Galv. v SS.

[Gordonmc]

Any advice welcome on this one...

My Hillyard has rusted chainplate bolts which need replacement the first time the mast is stepped. I have been advised by the surveyor to remove and paint the chainplates themselves as they are showing rust. Standing rigging is galvanised, apart from the forestay which was replaced with stainless steel when roller furling was fitted.

1. If I replace the galvanised rigging with stainless, will I get an electrolytic reaction with mild steel chainplates. The stem and sternpost fittings are also mild steel. Would I get similar problems here with SS wire?

2. As an alternative to painting the chainplates should I have then galvanised or even replace them with bronze? If I can replace with bronze should I be using bronze bolts?

Thoughts?

 

[Peterduck]

Mild steel does not belong on a boat, full stop! Begin by knowing what the hull fastenings are made of. If they are copper rivets, then bronze [gunmetal] chainplates fastened with copper bolts will be compatible. If the hull is iron fastened, then galvanised chainplates will be acceptable. Do not create a problem in the hull while you are worrying about the rig. Whether to use galvanised or stainless shrouds is a moot point. I use galvanised on my 1917 ketch because stainless would be totally out of place, and I don't trust the stuff, anyway.

 

[Mirelle]

er um well...

Twelve years ago I pulled one pair of chainplates (we have 3 pairs) which were weeping rust, had them re-galvanised and, on the advice of the late Peter Brown, surveyor, had them re-bolted with bronze bolts.

Now for the silly bit. Two years ago I noticed that the other two pairs were weeping, so I asked the yard to do the same thing. In a fit of enthusiasm they did all three pairs, so I got a nice bill for quite un-necessary work, but when I looked at the pair that had been done before they were perfect, as were the swan through bolts and the oak and teak, so it did show that bronze bolts through galvanised chainplates, teak planking and oak frames work perfectly well - the whole lot is well above the waterline of course.

Peter Brown's reasoning was that it is more important to avoid any action between the iron and the oak, and an awful lot of zinc has to waste away before anything significant happens.

So, I would definitely have the cainplates off and re-galvanised, and personally I would re-bolt with bronze bolts.
Conclusion

 

[spark]

I agree with Peter Duck. If you go galvanised then you should give the bolts a good coating with a polyurethane bedding compound (e.g. 3M4200) before you fit them - it helps protect the steel from the oak.