Big Antifouling Test

Last June we coated the hull of a Hardy Commodore 42 with eight different antifouling products (see PBO August 2021). The motorboat Raymariner, which is the test boat for Raymarine, is based in the Solent and is used three or four times a week for trialling the company’s electronics.

The aim of the test was to compare traditional copper-based annual antifouls with a number of longer lasting and more environmentally sensitive alternatives.

We applied three non-copper antifoul paints and three traditional eroding paints plus IP Ultra 300, which is a hard coating, and Coppercoat, which is a non-eroding copper-epoxy coating.

Raymariner was lifted in January 2022 to have a transducer replaced, so we took the opportunity to compare the results after seven months of submersion.

Tightening regulations

These days, many of our buying decisions are influenced by our desire to be mindful of the environment. Antifoul is no different, and the Biocidal Products Regulation means manufacturers are subject to ever tightening regulations controlling the substances they are allowed to use.

Copper is still the most widely used biocide in antifoul coatings. Described, variously as copper powder, dicopper oxide or cuprous oxide, copper represents anywhere from 25% to 55% of the volume solids of many formulations. This is suspended in a paint matrix that gradually erodes as water passes the hull, releasing biocide at controlled rates, depending upon whether it’s a hard or soft-eroding type. It is the build-up of these biocides in marinas, harbours and waterways that poses a risk to larger marine wildlife.

Coppercoat is the exception to the rule, because although it counts as a biocide, it uses copper granules set in hard epoxy resin that not only gives it a lifespan of 10 years or more but ensures that only minute quantities of copper are actually released into the