This month’s tip is relevant to any rig with stainless steel fittings on aluminium, but I particularly want to highlight a problem with modern production boats.
Many of these have stainless steel slides in the lower side of the boom as mainsheet and boom vang take-offs. Perhaps because these mass-produced rigs are anodised, or perhaps just to save time, they do not appear to have anything between the two dissimilar metals to inhibit corrosion.
Over time the aluminium under these fittings corrodes badly, creating weak spots potentially leading to failure. It is worth drilling out the fastening rivets and moving the take-offs along to check the amount of corrosion. If present, clean it off – usually this means chiselling with a screwdriver because nothing else will fit into the space – then apply anti-corrosion compound and refasten
This is one instance, I believe, where the old-fashioned Duralac is superior to Tef Gel because it can be painted on and left to partially dry before securing the fitting. Otherwise, as you slide the fitting back into place the anti-corrosion compound squeezes out.
If possible remove the slides entirely so the Duralac can be painted on their upper face as well as on the boom. Use more Duralac when fitting, but be sure to wipe off the excess immediately for a neat job. Another way would be to fit a thin nylon spacer under the slides. Either way, remember to treat the new rivets too if they are stainless steel.
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