Mercury 40hp long shaft or short shaft?

dhonda

Seaman Apprentice
Joined
Aug 1, 2010
Messages
43
Hello, i recently found a 1993 mercury 40hp longshaft for sale that id like to buy for my 1957 crestliner viking 14" but my concern is it being a long shaft motor. I beleive mercury long shaft motors are 20" and the old gale 40hp thats on my boat now is only 18" long and the cavitation plate on that sits a couple inches below the boat. Will this mercury motor work or is it too long for my boat?
 

Barnacle_Bill

Admiral
Joined
Feb 8, 2004
Messages
6,469
Re: Mercury 40hp long shaft or short shaft?

It will work but not very well. It sounds like you need a motor with a 15" leg. The cavitation plate needs to be even with the bottom of the boat. Since you are replacing the one you now have (which is too long) get the right motor. You will be very pleased with the results.
 

Texasmark

Supreme Mariner
Joined
Dec 20, 2005
Messages
14,785
Re: Mercury 40hp long shaft or short shaft?

the old gale 40hp thats on my boat now is only 18" long and the cavitation plate on that sits a couple inches below the boat. Will this mercury motor work or is it too long for my boat?

You can go to the oldomc.de site and see a lot of old OMC(Gale mfgr) engines mounted on a lot of boats. You can see how far the OMC engines built for 15" transoms stick below the bottom of the boats. I think this extra length is due to the type of water pickup those engines had. The Merc didn't have the same type of pickup so their engines of the day were more like 15" for the 15" transom.

Your 20" is 5 inches too long for your boat and will create abnormal drag and undesirable performance. Get yourself a 15" engine.

Mark
 
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