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Author Topic:   Ideas for mounting Merc 50 4-stroke to 1970 classic hull
rb posted 02-27-2002 01:41 PM ET (US)   Profile for rb   Send Email to rb  
I ended up ordering a new Merc 50 4-stroke for my 1970 16' classic and after reading about Bruce Montgomery's beautful restoration on his Nauset I don't think using only the two existing bolt holes is going to be enough to support the engine. I had thought of using one of those transom saver bars that spans the two holes and perhaps two lag screws for the bottom holes on the engine mount, but would rather not use the screws. Anyone have any thoughts?
P.S. Thank you to Bruce for the e-mail imput
whalerron posted 02-27-2002 11:45 PM ET (US)     Profile for whalerron  Send Email to whalerron     
I thought the Merc motors all had the standard mounting template that is used by OMC. I was also under the impression that, like the OMC motors, the Merc 2-strokes had two blind mounting holes so that they could be mounted on the Whalers using bolts that pass through just above the bottom of the splash well. With this in mind, are you sure the Merc 4-strokes don't have those two blind mounting holes?

Bigshot, are you familiar with the Merc brackets? Did they really omit the blind mounting holes? That Nauset is a fine looking boat but it sure is a shame that he had to tear up the splash well to mount the motor.

I would never use the lag bolt method of attaching the lower end of the bracket. It is doomed to fail.

jimh posted 02-28-2002 08:44 AM ET (US)     Profile for jimh  Send Email to jimh     
[Minor edit of posts to improve readability--jimh.]
lhg posted 03-06-2002 11:50 PM ET (US)     Profile for lhg    
Use a 6" setback bracket. The bracket to transom connections can use the four 1/2" bolts needed, and still fall into the splash well. The bracket may have to have a set of higher holes drilled in it. Then the standard engine bolt pattern will mate to the bracket holes.
RKM posted 05-14-2002 12:17 PM ET (US)     Profile for RKM  Send Email to RKM     
Well what did you do? Last year I mounted a 90hp 4 stroke Merc on my 1969 Eastport. I used the top holes from the 55hp OMC, but had to drill another lower set, but also in the splash well. I plugged the lower holes from the 55hp. I refused to use the lag bolt approach. The motor is tight, but I do not do any wave jumping. The top mounts are the most important anyway.

Good luck

lhg posted 05-14-2002 02:54 PM ET (US)     Profile for lhg    
None of Mercury's engine brackets, using the NMMA standard hole pattern (30-250HP), have blind threaded holes. But the standardized hole pattern will work on a 16' hull. The bottom two holes line up with the drain hole.

The Nauset shown in the reference section shows these holes, which held a 1984 Merc 115 using the same engine bracket/hole pattern still in use today by Mercury.

Highwater posted 05-15-2002 07:45 AM ET (US)     Profile for Highwater    
lhg--I have often thought about using a setback on my 13'. I am curious how "back-heavy" this would make the boat. My 40 hp engine weighs 200 pounds. Do you know of any way to calculate what the equivalent weight to the back of the boat would be if I were to use a 6" setback to mount my 200 pound outboard to the 13' hull?
goldstem posted 05-15-2002 11:01 AM ET (US)     Profile for goldstem  Send Email to goldstem     
we just got a suzuki 50 fourstroke for our club's old 16 classic and had this problem.

we mounted the motor as low as it could go with all bolts and it ended up with the cavitation plate about 1.5 inches or so above the bottom. I was worried about it but it runs great. no ventilating, no blowout when turning. am very happy. I thinking I should raise the motor on the 1972 21' outrage a peg.

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