On Tue, 1 Dec 2009 15:27:32 -0700, "Bob La Londe"
wrote:

"Bruce In Bangkok" wrote in message
.. .
On Mon, 30 Nov 2009 18:42:10 -0700, "Bob La Londe"
wrote:

"Steve Lusardi" wrote in message
...
No. Aluminum is very reactive. Corrosion will occur for a multitude of
reasons. It is almost unavoidable and when it does, it is FAST, but
ultimately the scantlings of any boat is a product of size and hull
design. Your comment of .125" as heavy duty, that true if the boat
doesn't
exceed 18'.
Steve

"Bob La Londe" wrote in message
...
I find it interesting that a lot of the small boat aluminum designs seem
to say the main hull should be 3/16 and yet .100 is used in a heck of a
lot of commercially available small boats. .125 is considered heavy
duty.
Is it just CYA?

I've been looking at some of the smallest boats, and there are some with
hulls as thin as .043. Holy cow. No wonder they are riveted. When I was
first practicing aluminum welding I discovered that was below the
threshold
for my skills and/or machine. I could make two piece of .043 tube stick
together, but it wasn't pretty.

http://www.trackerboats.com/boat/specs.cfm?boat=3257

Holy cow. Its like tissue paper.

I suspect that it is mainly a matter of cost, or how their particular
shop is set up to work. Certainly there isn't much of a trick to
welding 1 mm stuff and that is thinner then .043" stuff so I doubt
that it is the wielding itself that is a problem. My guess is that it
is warping that makes them rivet it as welding seams in flat aluminum
can result in some very exotic shapes if considerable effort isn't
taken to prevent it.
Cheers,

Well, of course its "possible" to weld. I imagine if I went to a smaller
(maybe .23) diameter wire and got feed rollers for my spool gun to handle it
I might even be able to do it with my big MIG rig. Might have to go to a
helium mix instead of straight argon so I could reduce material removal
during cleaning, and then of course I would have to lock stitch and then
back fill. It's a big pain though, and that's why:

"No wonder they are riveted."

Its just not worth the effort of welding for a low price "throw away" boat.

A small TIG torch could handle it easily enough, but it would be
slooooooooowww.

P.S. You do the lock stitch and back fill method on thicker material too.

I know...

Cheers,

Bruce
(bruceinbangkokatgmaildotcom)