Re: [Paddlewise] Stainless hardware (and aluminum)

From: "Evan Dallas" <Evan_Dallas_at_notes.ntrs.com>

> So just one quick question on the mixing of stainless and aluminum.  When I
> last replaced my worn-out rudder cables, I used stainless cable, but
> connected it to my rudder using little aluminum sleeves that you loop the
> cable through, then crimp to hold the cable tight.  Is this kind of
> connection likely to fail prematurely?  (I actually did have one fail
> already, but I assumed that was due to using a little too much force on my
> crimper). 

Mixing two different metals will accelerate the corrosion; something to 
do with electrochemistry that I only vaguely understand.  Stick a piece
of zinc and a piece of copper into a lemon and you get a battery, with
two pieces of zinc or two pieces of copper you don't.  Putting a 
piece of zinc on a steel boat hull minimizes corrosion of the steel by
sacrificing the zinc. Ditto pipelines and stuff.  Since the zinc is not 
used for strength, no problem.  Zinc plating steel does the same.

In Britain years ago, they made a bunch of bridges out of aluminum
(or aluminium over there) but used steel bolts.  The bolted joints 
corroded dangerously and the bridges had to be replaced prematurely 
- something of a scandal at the time.

For this reason, using aluminum crimps on stainless cables has the
potential to corrode faster than if you used stainless crimps (or
zinc cables).  Since I haven't spent much time with my ruddered
kayak in salt water, I can't tell what happens in the real world.

It is likely that if you over-squished the crimps they could crack
and eventually fail.  If they corrode, there should be a white
powder on the aluminum and the surface should be rough.

> What would be a better way of attaching the stainless cable?

Do they use stainless crimps on most kayaks?  That would make sense.
I don't remember what was originally on my Solstice.

Mike

***************************************************************************
PaddleWise Paddling Mailing List - Any opinions or suggestions expressed
here are solely those of the writer(s). You must assume the entire
responsibility for reliance upon them. All postings copyright the author.
Submissions:     PaddleWise_at_PaddleWise.net
Subscriptions:   PaddleWise-request_at_PaddleWise.net
Website:         http://www.paddlewise.net/
***************************************************************************