ENVIRONMENTAL PERFORMANCE OF BIOCIDE-FREE ANTIFOULING COATINGS Linking Fouling Control, Fuel Use, and Marine Pollution for Recreational Boats in the Baltic Sea

Abstract

Biofouling on recreational boats reduces hydrodynamic efficiency, increases fuel use, and contributes to air pollutants. In the Baltic Sea, the primary strategy to combat biofouling is the use of copper-based antifouling coatings which release copper ions that act as biocides to prevent the settlement and growth of marine organisms. While effective in biofouling prevention, this approach is a major source of toxic copper emissions in an already vulnerable marine environment. This raises the question of whether biocide-free alternatives can provide effective and sustainable protection against biofouling. Previous research has shown the ecological risks of copper, including impaired growth and genetic damage in marine species, and identified recreational boating as a contributor to localized copper loads. However, there is still a demand for knowledge about the real-world performance and practical adoption potential of biocide-free coatings. This study evaluated the performance of seven biocide-free antifouling coatings in comparison to conventional copper-based coatings. Assessments included biofouling intensity, modelled fuel consumption penalties and associated air emissions, copper and zinc emissions to the marine environment, coating composition, and economic costs. Findings show that foul-release coatings performed comparably to copper-based coatings while avoiding copper emissions, though with moderate increases in fuel use. Hard and hybrid systems demonstrated lower efficacy, at equal or higher cost. The results highlight foul-release coatings as the most promising biocide-free option, while emphasizing the need for integrated antifouling strategies to balance ecological protection of the Baltic Sea and user feasibility for the individual boat owner.