Determined to reduce his environmental impact, a sailor seeks an alternative to ablative-based antifouling paint
Issue 149: March/April 2023
Andiamo with her old peeling ablative bottom ready to be soda-blasted.
Several years ago, my wife and I were cruising the Bahamas when I decided to go for a dip. In the crystal- clear waters, I could easily see my hull needed a cleaning. I had applied two coats of copper ablative paint a year before and by now the bottom was beginning to look like my hair at the height of the Covid-19 pandemic — pretty bushy.
Being a thrifty cruiser, I usually do this nasty job of scrubbing the bottom myself, but a fellow sailor told me of a local guy who does an excellent job at a remarkably reasonable price. So I called him, and the next day he showed up in a leaky skiff with nothing but a snorkel, mask, and fins. As he began to scrape away the growth, I peered over my lifelines and was horrified and embarrassed to see enormous clouds of bottom paint billowing around my boat and drifting downcurrent.
When I scrub the boat bottom in my home waters of New England, the effect is not nearly so obvious, since the waters are generally opaque with green algae. But in the clear waters of the Bahamas, the results were striking. I know antifouling paint is designed to kill barnacles and other sea life — it’s a poison — and here I was releasing clouds of it into these pristine waters near some of the most beautiful reefs in the world. So I decided to learn more about antifouling bottom paints and their effects on the world’s oceans. I discovered that what I was doing, what many of us boaters are doing, was much worse than I suspected.
The bottom after being soda-blasted to remove 30 years of old bottom paint.
A Deadly Problem
It’s not easy to find experts on this topic, and it appears that not much research is being done on it. But after several calls, I found Dan Rittschof, Ph.D., a professor of environmental science at Duke University and an expert on barnacles, fouling, and marine toxicology. Most modern bottom paints use copper compounds as the primary agent to keep organisms from adhering to our boats. Rittschof explained that copper bottom paint creates an extremely thin layer of copper ions in the water surrounding boats, which kills the free-floating larvae of marine organisms, also known as plankton. The seabed under boats moored in areas with little current, Rittschof said, will typically be a circle devoid of life such as marine worms, sea stars, shellfish, and other animals that have no interest in attaching to our boats. The bottom paint has killed everything. Now imagine the typical harbor containing hundreds and sometimes thousands of boats. Each of these owners is essentially slowly pouring several gallons of poison into the harbor.
It’s not as bad as it used to be. Back in the 1970s, most bottom paints contained tin, which was found to severely impair the reproductive systems of marine organisms and was banned in the United States and many parts of the world. Tin was replaced with copper compounds. Washington state and parts of Europe have now banned copper-based antifouling paints, and many more places are considering bans. But since there are no widely accepted alternatives, most bans are not being enforced.
Rittschof says the safest solution is not to use bottom paint at all, but rather to pull your boat out of the water after every use, which, although common among many small powerboat owners, is just not feasible for most of us with larger cruising sailboats.
Using the wrong rollers created an orange peel
surface that had to be sanded down.
I discovered that the problem is much bigger than just our harbors, since plankton are critical to the survival of our planet. Howard Dryden, Ph.D., chief scientific officer of the Global Oceanic Environmental Survey, explained that plankton extract more carbon dioxide from the atmosphere by far than any other means, including trees. The overwhelming majority of carbon dioxide removed from the atmosphere each day is removed by plankton, which we are inadvertently killing with our antifouling bottom paints. Research shows that the world’s oceans have already lost more than 50% of all plankton since the 1950s; that’s not just due to bottom paint, of course, but we boaters certainly are not helping.
I vowed that the next time I applied something to the bottom of my boat, it would be a less environmentally damaging solution while still being affordable and effective. I want to be part of the solution, not the problem.
Possible Solutions
There are several alternatives to heavy metal antifouling paints. Most bottom paint companies have come out with formulas that don’t contain copper, but as Rittschof points out, very little research has been done on the environmental effects of these chemicals.
One category of products creates a super-slick surface using silicone so the organisms slide off when you rub them off or drive through the water quickly. But if you’re not cleaning your boat regularly or moving it often, more growth forms on the bottom and after a while, it’s a lot of work to get off.
Another new product mimics a technique that sea urchins use to prevent hard growth. Called Finsulate, it is a material with a fine hair-like structure that is glued onto a boat’s bottom. I’ve never met anyone who has tried it, but as Rittschof points out, Mother Nature is ingenious and there is no product known to man that some organism hasn’t found a way to stick to. Yet another solution uses ultrasonic sound waves to discourage growth. That sounded high-tech and more complicated than I was willing to deal with, and according to some cruisers who have tried the product, such as the crew of SV Delos, it is not 100% effective either.
The hull was a little patchy after the author had to sand and repaint it.
