Anti-fouling paint for plastic boats

A. We have research info available on 2 systems in response to environmental restrictions on anti-fouling paints with specific application to large yacht and ship bottoms in steel, aluminum and GRP.

1) a removal method using non toxic, controlled release of entire bottom coating to bare substrate in a contained manner.

2) recoat with a non toxic, 6 year AAA insured non conductive barrier/antifoul coating. Coating has been tested for 18 years, with no hard growth ever.

A. The non toxic, metal free anti-fouling paint you are looking for is here! It's has been tested in the tropical waters of Fort Myers Beach, Florida for the past 3 1/2 years with excellent results and is now in the EPA for registration.

No metal content, so no electrolysis, no VOCs except pure water, residue and cleanup water goes in the sewer.

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Gentlemen, please try to assist these students with their research by advising at least the general nature of the products you refer to. Also, every approach to anything is always a balance of advantages against disadvantages. While you'd obviously like to sell your company's product, research students can't submit ads, devoid of technical info and lacking any attempt at balance, as their science projects! Thanks!

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

A. You have several toxic-free options, most of them are silicon based. (SeaJet Speed, Hempel's Hempasile, International's Intersleek series, etc.) But you should check out the Lefant-series from LOTREC (Sweden).

A. I'm no expert on this, but have heard that aluminum is best for salt water.

A. Freeman is one of this site's most helpful readers -- but he is apparently either a fresh water sailor or else the water up there in White Rock is awfully damn cold :-)

Down by me, barnacles start growing in 2 days no matter how smooth a surface is: electropolished stainless steel, spanking new gelcoat -- makes no difference.

I'm not discounting the possibility of the new technology approaches mentioned earlier on this page working, but I'm not familiar with them. My experience here is that a boat that stays in salt water overnight needs bottom paint, period! By "bottom paint" I mean an ablative copper-based paint that biologically deters marine growth and gradually wears away, exposing a fresh copper-bearing surface.

Regards,

A. Hi, James.

I think you, too, need bottom paint. But bottom paint is brittle and is really made for hard rigid surfaces, not the slightly rubbery surface you may be dealing with. There is a page at www.triumphowners.net/?page=questions#paint which suggests lightly scuffing the bottom, cleaning it with lacquer thinner [on eBay or Amazon], flame treating it (not as intimidating as it sounds), and then using a special primer before the bottom paint. Good luck.

Regards,

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Ed. note Oct. 2020: Sorry that link is broken, and you now need to register there to see potential solutions, so we don't know if that information is still there.

A. Hi Craig. Although technology keeps advancing, and I am not an expert on what is going on in such research, I don't think we've reached the point where coatings can prevent biofouling via slickness. TBT (tributyl tin) was an environmental tragedy we still haven't recovered from -- don't even consider that toxin which kills at nanogram levels. Ablative copper coatings ("bottom paints") are still the best approach as far as I know; although obviously toxic to marine life, the ocean is big, boats are relatively small, and their toxicity isn't the tiniest fraction of the toxicity of TBT; it's possible (but I don't know) that by the time bottom paint wears off the copper concentration is so low as to have no long-term effects. I'd encourage you to investigate the reports of non-toxic bottom paints mentioned earlier on this page, but I have zero experience with them so I can't comment.

Regards,

A. Hi Earl. To my knowledge titanium has no toxicity to marine organisms and therefore would not offer any protection against bio-fouling.

Regards,

A. Titanium with some copper (or silver) would do. Ti alone can prevent corrosion.

A. Hi Brett. Doesn't look like it's you who is the one "finally cleaning it" :-)
Although the previous postings are from 5 years ago or more, to my limited knowledge the situation hasn't changed: "bottom paint" (ablative copper) remains the thing to use to stop barnacles and bio-fouling.

Luck & Regards,

A. Hi again. Bottom paint will not hurt polyethylene; polyethylene will not hurt bottom paint.

The question becomes whether it will adhere perfectly, fall right off, or come somewhere in between and whether that amount of adhesion will be good enough to be worth it for you :-) On this thread we talk about the possibility of improving adhesion via flame treatment. But if you search the site for 'paint polyethylene' you'll find countless suggestions, successes, and failures. Until the link breaks you can see
www.bottompaintstore.com/blog/bottom-paint/apply-paint-polyethylene-polypropylene-abs-petpbt-blends/
for painting polyethylene with bottom paint specifically.

Ironclad answers are hard to come by because some instances flex more than others, some paints flex more than others, some applications abrade more than others, some have more temperature swings, etc.. Suggestions tend to be along the lines of what to try rather than what is guaranteed to work; but there will be no significant abrasion and no wild temperature fluctuations, and this dock looks reasonably rigid, so my guess is you can find success.

But bottom paint is quite expensive and your dock has a huge surface area; and probably the main reason bottom paint is used is to reduce weight and drag, which wouldn't seem to be an issue for a floating dock -- so I'd question whether it's worthwhile. Always wear leather gloves when handling or scraping; barnacles can give nasty cuts.

Luck & Regards,