Protecting Human Heath and the Environment with Proper Boat Maintenance

The Department of Pesticide Regulation set a cap on the leach rate of copper-based antifouling paints in the State of California in 2018 as part of a statewide initiative to reduce the quantity of copper entering harbors and waterways. The cap was set at 9.5 g/cm2 per day.

By slowly or completely preventing the growth of marine life (fouling) on boat hulls, copper is frequently utilized in hull paint. The poisonous properties of cuprous oxide (Cu2O), used in copper-leaching bottom paints, keep spores and larvae from adhering to the boat's hull.

Unfortunately, these paints also increase the amount of dissolved copper in marina sediments, where it is ingested by species that live at the bottom of the water, generally known as benthic organisms.

Copper-based antifouling paints can release levels of dissolved copper into water ways, threatening marine life. To reduce environmental discharges from these paints, follow the steps below:

• Utilize alternative nonbiocidal hull coatings instead of bottom paints that contain metals. Employ or contract only with divers formally trained in environmentally sound hull cleaning practices.

• Conduct hull scraping, sanding and stripping ashore over a drop cloth to catch all debris.

• When sanding, use a dustless vacuum sander. Avoid abrasive bottom-side cleaning that releases a colored paint plume. Choose frequent nonabrasive cleaning methods that minimize marine growth and help extend the life of bottom paints.

• Use nonbiocidal hull coatings as an alternative to bottom paints that include metals.

• Sanding, stripping, and hull scraping should be done ashore over a drop cloth to catch all debris.

• Use a dust-free vacuum sander for sanding. Use a high-density, low-volume paint sprayer for painting.

• Steer clear of bottom-side cleaning with abrasives that causes a colored paint plume to be released.

• Choose frequent nonabrasive cleaning to reduce marine development and prolong the life of bottom paints (e.g., using a soft cloth, fleece mitt, soft carpet, or a long, soft brush).