Coppercoat antifouling paint has been on the market since 1991 and is recommended by several people I know, including Good Old Boat contributor Ed Zacko. He recently wrote a piece about the refit of his boat, which included Coppercoat application. He’s been happy with it so far and recommends having the product applied by a yard that has experience with it.
Ironically, Coppercoat involves applying copious amounts of pure copper to boat bottoms. The practice harks back to the days of the British sailing warships, when the British Navy applied copper plates to boat bottoms to prevent shipworm penetration into wooden hulls and discourage growth. Unfortunately, copper plate is too heavy and expensive to be used on modern boats.
To accomplish essentially the same outcome, a British company developed Coppercoat, a mixture of 99% pure copper powder and epoxy. Once cured, Coppercoat is sanded to expose the copper embedded in the epoxy. According to the manufacturer, the product has a leach rate well below the most restrictive standards worldwide. An additional benefit cited by the company is that application does not release volatile organic compounds (VOCs), which have adverse health and environmental effects. And the product uses water-based epoxy, making cleanup simpler.
Coppercoat claims its product will last 10-plus years before a touchup is needed, which means fewer plastics going into the ocean — epoxy is a plastic and plastic is a major contributor to plankton dying. Touchups don’t require removing old Coppercoat, but simply sanding off the surface and adding a couple of extra coats to areas that have worn thin.
This all sounded good. However, a quick search for “Coppercoat problems” on YouTube turned up a distressing number of people reporting failures with the product. There are also other issues to consider. For one, Coppercoat is only designed to repel hard growth, versus slime and other soft growth. Using the product requires cleaning your boat bottom regularly to prevent any hard growth from using the soft growth as a base.
Cost is another issue. Applying Coppercoat requires first removing all previous bottom paint, usually via soda-blasting or some other method. My boat had 30 years of old bottom paint, which was peeling off in sheets (especially bad for the oceans), so I needed to do this anyway. Additionally, the product is pricier than some other bottom paints — it cost me $2,173 to cover the bottom of my 44-foot cutaway keel cruiser. And Coppercoat is applied over the course of a week or more, which increases yard and labor fees. On the other hand, if the paint lasts a decade or more, you may break even or even be a bit ahead in the long run.
Andiamo after the Coppercoat application, before the surface was burnished smooth.
Our Experience
It’s not easy to find boatyards in the United States that have much experience with Coppercoat. I found one in Rockland, Maine, that was highly recommended. Its paint manager said he had no experience with the product but was willing to give it a try if I supervised. I knew I was taking a risk, but given what I had learned about the effects of antifouling paints on plankton, I felt I needed to try it. One advantage of this yard was that my boat would be in a climate-controlled shed for more than a month while a new engine was being installed and the boat’s topsides were painted with Awlgrip. I figured if we followed the directions to the letter, I’d probably avoid any disasters.
The Headaches Begin
The project began in fall 2020, and there were problems right from the start. The yard hired a subcontractor to soda-blast the bottom, but the decades of paint on my boat required more time and materials than anticipated, exceeding my budget. Worse, the soda-blasting revealed a significant number of blisters, which had to be sanded and filled, further increasing costs. None of that can be blamed on Coppercoat or the yard; as most boat owners know, boat projects almost invariably turn up additional problems that need to be addressed.
Coppercoat can be applied without a barrier coat, but the company recommends using a ceramic-based coating called CK426, typically used to paint potable water tanks. That part of the project went well. The manufacturer recommends that Coppercoat be applied at a temperature above 50ºF and in low humidity. Since the epoxy in Coppercoat is water-based, rain, dew, or even just high humidity can apparently cause it to cure improperly. Though my bottom-painting project started in early September, the weather was cool and rainy, so the yard turned up the heat in the shed to dry things out and keep the temperature at 72ºF.
The crew at Johanson Boat Works, with the boat looking like new after two months of work.
Mixing and applying Coppercoat is not complicated, but it must be done quickly and precisely. Two experienced painters rolled on the product while I mixed and supervised. The company estimated that I would need 12 kits, which contain the epoxy, a hardening agent, and a bag of copper powder. After the epoxy and hardener are mixed together, the copper is slowly and carefully poured in to avoid creating bubbles. The painters went to work while I stirred the paint to keep the copper suspended, refilling their trays as needed. That part went smoothly.
The literature recommends using 1/8-inch nap foam rollers. We couldn’t find those at nearby chandleries and hardware stores, but we found rollers that were pretty close, and since time was running short, we decided to go with them. Big mistake.
In reading horror stories about Coppercoat, I identified two main types of failure. The first is that the paint does not adhere. I assumed that was because the wrong barrier paint was used, the sublayer was not cleaned well enough, or the temperature or moisture was wrong. I was confident I had gotten those things right.
