Coppercoat antifouling is a very polarizing topic amongst boaters. While researching different antifouling bottom paints to use on our Tartan 37, we heard everything from “It’s magic!” to “It’s snake oil–beware.” Surprisingly, we didn’t hear a whole lot of opinions in the middle, which only made the decision-making process more difficult.

Whose opinion do we trust? If it does work, why are there so many people claiming it’s worthless? And if it doesn’t work, why would so many people be raving about it?

Fortunately, after diving in and doing a bit more research, a few common themes bubbled up:

  1. Confusion about what Coppercoat actually is — How it’s different from other copper-based paints (Copper Shield, Copperbot, Copper Bottom), confusion about different brand names, and the use of DIY recipes being referred to as Coppercoat.
  2. Misrepresentation about what Coppercoat actually does — It’s not a magic potion, you do still need to clean your bottom on a regular basis.
  3. Blatant disregard of the manufacturer’s recommended application process — The application process is different than other types of bottom paint.

We want to set the record straight regarding this topics, and hopefully provide a clear, concise report of our experience using Coppercoat antifouling bottom paint without any sensationalism.

What is antifouling bottom paint?

Just to ensure we’re all on the same page, antifouling bottom paint works by discouraging growth on the hull of a boat. This is typically done with the use of some form of biocide–a chemical toxic to marine sea life. Antifouling paints are typically sub-divided into two categories: “hard” and “soft.” Soft bottom paints are more specifically referred to as ablative, which means that as the boat moves through the water, the paint slowly sloughs off in microscopic layers, revealing new/more biocide. Hard paints do not ablate, but rather typically have a slow release of biocide leeching out through the paint. There are other types of bottom paints, such as foul-release paints, that focus on anti-adhesion properties, meaning they are both physically and molecularly “slippery,” so sea life can’t easily attach to the hull.

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How is Coppercoat different?

Coppercoat is a an epoxy-based hard bottom coating system, meaning it does not slough off when the boat moves through the water. Copper is used as the biocide, but that is where the similarities to many other copper-based products end. Whereas most hard copper-based paints slowly leach their copper out into the water, Coppercoat is unique in that it suspends a very fine copper powder in the epoxy, which is exposed to the water after sanding. There’s quite a bit to unpack in this last paragraph:

  1. Coppercoat is an epoxy-based product, and not actually a paint. This means it has the added benefit of acting as a second layer of barrier protection for your fiberglass hull. Coppercoat still recommends the use of a barrier coat, but it’s nice to know after following the manufacturer’s recommendations there are no less than 6 coats of epoxy-based barrier protection on the hull.
  2. Being a “hard” bottom coating system means that once applied to a smooth fair surface, it can (and should be according to the manufacturer’s recommendation) be sanded to provide an extremely smooth, almost polished finish, which significantly reduces surface resistance and drag.
  3. Coppercoat is classified as a “non-leaching” anti-fouling system. As opposed to most other copper-based bottom paints, the copper in Coppercoat starts out as a 99% pure copper powder which is mixed into and suspended in the epoxy on the hull once cured. Once exposed via sanding, and upon immersion in seawater, the exposed copper powder forms a cuprous oxide layer that is a highly effective antifouling agent, deterring growth until the surface degrades further to become cupric hydrochloride. This final copper form is highly unstable, and is washed away by the movement of the boat, thereby removing any accumulating silt or slime. This automatically reveals a fresh copper rich surface, whereby the process restarts. With an average thickness of at least 12 mils of Coppercoat being applied in a treatment, and a typical corrosion rate of 1/4 mil per year, it is easy to appreciate how this coating offers such long lasting and effective protection.


Despite its fundamental differences from most other forms of copper-based antifouling, there’ve been a handful of other copper-based antifouling systems (Copper Shield, Copperbot, Copper Bottom), including some high-profile DIY recipes shared online–similar in nature to Coppercoat–that are not Coppercoat.  However, the Coppercoat name has somehow morphed into the term commonly used to reference the entire group. (Similar to how Kleenex [the brand name] is often used interchangeably with tissue [a generic term] regardless of the actual product being referenced).

Invariably some of these competing products and DIY recipes failed to live up to Coppercoat’s reputation, and a lot of bad press was generated using the Coppercoat name, despite the antifouling system in question being a completely different product.


The Coppercoat USA website reads a bit like it’s describing cure-all wonder product. That said, if you cut through the superfluous text and single out the specific claims it’s making, expectations become quite clear:

  • It is not considered a hazardous material; approved for use in California
  • It reduces maintenance costs because it lasts up to 10 years before needing to be reapplied
  • It reduces fuel costs, because it is sanded smooth with 320 grit sand paper after application
  • It’s better for the environment because it is considered “non-leaching”
  • It protects your hull against osmosis & blisters because it’s a two-part epoxy coating applied instead of a paint
  • Cleaning the hull is easier & safer because it can be done with an abrasive pad instead of a scraper and no toxic chemicals are scraped off into the water while cleaning

Despite these fairly clear and specific claims, there is a widespread myth that Coppercoat should act as some sort of magic spell that will prevent all growth on the hull of a boat. This just isn’t true, nor does the company claim it to be so. In the best case scenario, anti-fouling bottom coatings will slow the rate of growth on your hull. Yet somehow, after putting Coppercoat on their boats, a number of boat owners have become frustrated when they see growth on their hull, no matter how long it’s been since application or between cleanings.

