As the shipping industry navigates toward net-zero, emphasis is on emissions reduction and low-carbon fuel, while marine coatings play a significant role in improving vessel performance.
Marine coatings reduce the resistance of the ship hull through water, and reduce the needed engine power, thus reducing fuel consumption during transit. Hull condition and fouling control can affect fuel consumption, emissions performance, drydock planning and long-term operating costs.
New application methods and digital tools are changing how coatings are selected, applied, monitored and evaluated throughout a vessel’s life. Let’s take a deeper dive.
To learn more about how marine coatings work and how it can help the shipping industry decarbonize, I connected with Morten Sten Johansen, Global Category Director, Hull Performance in Jotun, and Joanna van Helmond, PPG Product Development Director, Marine Fouling Control, Protective and Marine Coatings.
Johansen told SeaNews that marine growth and roughness increase drag, and this can force operators to use more fuel to keep the same speed. A smoother, cleaner hull reduces resistance, so the vessel needs less power and fuel to maintain speed.
This is why the industry increasingly focuses on speed loss, he said. The internationally recognised ISO 19030 standard measures changes in vessel performance over time by comparing a ship against its own baseline set during the first year after docking, while correcting for operational and environmental factors. Speed loss matters because it directly affects fuel consumption and emissions. Lower speed loss helps maintain efficiency and reduce CO2 emissions.
Jotun’s hull performance solutions show average speed loss performance ranging from no measurable speed loss with our Hull Skating Solutions, to low single-digit percentages - all third party verified from DNV based on the ISO 19030 methodology.
Helmond says the hull remains one of the most impactful areas for improving a vessel’s energy efficiency. A smooth, clean hull reduces resistance through the water, which requires less engine power and fuel to maintain speed. On the other hand, hull roughness and biofouling increase frictional resistance, fuel consumption, and associated greenhouse gas (GHG) emissions.
The International Maritime Organization (IMO) estimates that effective hull biofouling management can help reduce a vessel’s GHG emissions by five to 25 percent. She believes advanced hull coatings should be viewed as part of a vessel’s broader decarbonization strategy, alongside operational measures and other energy efficiency efforts.
Here’s more:
Hull Friction
Helmond said the impact can be substantial. Frictional resistance, which is increased by biofouling, can account for 50 to 90 percent of a ship’s total drag. Studies estimate that even moderate fouling can increase fuel consumption and GHG emissions by up to 30 percent
This makes hull condition a significant factor in vessel performance. PPG SIGMAGLIDE 2390 coating can provide instant power savings of up to 20 percent and speed-loss performance of less than one percent, with actual performance varying by ship model and operating conditions.
A low-friction coating changes the interface between the hull and the water. By creating a smoother surface and controlling fouling, it reduces the resistance the propulsion system has to overcome.
For example, PPG Sigmaglide 2390 coating uses PPG HYDRORESET TECHNOLOGY water-responsive surface technology in a 100 percent pure silicone binder formulation. When immersed in water, the surface becomes non-stick and ultra-smooth, helping prevent marine organisms from recognizing or adhering to the hull.
The quality of the applied film can further improve the result. Electrostatic application, or ESTA, uses opposite electrical charges to attract the coating to the hull. Coating particles are negatively charged as they leave the spray gun, causing them to repel each other and form a fine, even spray. The charged particles are then attracted to the grounded hull, helping create a more uniform coating than traditional airless spraying.
The process also significantly increases transfer efficiency, reducing overspray by up to 50 percent, based on experience from more than 300 dry dockings using electrostatic application.
Distinguishing Coat Performance
This is one of the biggest challenges in hull performance analysis because vessel performance is affected by both hull and propeller condition, said Johansen. If performance deteriorates, the cause may be due to hull fouling, propeller fouling, coating degradation or a combination of these factors.
The coating’s role is to reduce fouling and maintain a smooth underwater surface, so coating performance and fouling performance cannot be viewed entirely separately. To distinguish between factors, we combine operational data with underwater inspections, hull condition reports and, where available, propeller inspections.
According to Helmond, operating conditions can influence both fouling pressure and the performance of the hull-coating system. Water temperature can affect the conditions for marine growth, while vessel speed, activity and time spent idle influence the opportunity for fouling to establish and accumulate. Ultimately, it is the resulting condition and smoothness of the hull that affects frictional resistance.