The second mode of failure is that the Coppercoat is not smooth enough after curing, leaving nooks and crannies for critters to hang onto. After Coppercoat is applied, it takes a couple of days for the epoxy to harden; it must be hard enough not to gum up sandpaper, but not so hard that it is difficult to sand. The yard workers kindly agreed to come in over the weekend to sand so that we got the timing window right.
But when we started to burnish the Coppercoat, we discovered that the rollers we used created a light orange peel surface. We needed to sand that off, but when we did, we also started sanding through the Coppercoat to the white barrier coat below. My heart sank. This was starting to look like one big, expensive mistake. I called the company and was told I could buy the correct rollers from them, so I ordered rollers and a couple of more kits to cover the places that we had sanded through. My wife and I applied the additional paint with the new rollers, which worked much better. Then I spent the next five days sanding off every area of orange peel I could find. In the end, the bottom looked patchy, but I was hopeful all my effort would pay off.
Andiamo’s bottom after about six months with
Coppercoat. A light layer of slime is visible.
Results
Despite all the complications, I figured if the product worked as advertised it would still be worthwhile, but I wouldn’t know for sure until I had the boat in the water for at least a season.
It’s now almost a year out from the Coppercoat application, and in that time we’ve sailed Andiamo from Penobscot Bay in Maine to Ragged Island, the southernmost point in the Bahamas, and back. Every few months I’ve been diving the bottom, inspecting it, and scraping off any growth with a metal paint scraper. I’ve found soft growth that’s easy to scrape off and a few barnacles here and there, but nothing too bad. The real test would be when I pulled the boat out and could give it a close inspection.
We did that in September 2021 in Maine’s Rockport Harbor. Since we’d been cruising in colder waters since the previous May, I hadn’t done much to inspect or clean the bottom. This would be the true test of my Coppercoat bottom job. As the boat came out of the water, I saw a moderate amount of growth that was clearly more than just slime. There were multiple places where more advanced growth had taken hold. I was a bit disappointed. It was not terrible, but definitely not perfect either.
It took me a few hours with a scraper to knock off the barnacles, which were small and came off easily. As I removed them, I made sure to also scrape off a thin layer of the epoxy, figuring that the copper likely wasn’t fully exposed in those areas. I also noticed that on the very bottom of the keel, where we were unable to apply Coppercoat because the boat was on blocks and instead applied some regular ablative paint before relaunching, there was a thick layer of large barnacles. So while the Coppercoat did not keep off all the hard growth, it did a good job of keeping most off.
I also found two nickel-sized places where some of the paint had chipped off. I’m not sure what was going on there. Perhaps I didn’t prepare the barrier coat well enough in these two places. I’m hoping that’s the extent of it and that I won’t see more flaking in the future.
The boat bottom after a year of cruising with Coppercoat. The slime and a small number of barnacles were easily removed with a powerwash.
Is Coppercoat Really a Better Solution?
I would not say Coppercoat is better at preventing growth than some of the other copper-based paints on the market today, which can do a good job of keeping both hard and soft growth off for a year or two. But they are not good for the ocean.
Is Coppercoat more environmentally friendly? Rittschof points out that solid copper, traditional copper antifouling paints, and Coppercoat all work the same way — they kill with copper ions. He is also concerned about the epoxy in which the copper powder in Coppercoat is embedded, since many types of epoxies contain phenylboronic acid (PBA), which is known to disrupt the metabolism, growth, and development of living organisms.
Discouraged, I reached out again to Dryden at the Global Oceanic Environmental Survey. He owns a cruising sailboat much like my own, and I asked him what he uses on its bottom. His answer: Coppercoat. Dryden goes so far as to say ablative paints, a major source of microplastics in oceans, should be banned. Hard bottom paints are better, he says, but they still leach toxins into the water. So does Coppercoat, but copper in low doses is a micronutrient naturally present in sea water, Dryden says. And since Coppercoat doesn’t have to be sanded down to apply another coat, copper entering the marine environment is minimized.
As Rittschof says, there is no free lunch. But for me, at least when I clean my boat bottom with its new Coppercoat paint, I won’t be releasing enormous clouds of microplastics and complex chemicals, as happened in the Bahamas. For now, I’ll have to live with the environmental consequences or stop cruising until something better comes along. I like to think that our full-time cruising lifestyle is very green, and hopefully that offsets some of the negative impacts of my bottom paint.
Gino and Carolyn Del Guercio have lived aboard their Brewer 44, Andiamo, for the past few years, spending summers in New England and winters in the Bahamas. Andiamo is one of very few boats that have twice graced the cover of Good Old Boat.
Thank you to Sailrite Enterprises, Inc., for providing free access to back issues of Good Old Boat through intellectual property rights. Sailrite.com
