1983 Merc 50hp mounting question

ledzeppelin135

Petty Officer 2nd Class
Joined
Jul 27, 2011
Messages
129
Hi all,

I am at the stage where I will be remounting my Merc 50 back on my 59' harvey. I realized that when I had it on previously, it was hanging down too low and I am now realizing that I need to raise it about 3-4", but I am puzzled on exactly how to do this. I understand that this boat is most likely preferred to have a short shaft motor on it, but when measuring the transom, it should be able to accept a long shaft as well. My question is the mounting bracket on the Mercury has a two lower mounting holes, two upper mounting holes, and then the set of mounting clamps on the top as shown in the picture. By raising the mercury 4 ", these clamps will most likely not be fastened to the transom, but by having the two sets of bolt holes fastened to the transom of my boat, would this be ample in holding the motor on? I am wondering if the bracket was designed for this use as well or if it is imperative to have the clamps attached?
 

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endurance

Seaman
Joined
Nov 10, 2009
Messages
69
Re: 1983 Merc 50hp mounting question

My merc inline 6. Ad 4 mounting holes 2 on bottom 2 on top
Just like the johnny v4. I think you will be ok. It seems like they did that
For various boat apps.
 

endurance

Seaman
Joined
Nov 10, 2009
Messages
69
Re: 1983 Merc 50hp mounting question

Do not forget to use silicone sealant. Around holes
Keep it waterproof so water does not get inside inner part of transom
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
27,278
Re: 1983 Merc 50hp mounting question

Most Mercs of that vintage were Longshaft motors (20"). Measure the transom on the boat from where the motor transom bracket would sit to the bottom of the hull. If the boat measures about 15", then the transom is expecting a shortshaft motor.

You cannot just bolt that motor on to the transom using the bottom mounting holes. Those transom clamps need to be used. You will need to extend the transom up close to 5". There are ways to do that, using steel and wood components, or using a jackplate.
 

ledzeppelin135

Petty Officer 2nd Class
Joined
Jul 27, 2011
Messages
129
Re: 1983 Merc 50hp mounting question

I had read various places that it would be ok to use the two holes at the very bottom and two holes towards the top of the bracket to mount the motor, it is similar to the mounts that my old 69 evinrude took
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
70,622
Re: 1983 Merc 50hp mounting question

I had read various places that it would be ok to use the two holes at the very bottom and two holes towards the top of the bracket to mount the motor, it is similar to the mounts that my old 69 evinrude took

Ayuh,... Then Go for it....

Though I'm thinkin' that if ya raise it 4", the top bolt holes will see nothin' but Air...
 

ledzeppelin135

Petty Officer 2nd Class
Joined
Jul 27, 2011
Messages
129
Re: 1983 Merc 50hp mounting question

anyone else have an answer, I am just wanting to make sure it is designed to be ok with this mounting system or a for sure not...
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
27,278
Re: 1983 Merc 50hp mounting question

Led, The transom clamps are quite strong, as they are made to stay together if you hit something. Bolting them up that high will weaken them a lot. Will they still be strong enough for your use, who knows....
 
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