The Best Antifouling Paint for Your Boat

The top 5 benefits of antifouling paint

The sheer volume of international trade and travel conducted on our seas and rivers shows our reliance on these waterways for much of our day to day life. The possibly harmful effects of this traffic on our marine environment cannot be overlooked, and this is driving the demand for effective, low cost, low impact antifouling coatings as part of a vessel’s complete coating system. Antifouling paint:

1. Lowers fuel consumption
2. Increases the maximum speed of a ship
3. Increases a ship’s durability
4. Decreases the risk of transfering harmful organisms into foreign waters (such as the zebra mussel)
5. Protects against damaging marine growth such as shipworms

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Types of antifouling paint: biocidal, foul release, and more

Traditionally, antifouling paints work through the action of a biocide – a chemical substance intended to destroy, deter, or render harmless, or exert a controlling effect on any harmful organism by chemical or biological means. The current biocide used in most antifouling paints is copper, with 90% of antifoul coatings using copper or its oxide as their active ingredient. However there is a trend away from biocides, and new products are emerging on the market which use different properties to fight biofouling.

Biocidal antifouling paints

The mechanism by which biocidal antifouling paints leach biocides into the surrounding water varies depending on the coating type. Pairing the right delivery system with the substrate, environment, and use of the vessel is vitally important for the correct functioning of the coating. The two main categories of biocidal antifouling paint are:

1. Hard film antifouling
   The delivery mechanism for these types of antifouling paint is called ‘contact leaching’. The coating is packed with biocide, and contact with water causes these biocides to leach out. As a result, the antifouling protection is not constant – it starts out high, then wanes as the biocides leach away and all that remains is the hard paint film. These coatings also lose their antifouling ability if kept out of the water, so they cannot be hauled and relaunched without repainting and possibly antifoul removal.
2. Eroding antifouling
   As the name suggests, this coating uses erosion to deliver biocides.  This can be caused by the friction of the water passing over the hull, or by a chemical reaction which is localised at the surface of the coating. The biocides are released in a controlled manner, which provides longer and more consistent biofoul protection. Unlike hard film antifouling, boats painted with eroding antifoul can be hauled and relaunched without repainting, since the biocides are chemically bound to the paint and are only active in water.

Alternative antifouling coatings

Recent developments and the global trend towards sustainability and “green” coatings is driving the study of alternative antifouling methods which do not require the use of a biocide. These include experimental surfaces such as teflon or silicone coated, hydrophobic, and textured hulls which may prevent the biofouling from growing.

Foul release coatings include silicone elastomers, teflon-based coating and fluoropolymer coatings, ceramic coatings, and wax coatings. These coatings are also known as ‘foul release’ coatings because the mechanism does not prevent biofouling from settling, but instead the slipperiness prevents it from attaching. The action of the vessel moving through the water is enough to detach biofouling from its tenuous hold.

Another type of antifouling measure is biomimetic coatings. The name comes from the greek for “life imitating”, and these coatings look to the natural world for inspiration. Coatings that imitate the closely scaled skin of a shark, flocked surfaces that resemble plants, or hydrophobic coatings based on the water-repelling surfaces of the lily pad are all biomimetic coatings.

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Questions to ask when choosing antifouling paints

Ultimately, the choice of antifouling paint comes down to the best option for the vessel’s substrate, the environment, and the intended use of the vessel. All factors need to be considered to ensure a successful coating. In order to determine which coating is best for your vessel, these are some of the questions you should be asking:

• What are the costs related to the coating?
  How much does the paint cost? Does the coating lead to greater fuel efficiency? What surface preparation is required? How often will it require repainting, and what cleaning procedures will be required? Prices per litre is not an adequate representation of price when it comes to antifouling, there are many cost factors at work.
• What is the lifespan of the coating?
  Not all coatings have the same lifespan, especially under differing conditions. Some will protect for 3-5 years, others for the vessel’s lifetime.
• How abrasion resistant is the coating?
  The abrasion resistance is relevant for racing vessels, vessels on trade routes that might encounter ice, bumps, or scrapes, as well as ships that require polishing. Highly abrasion resistant paints include the hard film coatings, Teflon, and ceramic coatings.
• Is the coating suitable for the intended lay-up times, time in port, and water conditions?
  Hard antifouling paints do not maintain their antifouling properties while hauled, where eroding coatings do. Foul release coatings require the ship to move at a certain pace (about 25-30 knots) for the best results, so long times in port or lay up periods would prevent it from functioning effectively. Mooring conditions in warm coastal waters where marine organisms are densest poses an additional biofouling threat, however many ports are now banning copper biocide to combat rising contamination levels.
• Where, and how frequently, will the coating and hull need cleaning?
  Can the coating be cleaned without damaging it? Will underwater cleaning risk environmental damage? Downtime from dry-docking and regulations in certain ports preventing underwater cleaning may be factors you need to consider.
• Are there any regulation changes which may affect the suitability of the coating?
  After the banning of TBT, marine authorities have been wary of biocides in general. Though copper is currently the most common antifouling active ingredient, and it is not likely to go anywhere anytime soon, the antifouling industry is broadening. Biocide-free options are becoming more common and better-performing as companies within the industry move away from biocides.

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Finding the best antifouling paint UK: companies and products

There are many companies operating in the UK that provide antifouling and foul release products. Among these are AkzoNobel (Intersleek products under the International brand), Hempel, Jotun, and Coppercoat. Price varies across products, but with the range available it is possible to find exactly what you are looking for. Many products are not available for retail markets, and need to be applied by professionals and shipyards. It is always best to consult with professionals when choosing an antifouling coating. Below is a table outlining some of the products available.

If you would like more information, our experts are here to help. Just get in touch and we will connect you with one of our coating partners to secure a quote for your project. You can do this  through our contact form by clicking the “Request a Quote” button at the bottom of this article. We will help you find the right coating solution for your needs.