Stainless and copper

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pennycar9

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I have a copper earthing plate fixed to the underwater hull of my boat. While out of the water for a bit of a refit, I took the plate off to see the condition of the wood under the copper.

I now need to refit the plate and cannot get any bronze screws any where locally, quickly.

Can I use 316 stainless screws? or will there be an interaction between the 2 different metals. We are relaunching on Wednesday!

Thanks,

Paul
 
Paul, Agreed Anglia Stainless. Saw you were out of the water. If you get stuck, come across the other side of Lake Lothing to the big tent and I'll see if I can find you a few silicon bronze screws!
 
Last edited:
Tranona said:
would think the copper will de-zincify. Bronze screws are available from Anglia Stainless Steel.
Click to expand...

Not a chemist or physicist, just an old builder, but isn't copper an element so no zinc in it? Of course your reasoning is sound, copper and stainless are too far apart on the galvanic table for safety.

On a wooden hull won't copper nails do the job?
 
It's galvanic action you need to be wary of when sticking stainless fastenings into wooden boats. If the stainless is too close to any bronze fastenings then it can cause delignification in the surrounding wood, and as copper is down at the bronze end of the galvanic table, I'd be wary of the same reaction.
 
thanks for your replies, boat now back in the water, with S/S bolts, but will change them when we come out again next month.

Paul
 
Stainless v copper

Stainless steel (all grades) is more noble than copper when it is passive so no problem for the screws but the copper will be the sacrificial part and waste away. Problem comes if stainless is not passivated as it then becomes less noble than copper and will corrode quite quickly.
Either way I suggest you change to bronze as soon as you can to prevent problems
 
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