Preparing pitted hull before anti-fouling...

[Captain Crisp]

How far should I go to prepare my rather pitted hull for anti-fouling? In previous years, I have simply picked off any obviously loose bits and cleaned. But I'm wondering if I should do more? Sand? Scrape?
Thanks!
Crisp

 

[KevinV]

From my very recent experience dealing with similar, either:

A) knock off the worst, slap on some antifouling and chuck it in the water where you can't see it.

Or B) get it blasted and do a proper job

I have just spent most of my free time over the winter getting decades of crud off mine, and she's only 22ft. The cost of blasting would have been worth every penny.

 

[Captain Crisp]

From my very recent experience dealing with similar, either:

A) knock off the worst, slap on some antifouling and chuck it in the water where you can't see it.

Or B) get it blasted and do a proper job

I have just spent most of my free time over the winter getting decades of crud off mine, and she's only 22ft. The cost of blasting would have been worth every penny.

How did you knock it off? (If you'll pardon the expresssion.)

 

[coopec]

Don't take my word without getting expert advice but I think I'd screed the pitting with thickened epoxy. If it is going to stay in the water I'd give the underwater hull a light sand and then give it three coats of barrier coat. My antifouling had to go on before the last coat of barrier coat had hardened.

 

[KevinV]

How did you knock it off? (If you'll pardon the expresssion.)

I didn't, I scraped and chipped (electric thingy) and sanded, then wire brushed (keel) etc, etc, etc - which is why I suggest NOT doing it that way!
I had to fight my way through bodged filling where they had put (very hard) epoxy filler in the pock marks - as suggested above - almost impossible to remove.
Hence - slap some antifouling on and forget about it - it'll be easy to remove when that time comes. Or do it properly. Doing anything in between is just storing up grief for a later date.
In my opinion, obviously.

 

[coopec]

Don't take my word without getting expert advice but I think I'd screed the pitting with thickened epoxy. Then I'd give the whole hull a light sand and then give it three coats of barrier coat. My antifouling had to go on before the barrier coat had hardened.

 

[Boathook]

If the pitting is just where the antifoul has come away, remove lose bits and repaint. You could try and smooth the edges with a scraper if really fussy. If the pits are bits of gelcoat then it is a lot more work.

 

[neil_s]

I just get the loose stuff off and then repaint. Don't make work for yourself. Over time, it all evens out, anyway!

 

[jac]

If you race or care about every single 0.1 knot, have new high tech sails and are ruthless about trim etc then get it blasted for a few hundred, maybe then some epoxy and new antifoul.

if you just cruise and put up with slightly worse performance then just remove the loose stuff, slap on 2 coats of eroding and hope for the best.

 

[jac]

Don't take my word without getting expert advice but I think I'd screed the pitting with thickened epoxy. If it is going to stay in the water I'd give the underwater hull a light sand and then give it three coats of barrier coat. My antifouling had to go on before the last coat of barrier coat had hardened.

I think op has just got flaky antifouling- if he is going to chuck epoxy that I would worry that his nice new smooth epoxy would be stuck to paint that is not especially well attached.

I think your advice would be fine if it was pitted grp.

 

[Tranona]

Don't take my word without getting expert advice but I think I'd screed the pitting with thickened epoxy. Then I'd give the whole hull a light sand and then give it three coats of barrier coat. My antifouling had to go on before the barrier coat had hardened.

That is not his problem. Good solution to a different problem - and what he may have to do if he has it blasted back to GRP. As it is waste of time doing that over existing antifouling. BTW the video says for "badly pitted and porous gel coat ONLY"

 

[William_H]

As said the question is regarding the pitting is it old A/F paint or actual pits in gel coat. Most likely pits in a/f paint. (use filler to fix if it is in the gel coat) Scrape or chisel old a/f off. What will happen is that you will set out to do it all properly and give up. Don't be at your self up. This is normal. Just slap on more a/f and delay whole remediation till next winter (never) I get the same dilemma every winter ol'will