Replacing my front motor mount
 

Not the metal part, but the part of the boat that the metal attaches to. To
make a long story short, I found that the wood that my front motor mount is
screwed into is rotten. (The long version, with illustrations, is he
http://users.adelphia.net/~blizzard3/boat/mm.htm) It's an old fiberglass
boat, 1977 Thunderbird S-18, to be precise, with a Merc 165 IO. The pad that
the front motor mount sits on is basically a big block of wood encased in
fiberglass. I've dug it out and I'm getting ready to rebuild it. What I'm
wondering is whether I should try to duplicate the original wood and
fiberglass construction or would there be something better to make the
mounting pad out of? (I don't want to have to do this job over every 27
years.)

Replacing my front motor mount
 

If adjustment allows, I use a piece of 2" wide 1/4" thick aluminum angle as
long as possible to span the bad wood full length if possible. There is a
chance that the only real bad portion is where the lag bolts are attached to
the wood and that there is good wood on beyond that. Use lag bolts to
secure the aluminum to the original wood, on both faces of the angle but
this time coat the lag bolts and force plenty of sealer such as 3M 5200 into
the pilot holes. Do all possible to seal out water in the future. (Most
likely the manufacturer didn't do this step).

Naturally you'll have to re-adjust the motor mount so the shaft and gimbal
bearing run true due to the additional 1/4" height. Should last "forever".

Don Dando


"Joe Blizzard" wrote in message
...
Not the metal part, but the part of the boat that the metal attaches to.
To
make a long story short, I found that the wood that my front motor mount
is
screwed into is rotten. (The long version, with illustrations, is he
http://users.adelphia.net/~blizzard3/boat/mm.htm) It's an old fiberglass
boat, 1977 Thunderbird S-18, to be precise, with a Merc 165 IO. The pad
that
the front motor mount sits on is basically a big block of wood encased in
fiberglass. I've dug it out and I'm getting ready to rebuild it. What I'm
wondering is whether I should try to duplicate the original wood and
fiberglass construction or would there be something better to make the
mounting pad out of? (I don't want to have to do this job over every 27
years.)

Replacing my front motor mount
 

"Don Dando" wrote
If adjustment allows, I use a piece of 2" wide 1/4"
thick aluminum angle as long as possible to span
the bad wood full length if possible. There is a
chance that the only real bad portion is where the
lag bolts are attached to the wood and that there is
good wood on beyond that.

I've already removed all the wood. There was still some good wood in there,
but it wasn't secured to anything. The whole mounting pad was only held in
place by a single layer of woven roving fiberglass over the top of it.

Do all possible to seal out water in the future. (Most
likely the manufacturer didn't do this step).

That's my plan and no, they didn't. In fact the fiberglass around the wood
created a little well that held water.

Naturally you'll have to re-adjust the motor mount so the shaft and gimbal
bearing run true due to the additional 1/4" height. Should last
"forever".

I already had the drive off for bellows replacement when I started this, and
was planning on a realignment anyways, so that's no biggy.