Len wrote:
Does your remark include repairs on a welded, multichine hull, of 6, 8
and 12 mm AlMg 4,5 Mn ? If so what wouldin your opinion be the best
way to repair say a hole of 10" diameter ?
I'm told TIG welding is perfectly suited for these kinds of repairs
and would not leave weakened areas behind. Am I being lied to ?

Well just about any marine aluminum alloy will be decreased in
strength when welded - but it's the only way to build a larger
aluminum boat. So designers take into account that the material will
be weakened. There is nothing wrong with welding up a hole like that
in that thickness of hull.

I guess a possible exception would be in a highly stressed transom
where you might increase the size of the patch to avoid an outdrive
(i.e. keep the weld from the highly stressed area).

MIG and TIG is used for welding aluminum boats with TIG preferred.
Make sure all welding is done indoors or erect a tent to keep the
inert gases from being blown away by a breeze.

Evan

Go to this site. So long as everything you have to weld can be laid
horozontally there is a product that will form an extremely strong
weld with 750 degrees of heat (available from propane, butane, map
gas, etc.).

http://durafix.com/




On 17 Feb 2005 15:07:47 -0800, wrote:

I have a 16' aluminum boat that I've been using for a while and I want
to customize some things on it, such as rod holders, downrigger mounts,
etc..

My question is do I need to take off all the electronics, including
30hp outboard, from the boat so that the welding doesn't affect/fry any
of the electronics?

My assumption is yes, get everything electronic off the boat.

Also, what alloy of AL should I be using?

On 17 Feb 2005 15:07:47 -0800, wrote:

I have a 16' aluminum boat that I've been using for a while and I want
to customize some things on it, such as rod holders, downrigger mounts,
etc..

My question is do I need to take off all the electronics, including
30hp outboard, from the boat so that the welding doesn't affect/fry any
of the electronics?

My assumption is yes, get everything electronic off the boat.

Also, what alloy of AL should I be using?

Joe Bleau wrote:
Go to this site. So long as everything you have to weld can be laid
horozontally there is a product that will form an extremely strong
weld with 750 degrees of heat (available from propane, butane, map
gas, etc.).

http://durafix.com/


*NOT* IMHO suitable for long term exterior marine use.
Its basically just Zinc rod and the joint will corrode pretty fast.
Remember you bolt zincs onto your outdrive so that they corrode and it
doesn't. OTOH if its to fix some engine part that is in a sheltered
location, or as a quick short-term fix until the parts come in or you
can get the hole in the hull to a pro, their product should work as well
as any of the Zinc based brazing rods.

The OP had better be ready to paint the joint with something like
bitumastic paint to keep the water off or be planning on selling the
boat next year or scuttling it the year after :-)

Me, I'd go with Stainless fittings bolted on with a neoprene gasket
bedded on Duralac anti-corrosion jointing compound.

http://www.sanshin.co.uk/duralac.html

Good stuff to have handy if you are mechanically fastening anything to
aluminium on a boat.

--
Ian Malcolm. London, ENGLAND. (NEWSGROUP REPLY PREFERRED)
ianm[at]the[dash]malcolms[dot]freeserve[dot]co[dot]uk
[at]=@, [dash]=- & [dot]=. *Warning* HTML & 32K emails -- NUL:
'Stingo' Albacore #1554 - 15' Early 60's, Uffa Fox designed,
All varnished hot moulded wooden racing dinghy.