Boat Hull Maintenance Strategies to Minimize Marine Pollution
Boatyard managers and boat owners are essential to preserving water quality and healthy marine life. Here is a short introduction to antifouling paint additives, aquatic impacts, followed by several best practice factsheets and videos below.
By nature and intended purpose, antifouling additives in hull paints (also called biocides) are toxic to certain marine life, and sometimes at very low concentrations. The biocides leach from boat bottoms over time, to protect the boat bottoms from fouling, algae, and other marine growth, such as mussels.
Copper compounds and zinc pyrithione are examples of metal-based biocides. Chemical biocides include Econea, Irgarol, and Sea-Nine 211. All are federally regulated pesticides. Non-biocidal coatings rely on hardness, slickness, or photoactivity to deter fouling, instead of biocides.
Another marine toxin is contributed by sacrificial zinc anodes, which protect underwater metal boat parts from corrosion. Traditionally, anodes have been zinc, with a possible trace of cadmium. Both exhibit high marine toxicity to some marine species.
Biocides and zinc anode pollution are concerning when many boats are concentrated in a marina or inlet. These chemicals release over time, and concentrate due to low water exchange, and can affect marine life and plants. These areas are attractive breeding grounds where early life stages can be sensitive to biocides and zinc.
Biocide concentration in marinas can further increase when paint dust, particles, or sludge from hull paint removal, pressure washing, or other hull maintenance activities and wastes are mismanaged.
This may contribute to additional biocide contaminants reaching water bodies through stormwater drains or airborne deposition.
Zinc Anode Alternatives & End of Life Management (English)
Additional References & Resources
Rapid Response Service – free technical assistance on best practices relating to antifouling/biocidal paints and waste streams containing biocides. Contact firstname.lastname@example.org
Washington State Department of Ecology, 2016. Boatyard General Permit.
Washington State Department of Ecology, 2016. Fact Sheet for NPDES and State Waste Discharge General Permit for Boatyards.
Port of Port Townsend Best Practice Video on Haulouts and Pressure Washing (plus other videos shown at this link).
Washington State Department of Ecology, 2017. Report to the Legislature on Non-Copper Antifouling Paints for Recreational Vessels in Washington.
Northwest Green Chemistry, 2017. Boat Paint Alternatives Assessment.
Canadian Yachting, 2018. Time to Sink Zink.