Antifouling removal and Gelcoat DAMAGE!!!

[Eric_Cartman]

Hello peeps!

I'm afraid I'm in need of some advice....

We're just enjoying the task of removing 11 years of antifouling from our boat. As you can imagine it's not an inconsiderable task and we've taken advice from various sources. My (well in fact it's my brother's BIG concern) is the damage that might be done to the gelcoat.

We've been using one of those scrapers and although it does remove the antifouling (albeit slowly!) there are odd scrathes and grazes on the gelcoat and a couple of small patches where the top layer has come away with the antifouling.

What should be do?

I would be most grateful if you could reassure us that she isn't going to sink next month and also advise what sealant/preparation we should apply before the antifouling is applied (Cruiser Uno)

Many thanks in advance for your comments

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[oldsaltoz]

G'day James,

Given your description, I would use a Dremel or grinder to clean the areas to be treated, wipe with a little acetone and white cotton after grinding.

Coat with epoxy resin and wait about 20 minutes to let it start to cure, then mix some 'closed cell' micro balloons or 'Q' cells (also closed cell) to a thickish toothpaste consistency and apply with a plastic card; old credit cards are handy.

The next day, sand to a just below flush finish and give it at least 3 coats of resin, this will also need sanding after it has cured to provide a good key, though you can apply a single coat of antifoul over the resin when it is still just tacky, this saves the sanding off later.

Two items to note: Only use epoxy resin when working over standard poly resins, and only use closed cell fillers below the water line.

I do hope this helps.

Andavagoodweekend......



<hr width=100% size=1> Old Salt Oz /forums/images/icons/cool.gif Growing old is unavoidable. However, growing up is still optional.

 

[scarlett]

How about a complete epoxy anti osmosis primer while you are at it? If you have damaged the gel coat it must be a concern.

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Growing old is better than the alternative.

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[Birdseye]

dont like the sound of patches of gelcoat coming away with the antifoul. the gelcoat to laminate bond is (should be) a chemical bond formed during manufacture and you shouldnt be able to split the layers at all. the laminate including the gelcoat should be one solid piece. might simply be that the boat was painted rather than gelcoated, or has been epoxied before. could also be that you removed the top of a blister. impossible to tell from your description and without looking. get it checked out by someone who does know.

once you've gone through all the labour of removing all that antifouling, you might as well do the job properly. check the moisture level of the laminate before applying epoxy otherwise you could simply be sealing moisture in. then if it is ok to coat (blakes technical helpline will advise you on moisture levels) you need to abrade the surface to provide a key for the epoxy.

if you dont want to try applying antifoul to a still-curing epoxy (am not keen myself), then use a primer (mine looked like aluminium paint) after following the primer manufacturers instructions on preparation.

all my previous efforts to simply abrade the epoxy surface and then directly apply antifoul failed, sometimes after a year or two when the antifoul came off due to a poor key.

there is a wealth of free good tech advice available from the tech helplines of the epoxy makers. rather than use comments from the web site when its difficult to tell the pros from those ( like me) who think they know but dont really, use the helplines.




<hr width=100% size=1>this post is a personal opinion, and you should not base your actions on it.

 

[Avocet]

I'd be worried about the "patches" that came away too! How big / numerous were they? I've just finished a similar exercise on mine (only 7 years antifouling though!) and, like you, I left the odd gouge here and there. I have decided to epoxy the whole hull having done all that work and the local yard just stuck a moisture meter in a few places for me and gave it the "all clear". It was well worth the tenner it cost for the peace of mind - otherwise you'll end up splashing out a few hundred quid on epoxy for (possible) no good reason!

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[barry1971]

Hi Cartman,

we have just finished the task of stripping the entire grp hull from deck to keel and found the best least harmfull way to remove the antifoul was a good power washer with a path cleaning nozzle ( the one with the little spinner inside the nozzle ) this took the 10 or so layers of antifoul off like a hot knive through butter. There were a few stubborn patches which came off easily with an ANZA scraper. total time to strip the bottom of the boat - 1 day for 28 ft. I too found a few areas where the gell had been damaged and once i picked myself up from the swindelry floor when pricing the epoxy, took a note of the suppliers name from the tin and contacted them direct. BIG difference in price not just a couple of pounds here guys 3-400 % I suggest that you do the same. Remember to put on enough filler to cover the area and not any more as it can be a pain in the ass to sand once cured.

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[JBofBideford]

So are you going to post the link to the supplier so others don't have to go through the "fainting in the swindlery" bit?
Regards, John

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[barry1971]

The address is

Allscot Plastics Manufacturers
5-7, Lawmoor Place Dixons Blazes Ind Est
Glasgow Lanarkshire
G5 0XD

Tel: 0141 429 2424

I cant see a website for them.

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