Antifouling without biocide

Opting for an eco-friendly approach, Ali Wood tries silicone antifoul on the PBO Project Boat-and is impressed with the results

Does silicone antifouling work? It's not flying off the shelves yet, according to suppliers, but the results from our Project Boat are promising. In fact, in the words of the boatyard that lifted Maximus out, "Brilliant. It's fantastic. Everyone should use that!" It's not often we're so effusive about a new product in PBO, so it's worth recapping how we came to choose silicone antifouling, how we applied it over a sunny weekend and why a Poole boatyard, located in an internationally important nature reserve, was so impressed.

The story began in the summer of 2021, when we acquired Maximus, our 44-yearold Maxi 84 cruiser. She'd been in a Chichester boatyard for two years and needed some serious TLC. I was keen to test new products, as we restored her to her former glory, and the hull was the obvious place to start.

Marine growth impedes your boat's performance, so choosing the right antifouling for your hull is essential.

Although there are many tried and tested products out there (see our test in PBO May 2022), I opted for the most environmentally friendly type.

Eco credentials matter, but our antifouling still needed to perform well; after three gruelling days of hand-scraping the hull to gelcoat, I didn't want to apply a product that was either ineffective or short-lasting!

Why silicone?

Copper is still the most widely used biocide in antifouling paints. This is released into the water as the coating wears away. Because of this, antifouling is regulated by the Biocidal Products Regulation (BPR) and manufacturers are subject to ever-tightening controls.

We looked at a few different antifouling products including Coppercoat, which is a durable epoxy resin rather than an ablative paint and has a leach rate at one tenth of that allowed in places with the toughest marine biocide restrictions such as Sweden and California.