Minimum practical thickness of aluminium?

[Raggi_Thor]

What is the minimum practical thickness of aluminium?
It seems like even the smallest boats are built of minimum 2mm alu?
I ask because "aitchem" asked for an aluminium version of the Backman 18.

I have always thought that for small light boats it's the local stiffness that is the dimensioning factor while for large (long) heavy boats you also have to look at the global stiffness (the hull as a beam supported at each end).
If 6mm plywood at 3kg/m2 is a practical minimum, I can't see how small aluminium boats can be as light as a plywood boat.

Any comments from the metal boat builders?

[Raggi_Thor]

Did I post to the wrong forum?
Is 3mm the minimum practical thickness to weld?

[alyne]

Not sure about sheet alluminium, but I have just had a frame tig welded together using 16guage (approx 1.6mm) thick aluminium tubing. Worked a treat!

[Thunderhead19]

Being able to weld it is the real issue on small boats. Riveted hulls can be as thin as 1mm. 3mm makes a good easily, inexpensively, weldable, durable hull, 4mm and you can go ramming other boats.. well not quite..

[Raggi_Thor]

Thanks to both of you, maybe riveting or gluing is the way to go in very small boats?

[gonzo]

Palmer Johnson used to build 12M boats in glued, lapped aluminum.