copper rivet in clinker hull problem

[gary3029]

I have a clinker hull which is held together with hundreds of copper rivetts. I was scrapping down this week ready for antifouling when I noticed a green colour substance coming from one of the copper rivets. Is this the start of something more serious?

 

[Peterduck]

The 'green substance' is called verdigris, and is a normal product of the corrosion of copper. If you are talking about the rove end, wire brush it clean before you varnish. Inspect closely to make sure that corrosion has not compromised the strength of the rivet. at the head end, you'll probably have ti dig around a bit to get all the verdigris off, but persevere with it. Again inspect the head to see if there is still enough there to be effective. As with rust on iron, it takes very little of the original metal to make whole lot of the corrosion product, so finding the verdigris is not an automatic 'death sentence' for the rivet.
Peter.

 

[FAITIRA]

If it,s copper not brass, I would have thought it was ok, be interesting what the real experts think. Bill.

 

[KenMcCulloch]

I also have a clinker hull held together with hundreds of copper nails and roves. When I bought the boat just under a year ago, the surveyor noted some evidence of corrosion on nails and advised that a sample of nails should be drawn for inspection. My friendly shipwright has just done that for me (quite a simple job really but I thought it worth paying someone who knows more than I do). The sample of 6 nails from various areas of the hull above and below the waterline were still in good condition. Yours probably are too if they are metal with a high copper content. Some 'copper' nails apparently have a bit more zinc in the alloy and are more vulnerable to corrosion. Scrape off the verdigris or any powdery pink surface and see if there is bright metal underneath, if there is you are probably OK.

 

[gary3029]

Thanks for the replies Ifeel a little happier now. As there is only one effected and it is below the water line, if I clean it up and it is ok, is there anything I can paint on it to stop it happening further

 

[Seanick]

Owatrol may help.

 

[Paglesham]

All bare copper will get a coating of verdigris on it. Look at church spires, etc. It's a natural oxide, like silver going black (OK that's a sulphide), but it's nothing to be worried about.
If you wire brush, be careful you don't damage the surrounding wood. Use a brass wired suede brush or scrub with a stiff whiskered scrubbing brush. Verdigris just means "green/grey" in yer akshul French!
Martin