If you were an engineer, you'd know what an impossible question you've
asked.

I can't imagine using a single flat plate of aluminum to clamp a 200 hp
outboard motor to. I'd add bends and channels and the strength and
stiffness would increase vastly, but that's before the motor clamps dug
holes in the metal thru electrolysis and friction. (Actually, I think I'd
use a hardwood beam with aluminum brackets, but you'd be better off going by
the boat store or marina and seeing what the professional designers used.)

What distance would this transom span between supports?

How would the torque, weight and thrust be transferred to the hull?

Did you figure that for the motor in both up and down positions?

Given the expected shock loads, better use a safety factor of at least ten
when figuring stresses.

Don't give me the numbers. They're for you to mull over. The last class I
had in that kind of design was 1952.

Roger

http://home.earthlink.net/~derbyrm

"André Langevin" wrote in message
...
mmmm seems nobody is building in aluminum...

"André Langevin" wrote in message
...
Hi, does someone knows the thickness required for an aluminum transom to
support the weight and pushes of a 200 HP engine without deforming ? I
guessed 3/8" but i'm no engineer.

Any advice would be truly appreciated.