On Fri, 23 Jul 2010 18:12:44 -0500, DougC
wrote:

On 7/22/2010 7:50 PM, Bruce in Bangkok wrote:

....
"Thinking outside the box" seems to be all the rage these days but to
be useful it really needs to include some consideration of "Why didn't
anyone else think of this bright idea"?


The main reason is just to make it look nice: I like the look of the
shape of the plank hulls, but also like the zero-maintenance aspect of
aluminum.

Doing what I want would involve more labor than typical welded-aluminum
boats--but for a leisure/hobby project with no pressing schedule for
completion, that's not really a "cost" as such.

And, finally, what would be the advantage of a welded aluminum, 15 ft.
boat over a wooden or fiberglass boat of the same size?


Mainly it's that I think I could do a better job building with metal
than with wood or composite.

People getting into this probably tend to choose whatever method they
are most-familiar with, and for most people that's woodworking, because
they have accumulated some tools for that to do around-the-house jobs. I
have nearly no woodworking tools, but a fairly big amount of
metal-working and welding equipment.
~

Doing what you want to do is always a valid reason, but...

Assuming a 15 ft. boat you are probably looking at something like
1/16" skin, or thinner. Try welding two narrow 15 ft. lengths of
0.062", or thinner aluminum edge to edge and see how you do?

Yes, you could use thicker material and you could use interior
framing, as is commonly done in metal boat building, but then the
thing gets heavier, perhaps to the point that it becomes impractical.

There is an alternative but how practical it is I'm not sure. Use some
sort of temporary backing strip - copper bar comes to mind - formed to
fit and clamped behind each strake. then TIG it using the correct wire
and gas mix.

To be frank, talking about "maintenance" on a 15 ft. boat is somewhat
over kill. I've seen wooden 15 ft. boats that lasted for years and
years with no maintenance whatsoever. I used an 18 ft. dory once that
had been build by the present owner's father and was probably 20 years
old. A coat of barn paint every few years, replacing the "false keel"
when it got too broken up, and re-swelling it each spring was the only
maintenance it ever had.

Cheers,

Bruce
(bruceinbangkokatgmaildotcom)