Prevent fouling without poison

Buying antifouling for your yacht online is easy. The most used online shops in western Europe ship a can of biocide containing paint to your front door. In a quick test, we placed orders at two online chandler’s shops that operate in a multitude of west-European nations. Buying and delivery of the biocide antifouling showed no restrictions. The test was performed from The Netherlands. In Germany, straight delivery would have been marked illegal.

The Chemicals Prohibition Ordinance (ChemBiozidDV) came into force from the start of 2025 in Germany. This regulation prescribes that anyone buying bottom paint for a boat that contains poisonous chemicals, would have to prove boat ownership or show a sailing permit and have an instructional conversation with a yacht coating professional. This professional is instructed to provide information about biocide-free alternatives for the antifouling paint the yacht skipper is planning to acquire. The quick online ordering test reveals how regulations differ over various European countries, let alone internationally.

Hull-swiping divers

Also in the United States, laws that define which types of anti fouling coating may be used, are different from state to state. In the state of California, the state Department of Pesticide Regulation (DPR) aimed to restrict the cleaning of boat underwater hulls so no particles of the biocide containing antifouling coatings would come loose and spread in the water. A study that revealed an alarming level of copper ions in the waters of Californian marinas urged the DPR to do so.

Copper contamination in marinas was found to be much higher than Federal standards for water quality would allow. Paint manufacturers however, argued that the DPR’s purpose is regulating pesticides for crop growing and fouling release, not restricting divers to swipe boat bottoms.

Series of reports

The state of Washington was aiming to prohibit the use of copper-based antifouling paints by the start of 2026. Copper ions in the water are harmful for Salmon and other marine life, the state argues. The history of the efforts to ban biocide antifoulings is long. In 2011, Washington enacted legislation to ban the use of copper-based antifouling paint from 2018. Two follow-up investigations by The Washington Department of Ecology in 2017 and 2019 showed that some non-copper alternatives might be more harmful to the environment than copper-based paints.

In 2020, the ban was delayed. Again, a study was performed to establish if safer and effective alternatives for copper would be available. The 2025 report did not provide that information. A follow-up report will re-evaluate the biocide free alternatives by 2029. The ban on copper-based antifoulings is postponed once more. Yet, other legislation has successfully been put into force. The maximum ‘leach rate’ – meaning how much copper oxide will wash into the water per square inch – is determined. Antifoulings allowed in Washington State need to prove that their leech rate is below maximum. The component ‘Irgarol’ that had been used in anti fouling paints over decades was banned. The efforts of the Environmental Protection Agencies in both states, show how hard it is to enforce legislation that stops the use of poisonous coatings.

Lasting approval

In commercial shipping, the United Nations shipping authority International Maritime Organisation (IMO), has succeeded in restricting the use of anti-fouling coatings that contain biocides. In the EU, the use of hull paint containing the specific biocide cybutryne was banned beginning 2023. This includes 27 countries which represent a large market in leisure boating.

Still, no worldwide regulations exist. There is no international authority for leisure boating. Uniform international rules would provide clarity for boaters and paint manufacturers about what is permitted and what not. Despite the lack of harmonisation, the overall trend is that regulations on the use of fouling preventing coatings are getting stricter. In order to stay ahead of restrictions or even prohibitions, paint manufacturers and yacht skippers need products that will be approved everywhere and for years to come. The best way to do it: include no harmful components at all.

Biocide-free solutions

Biocide-free fouling release coatings are ready available. A variety of solutions is available to prevent the growth of algae, pocks and other marine flora and fauna to hulls. Noise, electrolysis, extremely hard surfaces or flexible but slippery surfaces and even hairy wrappings can be used. Effectiveness of the different solutions depends mostly on the use of the boat and the environment in which it operates: sailing every day or a couple of days every year, going at high speed or slow, being kept on salt or sweet water – these are some of the key variables that determine the success of one solution or another.

The alternatives:

Most paint and coating manufacturers have added biocide free fouling release coatings to their product range. Here is an overview of the (most used) alternatives offered use different solutions to prevent fouling.

• Silicone coatings.
  The structure of silicone is always flexible, but the surface is really slick and makes it hard for marine plants, algae and shells to attach to it.
• Hard coatings.
  By creating a very smooth, hard outer layer of epoxy coating around the hull, marine life gets a hard time attaching to it. If there is some fouling after a period of laying in a marina, this will wash off easily when the boat speeds up or when a diver swipes the hull.
• Nano coatings.
  Like the nano treatment of cars that makes the paint on automobiles dirt- and water repellent, nano coating under a yacht’s hull can provide a layer with a specially designed molecular structure that is so slick, there are no microscopic uneven parts in the structure for organisms to cling on to.
• Biomimicri. 
  Paint manufacturers have tried to create a coating that will dry up to form the ‘sandy’ structure like on a shark’s skin, where slightly moving parts of the surface scrape along each other and remove fouling before it gets the chance to bond.
• Hairy surfaces.
  A wrapping of the under water hull has a hairy structure like animal fur. The hairs constantly move in the water and offer no surface for the fouling to attach to.
• Ultra sonic fouling prevention.
  Speakers that produce sound waves, out of the reach of what a human ear is capable of hearing. These speakers are mounted to the inside of the yacht’s hull and make sure the hull is constantly vibrating while moored. Fouling can not attach.
• Electrolysis.
  Titanium coated anodes are attached to the hull or hung in the water when the yacht is docked. By creating an electric polarity on the anode, the surrounding seawater and the salt in it, will generate chlorine, which is poisonous to the marine fouling organisms. The chlorine however, does not spread to contaminate the surrounding waters.