In our last post, we discussed the decision-making process behind ultimately choosing Coppercoat for our antifouling and touched on some of the confusion surrounding the product. In this post, we’ll share a more detailed account of our experience prepping the bottom and the process we followed for applying Coppercoat. We’ll follow up with a future post to share results after being in the water for some time.

If you haven’t read that first post, go check it out now (Is Coppercoat the Best Antifouling for Your Boat?) before diving into this one–it’s a good primer for what we’re going to cover below.

While researching Coppercoat, one of the biggest criticisms we heard was: “It’s so expensive!” (Sailing Soulianis Patrons get a discount!) Upon further investigation, this appears to be only partly true–and only for some people.

You can divide boaters into groups many ways: sailors & motorboaters, weekend warriors & liveaboards, racers & cruisers, but this time let’s go with Do-It-Yourselfers & Hire-It-Outers.

We learned a pretty tough lesson early on about hiring people to work on our boat (see DIY or Hire a Pro? A Tale of Two Boat Projects). So the decision to tackle this project ourselves was a no-brainer; for us there was no other option. We had never done anything like this before, had no idea what we were doing, but we’d roll up our sleeves and figure it out. This was no different than any other project we’ve tackled before or since. When we started looking at the material costs involved and compared it to similar products on the market, it was difficult to understand what the fuss was about.

Two weeks into the project, however, it was painfully obvious…in the form of incredibly sore shoulders we felt each night after hours of scraping and sanding in awkward overhead positions all day long. To answer the above question, yes it absolutely IS a DIY job; you can do it with zero experience, and our hull is proof. But, be forewarned: It is one hell of a big job.

Labor is the biggest barrier to entry for most people choosing Coppercoat. For the DIYers it’s a huge undertaking, especially when changing from another form of antifouling paint. For the HIOers, that translates directly into added costs, and that’s where the expense comes from. The product itself is not expensive, but the process to prep the hull properly and apply Coppercoat is expensive if you’re hiring the job out to someone else. The complaint about Coppercoat being expensive is partly justified, but if you do the job yourself the raw costs are not much more than any other antifouling–especially when you extrapolate the cost out over the 10 years Coppercoat is supposed to last, it becomes significantly cheaper.

Prepping the Bottom for Coppercoat

The application process for Coppercoat is not like most other types of antifouling paint. This is beause Coppercoat is not actually paint, it’s a two-part epoxy. Surface preparation for any painting job is important, but for this application it’s critical. Coppercoat cannot be applied over the top of any other bottom paint–it can, however, be applied over the top of barrier coats. This means unless you’re working on a brand new boat, all antifouling bottom paint must be removed before Coppercoat goes on the hull.

Removing Old Bottom Paint

There are a number of ways to remove bottom paint. The most common method recommended by boat shops, other boat owners and online was to get 40-60 grit sandpaper with an orbital vacuum sander attachment (to contain the dust) and sit for hours while the sandpaper slowly chews away at years and years of built-up bottom paint. We’ve seen this approach in just about every boatyard we’ve stepped foot in. Most people end up looking like Smurfs by the end of the day, with blue paint dust all over their face, hands and clothing. Not only is the dust toxic, it gets everywhere, no matter how much personal protective equipment you’re wearing. The sander and vacuum are extremely loud, and running them for hours at a time will undoubtedly result in hearing loss without ear plugs. To top it off, it takes FOREVER. This was the least desirable approach for us and I wanted to avoid it at all costs.

Before coming down the rivers, we got a great tip from our friend Bruce, our old boat neighbor in Racine, Wisconsin. He had repainted his bottom a year earlier and recommended we get a carbide scraper, and most importantly a two-handed design. Specifically this one:

His advice was to start with the scraper, then finish sanding whatever the scraper couldn’t remove. This will most likely not work on boats with hard bottom paints, but on ours and many others with years of built-up ablative paint, this thing was a lifesaver. We ended up buying two extra carbide blades since we found they did eventually dull, and having a nice sharp edge made it significantly easier to peel the paint off.

We followed his advice with one modification. About two hours before scraping, we applied Blue Bear 670AF Paint Stripper. It needs to stay moist to soften up the paint, so I wetted it down with a spray bottle about every half hour while it sat on the hull, then again immediately before scraping. This made the paint soft and easy to scrape, and it cut down immensely on the dust. Once I found my rhythm I was able to scrape through every layer of ablative bottom paint–including most of the barrier coats–with one quick downward stroke.

