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-year-old 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 antifoul paints out there, 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! Article continues below… 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. However, silicone antifoul products don’t contain any biocides. They work in a different way altogether. Antifouls such as Seajet Bioclean and Hempel Silic One prevent fouling due to their super-smooth hydrophilic surface. In other words, the coating is simply too slippery for marine fouling to attach itself. If your current antifouling is in good nick (i.e. not flaking or peeling) you can use a ‘tie coat’ then apply silicone antifoul on top. However, in our case we would be working from bare gelcoat, so needed to start with primer. When to replace silicone antifouling Seajet expects Bioclean to last for at least three years, after which point, another tie coat and top coats are likely to be needed, although as this was a new product the recommended routine wasn’t yet fully established. Scraping to gelcoat When we acquired Maximus she had a mix of incompatible antifoulings, and after several seasons’ applications, the paint was just too thick and needed to come off. Self-eroding antifouling should, as the name suggests, gently remove itself during the year but layers of hard antifouling, and even the eroding type, will eventually build up. So my husband, James, and I spent the … Continue reading Seajet Bioclean silicone antifoul review: Our verdict after one year on the water