That is the stuff.

For homebuilding, I would just build a flatbar flange at the base of
the superstructure. Bolt and aluminum flatbar to it and then build
the aluminum superstructure on top. Unbolt after it's done, lift, and
insert a suitable gasket material. Then bolt it back on.

Being able to remove the superstructure would have a lot of advantages
if you had to do major repair on the interior.

Actually, I would build the whole boat out of aluminum. Stronger at
the same weight, more likely to deform in a way that stays watertight
in event of major damage, and easier to drill for temporary patches
with hand or battery powered tools. I'd much rather go up on a reef
in a far away place in an aluminum boat than a steel on unless the
latter was large enough to carry a full welding outfit.

Also, less compass issues with an aluminum boat.

--

Roger Long



"André Langevin" wrote in message
...
Very interesting Roger what you bring. As you said, i've searched
also in internet but there is not much reference. I will talk with
a local machinist also and keep you posted.

There is this company though: www.spurind.com but it might turn
out very costly since it seems to be a specialty.

André

"Roger Long" wrote in message
...
Sorry, but the following is completely wrong. The explosively
jointed bimetallic strips have a long and successful history. The
aluminum is welded to the aluminum side and the steel to the steel
side. The strips simply seem to have become hard to locate, at
least via the web.

Regular steel and stainless steel are often joined. Problems can
occur, especially if submerged in salt water but you'll see mild
steel / stainless joints on fishing vessels that have been going
for years and years.

True, you can't weld aluminum directly to either.

How do I know about aluminum superstructure on a steel hull?

I did it on this boat:

http://www.bbsr.edu/About_BBSR/Facil...herbird_ii.htm

--

Roger Long



wrote in message
...
I have just double check with my friend who worked as a welder for
35 years in a shipyard that build commercial, coast guard vessels,
battleships and drilling platforms.
If you have an aluminums structure welding steel plates on or
doing the reverse was not in practice. Aluminums and mild steel
or cold rolled steel are not compatible. The same thing applies
to welding stainless steel. What takes place is a white inter
granular corrosion that is hardly visible to the naked eyes.
Given time the white corrosion will cause a structural failure.
Not to mention the saline atmosphere at sea that will accelerate
the process.

"André Langevin" wrote in message
...
Hi to all,

I am a newcomer on this newsgroup and you'll see me around as i'm
starting the construction of a new boat. I currently have a 34
feet powerboat in aluminum and my nest boat will be a 44 or 45
steel sailboat. I'm looking at building a Bruce Roberts design
and i would like the deck superstructure to be in aluminum. I've
seen many commercial boat done this way and even old Coast Guard
patrol boat of 30+ years old without any corrosion problem so it
is something i'd like to do. But i can't find any industry that
carries the special strip that isolate both metals but still
permit to weld them both.

Does someone ever see this ?

André