Anti foul removal

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grafter

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I have just bought a 1997 Bayliner capri, in nice nick, unfortunately the boat has been anti fouled badly! How do I remove the anti foul without damaging the gel coat, I used to be a car body repairer, so the use of any tools that may be required is not a problem, I just don't know what solution to use, and wondered if cellulose thinners would do the job, i realize I will have my work cut out polishing for the for seeable future, but any advice will be gratefully received!
 
A couple of ways, one is mechanical. Either a power sander though this does run the risk of gel coat damage, or slurry blasted which is 'less' damaging to the gel coat.

Second way, which is my preferred, is chemical. Interstrip is my favorite product, but I have used nitromoors before.

Whatever method you use, you've some 'fun' days ahead /forums/images/graemlins/tongue.gif
 
It depends on whats underneath the antifoul. I found the best, if hardest way, to get a nice clean finish is a paint scraper (with the edges rounded off) and a lot of elbow grease.

Its hard work and uncomfortable, but having used this method its impossible to tell that our 8 year old boat has ever been antifouled.
 
not tried it, but someone has said lots of acetone and cloths-just rub it off. Guess not an approved idea under health and safety, but easy- as I say... havent done it myself
 
I had 18 year old 31ft x 11ft 6 fairline corniche it took me 2 full days to remove evey bit and sand with orbital sander, I used a bosch powerfile from screwfix works very well but noisey to the ears!.
 
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while cleaning my boat with a pressure whasher (very high pressure) some of the antifoul came off...

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I agree with this. Use a high pressure washer but make sure to go at it at an engle, not head on (as you risk gelcoat damage). Just today I blasted a good bit of my gelcoat off with a power washer. Would take lots of patience, but it will get the light stuff off, then could use another method to get rid of the rest... may make the job easier
 
My Fairline 29 aft cabin had 5 or six layers of different coloured antifoul when I bought her. The surveyer advised me to strip it all off as it would definitely improve performance. He had exposed areas as part of his survey so I started from one of these with a 2" scraper which I later attached to an extension (much easier). It took 3 days to scrape every bit off and re antifoul but it was well worth it just to get rid of the unsightly high and low patches. It did feel as though it glided through the water easier but I never took any data to bear this out
 
Hello headrow, thanks for your advice! When i use Acetone, how do I apply it, I mean do I use a paint brush, or roller/rag etc? After applying the Acetone, do I use a paint scraper, or would I be better off using a power washer?
Sorry to have to ask so many questions, I know nothing!
Cheers!!
grafter..
 
Acetone dissolves the antifoul and does not affect the gelcoat (despite what some people round here will say). Apply and rub off with a well soaked rag. Don't try to get it perfect at first go; any remaining film will rub off easily second time. You'll get the hang of it as you do it.

It's messy, but it leaves the gelcoat beautiful. I've done 21ft, 26ft and 34ft boats. I found on the 21 footer: 14kts fouled, 32 kts pressure washed, 42kts polished gelcoat. Less effect on larger hulls, but still noticeable.

Have fun.
 
Did not need to use acetone or any other chemicals for that matter! Just got the edge of the antifoul and gelcoat and pushed hard with the scraper. It was hard going but it was effective without any damage to the gelcoat.
 
I recommend against a slurry blast short cut

A few years ago at lift out a friend had his 1987 Fairline corniche at the side of my 1988 corniche.
He wanted me to join him for a slurry blast of 'gentle soda'.
I wasn't keen even when offered a two for one deal and declined.
My mate went ahead and I saw the damage the following weekend

Whole hull was riddled with small holes in the gel coat.
The whole boat had to be filled and epoxy coated.
At some stage a section of 1 ft by 2 ft on my bow had also been blasted.
It is unclear if
they started on the wrong boat.
they hit it by accident
they wanted to see if my hull would also be wrecked
they thought it was such a good job I would want mine done


My 'test' section was also covered with pin prick holes that I needed to fill.
I was pleased a small section had been tested as it confirmed to me that GRP shouldn't be grit blasted unless it needs an osmosis treatment.
A friend was then kind enough to clean my hull with an electric chisel, the old antifoul came off and left beautiful white shinny gelcoat with no visible signs of weakness.
It is clear that older boats have naturally occurring bubble holes deep within the gel coat that are created during the mixing. These bubbles are fine and will not cause a problem unless the Gel coat is overpolished with compound, over sanded or slurry/grit blasted.

The slurry blast had not made the holes but it had exposed voids that had been water tight for 15 years (moisture reading were very good).

The grass under the treated boat has still not grown back and turned into a bog for a while.

From my experience I would only have a slurry blast on a modern boat that had used a vacuum technique to mix the gel coat and so reduce the amount of bubbles.

If you read the professional sites they warn about this in a round about way " leaves a nice key finish ready for filling and epoxy coating " shouldnt the surface be ready for AF Primer ?

Bosch power chisel made a perfect job ( A good Friend did mine for me)
 
Thats a good tip.
So that's why Little Ship dashes a long so quick.
Keep that tool away from the Juggler!!
One of Tom's crew has been named "The Juggler" folks cos He keeps lobbing stuff over board, unintentially like .
Well at 7 kts all Hell must be brakin loose! /forums/images/graemlins/grin.gif
 
Don't believe all the removall hype. Didn't work effectively atall on a small sample area on my boat even after 'soaking' for 2 days. PLUS one local yard refused to have the stuff on their site. Tried returning it but supplier wouldn't take it. I tried scraping and the stuff wouldn't come off. Tried acetone and that just turned the 6 layers into a mucky goop so thick I couldn't even scrape it off. Resorted to slurry blast, but did need a good belt sanding and gelshielding (6 coats!) afterwards. Slurry blast did take some gelcoat off right back to the fibre on a small area of one chine and needed re-filling/re-finishing....but now I'm in complete control of what AF goes on, my blistering and cracking AF shouldn't happen again! (5 AF coats were pulling away from the first coat that Sealine put on when the boat was new - and that first coat was so hard nothing would touch it or dissolve it - other than slurry blast)
 
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