Gear Tests

The Search for an Effective and Environmentally-Safe Antifouling

Goose barnacles growing on Mollymawk

The purpose of antifouling is to prevent marine plants and animals from colonising the hull, and the easiest way to do this is by killing them.
The ocean is brim full of planktonic larvae and planktonic algal spores whose further development depends on their finding a suitable surface whereon to rest their travel-weary selves and develop into something more adult. Flotsam, and most kinds of jetsam, are surfaces quite suitable enough. Ultra-slippery fast moving things escape the grasp of the creatures – and thus glass bottles seem to be immune to colonisation – but few other items can cross an ocean without collecting passengers and surfaces which sit still, whether at anchor or at sea, are even more susceptible to the development of a thriving miniature ecosystem – unless, that is, they are coated with toxic paint.

At work in our portable marine ecosystem

Ownership of a portable marine ecosystem provides a fascinating site for snorkelling, and it encourages fish (= dinner) to accompany us on our way; but it also makes journeying embarrassingly slow. A luxurious pile-carpet covering of sponges and exotic seaweed, together with a crusting of king-sized barnacles and a cargo of resident crabs and starfish rather spoils a yacht’s performance, to the extent that her ability to get herself out of danger can even be compromised. Extermination of the causative larvae is only reasonable – but it would seem that an effective antifoul does more than this.
Antifouling leaches its biocide into the surrounding environment, damaging or destroying not only those organisms which touch the hull and attempt to settle there but also all others in the vicinity. Biocide means life-killer, and the more biocides we allow into the sea the greater their concentration in the water. They don’t decompose and vanish after they have leached from the hull. Rather, they accumulate in the sea, converting it into a toxic soup.
Thus, it behoves us to find an antifouling which is non-toxic.

What will the ocean be when it is devoid of life?
If we continue to ravage the seabed with trawls, and if we continue to use ever more efficient means of rounding up those few fish which remain, it will soon be as bare as a desert.
And if we continue to use the sea as a waste disposal unit, and we continue to poison its waters through selfish concern for keeping our ships and fish-farm tanks and yachts completely clean and free of any fouling, then it will become utterly toxic.

Yellow nosed albatross searching for her supper

When we sail, the highlights of our days are encounters with whales and dolphins. We also delight in naming the birds which wheel about our boat or patter along astern, and we are thrilled when we have the pleasure of their company for days or weeks at a time. Our calendar is marked out with these small adventures; they are the stepping stones which carry us from one side of the ocean to the other.
When the fish and smaller fry are dead and the birds have wasted away, then the wind and the waves will seem less kind – will even seem cruel, I think – and traversing the sea will be a lot less wonderful. From a purely personal and selfish point of view, therefore, it is in our interests to avoid damaging the minute organisms which are the basis of the ocean’s web of life.
It is in our interests to find an environmentally safe antifouling.

from How NOT to Build a Boat

The story so far

In December of 2008 we slipped Mollymawk in a boatyard in Melilla and painted her bottom with Coppercoat antifouling. Coppercoat is the original copper-epoxy paint. It was formerly marketed as Copperbot, and we had used it, many years before, on our previous boat, Maamari.

Maamari with the original Copperbot

A few weeks after painting Maamari we took her down through the French canals. She arrived in the Mediterranean with a completely clean hull – as, indeed, did every other boat which had made the same journey. Marine weeds won’t survive in fresh water, and the freshwater ones had not had time to set up camp. Thus, when we moored for the winter in Port St Louis, Maamari and her neighbours were all scrupulously clean.
At the end of our stay Maamari was still entirely weed and barnacle free, but the other boats were all wearing shaggy green carpets on their bottoms, and some were so foul that their props would not turn. Without a doubt, the original Copperbot paint worked – or at least, it worked for us.

