Antifoul removal

Mei Mac said:
HI. I'm considering getting my boatyard to blast the antifouling off my 35 footer. GRP hull, 40 year old boat. Once it's off what do you reckon? I've been advised by a local chanldery to gor this approach considering the age of the boat:

Sanding, 2 coats of epoxy primer, 1 coat hard antifouling then a softer antifoul which will be jet washed and repainted annually.
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Given that it’s a 40 year old boat, I wouldn’t bother with doing anything to the hull once stripped other than applying a primer comparable with whatever antifoul you choose and then putting 2 coats of antifoul on. I see no need to sand the hull, it’ll be pretty smooth after blasting anyway and if there’s any paint left the blasting person hasn’t done the job properly. The primer will fill any minor imperfections.
Anyhow, that’s what I did when I removed the antifoul off my 51 year old boat. It worked fine with no adhesion problems with the primer or antifoul. I used the cheapest antifoul and primer combo in the local chandlers and it works.
 
DJE said:
Well it looks good but it's about £15 for a can that does 0.8 square metres. So about £330 for my boat. That makes my 18 hours of scraping look pretty well paid!
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I paid about £8 per can. Bought 10 cans. Made light work of removal especially in the heavier areas. Money worth spent IMO for time an effort.
 
Skatt said:
I paid about £8 per can. Bought 10 cans. Made light work of removal especially in the heavier areas. Money worth spent IMO for time an effort.
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The £15 was from a quick look on Amazon and Ebay. A bit more Googling gets it down to £10.20 per can. Amazingly one of the cheaper quotes is from a Chandlery! How much boat can you do with 10 cans?
 
DJE said:
The £15 was from a quick look on Amazon and Ebay. A bit more Googling gets it down to £10.20 per can. Amazingly one of the cheaper quotes is from a Chandlery! How much boat can you do with 10 cans?
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I started on the heavier areas followed by the rest. I managed to cover the hull (long keel 31ft) excluding the rudder as that had to be reglassed anyway.
The lighter areas required a lighter spray of the stuff.
There is someone on ebay selling it for £7.99 , i found.
 
Poignard said:
Thanks for the tip. I'll try it next year,
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Yes, thanks from me too, never heard of the stuff before and as someone else has mentioned there’s a chap selling the stuff on eBay for £7.99 a can. I’ve just ordered a single can to try it out on a 0.8 square meter test area. If it works i’ll be investing in enough to do the whole hull otherwise it’s back to the scraper.
 
Wandering Star said:
Yes, thanks from me too, never heard of the stuff before and as someone else has mentioned there’s a chap selling the stuff on eBay for £7.99 a can. I’ve just ordered a single can to try it out on a 0.8 square meter test area. If it works i’ll be investing in enough to do the whole hull otherwise it’s back to the scraper.
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I've done the same. £8.98 inc delivery.

Worth a try before it gets banned .?:cry:
 
MJWB said:
Hello all. Coates of antifouling eventually build up.
How long should one go before removing the lot and starting again?
How do you remove it?
Once off, how do you treat the hull, what checks are worth doing before starting to re-coat?
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When you examine the hull closely you will find some areas more broken up and flaking than others. I recommend you attend to these rather than a whole hull job which from personal experience I can tell you is hard and dirty work. the bow waterline to midships is an obvious area to keep in relatively good shape.

This year I went round the waterline and used a drag blade to remove the thicker layers. I've used all the jelly removers etc over time - waste of effort. A/F primer then new A/F. I otherwise leave the underside as is - it attracts very little weed. A few flakes make no difference to performance - unless in your mind, but you have to withstand a bit of yard ribbing that you've too ancient to do a whole hull job....no prob for me; my pride is confined to not spending more time inhaling spent A/F than I absolutely have to. Think covid!


PWG
 
This works well on a steel hull, belt from a belt sander fitted to a drill. Might be a bit much on GRP though, maybe worth a try though. .

aMSXoRN.jpg
 
duncan99210 said:
Given that it’s a 40 year old boat, I wouldn’t bother with doing anything to the hull once stripped other than applying a primer comparable with whatever antifoul you choose and then putting 2 coats of antifoul on. I see no need to sand the hull, it’ll be pretty smooth after blasting anyway and if there’s any paint left the blasting person hasn’t done the job properly. The primer will fill any minor imperfections.
Anyhow, that’s what I did when I removed the antifoul off my 51 year old boat. It worked fine with no adhesion problems with the primer or antifoul. I used the cheapest antifoul and primer combo in the local chandlers and it works.
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Thanks for the valuable advice. The boat has been on a cradle for two years so the hull will be dry, however the blaster uses water as opposed to dry media, so I'll need to let the hull dry for a while before epoxy primer. How long do you reckon? A week or so?
 