Don’t get me wrong, this was an intensely physical process. But as I worked at it, it became almost meditative. I’d put in some headphones and enter a strangely calm mental state, making visible progress one scrape at a time. Watching all that paint falling off in chunks was very satisfying, almost cathartic. The blade is only 2.5 inches wide, so while it was still pretty slow, it was very motivational. I could immediately see the results of my work, and with each new stroke of the blade a small section of white gelcoat appeared. The sander, on the other hand, was a mind-numbingly boring experience (and hand-numbing from the sander vibrations).

Other Options for Removing Bottom Paint

Prior to scraping the hull we had investigated a number of other methods for removing bottom paint. Sand blasting, soda blasting, walnut shell blasting, etc. Effectively all the same process, which is using an abrasive material hurled at the hull at a high rate of speed to remove the paint. The differences are mainly the abrasive materials used and the methods for containing the waste product which is a toxic mix of antifouling bottom paint and whatever abrasive material was chosen.

Some of these blasting services are marketed as being “dustless,” usually meaning they use water as a medium to contain the abrasive material. This works well to contain the dust, but then what’s done with the contaminated water? We made a number of inquires to various ‘blasting’ services, and the reputable ones had plenty of information about how to contain the dust and/or waste material. In the end, our boatyard didn’t allow any blasting anyway, no matter how well it was contained, dustless or not.

If you choose to go the ‘blasting’ route (and we do recommend it), find a boatyard that either provides this service in-house, or allows you to hire an outside company to do it for you. If we ever need to do this again, this is exactly what we’d do.

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The Application Process

We were starting with a nearly bare hull. We had removed everything down to gelcoat in the process of scraping and sanding. So prior to applying Coppercoat we needed to put on a barrier coat. If your boat’s barrier coat is in good shape without any osmosis or blistering and you’re happy with it, your next step is to give it a once over with 80-grit sandpaper.

CK426 Barrier Coat

Any epoxy-based barrier coat is suitable under Coppercoat, but for those of us needing a new barrier coat, Copperoat USA recommends a product called CK426, a two-part epoxy-based ceramic coating. The major benefit here is that we can skip the sanding step in between the barrier coat and Coppercoat as long as the first layer of Coppercoat goes on within 24 hours of finishing the last layer of CK426. After all the sanding we did to get to this point, this was a huge bonus, and we happily followed their recommendation.

After sanding, repairing and fairing all the blemishes in the hull, we gave the boat a good wash down to remove as much dust as possible. Just prior to rolling on the CK426, we wiped the hull down again with isopropyl alcohol to remove any additional oils and residue. Now it was time to roll on the CK426. Coppercoat recommends at least 2 layers. We had enough on hand to do 3 thin coats.

It goes on translucent and can be difficult to see, especially against our white hull. If we were to do it again, we’d definitely tint it. The mixing process is pretty straight forward, requiring a healthy 4-minute pre-mix of the resin to suspend the ceramic particles. Then the resin and hardener are mixed at a 2:1 ratio and thinned 10% by volume with isopropyl alcohol.

The only difficult part is ensuring you can roll it all on the hull within the pot life of each mixed batch. The pot life is only 30 minutes at 72 degrees, so on any given day in Florida, that means you need to move quickly, or start mixing smaller batches.

Subsequent coats can be applied while the product is still tacky, but must be done within 24 hours or you’ll need to do a sanding with 80-grit in between.

Read the entire technical data and instructions for CK426 barrier coat provided by Coppercoat USA.


The application process for Coppercoat is extremely detailed and specific, which can make it a challenging DIY project. That said the Application Information page Coppercoat USA has developed is very helpful, including a series of “How To Videos” and a detailed list of “Do’s and Don’ts.” These are a result of over 12 years of working with customers in the US and the Caribbean. We highly recommend familiarizing yourself with all the information on their website prior to starting. We read through the instructions multiple times while acquiring the necessary tools and prior to painting to make sure that the process was engrained in our heads. We have also put together a list of most of the gear we used to apply Coppercoat to help save you some time when acquiring supplies.

A few things to note:

The instructions call for 1/8 nap mohair epoxy paint rollers. We tried a couple different brands because these were EXTREMELY hard to find locally or online, and we couldn’t get our hands on very many from any one source. There were one or two that worked OK, but we found that the small high density foam rollers we picked up at Home Depot gave a better, smoother finish overall.

If we were to do it again, we’d stock up on a bunch of the larger 9″ size foam rollers beforehand because they are harder to find. But in a pinch we did alright with the 4 & 6″ variety. We went through quite a few of these, so make sure to have a bunch on hand before beginning. The day moves quickly, and you don’t want to run out.

