Removal of antifouling

Lady Campanula

Lady Campanula

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I'm considering stripping existing coatings back to bare gelcoat, then abrading, prior to application of Coppercoat. 'Slurry blasting' is not an option.

I have access to handheld carbide scrapers, angle grinder holding twisted knot wire brushes, similar but with flap wheels, similar but with flat scouring pad....

Who's done this? What have you found effective...?
 
A two-handed carbide scraper will do the job effectively. Fairly hard work on the arms, but a 30 footer or so should be doable in 2 or 3 half day sessions provided the AF isn't too thick.
I would suggest abrading the bare gelcoat with an orbital sande and coarse paper. An angle grinder and sanding disc would be too vicious IMHO.
Not tried flap-wheels or wire brushes, but I can't see them being too effective.
 
Antifoul Removal

After painting sections of the hull ,about a half sq M at a time with the cheap Caustic Soda, Wallpaper Paste mix the 'Bahco' Carbide bladed scraper makes the chore a reasonable one. Chemical proof gloves and goggles essential.
 
I've done several (racing) boats with long boards. Time consuming. You can cancel your gym membership over the winter as you'll get enough exercise in the boatyard. Probably breaches some part of the Human Rights Act if you make your crew help you.

Tried my own (cruising) boat with orbital sanders. Dirty. Actually harder work than you'd expect. Orbital sanders have surprisingly short life expectancy.

Finished it off with scrapers. You have to be careful not to gouge the gel coat and some patches of anti-foul come off easier than others.

Helped on one boat where they were using blades from wood planes which had been removed and attched to handles. Pretty effective, but you have to be very careful not to dig into the gel coat.

Also used cellulose thinners we had a 5 gallon tin of the stuff - doesn't work on epoxy, but you can make good progress. Obviously need protective clothing. It can make short work of rubber gloves.

Another technique I've seen is to use Interstrip with cooking foil. My experience of Interstrip is that it is pretty useless, but if you cover it with cooking foil it does seem better. There seems to be an optimum time to leave it which seemed to be about two days. After about four days the paint seems to set again sticking the foil to the hull. Time it right and you can just peel off the foil, use a plastic scraper to get off the gunk and then thinners or acetone to clean up the left overs.
 
I did mine with a 1 1/4" chisel. I found pushing to scrape much easier than pulling a scraper. Not a very quick job but I found the thicker the A/F the easier it came off. Round the corners off any chisel/scraper to avoid gouges.
 
Antifoul removal

I used carbide steel scrapers to completely remove the anti foul on a Sadler 34. It took two days of solid work. A fairly straight forward job but hard at your arms and it is very dirty work. As suggested in previous posts, round the corners of the blade to avoid marking the gel coat.

Tried Interstrip but this proved ineffective and expensive.

An angle grinder with flapper disks is far too agressive unless you need to remove the gel coat and a considerable amount of laminate. For that purpose an angle grinder and flapper disks are very effective but do create a lot of dust

An angle grinder with knotted wire brush is far too agressive and uncontrollable to be used anywhere on a laminate hull.

An orbital sander will not work well either as the paper clogs up very fast. It will take a very long time, an unbelievable amount of disks and created a lot of toxic dust.

Interstrip and or orbintal sander may be usefull for the final finish after you have scraped off virtually all antifoul.

You do need protection, the most effective / comfortable to use is an air blown mask driven from a compressor, not too expensive and well worth it if you have access to a substantial compressor.

Kees
 
Did it on my boat some five years ago; not looking forward to doing it again on my newly acquired 'classic'.

The thicker areas I did with a Skarsten scraper / sharpened putty knife / old wood chisel as appropriate. The thinner areas I removed with an American chemical called 'Strip-it-off' - or something that sounds like that. (I can look it up if you want). It is a gel that is similar to what was already described and the goo that doesn't come off with the covering sheet can be washed off with a jet of water. Probably some kind of caustic soda concoction. Use eye protection against splashes.
 
pvb said:
I've used Dilunett to remove antifoul. It is absolutely filthy stuff, and I'd recommend you avoid it.
Click to expand...

