California Sea Grant Sizes Up Alternatives to Copper-Based Paints for Recreational Boaters

March 3, 2006

Contact: John Stumbos, jdstumbos@ucdavis.edu, 530-754-7770

SAN DIEGO–Shelter Island Boatyard manager Bill Roberts has a message for recreational boaters that extends well beyond the waters of San Diego.

San Diego Marina Credit Cesar J. Alvarez

"It's just a matter of time before the Feds ban it like they did tin," he said during a recent visit. "It" is copper-based boat bottom paints. California water quality regulators are creating thresholds called TMDLs or "total maximum daily loads" for copper that the boating community in crowded harbors like those in Shelter Island, Newport Bay and Marina Del Rey will be required to meet in coming years.

Meeting those requirements will involve a combination of environmentally friendly alternatives that need to be understood now so boaters can continue enjoying their favorite pastime with minimum frustration ahead. The San Diego office of California Sea Grant's Extension Program (SGEP) has been working closely with the boating community for more than a decade on nontoxic boat bottom coatings.

"The antifouling properties of copper have been known for centuries when intrepid mariners would line their hulls with sheets of copper," said SGEP Marine Advisor Leigh T. Johnson. "Most modern-day boaters use cuprous oxide paints that are engineered to leach out copper over time and thus retard the growth of barnacles, algae, tubeworms and other critters that inhabit the world's harbors. When these organisms attach themselves to boat hulls, they reduce maneuverability, increase drag and corrosion, and decrease fuel efficiency."

Copper is an essential micro-nutrient for animals, including humans, but in high concentrations it becomes toxic. Scientific research has shown that dissolved copper levels as low as 3.1 parts per billion (ppb) in water will reduce growth, development and survival in marine organisms and cause reproductive problems in mussels, oysters, scallops, sea urchins and crustaceans. This is the underlying environmental concern driving water quality policy on the issue in California and elsewhere in the United States. Copper-based paints have already been banned for use on recreational boats in Sweden, the Netherlands and freshwater areas of Denmark. Other European countries are closely monitoring levels of dissolved copper in coastal and inland waters.

Fortunately for boaters, a whole new generation of nontoxic boat bottom coatings is emerging. High-tech coatings manufactured with silicone, epoxy, ceramics and polymers have entered the marketplace. Each has its own strengths and weaknesses in durability, performance and cost. Traditional copper-based paint needs to be recoated on San Diego boat hulls every two to three years to maintain an effective, antifouling shield. One of the advantages of nontoxic alternatives is that they will last six to 12 years. The tradeoff is nontoxic surfaces require more frequent in-water hull cleaning by professional divers who need specialized tools to clean different surfaces. For instance, comparatively softer silicone surfaces require more delicate cleaning, while epoxy and ceramic-epoxy surfaces require more aggressive cleaning. Power tools and larger boats to carry them are needed by boat hull cleaners to clean heavier fouling that develops on nontoxic coatings.

SGEP has been working with boatyard managers like Roberts to test alternatives and hold demonstrations for the boating community. Although field demonstrations ended in 2003, Sea Grant researchers continue to monitor how well the alternative coatings are performing. Johnson reports that as of fall 2005, all of the epoxy and ceramic-epoxy, nontoxic hull coatings were in good condition. A sailboat owner whose boat has had an epoxy coating for seven years has more than broken even on the cost to switch to and maintain a nontoxic coating. The owner of a powerboat that has had an epoxy coating for more than three years cut hull-cleaning costs by using a slip liner. A racing club whose sailboat has had a ceramic-epoxy coating for more than three years competes well when the boat's hull is cleaned before a race. The owner of a diesel-electric boat that has had a ceramic-epoxy coating for more than three years has the hull cleaned every two weeks and would recommend the coating to others.

"Our economic research found that longevity of nontoxic coatings can, over time, more than offset the extra costs to switch and to clean them more frequently." Johnson said. "The boats with nontoxic epoxy or ceramic-epoxy hull coatings have already exceeded the typical life of a copper-based paint and are still in good condition. One of them has lasted seven years, with more useful life expected."

The Sea Grant Extension Program has several educational resources available free or for a nominal amount to help boaters make the best decision for their boats, marinas and the environment. One of the most recent is Time for a Change-Alternatives to Copper-based Boat Bottom Paint/Es Hora de Cambiar-Alternativas a la Pintura a Base de Cobre para Cascos de Botes, a half-hour, bilingual DVD produced by Johnson and SGEP Program Representative Jamie A. Gonzalez. The DVD provides a comprehensive look at the situation from the perspective of boat owners, marina operators, port officials, boating and coating businesses, government agencies and environmental organizations.

A number of fact sheets and booklets that provide more in-depth information on nontoxic antifouling strategies are also available from Sea Grant. Two of them include:

Making Dollars and Sense of Nontoxic Antifouling Strategies for Boats (publication T-052) - Includes a worksheet to calculate costs for bottom coatings
Staying Afloat with Nontoxic Antifouling Strategies for Boats (publication T-054) - Includes in-depth analysis of different bottom coatings
To obtain copies of the DVD or these publications, contact the California Sea Grant Communications office at (858) 534-4446. Additional information is also available online at http://seagrant.ucdavis.edu/

NOAA's California Sea Grant is a statewide, multi-university program of marine research, extension services, and education activities. It is the largest of the nation's 30 Sea Grant programs and is headquartered at Scripps Institution of Oceanography at the University of California, San Diego. The National Sea Grant College Program is part of the National Oceanic and Atmospheric Administration (NOAA), U.S. Department of Commerce.