For the benefit of non-boating readers, anti-fouling is a special type of paint which is applied to the parts of the hull which are under the water. This is meant to stop barnacles and other growth from attaching itself to the boat. Without an effective anti-fouling system the bottom of the boat would end up encrusted with a layer of cement-like barnacles and looking like your back garden 🙂

Depending on the temperature of the water, growth happens differently. This is also dependent on how much the boat sits still and how often it moves. A boat laying in a marina for months on end is the worst and its generally necessary to dive underneath and clean the hull frequently. In some places, the hull can be badly fouled in just a few days! Anti-fouling paint normally needs renewing every 1-2 years. This is not only an expensive job, but a real hard one too! The boat has to be lifted out of the water (expensive in itself) so the whole hull can be sanded down. It is then repainted with several coats before being launched again.

On Destiny, we are using some different techniques to protect from fouling.

  • Coppercoat – environmentally friendly anti-fouling paint on the whole hull
  • Ultrasonic – a new concept using ultra-sound to supplement the performance of Coppercoat
  • Amorsil – special anti-fouling product for mechanical under-water gear which can’t be treated with Coppercoat – although this didn’t work! So we replaced it with PropSpeed.


We have opted for a special product called CopperCoat for our anti-fouling paint. The product is very expensive to start with but it has a lifetime of at least 10 years. A much better performance than the 1-2 years expectation for normal anti-fouling paint. The manufacturer also claims to be much more environmentally friendly than traditional paints. Although the paint does contain the maximum amount of copper allowed by law, the paint does not wear off. It’s a non-ablative product. Certain anti-fouling paints are designed to “rub off” (ablate) gradually in the water which is how they work. They take the marine growth with the layers of paint. CopperCoat works differently and does not give off as many damaging products for sea life.

Coppercoat anti-fouling paint

We have experience of CopperCoat on our sailing yacht and over the years have done extensive research on it. The product consists of a copper powder, a resin liquid and a hardener. You also use a particular brand of thinners. The components are mixed together into paint consistency in small quantities.

Application Process

The application process and environmental conditions are critical for the success of the product. If wrongly applied, then it will not remain on the hull and will not perform is it is expected to. We’ve got experience of this too on our sailing yacht, where the initial application by the commissioning company was not done as it should have been! It can only be applied at temperatures above 8 degrees C – on a fully prepared hull. It can’t be applied in the rain or in very hot and humid temperatures.

There should be 4-5 coats applied – by roller or by spray. It is not a product which can be applied with a brush. Each coat must be applied on the “tacky” previous coat. To apply the product properly, a team of people is ideal – so they can follow each other with the coats, working on small areas at a time.

How do you do this?

The instructions from the supplier were to use 0.5 kg of hardener and 0.5 kg of resin with 2kg of copper. This is the mix which gives the maximum copper allowed. He stressed that the hull should be sanded with 80 grit sandpaper with an orbital sander, then rinsed and allowed to dry.

A minimum of 4 coats need to be completed in 1 day using the wet on tacky method. When the first layer gets tacky you start applying the second coat. This is normally about 2 hours after you have started. This could mean you have to start the second coat before you have finished the first coat! Therefore, this is best achieved by having two teams of four people painting. An additional person is mixing the paint all the time so that the copper doesn’t sink to the bottom.

The rollers should be of mohair short pile and nothing else!! Just before launch the hull needs to be sanded lightly with 240 grit to activate the CopperCoat. This needs to be a minimum of 1 to 2 weeks after application but can be longer.

What happens if you don’t follow the instructions?

Basically, the paint normally fails to stick to the hull and starts to bubble and peel.

Based on the results in the Mediterranean on the sailyacht. After the first year when she was lifted, the entire keel was peeling and covered in bubbles – as were parts of the hull. She was sandblasted back to bare GRP and the product was applied again – properly this time. Now, 5 years later, it’s a different story. All we have to do is give her a clean while we’re swimming with a sponge cloth and jet-wash when she is lifted.

We read the riot act to Jet Tern about the application process and the risks as above! We also gave them the instruction video below which might be useful for anybody considering this product.

What happened on Destiny?

Well, the yard didn’t do too well – mostly because they did not properly sand and epoxy the joins where filler had been used to join sections of fibreglass. They also did not realised just HOW smooth, the sanding had to be! To give them their due, the application was supervised by the so-called CopperCoat local dealer. However, this dealer was as new to the product as the shipyard!

In addition to the errors of application, the boat was launched but then proceeded to stand still in the river water at the harbour for almost a year. This was due to the covid lockdown and lack of progress. After launch, the engine could not be commissionned – so the boat was unable to move.

The state of the hull when the boat was lifting was shocking though – even when we didn’t expect it to be good!

It is unreasonable to expect any anti-fouling product would perform properly in these circumstances so the yard had to sand it all off and start again. In fact, on the areas where the Coppercoat had been properly applied, it actually stood up extremely well – look at the top right photos in the gallery above.

Ultrasonic Anti-fouling

This is a new one on us! Ed spent a long time with the suppliers of this product at the METZ trade show in Amsterdam and also at the Dusseldorf Boat Show. We decided to try it out and see if the claims of the manufacturer were indeed true. We can’t comment yet … but watch this space.

This product is not a paint at all – it is an electronic anti-fouling device which emits ultrasonic signals into the water. The idea is that the marine life is repelled by the sounds – which of course can’t be heard by humans. They will hopefully go away and pick another boat to stick to!

The manufacturers say that it doesn’t replace anti-fouling paint but it does prolong the life of the paint and improve the performance. Combined with our CopperCoat, we are hoping for an exceptionally clean hull! However, we are starting our cruise in the tropics which has the worst conditions for hull fouling. We are therefore testing the combination in the harshest way.

What is this product?

The Ultrasonic product consists of a small control box which operates on 12 or 24 V DC. There are also AC versions available. We have gone for the more powerful model – the UltraSystem Power Plus. The product emits a range of frequencies and comes with a 5 year warranty.

The box can be installed in any convenient location. It connects to sets of transducers which emit the ultrasonic signals through the hull into the water. The supplier provided us with an installation plan based on our boat and we have four transducers in total. These are not through-hull transducers – so are easier to install.

The current draw of the DC system is a maximum of 6.8A @ 12v or 3.4A @ 24v. The average draw much lower than this.

Amorsil then PropSpeed Anti-fouling Paint for Moving Parts

The last part of our armour in the war against marine growth on our underwater gear was Amorsil paint. CopperCoat cannot be applied to any of the underwater mechanical parts (except for the rudder) and neither can most other anti-fouling paints. For this reason, the prop and other moving parts underneath are often still fouled. They will need regular cleaning in order to maintain the performance of the boat.

Amorsil anti-fouling prop paint

We applied a product called Armor-Sil® R/G to the moving parts. This means the main prop, the bow and stern thruster props. This paint is especially designed for mechanical parts and is a silicon based, non-ablative paint.

Apex Marine Solutions, who supply the product, informed us we could expect 10 years of good performance. We guess they did not expect the conditions our hull was left in for the first year ….

When we lifted from the water, there was no sign of any Amorsil at all on the prop or any of the other moving underwater parts. We did want to try again – in the circumstances. But Amorsil were unable to ship us any replacement product. We therefore had to apply a different product called PropSpeed. We’ll see how that one does!