Save costs? Antifouling ensures less fuel consumption!


Fouling on ships is biological growth that can settle on the underwater hull of boats and ships. The consequence of this is a strong roughening of the surface, which increases the resistance of the ship during sailing. As a result, the ship slows down or requires more fuel to maintain the same speed.

Fouling in sea water (marine environment) is much stronger than in fresh water. There are many more different types of organisms in the sea and often in larger numbers. The composition of the seawater and other environmental conditions also make a big difference: in tropical waters there is much more growth pressure than in the brackish northern waters of Scandinavia. That does not mean, however, that fouling in the Baltic Sea would not be a problem.

Antifouling or fouling is a collective term for various techniques that can prevent or reduce fouling or fouling. The most common technique is the use of special coatings or paints that are applied to the underwater hull of the ship. There are different types of antifouling paints, some especially for pleasure craft, others for marine shipping. For the large ships there are also different products for vessels that sail a lot or very fast or little and slow.

The effect of antifouling paints can be based on two mechanisms:

  1. Prevent fouling from settling on the coating surface
  2. Prevent fouling from adhering strongly to the coating surface.

Many antifouling paints are based on the action of toxic substances, also called biocides. These substances are slowly released from the paint and kill the small larvae of fouling organisms that would like to settle on the surface. Paints with these types of substances are therefore based on mechanism 1 (see above).

Due to the release of biocides into the environment, the government imposes requirements on the properties of these products. Producers will have to demonstrate through prescribed research protocols that their product meets these requirements, only after that a product may be sold. The regulations for the authorization of antifouling paints have been tightened up over the past 15 years. The authorization policy for biocides and therefore also antifouling paints is now based on a European basis in the so-called Biocidal Products Regulation.

In addition, there are also paints that are not based on the effect of toxic substances. The most important category in this is the so-called “fouling release” or also “non-stick” coatings based on silicone binders. These paints have such surface properties that fouling organisms cannot (properly) adhere to the paint. This means, for example, that creatures that try to settle on the hull of a ship with such a coating can easily be sailed away if the ship starts sailing again at a certain speed. With the first generation of silicone paints, this was still a speed of over 20 knots; for currently available fouling release coatings, some manufacturers already claim a clean sailing effect from 8 knots, but the substantiation of those claims is often very poor. Nevertheless, we can conclude that the paint suppliers have made a lot of progress in the development of such non-toxic products.

How and why to prevent fouling?

The main reason for using antifouling is to prevent extra fuel consumption and thus cost savings. A second aspect related to this is that less fuel consumption also produces less greenhouse gas emissions. With the right product on the ship you can therefore save on transport costs. You must choose the right product on the basis of information about the (long-term) effect of the coating. Various test methods are available to determine this effect. Endures has the knowledge and experience (more than 50 years) in-house to be of service to companies and organizations in this area. Depending on your specific question, we are happy to explain the options.

Den Helder is the home port of the Dutch Royal Navy. The Endures laboratory is also located in the same port. Our laboratory has flowing natural seawater in which we can perform all kinds of exposure experiments with panels with coatings, but also with material samples, parts of installations up to complete box coolers.

The expertise and experience of Endures lies mainly in the field of maritime corrosion and anti-fouling, and we also have very long experience with corrosion and damage research. Companies that have questions about material use and material protection or are confronted with damage as a result of material failure or corrosion can always contact Endures.

The IMO (International Maritime Organization, part of the United Nations) established a so-called Antifouling Convention (AFS Convention) in 2001 in which the use of harmful antifouling paints, in particular products based on organotin compounds, is banned worldwide. In 2008 this convention came into effect and there is a “Certificate of Compliance” that ship owners must be able to show for the paint system that has been applied to their ship. To find out which products are and which are not regulated under this convention, please contact Endures.

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.

More information about these tests?

Would you like to know more about performing (the best) tests for the coatings of your ship / ships?

Companies and organizations that want to know more about antifouling products and techniques can contact Endures for the following activities, for example:

  • Exposure testing in still or flowing natural seawater
  • Static exhibition on the test raft in the port of Den Helder
  • Dynamic aging of coatings in natural seawater
  • Erosion measurements on (self-sharpening) antifouling paints
  • Resistance measurements on coatings with and without fouling
  • Test regimes that simulate the sailing pattern of a ship by a combination of static and dynamic aging and the effect of antifouling paints is determined by means of resistance measurements.
  • Inspections at the hull of the ship (fouling condition and coating roughness) and advice on hull maintenance
  • Supervising dive inspections on the underwater hull
  • Advice and expertise on regulations and authorization of antifouling products. Consultancy and applied research into the operation or side effects of alternative antifouling techniques.

An important technique to protect metals against corrosion is the use of anti-corrosive or “protective” coatings. There are many types of “protective” coatings on the market, often also specially developed for specific applications in which more or less protection or service life is required. Especially on ships and structures that are used on or in the sea, the performance requirements for such coatings are often high. Incorrect choice of products or incorrect method of application of a coating can be disastrous for the economic yield or life of the ship or installation.

Companies and organizations that want to learn more about the performance of protective coatings for civil and maritime applications can contact Endures for the following activities, for example:

  • Weathering tests in maritime (C3 – C4) environment
  • Coating testing in cyclic exposure (wet / dry, thermal shock) regimes in still or flowing natural seawater
  • Coating tests under imposed current (cathodic disbonding tests) in sea water
  • Coating tests during exposure to chemicals or reaction mixtures
  • Corrosion testing of coatings exposed to ballast water treatment systems based on chemically active principles (G9 approval IMO / GESAMP)
  • Electrochemical Impedance Spectroscopy (EIS) for determining barrier properties of coatings
  • Measurement of anti-corrosion properties of coatings on site (pipelines, ship tanks, ship 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

Would you like to know more about antifouling and protective coatings?

More information about Antifouling and protective coatings?

Picture of Joost van Dam

Joost van Dam

Expert Corrosion & Materials

+31 (0) 6 13 96 83 39