Sanding off coppercoat - what tool?

S

SV Kittiwake

Well-Known Member
Joined
1 Feb 2017
Messages
150
Visit site
The old coppercoat coating on our boat has left a lot of pockmarks / rough surface texture. It's made the bottom very unfair and needs to come off. The PO just antifouled over it but I want to take it back to the epoxy coatings underneath on the next haulout. What tool will be best for this? I think the options I'm thinking of are either the Bosch GEX 125 random orbital sander or a Makita angle sander - like a variable speed angle grinder basically. It needs to be able to to convex curves of the keel and also remove material quickly but controllably. Any other options or opinions? We've got a big underwater area so need to get the tool right.
 
Are you sure that there is an epoxy coating under the coppercoat?
i did not put one under mine as it is not necessary.
I would also suggest that if you sand off the old antifoul paint you do not have to sand off the coppercoat everywhere as it is epoxy based anyway. Just get it smooth
The keel (if metal) is different , of course
 
Yep, I was thinking ahead to after the ablative AF was removed. There's definitely epoxy coats under the coppercoat. As it's pockmarked / unfair over most of the surface and to save the risk of any more coming off in the future, I just want to remove it completely. We may reapply coppercoat with a coppercoat primer or just antifoul over the epoxy but either way I want the hull smooth and fair all over. I'll look up abranet discs.
 
Hey Skutiwake! :p

Agree with Graham, scrape off the antifoul (Bahco 665), then sand the Coppercoat. If you find well adhered Coppercoat in sufficient thickness, you can stop when it's coppery coloured again - new coppercoat or other antifouling will stick to that, after filling and fairing any pockmarks (and sanding that again).

If it's crumbling off, riddled with pockmarks, has osmosis blisters or other defects in the layers below, you'll have to keep sanding until you get it all off, possibly the layer below too, then fair and probably even apply a barrier coat. Beware, Coppercoat is hard and will be a pain in the stern to sand off over a large area. Especially if the underlying layers also have to come off, you might want to look into a Gelplane or similar tool, but the prices are frightening. That would be a pretty terrible scenario.

Abranet discs mostly help when having a vacuum attached to the sander, as it lets the dust get sucked out better. They cost more than a pack of good quality sanding discs though.

Angle grinder with flap disc I would avoid, as you'll end up fairing a lot more!

Good luck! We must've sailed past you somewhere near Zakynthos :)
 
If you really want to remove the lot- i agree that is the best - why not just get it blasted and save all the hassle. By the time you have spent hundred squids on sanders etc and travelled too and from the boat ( fuel and time) you would have a proper job
 
Yngmar - yep, we're in Sardinia now. I hope the rest of Greece is as good as the Ionian, we loved it and were sad to leave.

I won't be using a flap disc unless it gets desperate.

I think the having it blasted would remove the epoxy layers as well, or at leas damage them... something I'd rather avoid and we'd be living on the boat so don't need to pay to travel to it. I also much prefer to do things myself wherever possible.
 
Don't sand it off as it is epoxy, just sand it smooth, the fact that it has some copper in it will not hurt it.
After just use 1 coat of primer then antifoul.
Loads of boats in our yard have done this
 
There's no way I can just sand it smooth, there's too much that's flaking off. Also if more comes off in the future then it's going to be more of a ball ache to sort out.
 
Thanks for the tip, is it definitely powerful enough to sand through coppercoat? Have you used it to sand coppercoat or epoxy layers off?
 
I used a P36 grit on a GEX150 bosh sander . It took me a week to abrade my epoxy/copper anti-foul. You've got no chance of removing it with a sander without serious back breaking work day in day out. Better to have it blasted it at all possible.
 
I was faced with this. Sanded the loose stuff off with a disc sander, filled the pockmarks, sanded again and overcoated with soft antifouling.

Worked well and the antifouling stuck correctly until being pressure washed at the end of the season whereupon it all came off, exposing the coppercoat, ready for next season.

There's no reason to take off the securely stuck coppercoat as it is epoxy and is protecting the hull.
 
You must log in or register to reply here.

Share this page

Top