Antifouling systems for pleasure boats : Overview of current systems and exploration of safer alternatives

Abstract

Antifouling paints are often used on the surfaces of pleasure boats to prevent the growth of algae and shellfish below the waterline. These paints contain toxic substances. The Dutch government is committed to encouraging boat owners to switch to the use of antifouling systems that are safer and have less environmental impact. The National Institute for Public Health and the Environment (RIVM) has therefore drawn up an overview of current and future possibilities for preventing the fouling of the surfaces of pleasure boats under the waterline. A number of systems are expected to have considerably less impact on the environment than those now in use. RIVM also puts forward suggestions for promoting the use of these cleaner antifouling systems. Existing antifouling paints are often 'self-polishing paints' which contain copper as a biocide and zinc as a co-formulant: the paints wear during sailing, gradually releasing these substances. As a result, heavy metals end up in the water and impact the environment. There are already various systems available for pleasure boats that do not contain biocides, some of which have probably less impact to the environment than the self-polishing paints that do. These include hard 'foul release coatings', other hard coatings, films with flexible plastic fibres that act as spines and systems based on ultra sound. Some promising antifouling systems that, for example, use ultraviolet light or natural, readily degradable biocides that stay in the coating are still in the research phase. RIVM recommends examining the legal possibilities for reducing the use of antifouling systems that contain biocides and self-polishing paints. How well or badly existing possibilities score in the field of antifouling performance, safety and environmental impact should, furthermore, be clearer for consumers. The development of a standardised test that can be used to determine the efficacy of antifouling systems under different conditions is also desirable.