Re: Corrosion

[Shevy Gunter <drlaser (at) roostergraphics.com>]

In a message dated Sat, 30 Dec 2000 21:32:50 -0500, Raymond Hicks asked:
> Has anyone used aluminum "rivet nuts" to secure fittings instead of 
> regular rivets or thru-bolting.

On my DEATHROLL, last year I replaced all the stainless fittings on a
boom with aluminum rivets for the sake of experimentation. 

The vang and mid-boom block eye rivets did not show any visible problems
within six months of heavy use in conditions involving up to 22 knots. 
However, elongation and distortion of the rivets were a major problem on
my boom-end-block eye.  With the gybes, the lateral sudden loads on the
boom-end block distorted and loosened the rivets, and double-blocking
started elongating the rivets. As a result, the loosened metal eye strap
started digging into and eating the plastic cheeks of the boom-end
becket block. 

If you use aluminum rivets to prevent corrosion, it is a good idea to
drill out and replace your rivets every season, and also to check them
before every serious regatta and after every heavy weather sailing day.
(I have a second boom with all stainless through-bolt + rivet fittings
-- except on the outhaul cleat.)

Assuming the ILCA Fundamental Rule does not prevent it, drilling a large
or small hole on the outboard end of the boom is an invitation to
filling your boom with water if you ever dip the boom-end in the water
and whenever you capsize. Thus, if you drill any holes on the end cap,
it should be securely taped shut before sailing to preserve the buoyancy
of the boom.

Depending on what is meant by "large", I'd guess that a large hole
drilled at the end cap to facilitate rinsing may also structurally
weaken the cylindrical tube shape at boom end and may make a later
through bolting of the outhaul fairlead/becket block eye pair a risky
venture. 


Happy New Year to all!


Shevy Gunter
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