PabloPicasso said:
A pull scraper like these View attachment 92087
with a hose gently spraying a mist to keep the dust down should do it. This was how I stripped my rudder before rebuilding it about 5 years ago
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I did this. About 6 years ago. It's one of those jobs you do once in your life. Also... i think i have slight OCD so had a compulsion to do it properly once I had started. Scraping and sanding with various grades of sandpaper over the winter.. often in the dark. Coming home with a Fred Flintstone face from the facemask and the dust. When all that work was done I decided I'd go for Coppercoat and another journey started as I raced against time and temperature to get it done before lift in day. My best memory is of putting a tent around the keel in the unseasonal freezing rain that yearand resting an electric radiators up against it to get it done on time. For what it's worth... pay someone to do it!
 
Mei Mac said:
Thanks for the valuable advice. The boat has been on a cradle for two years so the hull will be dry, however the blaster uses water as opposed to dry media, so I'll need to let the hull dry for a while before epoxy primer. How long do you reckon? A week or so?
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Once it’s touch dry, you should be fine to paint. If the blaster is using a screen (he should) then if that can be left in place it’ll keep any rain out whilst things dry.
 
Slight thread drift but my boat hasn't been out of the water since spring 2019. Usually out every year for checks and antifouling but not done this year due to Covid and I didn't expect to get any sailing done this season. Anyway, managed to get a few weeks sailing in and despite much growth on the hull I can't say I noticed any difference in the boat's speed or performance. She comes out of the water this winter for a good tidy up, antifoul etc but the lesson for me is not to get too worked up about a bit of fouling. Different if you're racing, I'm sure but nothing to get het up about for a wrinkly like me!
 
Mo
duncan99210 said:
Once it’s touch dry, you should be fine to paint. If the blaster is using a screen (he should) then if that can be left in place it’ll keep any rain out whilst things dry.
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I'm thinking:
1 coat Hempel Underwater Primer (not an epoxy I believe)
2 coats of the Hempel Classic (soft) antifoul.

Haul out and jetwash & repaint with the Hempel Classic annually.
 
duncan99210 said:
I removed 50 years worth of antifoul from my boat. Tried using a paint stripper, didn’t work too well and softened the gel coat. In the end, it took about 5 days of hard graft with scrapers to get to off. And that’s on an 18 foot full keel boat. I will not b repeating the exercise: if I ever need to remove antifoul again, I’ll find the money to pay someone else to do the job!
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How different things are nowadays from early PBO! You would not have seen an admission of PAYING SOMEONE TO SCRAPE YOUR BOTTOM on here a few years ago. We're obviously too wealthy these days.?
 
ghostlymoron said:
How different things are nowadays from early PBO! You would not have seen an admission of PAYING SOMEONE TO SCRAPE YOUR BOTTOM on here a few years ago. We're obviously too wealthy these days.?
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But I didn’t pay someone this time.... I just said if it ever needed doing again, it wouldn’t be by me. Given the age of the boat, the age of me and everything else, the chances of needing to remove the stuff again before I loose interest in the topic are slim to none existent.
 
ghostlymoron said:
We're obviously too wealthy these days.?
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Must be

I tried to help a friend with removing thick antifoul from his boat but found the paint had set like concrete and we were making very little progress. The marina priced the antifoul removal at £500 (36ft boat) so he went for that . The surface still needed to be sanded to remove every last trace of the previous paint but that was relatively easy .

When I came to do my own boat last winter the old antifoul responded well to wet sanding . I tried dry sanding at first but as said earlier in this thread it was hazardous even when wearing PPE . I wet sanded by hand until the gel coat started to show through. Then used a primer /barrier coat before the eroding type antifouling. Next time I hope less effort will be necessary .

Although not a quick job and hard on the back muscles the results were quite satisfying.

I did consider a hard antifoul but decided against due to the potential issue with future work.
 
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