Removing Antifoul

Mexican

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Just been into Wickes (builders merchants) and seen a sand blast attachment for a power washer @£24.99. You connect up to your power washer and insert the other end of the attachment directly into a bag of sand and off you go!!

Seriously thinking of this for end of season to get rid of years of build up and 'key-up' in one go- any thoughts ?.
 

DAKA

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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 ?
 

longjohnsilver

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Another alternative is to find a friendly local boat owner who has a large tub of anti foul remover in his garage that he hasn't got round to using and make him a very generous offer to take it off his hands!
 

Andrew_Fanner

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I shelled out for the scraper thingy that you can attach to your vacuum cleaner (don't tell SWMBO) and was, to say the least, very pleased. Scraped Jedi's hull in a day (OK, a very long day) with the help of SWMBO and children and it was pretty much back to the substrate all over.
 
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