When the time came to paint Mollymawk we couldn’t afford to buy the real thing, and so we mixed our own copper-rich epoxy paint. This was only moderately effective. In the early days it was out-performed by the conventional poison which we applied, as a control, to our self-steering rudder. However, after six months the conventional paint had spilled all of its toxins and the seaweed and barnacles were already moving in. Within a year the rudder looked as if it had never been painted with antifouling. Meanwhile, the copper-painted hull was still reason ably clean.
Conclusion: our home brew worked, but not as well as the real thing.

Mollymawk, 8 years after we painted her with our home brew. (Photo taken after high-pressure hosing.) The entire hull is covered in a residue of barnacle glue and white-coral.

Eight years and several thousand miles down the line we were fed up with diving, every two or three months, to clean the hull, and so we decided to do the sensible thing and invest in some of that super-effective stuff which had protected Maamari; we decided to buy some genuine Coppercoat.

Unfortunately, it didn’t work.
Within a year we were back to the old routine of diving regularly to clean the hull.

August 2009

When we contacted Coppercoat they suggested that the antifouling would become more effective as the years go by:

Please remember that unlike conventional anti-foul (that starts off at full strength and becomes weaker by the day), Coppercoat is actually quite a mild anti-foul when new. Coppercoat increases in potency as the months and years pass. … It is likely therefore that you will see a further improvement in the performance of the coating in the coming years.

Since we published our Coppercoat review numerous people have written to us asking whether this claim was justified. Have things got better?

June 2011

Unfortunately, they have not got better. The most we can say is that they have not got much worse.
If you study the photos you will see that the boat is becoming increasingly coated with a residue of barnacle glue and “white coral”. In another four years time she will probably look as she did when we slipped her in Melilla.

3 years later…

Scrubbing off as the tide falls

While we were in Itaparica (Brazil) we took the opportunity to lean Mollymawk on a quay and scrub her off as the tide fell. The boat had been scrubbed a few weeks earlier when Caesar dived on her (with scuba gear) and yet, despite this, the fouling was such that it took four people the entire tide to thoroughly clean her. We began work as soon as the boat touched the bottom and we continued until she was afloat again, some twelve hours later.

Originally we had planned to take the opportunity to abrade the entire hull – because this is another thing which is supposed to improve the efficacy of the paint. Unfortunately we didn’t get the chance to do this, but we did find time to abrade certain areas. Some of them are now collecting less growth than the rest of the boat – Caesar can still find the place where he wrote his name – but others have vanished without trace. It would seem that the abrasion needs to be very forceful and thorough:

Abrading the for’ard section of the keel

Don’t waste time sanding back by hand. Use a random orbital with a soft pad and use P120 grade paper. You have to expose a totally bright copper finish, or it just won’t work!
www.ybw.com/forums/showthread.php?t=217194&highlight=coppercoat

This is probably true, but we were reluctant to do a Lizzie McMullen. Power tools should not be used unless the boat is high and dry.

Are we expecting too much?

The amount of fouling that a boat collects depends, more than anything, on where she is moored. As I write, we are on the Argentinian side of the Rio Plata and since this is a freshwater location – and since there is a high level of pollution – there is absolutely no fouling. By contrast, six months ago when we were on the Rio Paraíba, in northern Brazil, we needed to clean the bottom every fortnight.
On average we need to clean the hull every month or two.
Some folks seem to find this perfectly acceptable:

The coating is not maintenance free – but what coating is? Frankly having to brush off the entire underwater hull isn’t a big deal, and it allows you to monitor your rudder and prop. I’m not sure what kind of miracles you are expecting?
Chris Kirk, via the contact form

I guess the answer is that we would like to experience the same miracle which occurred when we painted Maamari with the original Copperbot antifouling!

This kind of stuff (which accumulated in just a few weeks) does not simply brush off.

