Aluminum scantling for transom
 

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.

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.

I would think that it depends on several factors... width and height, where any additional braces would be... it isn't just a simple answer.

Ed

--
When replying via email, replace spam with speak in the address.
"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.

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.

I currently have 1/8 and the force applied by the stern will be 2000 pounds. The plate would be 25 x 32 inches and would be supported by frame or weld. Only concern is that i don't want it to flex at all. So i've though of 1/2 in 5000 series.
"Ed Edelenbos" wrote in message ...
I would think that it depends on several factors... width and height, where any additional braces would be... it isn't just a simple answer.

Ed

--
When replying via email, replace spam with speak in the address.
"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.

Agreed. The best thing for the uninformed to do is to go find a similar
boat that's commercially made and runs at least as much horsepower, then
give it a close examination ...sketches, measurements, lots of photos. Then
go home and duplicate it exactly. If the boat is not going to be engineered
and the deflections and section moduli known up front, then imitation is
your next best bet (good way to verify your design work even if you ARE an
engineer and did the calcs too.)

Brian



"Roger Derby" wrote in message
link.net...
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.

On Sun, 11 Sep 2005 09:56:45 -0400, André Langevin
wrote:

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.


Not quite what you asked for - but to fix up a bass boat with a broken
transom for my son, I added a 1/2 ply false transom outside, and two
two by four cross-beams inside (bending in their weak dimension)
through which the engine was bolted.
This was to handle a 90 HP engine which it has done faithfully for
the following eight years,

Brian Whatcott Altus OK