think.

 

[bowhunterfanatic]

you could get your transom built up to 25in and then bolt the motor straight to the transom. the more setback you have with more weight will make the backend squat more than you think.

That makes sense. Hadn't thought about that. I'll keep looking and see if I can't find a better deal on the 20 inch version somewhere. Thanks!

 

[GMONEY865]

That makes sense. Hadn't thought about that. I'll keep looking and see if I can't find a better deal on the 20 inch version somewhere. Thanks!

no problem.

 

[MickThompson]

you could get your transom built up to 25in and then bolt the motor straight to the transom. the more setback you have with more weight will make the backend squat more than you think.

This is what I would do. Need the motor even higher as you add setback.

It will almost certainly void any warranty on the hull though.

 

[hammer33]

Price having the bottom end swapped out. Probably more expensive than getting the "right" motor but who knows.

 

[TNLynn]

SEI lower units out of Florida for cheap with warranty.

 

[MickThompson]

I think you'd have to swap the foot and the midsection.

 

[vanleerbuckbuster]

SEI lower units out of Florida for cheap with warranty.

Sei is good people