first of all - - :WELCOME: to the "forever boats" forum !!!
Okay, here is how my 1648 Blue Fin was when I bought it.
I had no idea of how the transom was constructed - never seen this style before.
When the 35hp Force died from a water pump failure, I found another one but
was 2" longer . . . so, the transom had to be redone. Here is how I did it.
I will try to get the pics in order from start to finish, just try to see it in your mind.
When you mention welding 2x6" together, personally, I think that is a little overkill.
BUT-it will work quite well.
For me, in MY world, I would use 1-1/2" square tubing with a 1/4" plate either spot welded
or glued and riveted (which is a bit cheaper).
Now, attaching it to the transom, with never worrying about corrosion, is another matter
all by itself. ALL surfaces must be surgically clean, etched, primed and painted correctly.
I would not weld the transom board directly to the hull as it can never be removed "when"
you have some corrosion issues to address. EVERYTHING made out of aluminum will need
proper maintenance to last a life time. Just figure out some kind of barrier to go between
the 2" transom board and the hull. PVC sheet, plexiglass, something that will not absorb
and retain water - especially salt water, should you ever go there.
Basically what I have made is a "jack plate" motor mount that can be adjusted from 18" to 22"
just by removing the mounting bolts and drilling new holes to the desired length.
It is two sheets of 1/4" aluminum plate glued to the 1-1/4" tubing with construction adhesive.
Which brings the total thickness to 1-1/2".
I did not use 3M5200 or silicone because in my mind, they actually
promote corrosion.
Once bolted into place, it holds the 50hp in place quite well with NO flexing what-so-ever.
You could use this same concept but run the tubing horizontal and bolt it to your transom hull.
EXTREMELY IMPORTANT::::: try to arrange everything so the holes that you have to drill for your
motor do not fall where the two tubes meet together !!!! Very Very hard to drill through the WALLS
of that tubing !!!! (( go ahead, ask me how I come to know this little tidbit )).
Some photos of
your transom would help a lot.
Jus my dos centavos
