Removing antifouling (but not the undercoat)

[AndrewB]

I have a steel yacht, epoxied throughout, which has just been lifted for maintenance.

The old eroding antifouling is a terrible mess, thick layers in places, blistered and peeling off in others. But the epoxy undercoat is still quite sound and keeping the hull rust-free.

I'd like to get off all the antifouling without disturbing the epoxy. Is there a way?

(PS tried sanding, with suitable protection, but the old antifouling just rubs into a sticky mass that immediately clogs the paper).

 

[vyv_cox]

We have done the same over last winter but with an epoxied GRP boat. We used a hardened scraper that attaches to a vacuum cleaner. Very effective and mostly does not harm the epoxy, although I ground off the corners of the blade to help in this respect. Slight filling repair of the epoxy carried out on completion. Having used various chemical methods in the past (best we found was Dilunet but not allowed here in Holland) I would say that the scraper method has been cheaper, harder physically, cleaner and took less time. I have seen a couple scrape clean all antifouling from a 29 ft boat in one day. We could have done our 34 ft in a weekend but took it more slowly.

We took every last speck of antifouling off in order to re-Gelshield, for which I successfully, but slowly, used an orbital sander. For re-antifouling the scraper finish is perfectly adequate.

 

[hugh_nightingale]

You MUST NOT do this dry.

Certainly not without an awful lot of protection. It is very toxic (as its designed to be).

Do it wet with wet and dry paper. Its slow but effective and you can concentrate on those bits that are most flaky and just rough up the good bits. Use plenty of water. You end up the same colour as the old antifoul but it washes off.