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  #1  
Old 10-08-2019, 03:02 PM
Powder Powder is offline
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Join Date: Feb 2014
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Default long shaft motor on short shaft boat?

I'm not wanting to do this on purpose but what would happen if I had a long shaft motor on a short shaft boat? I'm thinking the scenario would be a 20hp on a 14ft boat. Would it work and just stick out lower?
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  #2  
Old 10-08-2019, 04:01 PM
grizzley grizzley is offline
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Google> long shaft motor on a short shaft transom.
It will work, but it's far from the best setup, I added a riser to a 1648 Tracker GRIZZLY to raise a jet to where it needs to be, some guys use jack plates.
First of all, the cavitation plate will be way lower than it should be, second the lower unit being further down in the water will create more drag, and third you will need more depth to run in.
I would say you need either a riser, a jack plate, or a boat with the proper transom, if you like the boat I would look into simply adding a riser to the transom, many guys have done that.
Here is a pic. of the riser I made for mine.
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Old 10-08-2019, 04:10 PM
Huntindave Huntindave is offline
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Quote:
Originally Posted by Powder View Post
I'm not wanting to do this on purpose but what would happen if I had a long shaft motor on a short shaft boat? I'm thinking the scenario would be a 20hp on a 14ft boat. Would it work and just stick out lower?
Will it "work"? Short answer, very poorly.

Many older motors were built such that they could be switched from long shaft to short shaft and vice-versa by way of switching a few key parts. This can be a relatively inexpensive solution using used parts. You might want to do some research to see if this an option in your situation.
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Old 10-09-2019, 08:56 AM
DW DW is offline
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Or you could buy a used 15 lower unit and sell or trade your 20. There is a robust market for used lower units.
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Old 10-09-2019, 01:04 PM
jjy jjy is offline
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I purchased some Aluminum Angle and drilled a few holes to match my transom and motor holes. That enabled me to run a 20" shaft on a 15" shaft transom. I had to play with engine height but got it dialed in. I'd start with motor cavitation plate 1" above boat bottom. I purchased from Speedy metals.
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  #6  
Old 10-11-2019, 10:46 AM
Tdobb Tdobb is offline
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Here is the "jackplate" I built for my old boat with a 2x8x3/16 aluminum tube. Mounted that to the back of the boat and ran it all the way down to the bottom of the boat and angled up slightly to reduce the amount of water coming up into the tube as I am running the lake. Running it down really helped stiffen the transom on the old Lund.

https://live.staticflickr.com/3928/3...162ceb40_z.jpg
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