On 7/22/2010 2:20 PM, Steve Lusardi wrote:
Doug,
Your question is not so silly, but it is impractical. Welding long
aluminum seams would cause way too much distortion.

It would seem like it, but then again, very complex aluminum shapes are
welded up from sheet by car-body shops and airplane shops. With
bass-boats and jon-boats it goes both ways; the better ones are
fully-welded while the cheaper ones are riveted.

The thickness of the
aluminum in a boat that size could not be more than 2 mm at most or it
would be too heavy.

One canoe company online says their metal canoes are .050", or 1.27mm
thick. A (different) bass boat company indicates that they use
5052-alloy sheet.

I can tell you that welding very thin metal is not that difficult, with
the proper equipment and a bit of practice. Aluminum isn't as easy to
work with as steel, but it certainly isn't impossible.

Using less than 2 mm would make the boat susceptible
to corrosion that would be too expensive to repair economically.

One thing I can say for certain is that this is a freshwater-only boat,
as I live near the geographical center of the lower-USA. Considering
that, I would not think that corrosion would be a problem with aluminum
at all, but the boat wouldn't even be left overnight in the water anyway.

Are you referring to ocean/marine use, in this instance?

Lapstrake construction would look silly at 2 mm or less scantlings.

I don't know anything about boat construction in particular, so I dunno
what you mean there. I mean--I looked up what "lapstrake construction"
was, so I understand that bit. The part about "looking silly" I don't get.

The lapstrake is one answer to the question of if the planks are tapered
or not, in that they may not need to be. But I can imagine a method for
tapering the planks accurately and reliably, too. It is a method that
would work for thin sheet metal but wouldn't work very well with
(thicker) wooden planks though, leaving me wondering how wooden-boat
builders do it.

The
shape you want is achievable with both aluminum and steel sheet, but
would be very labor intensive and that labor would have to be very
highly skilled sheet metal people. They are very scarce and expensive.
Those are the reasons they are not made. People would not pay those
costs for the end product.......but as a hobby, you could do it in about
10 years, after you gained the required skill set.
Steve


I cannot seem to find much of anyone online doing DIY (small) metal
boats. I think all I've found was wood plank, plywood, skin-on-frame or
composite construction. Is anyone building welded sheet metal boats at all?

---------

This is a rather preliminary discussion. This whole project might not
happen, just because I've got plenty of other things to take up my time
and money.

First I guess I'll have to get a smaller sheet of aluminum and try
making a model.

~