If a boat sits for a long period of time in nutrient-rich stagnant water, life will find a way to exploit every nook and cranny it can find. Coppercoat is not a magic potion, the bottom of your boat will still need to be cleaned from time to time–especially if it’s left to sit. Going into this project with the expectation that it won’t need cleaning doesn’t reflect poorly on the product… Which brings us to the final point:

Disregarding Manufacturer’s Recommended Application Process

The application process for Coppercoat is extremely detailed and specific, and can make this a challenging DIY project. That said, Coppercoat USA has developed a very detailed list of “Do’s and Don’ts” over 12 years of working with customers in the US and Caribbean that makes the application easier to understand. None of the other Coppercoat distributors have these detailed instructions which has caused application issues for some customers.  We found it’s especially important to follow these instructions carefully when:

  • Controlling temperature & humidity — because it’s a two-part water-based epoxy product
  • Ensuring mixing is done properly — the powdered copper needs to be held in suspension until applied
  • Paying attention to foam roller specifications — it needs to be applied very thinly and evenly
  • Sanding/burnishing the finish — once it’s on the hull, the copper needs to be sanded so it will be exposed to the water

Yet, for whatever reason, there seems to be a fairly significant number of people that do not follow these instructions, and complain about Coppercoat’s sub-par results. Whether the failure to follow the instructions is is due to arrogance, ignorance or carelessness towards the process, the product can hardly be faulted. Following the steps traditionally taken to repaint the bottom of a boat, no matter how much experience someone might have doing it, will absolutely yield sub-par results, because these are not the correct steps to properly apply Coppercoat–because it’s not a paint. We’ll cover this in more detail in our next post, “Our Experience with Coppercoat”.

So why did we choose to use Coppercoat?

After doing our research and wading through all of the content online from people raving about how well it does or doesn’t work, we came to the conclusion that the majority of instances in which people were complaining about Coppercoat could be chalked up to one of the reasons above, and that the people raving about how well the product performed were probably justified. Ultimately we assumed that if we could avoid the pitfalls detailed above, we would see the long-term benefits of using Coppercoat over any other type of antifouling bottom coating far outweighing the short-term pain of completely removing the old bottom paint from the boat. And in the end, we hoped to be happy customers.

The Decision-Making Process

When we bought our boat, it had Petit Hydrocoat Eco on the bottom. It worked OK in fresh water, but was not in the greatest shape and didn’t seem to be performing all that well in the warm tropical waters we were now hanging around in. Since you can only apply ablative over the top of ablative, we needed to make the following decision:

Should we continue the process that had been started years ago? (Give it a light sand & slap on another couple of coats of ablative.)


Should we completely start over from scratch, and apply whatever we thought was best?

Option One: In which we would simply keep applying more ablative, was the easy fix. It wouldn’t require a significant amount of work up front, but it would put us right back in the same place with the same decision to make next year. Because this had been the process for so many years, and the current state of the paint was pretty poor, there were spots where it was excessively thick and others where whole chunks had fallen off over time and it was bare.

Option Two: Starting over from scratch would require a significant amount of work up front. But by removing all the paint, we’d be able to fully inspect the hull, and it would pave the way for choosing the best performing bottom paint for our boat and cruising style, regardless of whether it was hard or soft.

Ultimately, we were sold on Coppercoat for a number of reasons: The biggest of which was we knew removing and repainting the bottom is a terribly dirty, physically intense and mind-numbingly boring process, and ideally we’d never need to do this job again on this boat. 😀

There were a handful of other reasons to go with Coppercoat:

  • Reduced toxicity — The first time I cleaned the hull in Lake Michigan, I had no idea what ablative paint was. As I scrubbed the bottom, I quickly realized I was swimming through toxic clouds of blue dust surrounding me in the water. I ended up with a horribly sore throat and sinus infection that lasted weeks afterwards. This wouldn’t happen with a hard bottom paint.
  • Reduced maintenance — From our research, Coppercoat did seem to prevent growth longer than most other bottom paints, and because it is an incredibly smooth hard bottom coating, the growth that does occur is mainly soft growth, meaning that instead of scraping away at hard/sharp barnacles, we’d use a spongy scouring pad and clean it all away with a light swipe.
  • Flexibility for the future – If we went with a soft ablative paint, we’d likely need to haul the boat every 1-2 years just to reapply paint. And, for most other hard bottom paints, if we decided to haul the boat for longer than a few days, we’d HAVE to repaint as all the biocide quickly leaches out while the boat drys out in the air. The flexibility in choosing to haul the boat out each year without having to reapply bottom paint each time, or to leave the boat in the water for many years to come without needing to repaint, was a huge benefit.

And so, with our decision made to go with Coppercoat, the only thing to do was get to work!

In next week’s post, we’ll cover the steps required for using Coppercoat, share some tips from our experience, and evaluate the results after some time in the water.

Let us know what you think!

Do you have first hand experience with Coppercoat? Did we miss anything? We’d love your feedback!

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