Whilst we would agree that “having to brush off the entire underwater hull” is not a big deal – provided that the water is clear and warm, and provided the crew are fit enough for the job – we find that we have to do much more than this. We find that Coppercoat allows colonisation not only by weed and slime and plant-like hydrozoans, which can be brushed off, but also by barnacles, oysters, and the dreaded “white coral”, none of which can be shifted by brushing; their removal requires the use of a metal scraper and large amounts of force.
Worse still, even after the living creatures have been evicted one is still left with a calcerous deposit.  (The glue which barnacle larvae secrete is said to be one of the strongest adhesives known to man.)
This must either be ground back or, if you prefer the easier option, dissolved in nitric acid. Clearly, neither of these methods works underwater; and yet, if you don’t get rid of the deposit the area will quickly be recolonised.
There’s no getting away from it: for us, Coppercoat has not worked. We spent the money, but the result is no better than our own home-brewed version.

The web is plastered with stories from dissatisfied Coppercoat customers:

I applied Coppercoat last winter 2004/2005 and launched the boat in April and hauled it out at the end of September. The result was one of the dirtiest hulls of many hundreds of boats hauled at the end of the season.

We are in a high fouling area and so no antifouling works very well, and Coppercoat is no exception.

Save your money, it doesn’t work. Just ask any yard manager who does boat scrubs.

(All from www.ybw.com/forums/showthread.php?t=217194&highlight=coppercoat)

However, we have recently had a couple of comments from people who rate Coppercoat as effective:

I had Coppercoat applied to a new 48′ catamaran in controlled factory conditions before launch Nov 2010. I am delighted in the results so far – I dived on the hull in Dec 2011, cleaned off a small amount of weed with a hard sponge, and coating was back to new. There was not one single barnacle on the Coppercoat – numerous on the saildrives rubber seals and saildrive legs. … I cannot understand why so many different and unfavourable experiences have been reported.
Mike Bouch, via the contact form

I applied Coppercoat in April 2005 to my MG Yachts CS40. The boat was based in Portimão, Portugal at the time and the results were initially disappointing. It did improve, however, after the first haul-out for cleaning, when the hull was burnished again. We moved the boat to Cascais, Portugal in 2007 and we have been very pleased with the performance over the past few years. I hauled out this morning and the was little or no growth on most of the bottom since the last scrub, in August last year. On the other hand, there was a generous crop of weed, almost 2 inches long, in a few spots where the antifouling had come off.
John Duggan, via the contact form

There’s really no denying it. The genuine coppercoat has not worked any better than our home-brew.

Why doesn’t the new stuff work?

Why would an antifouling be more effective in some cases than in others, one wonders? According to Ewan Clarke, the main man at AMC Coatings, “The performance of any individual application of Coppercoat is determined by many factors such as (but not only) the quantity applied, the application technique, the mixing technique, the climatic conditions during the application, the environment within which the product is used, the age of the product etc.”
That being the case, one wonders what the optimum conditions might be.
The instructions warn against letting the paint get wet before it is cured, but our highly efficient Copperbot was applied during a rainy weekend. Unaware that the coats were supposed to go on wet-on-wet we allowed the first coat to dry overnight, and by the following morning it was attractively streaked all over from the rain pouring down the hull.
The ineffective Coppercoat, on the other hand, was applied in perfectly dry conditions and was painted exactly according to the rules.

The best that can be said is that an ineffective antifoul is kind to sealife!

On the plus side

The best we can say for Coppercoat is that it is less damaging to the environment than any conventional, poison-leaching antifouling. And that, for us, is a very important factor. The sea is our back-garden – quite literally – and we don’t want to do anything which will harm it. Thus we are willing to put up with a less than perfectly wonderful paint if it means that we will still be able to see fish flying, and dolphins leaping, and funny little bits and bobs of plankton sparkling by.
However, having tried both the genuine thing and our own mix, we can’t see any point whatsoever in forking out a ton of money for something which is so easy to make for yourself. The recipe? Take a reasonably runny epoxy, add pure copper powder, mix until the copper is all in suspension… and enjoy!