In addition to the instructions above, we want to emphasize being extra careful with the following:

  • Controlling temperature & humidity — It’s a two-part water-based product, moisture has a major effect on its curing process.
  • Ensuring mixing is done properly — The powdered copper needs to be held in suspension until applied on the hull, which can be difficult.
  • Paying attention to foam roller specifications — Coppercoat needs to be applied in very thin and even layers.
  • Sanding/burnishing the finish — Once Coppercoat is on the hull, it needs to be sanded to expose the powdered copper to the water.

We put our first layer of Coppercoat on about 18 hours after our last coat of CK426. We started at 9:30AM which allowed for some of the morning humidity to burn off and gave us plenty of time to get all four coats on in one day with the help of our friend Chris. (Thanks Chris!)

Coppercoat is a two-part epoxy just like the CK426 we applied earlier, but the mixing process differs slightly. Coppercoat is a 1:1 mix of hardener and resin, which we thinned again with isopropyl alcohol. Only after thinning do you mix in the powdered copper. This is where things get tricky. It’s actually this copper powder that does all the heavy lifting for your antifouling. The powder needs to stay mixed in with the two-part epoxy as it’s rolled on. Any left at the bottom of the tray is wasted, and will reduce the effects of the antifouling. It’s important to ensure the epoxy is well mixed in the tray throughout the rolling process.

Coppercoat is applied “wet-on-tacky” and only requires about 20-30 minutes between coats at 70-75 degrees. It took us about an hour to cover our entire hull, meaning as long as we timed the mixing right we could basically do laps around the boat without stopping for drying time in between.

We did two coats back-to-back in the morning, took a break for lunch, then put on the final two coats back-to-back in the afternoon. This worked quite well, but still took the better part of the day with three people.

Controlling Humidity

Because Coppercoat is water-soluble it’s vitally important to ensure no water drips down the hull onto the newly applied Coppercoat before it fully cures. While we had a bit of practice constructing a mini “dew-skirt” when applying the barrier coat, we decided to go all out when covering the Coppercoat. Since it needed at least 48 hours of drying time, we constructed a giant floor-length dress for Soulianis ensuring nothing could find its way below the waterline.

We even put our dehumidifier under the boat to suck water out of the air and ensure it was as dry as possible. I think most people in the yard thought we were crazy at this point. “What are they going to do, dehumidify all of Florida?!”  They had a point, and initially I thought this might be taking things a little too far. But we had the dehumidifier, so why not? especially with the forecast for the next morning predicting 94% humidity.

Sanding/Burnishing the Copper

After letting the hull cure for ~72 hours we deconstructed our carnival tent and put away the dehumidifier. It was time for more Sanding, Glorious Sanding! At this point there wasn’t anyone left in the boatyard that thought we were sane, and they were not shy about telling us as much. After witnessing all the prep we did to remove 100% of the bottom paint, seeing how complex the application process was, and now we were sanding it back off?! We must be absolute bonkers.

But this is a critically important step for Coppercoat. The entire hull must be sanded using a 320-grit paper to expose the copper powder to the water. Coppercoat even supplies a handy visual guide to compare your hull to the recommended level of sanding. And it’s here where any imperfections in the hull become a nuisance.  Ideally, the hull should be absolutely smooth so that 100% of the surface can be sanded down and exposed. But any drip, run, bump or other imperfection will leave a valley that can’t easily be sanded, and if it’s not sanded, no copper is exposed and there will be zero antifouling capability on that spot.

Finishing Underneath the Jack Stands

With the entire hull sanded to spec and looking like a newly minted but rather dull penny, it was time to start all over again under the jack stands. We asked the boatyard to move the jackstands and took it from the top: scraping, sanding, 3 coats of barrier coat, 4 coats of Coppercoat, and sanding down with 320-grit paper.

Final Thoughts & Preliminary Results

It was a hell of a lot of work. But we are extremely glad and happy we did it. The process was detailed, but not so much that we couldn’t do it ourselves. After our solar arch debacle (Glad THAT’S Over – Ep. 38) we’ve decided that we will always try any project at least once. If we hit a roadblock we really can’t handle, and find we’re in way over our heads, we’ll hire someone, but thankfully that hasn’t happened yet and we have learned so much.

We went into this project knowing it was going to be a tough job, but if we did it once, we’d know how tough it was and wouldn’t feel as bad forking over money to hire someone to do it the next time around, should we ever need to do it again.

And for preliminary results, we’re quite pleased. Stay tuned for a follow-up post including photos from regular intervals in the water!

Let us know what you think!

Do you have any experience with Coppercoat? Did we miss anything? We’d love your feedback.

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