uh-oh coppercoat on the saildrive - have i mucked up?

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tcm

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The coppercoat workd fab in the med so i thought we could put it on the saildrive which was riddled with barnacles. The coppercoat guy sed put some ally primer on and all should be ok. The primer had a lot of aluminium in - looks like metal paint. Primer on, then coppercoat and sanded it down a few days later, looks great. Then i saw some electrical metallurgy ooer things here and thought ooer, coper and aluminium and don't remember summink about people in ally boats ruining things if they drop a penny? I can liftout in the caribbean and there's nice new anodes, or there were two weeks ago, erk. Thoughts please, it might not be great news...
 
VicS - you beat me to it...

And tcm, your worry probably lies from hearing about copper based antifoulings when applied on or near saildrive legs - and since most antifoulings do contain copper then you were right to be worried.

Coppercoat - as the pdf says - is good on the saildrive with the epoxy primer underneath.
 
The epoxy primer prevents the small copper particles coming in contact with the aluminium as i understand it, so I'm not all sure the aluminium primer not cause you major problems as it may react with the copper.
 
I have no experience with Coppercoat other than I have watched it when applied to a few boats. Owners certainly seem generally happy although there is an occasional user that feels it has been ineffective.
It is claimed by some that copper based antifouling can be used on aluminium boats providing there is a good barrier coat of epoxy first.
On my boat and most other aluminium boats I know we play it safe and use both an epoxy barrier coat (Consisting of 5 coats of Interprotect) then a non copper based antifouling.
Coppercaot should be less reactive than copper based antifouling because the copper is in resin and has less opportunity to form an electrical connection with the aluminium, particularly with say a scratch which may penetrate the barrier coat. However the rates of corrosion are related to the amount of material. An aluminium hull is a large structure and will experience much less corrosion if something is done wrong, than a sail drive which has several orders of magnitude less aluminium.

The above is purely a theoretical discussion of Copercoat on a saildrive and practical experience from other users will mean more.

Monitor the zincs, be careful of any scratches (make sure when removing the prop tools don’t slip)
For others considering this system personally I would prefer to see many coats on the barrier protection (International recommend 5 coats)
 
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Thanks all. I'll dive and keep a good look at the zincs. I would have been happier with specific epoxy primer for elec protection eg International as above but it wasn't readily available in the Canaries where i lifted out.
 
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