I'd add that it's fairly ineffective, at least when I used it. I've helped strip a boat with Interstrip, somewhat better than Dilunette but you finish up with piles of gooey strands of paint all over the place, and the cost mounts up.
 
ripvan1 said:
I've been looking for paint stripper for use on GRP and was today recommended by very experienced boat painter/sprayer to try this stuff.

http://www.boatpaint.co.uk/acatalog/Dilunett_Paint_Remover.html

Now trying to find stockist who sells in the 1 litre bottle so to save postage
Click to expand...

Thats the one, previously known as Dilunet, which is caustic soda based. Make your own by thickening a caustic soda solution with wallpaper paste.

Good protective clothing needed including gloves and goggles but preferably full face protection.

There must be absolutely no chance that it can be splashed into your eyes. Without assistance you cannot open your eyes to flush it out and permanent damage is very likely

Safety Data Sheet

.
 
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If dilunett does what it says on the tin (or somewhere near it) without damaging gelcoat, I'll put up with the filth.

Whatever you use ends up a pretty messy job anyway.

By the way another boatyard worker suggested flour and water and caustic soda, this makes sense in the same way as previously mentioned wallpaper paste which ain't cheap these days. (If you want to be even more frugal he said you could use potato starch instead of flour)
 
By the way another boatyard worker suggested flour and water and caustic soda, this makes sense in the same way as previously mentioned wallpaper paste which ain't cheap these days. (If you want to be even more frugal he said you could use potato starch instead of flour)
Click to expand...
I can remember when wallpaper paste was flour and water! :o
 
Get hold of a broad chisel minimum 1 inch, grind off the cutting edge until flat ( like a screwdiver blade) with a very slight angle on it. Then remove burrs by honing it upright on an ordinary oilstone. Clean up. Now repeat using a fine Arkansas stone with plenty of oil. Take off any further burrs and particularly pay attention to the corners. Use this new tool with the sharper angled edge applied to the surface you need to scrape. You will find it more effective than an ordinary scraper.

A friend of mine used wet or dry to do the entire hull to prepare it for Coppercoat. It took him just under 4 weeks for his 40 footer.
 
We spent the winter three years ago stripping our 37 footer. It seemed never-ending. Tried just about eveything previously discussed, results as follows:

Dilunett - hopeless, messy and expensive

Skarsten scraper - effective at removing anti-foul, but even more effective at gouging the GRP

Wood chisel - ditto

The most effective tool that we found was an electric scraper like this one: http://www.amazon.co.uk/Bosch-PSE-180-Electric-Scraper/dp/B0000C6Y67 It was very slow, but easily controllable. We didn't buy the Bosch one - picked up a cheapie for £15 on ebay, but it's still going strong.

I doubt that we'd do it again by hand.
 
ripvan1 said:
I've been looking for paint stripper for use on GRP and was today recommended by very experienced boat painter/sprayer to try this stuff.

http://www.boatpaint.co.uk/acatalog/Dilunett_Paint_Remover.html

Now trying to find stockist who sells in the 1 litre bottle so to save postage
Click to expand...

I used Dilunett on "several" coats of anti foul. I put it on in the afternoon/evening and left it overnight. Washed off with a hose and cold water! Some areas needed two coats! Incidentally it also strips anti-slip paints too! It can be a little messy trying to avoid drips, but starting from the bottom up, makes a big difference.
 
Lady Campanula said:
I'm considering stripping existing coatings back to bare gelcoat, then abrading, prior to application of Coppercoat. 'Slurry blasting' is not an option.

I have access to handheld carbide scrapers, angle grinder holding twisted knot wire brushes, similar but with flap wheels, similar but with flat scouring pad....

Who's done this? What have you found effective...?
Click to expand...

This is the best tool for removing Anti-foul it takes it stright off and if connected to a vacuum leaves the area clean.

http://www.gelplane.co.uk/proscraper/product.asp

Did my boat in two half days, its still hard work but much safer than chemicals or sanders ect.

Tom
 
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