Boom corrosion

[chris-s]

Whilst the mast is off for new rigging, I thought I should check out the boom and found some corrosion around the rivet holes for the main sheet attachment points.

It’s an old isomat boom on a late eighties Oceanis 320. The rest of it is fine.

I figure on repositioning the mounts so they straddle the existing holes and reaffix them using tefgel and maybe a thin isolating sheet in between. Sound ok?

It’s possible I could make up a ‘backing plate/strip’ to fit on the inside which the rivets could also go thru, would be fiddly but doable. Could even be made of stainless to me a bit stronger and wrapped in some isolating material aka tape and tefgel.

Chris

 

[vyv_cox]

The problem appears to be crevice corrosion. Hobie Cat addressed a very similar problem by using sticky-back plastic, a neat production method.
Your other suggestions seem sound to me but isolating the inner reinforcement would also be worthwhile.

 

[doug748]

You could, and I probably would, make a longer alloy backing strip to cover the whole extent of it. Then re-fix the fittings, in their new position, through that. I would not put anything inside and certainly not stainless.

Annoying how many times stainless fittings get put onto masts without an interface, even by would be professionals, it always causes problems.

.

 

[chris-s]

I can fit a strip 40mm wide and extended 150-200mm for eitherside of the pair fittings. I guess if I was to do that, then I could reaffix them back in their original positions as the backing plate would be taking the load anyhow.

 

[B27]

I think those boom slides slide in a track, the lower wall of the track takes the load.
Simplest thing to do is put it back together with plenty of Duralac.

 

[lustyd]

While you’re at it, if you have a boom support check the washers/spacers. We noticed in the CIs that all of ours had disappeared, being plastic and 20 years old, and that the pins were about to fall out as a result! I hadn’t realised it should have had spacers because there were none when we bought the boat but on inspection it was obvious.