Crusty rusty bolts and nuts

[Alan Mighty]

Originally Posted by sune

My new problem that I don't know how to deal with, is where the chainplates were mounted. It has crumbled or broken apart. The wooden bulkhead behind seems ok, but the epoxy (if that is what it is) has fallen apart.
Is it epoxy?
How do I fix it before remounting the chainplates?

I've had second thoughts, Sune. That's because I don't know your boat. And I think this might be a complex area - the area where the bulkhead is tabbed to the hull.

Your bulkhead was very likely tabbed to the hull, with polyester resin-impregnated strips (or tabs) of glass fibre cloth bonding the hull to the bulkhead. The tabbing on the bulkhead, both fore and aft sides of the bulkhead, when the thicknesses are added together, is usually around half the thickness of the laminate of the hull.

If your chainplates were then throughbolted through the bulkhead at that tabbing, and if some water has penetrated into that area, then it is indeed a structurally complex area.

So forget my earlier suggestion of grinding down to sound timber. You may be looking at tabbing, which has been slightly damaged or at least discoloured by water and rust, over the timber bulkhead.

If that were the case, you do not want to damage the tabbing unless you are going to re-establish new tabbing.

Some investigation work for you:

* is this at the junction of bulkhead and hull?
* can you see tabbing: strips of glass cloth that have been laid to overlap the hull and the bulkhead, binding the two together?
* has the timber and/or the tabbing been damaged by the water? (water can penetrate polyester, get between polyester resin and timber on which the resin has been laid, and cause the resin to separate from the timber).

The tabbing work may have been uneven to start with. But that does not mean it was not structurally strong.

The water and rust may have discoloured the tabbing, but not weakened the structural strength of the tabbing. If that is the case, then you just need to clean it up, apply some bedding compound, and fix new chainplates.