Having a smaller environmental footprint AND lower costs overall? This is the holy grail of “sustainable products”, and the promise of Copper Coat bottom paint, which we are re-applying on Selaví. But it comes with its challenges.
HOW BOTTOM PAINT WORKS
Normally anti-fouling bottom paint is quite toxic. It prevents algae and barnacles from growing on the hull — which slows the boat tremendously and can mask problems — by having a “biocide” that comes off over time into the water (especially ablative paints). This can bio-accumulate, especially in marinas with reduced water flow.
Growth on the hull. The green areas have been pressure-washed, the brown is algae after just 3 weeks
MAINTENANCE & IMPACT
Regular anti-fouling normally has to be re-painted every two years, which means hauling the boat out of the water, sanding the hull (and scraping all the toxic paint every 8-12 years to prevent over-buildup), and all the toxins usually go in the drains into the ocean.
Copper Coat is a very different type of anti-fouling paint: it is epoxy based. It’s biggest selling point is that it lasts 10 years instead of 2 years. This means lower maintenance costs from dry docking. The epoxy seals the hull, which can prevent blisters and other damage to the hull. Fewer haul-outs also mean much less impact from reduced sanding of toxic paint.
Sanding the hull with 80 grit paper. This is the nastiest part of the job, but still not as bad as with regular anti-fouling.
Epoxy based paints are non- ablative, which means that they don’t come off in the water column over time. This is much healthier for us sailors: when cleaning the hull with a brush, clouds of toxic antifouling paint don’t waft around, as they do with regular bottom paint.
Now for the challenges of Copper Coat. On the first application, the hull must be perfectly clean of paint and 100% dry, the latter being difficult in tropical environments. Then Epoxy Primer is applied, followed by the bottom paint itself.
The green part of the keel hasn’t yet been painted with the first coat. Note that the first coat is normally very spotty, and only by the third coat is there an even coverage. It doesn’t act or look like paint at all!
On our catamaran, the first application was 11 years ago, so it was time to re-apply (the growth was hard to keep up with, re-emerging every 3-4 weeks). The actual application of the epoxy paint like copper coat is really technical and quite difficult.
For comparison, regular anti-fouling paint is very tolerant of moisture; in fact sailors often paint “under the blocks” just 20 minutes before the boat goes in the water. If it rains, you stop painting, but it’s no big deal, just start again that day or in a few days. Copper Coat, on the other hand, is epoxy-based so it requires a very dry environment, making the substrate very dust-free. To make matters worse, the manufacturer recommends application of all 4 coats plus 2 water line coats in one day… which is really hard to do for a larger boat.
Applying paint into the night… not ideal for moisture in the air, but we were trying to get it done in “one day”
For our haul out in Raiatea, I was pretty stressed because it was rainy weather. Even when it is sunshine in the tropics, there can be rainshowers for 10 minutes out of nowhere, which would be a bummer.
Luckily we picked a day with just 5% chance of rain and there were no rain drops all day long. We had 3 painters plus occasionally a fourth. You have to mix one liter of copper coat at a time. This takes a full 10 minutes to ensure the copper powder is well mixed and isn’t settling. Then, at 80 degree weather, we found we only had 25 minutes before the paint started getting a bit gummy; after 40 minutes it would get impossible to apply, actually removing the previous layers you had just applied. Very frustrating.
Example of the paint being applied after it was already going off, and it actually removes the previous coat. Once it start doing this, it is very “slippery” and doesn’t adhere onto the previous coat. Have to throw away that batch.
Our first few hours were terrible. The paint was going off, we didn’t know why, it was a disaster. Then we finally figured out what worked for us. It was a marathon day: we worked from 7:30am to 10pm to apply all the 4 coats + 2 waterline.
Bear in mind this is for the tropics (hotter, so faster epoxy) and we are amateurs.
- Use large paint rollers. We were sold small rollers by the dealer, but we simply couldn’t apply the paint fast enough before it started to go off. Also this makes your ultra-long day even longer.
- Use 5% thinner isopropyl (alcohol). This was considered “optional” but we found it mandatory for the temperature. We’ve talked to professionals that didn’t thin the copper coat, but they are pros. The quality of the coats went up tons once we thinned it.
- Have minimum 3 people, and don’t let the epoxy go more than 25 minutes.
- Discuss with the yard beforehand about the need to re-block the boat in order to paint under the blocks and the keel. This is not what they normally do, so you can avoid hassles by planning this ahead of time. Also, if you have a multihull, consider where you will put the new round of blocks to support the weight of the boat.
- In retrospect, I would have hired someone to help who had already applied Copper Coat before. The first few coats are really terrible looking, even if applied properly, and this can be a source of confusion especially when you’re trying to work fast.
- It is possible to do 1/2 portions of the mixture (half liter at a time) to ensure that the paint isn’t going off as you’re applying it, especially if you don’t have enough people helping, or if it’s very hot.
Here’s the biggest question I have. If you paint over the course of 2 days, will the copper coat chemically bond? My intuition from working with other epoxies is that it will chemically bond, because the paint is still a little soft for 24hrs, only hardening after 48hrs. Acknowledging that this is a water-based epoxy which is different than what I’ve worked with. But if you could work in multiple days, and chemically bond the coats, this would make life many-fold better.
Counter to this, the manufacturer makes a point of insisting you apply it all in one day, or else you have to sand the hull and re-clean it. So that’s what we did, but it was HARD. It becomes a major area of stress if you push yourself to finish in 1 day in dry conditions. Note that the manufacturer recommends 72hrs before launching, but in the tropics 48hrs is probably plenty adequate. So even they are admitting that the epoxy is “curing” during those first two days. If it is curing, it stands to reason that it could chemically bond, especially after just 24hrs.
I’d be curious if other people have applied copper coat over multiple days and whether that worked out for them.
Thanks for reading. We’ll keep you posted on the performance of our copper coat paint on this blog on our catamaran Selavi.