shaft length

chuck172

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Joined
Aug 29, 2007
Messages
11
I'm looking to buy this used Johnson 8HP. When I asked him the shaft length he said from the plate above the prop to the clamp is 18".
Is this considered short or long shaft. I need a long. I thought short is 15", long is 20"
 
Last edited:

Scaaty

Vice Admiral
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May 31, 2004
Messages
5,180
Re: shaft length

I'm looking to buy this used Johnson 8HP. When I asked him the shaft length he said from the plate above the prop to the clamp is 18".
Is this considered short or long shaft. I need a long. I thought short is 15", long is 20"

If 18, its for a 15 inch transom..short shaft.
Long shaft would have a 5 inch extension, and mostly used for bigger boats/sailboats, as a kicker...some have 25 inch shafts, strictly (well, mostly) for sailboats
 

nntw4

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Joined
Aug 3, 2007
Messages
7
Re: shaft length

My 14' aluminium has a 15" transom. We have an old motor that came with our cottage, but it's not a good match.

So, I should shop for a "short shaft" motor with a 15" shaft? Thanks!
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,771
Re: shaft length

On an 8 HP engine, that shaft length will not make any difference. If the engine is a good buy otherwise, go for it.
 

nntw4

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Aug 3, 2007
Messages
7
Re: shaft length

thanks, but i'm looking for a 15 hp, max the boat can take. think i want a 15" shaft, yes?
 

nntw4

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Joined
Aug 3, 2007
Messages
7
Re: shaft length

thanks- that's what I figured. I've got a line on a 15 hp 2005 mercury 4 stroke that supposedly has minimal use on it- just have to check it out and then part with the money- just in time for winter storage up here in toronto!
 

chuck172

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Joined
Aug 29, 2007
Messages
11
Re: shaft length

My 14' aluminum starcraft seafarer measures 17' from the top of transom to the bottom of boat. Not counting the keel.
I have been told I need a long shaft engine (20")
Now this deal comes along on an older Johnson 8hp. The owner measures the motor and tells me its 18" from "the clamps to the plate above the prop"
This confuses the hell out of me. I thought motors are either 20" -long, or 15"-short.
Maybe the owner didn't measure correctly.
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,771
Re: shaft length

Ya think??? It could also be that the engine was tilted a little off vertical. That could easily alter the measurement and you have no idea what points the measurement was taken from on either end. Your 17 inch transom would very likely handle either a 15 or 20 inch shaft. I really doubt the 8 HP had an 18 inch length, and if it did, its perfect for you is it not?
 

chuck172

Cadet
Joined
Aug 29, 2007
Messages
11
Re: shaft length

Thats good news that my boat could handle both long and short shaft engines. I was told that with the 17" transom measurement to make sure I get a long {20"} shaft motor.
 

steelespike

Supreme Mariner
Joined
Apr 26, 2002
Messages
19,069
Re: shaft length

Measure the line perpendicular to the keel. will be somewhat less than measured along the actual transom.
 
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