For PPG Sigmaglide 2390, PPG HydroReset Technology is water-responsive. This helps maintain a low-friction surface and limit speed loss over time.
Vessels
Johansen said that rather than developing one coating for each vessel category, Jotun uses a Tailored to Trade approach. Two ships in the same segment can have very different fouling risks depending on trade routes, operating speeds, port stays and idle periods.
That is why we focus on how the vessel operates, including speed profile, predictability, time at anchor, water temperature, and maintenance intervals. Jotun’s large installed base, being the clear market leader in marine coatings, gives us extensive hull performance experience and data. This helps us recommend solutions matched to specific operating profiles and fouling risks.
The result is a solution tailored not only to the ship type, but to how the ship will actually trade throughout its service interval.
Helmond says selection should be based on the vessel’s operating requirements and the type of fouling-control performance required. For vessels where low friction and long-term fouling-release performance are priorities, PPG Sigmaglide 2390 offers a biocide-free solution based on a 100 percent pure silicone binder formulation and PPG HydroReset Technology.
Depending on ship model and operating conditions, the coating can deliver instant power savings of up to 20 percent and speed-loss performance of less than one percent. So, rather than choosing a coating based on vessel class alone, owners should consider the vessel’s specific operating and performance requirements.
She commented that the greatest savings potential generally comes from the amount of frictional resistance you can avoid. That makes the vessel itself and how it operates important: ship model, operating conditions, fouling exposure, and hull condition can all influence the performance achieved from a coating.
For a vessel that spends significant time in service, even a relatively small improvement in hull efficiency can accumulate across many operating hours. Equally, vessels exposed to greater fouling pressure have more to lose if hull condition deteriorates.
The value of the coating therefore comes from maintaining hull performance over time and avoiding the additional power, fuel consumption and emissions associated with increased frictional resistance.
Environment
For ships, is there one coating for every environment – like Black Sea, Pacific Ocean, North Sea, etc?
Johansen pointed out that there are different coatings for different environments.
He explained that different regions create different fouling pressures. Warm tropical waters typically create higher fouling risk than colder waters, while port stays, trading patterns and idle periods also matter.
Jotun assesses the vessel’s overall fouling risk, including environment, speed, maintenance intervals and expected service profile. This is central to our Tailored to Trade approach.
For some vessels, the priority is maximum fouling protection in challenging waters. For others, it is maintaining efficiency in predictable deep-sea operations. The goal is always strong hull performance throughout the operating cycle.
We believe the best-performing coating is also the best choice for the environment. By keeping the hull clean and reducing friction, coatings help vessels use less fuel, lower CO2 emissions, and reduce the cost impact of regulations such as FuelEU Maritime and EU ETS.
At the same time, we follow evolving regulations and expectations for marine ecosystem protection. That means developing solutions that deliver strong fouling control, help manage biofouling risks, and support shipowners in operating more efficiently and responsibly.
Lifespan and Challenges
Helmond told SeaNews that ship owners and operators can expect no surface deterioration of the PPG Sigmaglide 2390 coating on the hull, as well as no leaching or surface porosity. This can provide an extended coating lifetime of more than 10 years with minimal maintenance requirements.
A vessel coated with PPG Sigmaglide 2390 can save two complete treatment steps during a five-year redocking and continue for another five years without full blasting or a full topcoat. That extended service life can significantly improve return on investment, she said.
One key challenge is meeting sustainability goals across both vessel operations and shipyard activities. That means looking at how the coating performs in service and how efficiently it can be applied.
Effective fouling-release coatings support sustainability goals by helping control fouling and maintaining hull performance during operation. ESTA complements this by improving coating-application efficiency and precision, reducing material use and supporting cleaner shipyard operations. Together, these technologies can support sustainability across both application and in-service vessel performance.
PPG has developed marine coatings that are compatible with ESTA and provides equipment and technical support to help shipyards integrate the technology into existing workflows.
Johansen added that the best-performing coating is also the best choice for the environment. By keeping the hull clean and reducing friction, coatings help vessels use less fuel, lower CO2 emissions, and reduce the cost impact of regulations such as FuelEU Maritime and EU ETS.
At the same time, Jotun follows evolving regulations and expectations for marine ecosystem protection.
That means developing solutions that deliver strong fouling control, help manage biofouling risks, and support shipowners in operating more efficiently and responsibly.