20 Comments

  1. Very interesting read! A new product I came across last week is Thorn-D. It’s a bit expensive, but would (supposedly) at least work for three years: http://www.micanti.com/industries-serving/shipping.html

    1. Caesar  (Mollymawk crew) 

      Thanks for the link. Thorn-D does look interesting; we hadn’t come across it before.
      It seems that the main intended use of it is to protect fishing nets from fouling, but I see that the website also mentions use as an antifouling on ships.

      It looks like it works by coating the whole of the bottom of the boat in fibres, or ‘thorns’.
      To quote from the website, “By applying very specific short fibres (‘thorns’) on a surface, the surface becomes prickly and unattractive for fouling organisms to settle … The basic thought behind Thorn-D® is that a combination of prickliness and swaying of Thorn-D® fibers makes the surface unattractive for organisms to settle.” Interesting.

      One point to consider, though, is the friction and disruption to water flow over the hull caused by these fibres. It’s unclear how long the fibres are, but the pictures make them look pretty long (it looks like a roll of carpet in one photo which they show in a few places). This could have a significant impact on boat speed – even a little slime on the bottom has an incredible effect.

      We’d be interested to know what Micanti has to say about this issue, and we’d also love to hear from someone who has used this product on their boat.

      Incidentally, another issue is that apparently the product must be applied by “authorized and trained partners of Micanti” – presumably an expensive process.

    2. Caesar  (Mollymawk crew) 

      I just found this page about drag tests on the Micanti website – where they state that “Within the shipping industry the main thought for the past decades was; the smoother the surface the better. We have proven this thinking to be wrong.” (no explanation of why it’s wrong…)

      However, they continue to say that (emphasis mine) “Though for sail boats the drag is mainly determined by surface drag and a drag increase was found, for most other ships and vessels, the drag increase is comparable to the effect a regular antifouling has on the drag. Moreover, as the drag level is constant, Thorn-D® outperforms the regular antifoulings within 6 months as slime formation increases the drag for regular antifouling coatings.”

      It would be nice to know just how much of a drag increase was found.

      1. It is expensive yes, on this Dutch website you can get an idea: http://antifouling.nu/contents/nl/basket.html

        I only know they’ve tested it on Pilot-boats in Rotterdam, but no info on drag/efficiency impact.

        1. Caesar  (Mollymawk crew) 

          Wow – €4750 for our boat!
          I don’t suppose many people will be using it at that price… it’s way too much for just 5 years of protection (even assuming it works well)!
          It’s a shame though, as it looks like one of the few antifouling products which uses no biocides.

          Of course, if they wanted to give us a small piece we’d love to test it on our self-steering rudder and write a review on the website! :-)

  2. I own a 40ft multihull, so it’s not within my budget either;-)

  3. Hello, I just read, and enjoyed, your antifouling article. Very well researched. I’m the fellow who “ladled” the powder into the epoxy. Thus far we are still in the testing stage as the boat is not yet launched. The test piece is submerged in the waters of central Fla and after 3 months has no sign of growth. It’ll be 9 months before we can have it checked again for growth, but we’ll let you know the results.
    The recipe: MAS laminating epoxy and as much powder as it takes to make a peanut butter consistency. In future we’ll be testing a “mayonaise” consistency mix. The peanut butter mix worked out to about 1 part epoxy to 3 parts copper powder. Get it on smooth during application, because once it hardens it sands like copper pipe!
    Cheers.

    P&C on Q.

    1. Caesar  (Mollymawk crew) 

      Hello Paul, Thank-you very much for the report.

      That’s a lot of copper! I’m assuming your measurements are by volume – ie 75% copper by volume. Coppercoat and our home-brew are both 30% – and are pretty runny. We were under the impression in the past that this was a legal maximum, but this turns out not to be the case – you can use as much as you like. So we’re definitely interested in trying more next time.

      It will be really interesting to hear the results of your longer-term test – do let us know what happens!
      Is your test piece in stationary water? What’s the fouling like in the area? Do you have other antifouls under the same conditions, as a comparison?

