Re: [Paddlewise] aluminum and salt water (was:blown out footpeg)

From: <rdiaz_at_ix.netcom.com>
Date: Mon, 25 Jan 1999 22:55:41 -0800
DANJW_at_aol.com wrote:
> 
> All this talk of metals and saltwater and corrosion causes me to wonder what
> the metallic frames of folding kayaks are made of , and how do they defeat the
> corrosion problem?  

I hope someone with more metallurgical knowledge that I have will pipe
up on this.  Feathercraft uses two different types of aluminum.  The
K-Light uses 6063-T832 extruded aluminum/magnesium whereas its bigger
brothers use a heftier 6061-T6 aluminum/magnesium.  In both cases they
are heavily anodized against corrosion.  The last I talked to them about
it, they had it anodized in the US even though they have plenty of
aluminum up in Canada.  It may be price or it may be quality but knowing
Feathercraft's high standards, I would suspect the latter as they go out
of their way to source their hypalon from France some 7 thousand miles
away from them rather than source in the US or Canada.

I don't know what Folbot uses in its aluminum but it is anodized.  The
frames do seem to hold up well though.  Early on in the Greenland 2
model back in 1989 or so, there was a simple aluminum part (I think that
plate at the front of the cockpit) that they did not watch what aluminum
they used and it corroded badly.  So Folbot is careful that everything
is now marine grade.

However, despite these precautions and good materials, you do get
corrosion in the frames.  That is part of the reason why you should not
leave aluminum frame boats assembled more than x months, a good bet is
to say x is 3.  This is especially true in the male/female joining
points.  These connections can fuse or seize up; part of the problem is
just guck and part of the problem is corrosion.  Feathercrafts have much
closer tolerances in their male/female connections and so are somewhat
more prone than Folbots, but only by a margin.  And it depends on what
connections one is talking about and which boats.  The K-Lights can fuse
at the four sliders that connect gunwale and chine bars at the middle of
the boat.  The sliders in the assembled position are pressed outward and
not in a straight line and that kind of contact can be quick to fuse. 
Those connections should be lubricated religiously and checked every
month or so and most certainly diassembled after 3 months.  On the other
Feathercrafts, the extension bars may corrode and should be watched.

There isn't anything that doesn't suffer in a marine environment.

ralph diaz

 
-- 
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Ralph Diaz . . . Folding Kayaker newsletter
PO Box 0754, New York, NY 10024
Tel: 212-724-5069; E-mail: rdiaz_at_ix.netcom.com
"Where's your sea kayak?"----"It's in the bag."
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Received on Mon Jan 25 1999 - 19:58:56 PST

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