Sailboats Out on the Hard on Saginaw Bay

Michigan Boaters See Effect Of Ban on Antifouling Bottom Paint

In the February 2012 issue of BoatUS, there was a special report on activity taken by several states to ban copper marine antifouling bottom paint by 2020. Copper is added to the bottom paint as a biocide to prevent slime, plant, and zebra mussels from attaching to the hull. Unfortunately, the typical recreational boat sits in her slip much of the time; the copper coating in the paint slowly leaches into the water and settles in the bottom. At the same time, copper is a naturally occurring element, especially in Michigan. The concentrations in the silt since its introduction in the late 1980s have created a poisonous wasteland in the basins in some ports and marinas.

A Ban on Copper Bottom Coatings

In the 1990s, Copper began to become a concern in some harbors in California. Two large harbors, Marina Del Rey and the Port of San Diego, were seeing high concentrated measurements. As a result, studies were undertaken to determine the extent of the problem and determine if remediation was necessary.

Michigan has over 200 marinas and over 900,000 registered watercraft. So it’s only a matter of time before the issue hits our shores. Currently, only Washington and California are actively taking steps to curb the use of copper bottom paint.

Sailboats Out Early in Caseville Harbor - Antifouling Bottom Paint
Sailboats Out Early in Caseville Harbor

Current alternatives to copper-based antifouling paint are being developed but have serious environmental and cost concerns. For example, switching to a non-biocide or organic requires stripping the existing coating from the hull. This can cost thousands of dollars and create a cloud of copper-laden dust which is considered hazardous waste. In addition, the application of the new coating requires the use of a sprayer. However, as the commodity cost of copper skyrockets, environmentally friendly alternatives may be cheaper in the long run.

It may be several years before Michigan lawmakers consider taking similar steps. In the meantime, the paint industry will continue to develop and refine non-copper alternatives. However, boaters should keep this issue in mind when they prepare their craft for the next boating season.

In 2018 a ban on the use of antifouling copper coatings in Washington state had been delayed until more research can be conducted to identify safe alternatives.

2023s Ban on Cybutryne

a boat on a trailer standing on a grass field
Photo by Aysegul Alp on

An article from Electronic Fouling Control provides an in-depth look at the recent ban on cybutryne-based antifouling systems, that went into effect on January 1, 2023. Cybutryne is a biocide that has been used in antifouling paints for ship hulls and other marine structures. However, it’s been found to be both acutely and chronically toxic to a variety of marine organisms.

The International Maritime Organization (IMO) has taken note of the environmental impact of cybutryne, and as a result, new regulations will come into force. If you’re a boat owner using antifouling systems containing cybutryne, you’ll need to either remove the system or apply a different coating that forms a barrier to prevent the substance from leaching into the environment.

Interestingly, the article also discusses an alternative to chemical-based antifouling systems: ultrasonic antifouling. This system uses transducers attached to the boat hull, emitting ultra-high-frequency waves that create micro currents. These currents act as a shield around the boat hull, preventing biofouling from attaching, without the use of harmful chemicals.

This information could be a valuable addition to your existing blog post on antifouling bottom paint, especially for those looking for eco-friendly alternatives. You can read the full article here.

Banning of Copper and Antifouling Bottom Paint in Other States

man wearing a hat on a boat


Washington State Department of Ecology focuses on antifouling boat paints, which are designed to prevent marine plants and organisms from damaging boat hulls. These paints work by releasing chemicals into the water, most commonly copper, to deter organisms from attaching to boats. However, these chemicals can also be harmful to marine life.

One such ingredient, Irgarol (also known as cybutryne), has been found to be more toxic to marine life than previously thought. As a result, Washington law has banned the use of irgarol paints on recreational vessels starting January 1, 2023.

In 2011, Washington adopted the Antifouling Paints Law to phase out copper-based antifouling paint. Studies were conducted to understand the impact of these paints on marine organisms and water quality. The studies revealed that non-copper antifouling ingredients might be even more harmful to the environment than copper, leading to a postponement of the law phasing out copper paints.

The state is also exploring non-biocidal options like boat washes, sonic cleaning systems, liner systems, and drive-in dry docks. The future of copper antifouling paint is contingent on finding safer alternatives by June 30, 2024. If such alternatives are found, the use of most copper-based antifouling paints will be restricted starting January 1, 2026. Otherwise, the ban will not take effect, and further studies will be conducted.

The department is currently collaborating with Washington State University to test various antifouling paints and better understand their performance in Washington’s waters.

For more details, you can visit the Washington State Department of Ecology’s webpage on antifouling boat paints.

Factoids on Copper and Antifouling Paint

How big is the market for antifouling Copper paints & coatings?

Who makes Copper and other antifouling paints & coatings?

Top players are BASF S.E, Sherwin-Williams Company, BoeroYachtcoatings, Nippon Paint Marine Coatings Co. Ltd, Chugoku Marine Paints Ltd, PPG Industries Inc., Chugoku Marine Paints Ltd, and others.

Why are Copper antifouling paints & coatings used on boats and ships?

Copper coatings or paints are used to prevent microbes from collecting on the submerged hull. Thus making it resistant to corrosion. Copper coatings also shield the ship from bacteria, algae, diatoms, which reduces the vessel’s running speed. In addition, this slick surface improves fuel conservation.

Is antifouling copper paint banned?

Tributyltin (TBT)-based antifouling paints have shown effective at preventing the fouling of ships’ hulls and consequently the transport invasive species. As a result, the U.S. partially banned TBT in 1988, and a global ban is expected.

Michigan's Thumb ThumbWind

Michael Hardy

Michael Hardy is the owner of Thumbwind Publications LLC. Michael was born in Michigan and grew up near Caseville. In 2009 he started this fun-loving site covering Michigan's Upper Thumb. Since then, he has authored a vast range of content and established a loyal base of 60,000 visitors per month.

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