      1. Hello, thanks for your comments.
        The test piece is in a salt water marina environment, the test piece is copper on one side and not covered at all on the other side. The area has a reputation for a lot of growth and we’re hopfull that it will be a good test for our undercoat.

        Now, to cover myself, and in the interest of full disclosure, since we ARE on the WWW:

        The measurements/ratios are by volume as you stated. As far as “legal” I have not researched copper content in antifoul (the rules are different in each country), as my “undercoating” is for abrasion resistance to enable beaching the boat, NOT anti-fouling. Our tests are simply to understand whether or not an antifouling will be needed.

        I’m sure you understand.

        Cheers.
        Paul.

        1. Caesar  (Mollymawk crew) 

          Hey Paul, I totally understand your legal disclaimer… :-) As it happens, even for an antifouling you’d be ok, since there don’t currently seem to be restrictions on amounts of copper (except in the Netherlands).

          One thing we were wondering, from a cost and weight point of view, is how think the mix went on – in other words, how much weight of copper did you end up with per square metre, say?

  4. Hello, thanks for your interest.
    For more information please send me an e-mail.

    Cheers.
    Paul.

  5. Hello Paul

    How did you trowel on the peanut paste consistency and yet keep it fair for the whole hull?

    I guess at that thickness, only one coat is necessary?

    I think your idea and recipe is getting close to the correct ratios for “abrasion” resistance.

    Thanks
    Niels

  6. Hey guys,

    Nice article… when I purchased my rusty bucket 6 years ago, she had the original CopperBot coat and seemed to work very well. Had to rebuild the boat and a lot of welding below the water line so it was a pitty the coat had to go. I resumed to regular ablative anti-fouling since I launched her 3 years ago but am getting quite tired and broke from the yearly ordeals, specially now that I’m in a wheelchair.

    So I heard of this epoxy and ceramic particles that they use on the structures of offshore oil-rigs and water dams. Many of those big cruise ships have porcelain sea cocks so I reckon it might be worth a shot since nothing really grows on glass or porcelain.

    The company that sells the stuff is AtoMetal ( http://www.atometal.net )and from what I read we’d be using AM-C-T200 for the epoxy undercoat and the AM-C-T310 for the epoxy ceramic antifouling.

    Has anyone heard of it???

    My project this winter is to replace my concrete ballast with lead and incorporate my water tanks in the keel, so there will be a great deal of welding and will sandblast everything below the waterline. So I would like to get it done with a product that I can haul out of the water once a year and have a spray down instead of the regular $1000 yearly ordeal of antifouling.

    Cheers

    Jon

    1. Caesar URUGUAY  (Mollymawk crew) 

      No, we haven’t heard of ceramic antifouling – although we have heard of a glass-based one which Greenpeace use on their ships, but which apparently only works at high speeds.

      Unfortunately there doesn’t seem to be much information around on the web. Atometal’s site does seem to say that the two products you mention would be the relevant ones, but has very little about them.
      I don’t know how easy it would be for yotties to get hold of, seeing as they seem to be marketing it for major offshore installations.
      I guess we should get in touch with the company and see if they can provide any further information, prices, etc.

      If you come across any further information, do please share it here.

  7. Tim Dickinson (Bonaire)

    Hi Mollymawks!
    Greetings from Mauritius! Very interesting article. Before leaving the UK, I watched the guys at Hayling Yacht Company applying a coat of copper to the bottom of a yacht that had just had its osmosis treated. They spread sheets under the boat and ‘pebbledashed’ particulate copper onto wet epoxy paint. I believe they used a hand wound dispenser, very similar to the sort of thing used for applying aggregate to wet rendering. Any excess was picked up and recycled. I reckon that this should achieve close to 100% copper coverage, although longterm adhesion could be a problem. I suppose you could always apply a second coat of epoxy and more particulate copper.
    Happy Travels!
    Tim, Steph Fin and Sam
    s/v Bonaire
    ps – great website!

