Antifouling AND Protective coating

Want to save costs in shipping? Proper antifouling reduces fuel consumption!


Fouling on vessels is a biological accretion which settles on the underwater hull of boats and ships. Consequently, the surface becomes rough and the resistance of the ship sailing through the water increases. The result is a ship that sails slower or increases its fuel consumption to maintain the same speed.

Fouling in seawater is a lot stronger than in fresh water. There are many kinds of organisms in seawater and they come in large numbers. The composition of seawater in different environmental circumstances also makes a huge difference; there is more fouling pressure in tropical waters in comparison with the brackish northern waters near Scandinavia. This, however, does not mean that fouling in the Baltic Sea and the North Sea is not a problem.

Antifouling is a collective name for different techniques that prevent fouling or reduce the growth of organism. The most commonly used technique is the use of special coatings or paints which are applied to the underwater hull of a vessel. There are many different types of antifouling paints, some especially made for recreational boats, others for shipping. Different kinds of products are used for large ships, depending on the speed (slow or fast) and duration of the docking cycle (2 – 5 years).

The function of antifoulingpaints is based upon two mechanisms:

  1. Prevent fouling to settle on the coating surface .
  2. Prohibit fouling from attaching to the coating surface .

Many antifouling paints are based on toxic substances, known as biocides. These paints slowly release substances that kill the little larva of the fouling organisms that like to settle on the surface. Paints containing these substances are based on mechanism 1 (see above). Because biocides are released into the environment, the characteristics of these products must meet the requirements set by government regulations. Producers have to prove by set research protocols that their product meets the requirements, and only then can a product be sold. Regulations regarding acceptance of antifouling paints have been tightening since the early 2000s. The acceptance requirements of biocides and antifouling paints is stated in the Biocidal Products Regulation of the European Union (EU).

There are also paints available that are not based on toxic substances. The most important category is the so called “fouling release” or “non-stick” coatings made of silicone binders. These paints have typical surface characteristics that prohibit fouling from attaching to the coating surface. Organisms that try to attach to the underwater hull of a vessel with a coating made of silicone binders are easily wiped away when the boat sails at a certain speed. First generation silicone coatings were found to be effective when sailing at a speed of 20 knots or higher. Now, some producers advertise with claims for fouling release coatings to be effective at only 8 knots, but there is not much independent research to support this. Nevertheless, producers of fouling release products have made a lot of good progress in developing toxic-free products.

Why use antifouling and prevention? And why work with Endures?

The most important reason to use antifouling is to prevent the consumption of additional fuel and thereby obtain cost savings.

Another aspect associated with this reduced fuel consumption is that it produces less greenhouse gas emissions. A vessel treated with the right product can also save on transport costs. Choosing the right product is based on information on the (long-term) performance of a coating. Several test methods are available to determine the performance of antifouling products. Endures has in-house knowledge, facilities and experience (over 50 years) to advise companies and agencies. Depending on your specific question, we can explain the options available to you.

The laboratory of Endures is located in Den Helder, the home port for the Dutch Royal Navy. Our laboratory has naturally flowing seawater in which we do a wide variety of exposure experiments with coated panels, material samples and smaller or larger pieces of equipment.

Regulations on antifouling

The IMO (International Maritime Organization, part of the United Nations) in 2001organized its own Antifouling Convention (AFS Convention), in which the use of harmful anti-fouling paint, in fact only products based on organotin compounds, were banned worldwide.

In 2008, this ban was put into action and there is now a “Certificate of Compliance” where ship owners have to show proof of the paint system applied to their vessels. Whereas more than 10 years ago legal production of organotin based paints was stopped worldwide, no such paints are available anymore.

In recent years, there has been more IMO talk about reducing greenhouse gas emissions in the shipping industry. It is expected that more stringent regulations will be added in the near future. Ship owners need to measure and monitor emissions and take measures to reduce emissions. Additionally, IMO has stimulated to work on drafting a new worldwide standard (ISO 19030) on hull and propeller performance measurements.

One important component for ship owners and operators to meet regulations is to choose a good (the best) antifouling coating for the hull of the vessel to reduce emissions. This can be a different product depending on type of vessel and operational activity. Endures carefully monitors the ever-changing regulations, so we are always aware of the most recent requirements.

Types of services that Endures can provide in the field of antifouling performance testing:

  • Exposure testing in static or natural flowing seawater
  • Raft exposure tests according to ECHA requirements in the harbor of Den Helder
  • Dynamic aging of antifouling coatings in natural seawater
  • Erosion measurements of self-polishing antifouling paints
  • Friction drag tests of hull coatings with and without marine fouling
  • Performance tests with combined static and dynamic aging protocols simulating different sailing patterns and idle times of vessels.
  • Inspections of the underwater hull of a vessel incl. fouling condition, coating roughness and advice on hull maintenance
  • Supervising diving inspections of hull coating condition
  • Advice and expertise about regulations of antifouling products
  • Consultancy and applied research into efficacy and side effects of alternative antifouling technologies

Need more information about current regulations?

Protective coatings

Want to save money? Select the right protective coating (and its application) every time!

An important technique used to protect metals against corrosion is the application of anti-corrosive or “protective” coatings. There are many types of protective coatings on the market, including many specially developed for specific applications in which different levels of protection or durability are required. The performance requirements for such coatings are often high, especially on ships and structures used on or in the sea. The wrong choice of products or the improper application of a coating can be disastrous for the economic value or lifetime of the ship or installation.

Companies and agencies that want to know more about the performance of protective coatings for civil and maritime applications can contact Endures for:

  • Weathering tests in maritime (C3 – C4) environment
  • Coating testing in cyclical exposure (wet/dry, thermal shock) procedures in static or flowing natural seawater
  • Coating tests imposed under current (cathodic disbonding tests) in seawater
  • Coating tests during exposure to chemicals or reaction mixtures
  • Corrosion tests of coatings exposed to ballast water treatment systems based on chemically active principles (G9 approval IMO / GESAMP)
  • Electrochemical Impedance Spectroscopy (EIS) to determine barrier properties of coatings.
  • Measuring corrosion-resistant properties of coatings on location (pipelines, tanks, ships, hull structures)
  • Coating inspections and measurements on structures, ships, buildings and installations
  • Advice and expertise in the field of application of (protective) coatings

More information

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