Antifoul

Over the past 2 winters I have removed 45 years of antifoul, the last part by salt blasting by a very competent blaster. (boat was getting overall paint job anyway including epoxy coat below water line). The estimate of old antifoul was 150kg (boat 9.7m long keel).
The previous finish was very lumpy with some patches to the gelcoat, others 3-4mm thick.
The boat goes nearly a knot faster now.

I'd previously wondered why people remove any antifoul.
 
Sailfree said:
Thanks guys.

You unfortunately confirm there are no short cuts.

With hindsight I wish I had the boat epoxy resined and copper coat from new but we are where we are.

Inviting my UK crew out next year for 1 wk boat maintenance rewarded by 1-2 wks sailing holiday later in year.

43' boat is a lot of work rubbing down for one person even a retired one. At least it's warmer here in Portugal.

Good news it came our relatively clean having sat in its berth here in Nazare since sailing it down last summer so Seajet antifoul works OK here.
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Chemical stripping is another method, but is also unpleasant. I did it once, never again. I agree that dry sanding without proper dust extraction is deeply antisocial because as well as the foul mess it's poisoning everyone else in range. Those little dust boxes on DIY sanders are just for show. I pay for blasting now every few years.
 
2nd question am I applying the antifoul too thick?

What quantity of antifoul would you expect to use on an annual coat for a 43' boat?

Some patches appear dry and others "wet". Easy to put thick coats on but what is adequate?
 
Sailfree said:
What quantity of antifoul would you expect to use on an annual coat for a 43' boat?
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I normally find 5l enough, but last autumn I put on 7.5l and hope to make it to next spring. 43' boat. 1st season with Seajet Shogun - normally used Micron Extra or Cruiser Uno up to now.
 
TQA said:
Do yourself and your back a big favor and acquire one of these

View attachment 71582

Usually called a drywall sander.

Mount it on a 6 ft pole and it makes the job of sanding much easier as you work standing up and use both hands. I sand my 44 ft mono in one easy day. NB most days in Carriacou are easy.
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I was in an Aldi last Thursday and saw this dry wall sander reduced to £49.99.
https://www.aldi.co.uk/telescopic-led-drywall-sander/p/095880199818200

Might be worth damping the antifouling and then power sand.
 
Tranona said:
The only sensible solution is blasting. an experienced operator will do exactly what you want - that is to remove just the antifoul and leave the epoxy coat (if there is one) and the gel coat. It is a very well established technique but costs - £1000+ and extra obviously if you want to have an epoxy treatment before AF. You should then have a sound base. sensible if you plan keeping the boat, but if you are going to that expense you might just as well have Coppercoat then no more AF for 10 years. If you stick to conventional AF then you will have the cost and graft every year. Do the sums and if you are a long term owner then you will get your answer.
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I paid £200 cash to a chap in bradwell marina to sand blast my hull. I stood by as he did it and he was super careful. He left some areas of old antifoul still on which i removed in 3 hours total although he stopped 50mm clear of the waterline and it took 8 hours for me to remove thevery thick coating there. After that the hull was as white as a sheet of a4 paper. The pinholes referred to in another post also appeared in my hull and these were clearly in the gel coat and not due to the grit blasting as some were evident under the small patches of remaining antifoul paint
i have copper coat , but as we all know it is only partially effective an as well as end of season winter storage i need a mid season lift and jet wash. Still better than re painting each year though
 
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Spirit (of Glenans) said:
When doing any work on the underwater hull, it seems to me that working from stern to bow is easier, psychologically, as you make quicker progress the further forward you go. Working from bow to stern starts off well but soon seems interminable.
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That's the best suggestion I've seen for ages. I'm almost looking forward to next spring..
 
For what it's worth, last year I used a Makita random orbital sander to go right back to gelcoat through several layer of hard paint (the elderly boat had been repainted several times, always dry sailed so no a/foul) . I thought it was going to be a nightmare of a job, so paid someone for a day and had a second sander on hand - an older Bosch rectangular orbital.

As it turned out, the hook/loop discs on the Makita, coupled with the fact that is several times better than the Bosch, meant that the two of us took it in turns and did the whole job in the morning. 30ft boat.

This year I took the antifoul back to epoxy, but used an air driven random orbital on my own and it took me under three hours. The reason for using air was that I could do it wet. The only improvement I have to make for next year is finding some more waterproof discs. I would have been changing them often anyway, but the glue was beginning to let the abrasive go before it was clogged/worn.

With that experience, I wouldn't bother with blasting.
 
Seajet said:
I seem to remember antifoul having a 3 month limit before immersion, but that must depend on the make and doesn't really matter as it isn't going to work anyway these days.:rolleyes:
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Showing how out of touch you are with the modern world again. Has not been like that for years.
 
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