    1. Caesar  (Mollymawk crew) 

      Hi guys, good to hear from you, hope you’re enjoying Mauritius!

      That sounds like an interesting method of applying the copper… If it worked then it should achieve a good amount of ‘active’ surface area, but like you say I imagine adhesion could be a problem particularly when scrubbed – one of the best things about the copper-epoxy system is that it’s so durable. I’d love to see a boat where the copper was applied in the way you describe.

  8. From all the info mentioned in both your articles on coppercoat/copperbot; I understand that the difference in the 3 products, copperbot, coppercoat and the home brewed copper mix with epoxy is the amount of copper particulates added to the epoxy. PERIOD!!
    The more copper you add the greater the length of protection. PERIOD!!

  9. Actually, I’m not sure about that, Sai.
    Yes, it seems that Coppercoat and our own homebrew are just as effective / ineffective, but the Copperbot was a miracle potion. Our friends at Coppercoat tell us that their product is produced to exactly the same formulation as was Copperbot, but the Copperbot which we used was so wonderfully effective that we’re inclined to wonder whether somebody slipped a little something extra into the pot!

    So far as the volume of copper is concerned, we’ve tried adding more – we’ve tried laying it on with a trowel, quite literally (on our self-steering rudder) – and it seemed to make no odds. Six months later, you couldn’t tell which parts were painted with the usual ratio of copper to epoxy and which were coated in epoxy-copper putty.

    Nor have we had any success by burnishing the Coppercoat. We’ve burnished parts of it, using the grade of paper recommended by the manufacturer, and we’ve had it looking as shiny as could be. But a few weeks later those parts were indistinguishable from the areas which were simply cleaned and sanded by hand.
    We’ll be slipping again, in a few weeks time, and if Coppercoat would like to fly out to Argentina and join us, and show us how to do the job properly, we would be delighted.

    All this having been said, we would still use a copper-epoxy bottom paint again because, so far as we are concerned, the environment matters more than the cleanliness of our hull. Copper-epoxy is not perfect, but it’s better than nothing and it’s better than poisoning the sea.
    We’ve found that the very best way to clean the bottom of the boat is to moor in a polluted river for a couple of months. All the marine weed and so forth dies, and nothing else grows (presumably because the river is dead…). Mind you, it doesn’t get the barnacles off. For that you probably need to moor next to Fukushima.

  10. My wife and I applied Coppercoat to a newly finished steel hulled boat. we followed all the instructions religiously and had suitable temperatures throughout. When finished it looked great and we thought ‘well done us’. Unfortunately it proved to be an expensive mistake. After 2 years we looked like a floating garden. We had the boat lifted and power washed. All the wildlife came off along with about 10% of the paint. We tried again; 2 years later even worse than before. Last summer we lifted again and slapped standard anti-fouling over the entire hull. So far it is doing better than the Coppercoat did.

    Coppercoat’s response was to blame us for faulty application or an incompatible undercoat which is an easy out and very difficult to disprove. They then went on to say we’d need to lift the boat every couple of years to scrub off the slime. Given our sailing area at the time this was not much use and I would not ever use Coppercoat again.

    In the commercial world of shipping the trend at the moment seems to be towards making hull paint too smooth for sea life to attach to; some paint manufacturers are looking at ceramic / silicon coatings as well as various super secret nano technologies. whether or not these may have environmental side effect i do not know. What I do know is that anti-fouling is a hugely expensive item in the commercial marine world and with current fuel costs there is a big incentive to reduce running costs due to excess marine growth.

  11. It’s a grim story – all that work and all that expense; and I’m very familiar with the feeling of pride and pleasure in a job well done and disappointment when the stuff doesn’t work as well as one hoped and expected.

    The manufacturer is certainly inclined to blame anything other than the product, but – with respect – if large amounts of the Coppercoat came off with the sealife this does tend to suggest that there was incompatibility between the two paints. What kind of undercoat or tie-coat did you use? (ie. what was the Coppercoat going on to?)

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