Antifoul

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Sailfree

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I know it's an old chestnut but wonder what you do.

1. Paint antifouling straight over pressure wash.

2. Paint over the hull after presure wash and light scour over with a green abrasive rub.

3. Paint over after presure wash and dry sanding.

4.paint over after presure wash a wet sanding.

Unfortunately my boat was not prepared properly from new in addition to not being rubbed down after 1yr (caught them just as they finished sufficient to see it was applied straight after pressure wash - no other prep work).

Hence for last 13yr has annual problems with areas becoming detached as thickness builds up - do others get this?

2 years ago sanded about 50% of loose antifouling extensively but diappointed to find 1yr ago other areas needed extensive sanding. This year it's quite good with just a few patches needed doing and also using antifouling primer on areas where sanded through a few layers.

Just wondering what's minimum work once I have a sound base as 43' boat is a big area to do on your own!!
 
The Very Worst Job In Boat Ownership is stripping old antifoul off !

I'd suggest a powersander - with goggles and mask - with coarse paper, then medium, then call it a ( several ) days, it's hard work with the thing over head height.

Wipe with white spirit then away you go with the antifoul; you're not out to win the America's Cup I take it, and even they debate about ' smooth v sharksin finish '.

If you ever pay to get your boats' bottom slurry, bead or grit blasted, beware;

at my club six of the members grouped to employ a chap who had come round touting his services - he not only removed the old antifoul, but also the entire lower gelcoats.

The boats and owners lost a season being re-gelcoated, I don't know what happened legally but it was jolly unpleasant, one must check credentials and references if having this done.

I have always used ' self eroding ' antifoul but there's still a buildup over the years.
 
Sailfree said:
Hence for last 13yr has annual problems with areas becoming detached as thickness builds up - do others get this?
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My boat came like that. And even worse the PO had used filler in some of the craters. Scraped it off back to the gel coat. Horrible job - worth considering paying to get the old anti-foul removed.

Since then most years have been a heavy wet scouring which has prevented build-up. Worst year was the year I paid someone to do the anti-fouling and I reckon he probably only slapped a single coat over the anti-foul after pressure washing.

I reckon it is worth looking after the anti-foul prep for a bit more speed even when cruising. That said I've longboarded a fair few racers in the past, so having to do anything less seems like luxury.

PS 43 footer too. Still waiting for someone to invent a button that shrinks the boat when on the hard.
 
My boat, a Furia 332, had so many layers of old antifoul when I bought it that lumps were falling off. I ended up paying someone €1100 to scrape it back to the gelcoat and apply two coats of epoxy primer. Worth every cent to me.
 
Dry sanding is deeply antisocial: noxious dust drifts everywhere including on other boats, also others breathe it in even if you don't. Wet sanding a lot better, though much of it ends up in waterways via storm drains. Scraping you can mostly contain the scrapings, and dispose of.

I too have a boat where they did not prepare the new hull properly: I do a light wet sand with mesh on a pole sander each year, and then prime any bare patches and paint the mininum AF I can get away with when dry - 2.5 litres thinned to cover a 35 ft hull. If you use good AF not cheap rubbish it works well.

This past winter a boat next to me was being grit blasted: all done in well-sealed "tent". I asked for a price from the contractor - about £1,000. Then talked to the boat owner a few days later who was busy filling lots of tiny pinholes in the underwater gelcoat of his rather nice Scandinavian boat. I didn't proceed any further with grit blasting.
 
jwilson said:
This past winter a boat next to me was being grit blasted: all done in well-sealed "tent". I asked for a price from the contractor - about £1,000. Then talked to the boat owner a few days later who was busy filling lots of tiny pinholes in the underwater gelcoat of his rather nice Scandinavian boat. I didn't proceed any further with grit blasting.
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Just for my education are you saying that the pinholes were a result of the blasting, or faults that had been uncovered by removing the anti-foul?
 
jwilson said:
Dry sanding is deeply antisocial: noxious dust drifts everywhere including on other boats, also others breathe it in even if you don't.
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Most decent sanders have an extraction port which can be connected to a shop vac with HEPA filter. Our yard certainly wouldn't be happy to see residue of wet sanding all over the support frame and ground. I certainly don't want to scrape another boat:blue:
 
I have a 44 ft mono that gets 2 coats of Seahawk Ablative every year.

It gets pressure washed which removes most if not all of the last 2 coats then I get the delightful task of scraping off the barnacle feet. This is followed by wet sanding with 80 grit.

This will be the 10th year and so far we have no crusty areas flaking off.
 
Elecglitch said:
Just for my education are you saying that the pinholes were a result of the blasting, or faults that had been uncovered by removing the anti-foul?
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The owner thought the result of blasting: the grit blasting company of course said they were there already .... Possibly a bit of each.
 
Surface preparation for antifoul application is the most horrible of jobs. Basically you do what you can bear to do. ie start off enthusiastic then give up after a while. Basically the more you rub and scrub the better. However IMHO you can get away with pressure wash and scrub with scouring pad. However eventually you get such a build up of A/F that it flakes off and leaves holes or steps where old paint is and insn't. You will probably then try to scrape off more possibly making it worse.
I have tried a sanding disc on a battery drill wet and that seems to remove a bit and can smooth out the edges. My boat is however particularly difficult as it is on a trailer with a bed of rollers cross members etc and quite low to the ground.
I have developed a regime of painting (not too thick) in spring before relaunch. It goes about 6 weeks before I ma in the water wiping slime off. From then through the season I wipe it off perhaps once per week. This graduates to wet and dry sand paper so that by the end of the season much of the a/f has gone. But still I make an effort to clean the surface before a/f application. (now I should explain relatively warm water so pleasant to swim underneath but also makes for fierce fouling.) But it is a small boat which I like to race so I am very fussy about bottom cleanliness.
Incidentally many clubs and marinas here have closed down slip ways and cleaning facilities due to requirements for sophisticated pollution collection requirements. All water run off has to be thoroughly filtered before returning to the sea and fouling and old paint must be collected and disposed off properly.
olewill
 
Sailfree said:
Just wondering what's minimum work once I have a sound base as 43' boat is a big area to do on your own!!
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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.
 
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.
 
Sailfree said:
Thanks guys.

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

.
Click to expand...

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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