MERC: Could antifouling paints be holding the key to green shipping?

February 11, 2025, by Sara Kosmajac

Shipping companies looking to cut fuel costs and reduce emissions are increasingly turning to silicone-based antifouling paints, but their application challenges and varying real-world performance demand careful consideration, a new report says.

Illustration only. Image Courtesy: Micanti; The Halul 12 with Micanti antifouling glued against the hull of the vessel

In its new report titled “An Overview of Silicone-Based Antifouling Paints” the Athens-headquartered non-profit organization Maritime Emissions Reduction Center (MERC) has spotlighted that ‘advanced’ hull coating systems and particularly silicone-based antifouling paints have gained more and more attention as an option to reduce greenhouse gas (GHG) emissions as they can be applied during dry-docks.

As per MERC, silicone-based antifouling coatings work by creating an ultra-smooth, non-stick surface with low surface energy, preventing the build-up of microfouling (slime), which, if not removed, is said to lead to a GHG increase of up to 25-30% depending on the ship type, speed, and sea conditions.

Eliminating slime has been linked to fuel savings, as well; namely, in a January 2025 study, researchers from the Swedish KTH Royal Institute of Technology (KTH) discovered that a “ship covered with a thin biofilm may experience up to an 80% increase in fuel consumption”.

In this sense, antifouling coatings that stop biofilm formation present an encouraging option for the shipping industry, with some manufacturers claiming that these solutions show the potential to offer up to 10% fuel savings, MERC unveiled.

In addition to this, as maintained in the analysis, unlike conventional antifouling paints, silicon-based coatings do not degrade over time and are not reliant on biocides—chemical substances, mixtures, or microorganisms intended to control harmful organisms.

The listed benefits of antifouling paints are in line with the findings of the International Maritime Organization (IMO). Specifically, the IMO has revealed in a November 2021 study that eliminating slime from ships’ hulls could slash GHG emissions by up to 25%, making the paints particularly attractive.

IMO study: Slime-free hulls reduce GHG emissions

Environment

However, according to MERC, silicone-based antifouling paints require careful selection based on vessel type, operating profile, and trade routes, as their performance can vary significantly depending on hull exposure and mechanical stress.

As explained, the coatings are particularly vulnerable to damage in high-impact areas such as the bulbous bow, boot-top, flat bottom and propeller, where contact with anchors, fenders or docking blocks can compromise their effectiveness.

To balance cost and durability, MERC suggested that operators consider hybrid schemes that combine silicone and traditional antifouling systems, applying each where it is best suited.

In terms of vessel type, the analysis highlighted that higher-speed vessels (e.g. boxships, roll-on/roll-off ferries) benefit the most from silicone coatings. Slower-speed vessels (e.g. bulk carriers) are understood to see ‘reduced effectiveness’ as silicone coatings require a certain level of water flow to self-clean.

Very large crude carriers (VLCCs) reportedly show ‘moderate’ success with silicone coatings but hybrid schemes are described as ‘more practical’ for them.

That said, MERC has accentuated that silicone and hard foul-release coatings cost more than conventional solutions. Not only does the paint come with a hefty price tag but there are more stringent requirements for surface preparation and application, the organization has shared, meaning that shipping industry stakeholders have plenty to consider.

To maximize the merits, MERC put forward that performance monitoring and biofouling management will play the ‘key’ role, as well as consistent maintenance of the coating in optimal conditions and ensuring performance over the entire docking cycle.