long shaft on short transom help

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Crazydawgs29@gmail.com

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OK let's start out with I know I should get a short shafts motor but can't afford 1 right now. Yes a transom elevator would work but my transom is odd ball so I don't think it will.

Here's the story I have a 1962 seahawk boat. It had a 1973 Johnson 40hp short shaft on it. Well the motor took a crap on me. I ended up finding a 1976 evinrude 40hp long shaft model 40655R for next to nothing. Mounted it to boat and it runs absolutely amazing. Bad thing is my plate is 5 inches lower then the hull.

Will I be fine running this motor on this boat will I be able to use it for fishing or what.
 

oldboat1

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Check them out for a l.u. swap. Water tube should use a removable extension for the long shaft, so no issue there. Short shift shaft should reach your current connector fine. If the driveshafts swap (same splines), you're in business. Sorry -- can't say offhand if it's a match....
 

racerone

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There was a change in driveshaft diameter in the last years of 40 hp production.---Not sure just what years it was done.-----If driveshaft spline is the same just change the long to a short.
 

F_R

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I'm pretty sure you are going to find the drive shafts are different. That '76 shaft is going to be a bit rare, so you probably can sell it.

You asked if you could use it as a long shaft. Sure you can, but you won't like it. Aside from the water depth needed, it will spray water all over and be slow.
 

Crazydawgs29@gmail.com

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It's not a speed boat. I only need to get to the fishing spot and back. I'll test it out and see what it's like. Eventually I'll change it to short shaft or get another engine
 

ondarvr

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What is it that's odd about your transom that makes it so you can't put a riser on it?
 
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Fishahollik

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I had similar problem with my flat bottom
with 15" transom. I built a large "jack plate" using marine plywood, gorilla glue, and fiberglass to raise it 5" and bolted it across the back of the boat using 3M 5200 around all the bolt holes. Works great.
.
 

interalian

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Once at the shop where I worked in the '80s, a customer brought in an old 18' cruiser boat with a toasted ~1960s 75hp V4 that had a 15" shaft. We sold him a 90hp with a 20" shaft. The transom was built up using 1/4" aluminum plate about 36" wide and 18" deep to cover the transom, a section welded on the top to match the transom thickness, and another plate welded to that, going down to the splash well. A trimmed 2x6 was fitted inside and the whole mess screwed and epoxied to the original hull. Once cured, the 90 was bolted on as usual. Worked well.
 

Crazydawgs29@gmail.com

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Well for anyone curious as I was I took the boat out and tested it. With my original 40hp short shaft I ran on average 24.5 mphs with this long shaft 40hp I was running 24mphs no rooster tail no issues planing at all in fact I believe it planed a little better. The only difference I saw was turning while WOT the turn was a little hesitant but drop the throttle a little and it acted just like the short shaft. In conclusion I really didn't see much difference at all. I'll run it like it is until I get the shorter lower end or trade it for a different short shaft.....
 

ondarvr

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The only thing that matters is if you're satisfied with how it works.
 

racerone

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Sounds like the " long " motor was in fact a short shaft.-See short shaft motors advertised as " long " all the time.
 

Crazydawgs29@gmail.com

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No the motor I took off was a short shaft. The motor I put on is a long shaft without a doubt. The cavitation plate is 5 inches below the hull of my boat. It's definitely a long shaft on short transom
 
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