Economic, environmental concerns advance marine coating innovation


Hull fouling has been a problem since ships started sailing. As far back as the 4th century B.C., Aristotle wrote about a suckling fish, echeneis (from the Greek echein, meaning “to hold,” and nays, meaning “ship”). It wasn’t until the 18th century that the maritime world saw the first documented case of an anti-fouling coating.

In 1761, the British frigate HMS Alarm was sheathed in copper as an experiment to see if the metal would protect the ship from worms. A report after the test remarked on the freedom of fouling on the bottom of the vessel.

Recent advances in antifouling coatings can be attributed to both economic and environmental concerns. Tributyltin (TBT) became the biocide of choice until it was banned because of its toxicity to non-targeted organisms. The shipping industry returned to the tried-and-true copper metal oxides, but there is growing concern that a significant amount of copper is leaching into the ocean. Add to that the International Maritime Organization’s 2020 sulfur cap, and you have the perfect impetus for innovation in efficiency.

Andreas Glud, group segment manager for marine and dry dock at Denmark-based Hempel A/S, said economic and environmental drivers of innovation are closely connected, as a reduction in bunker consumption reduces both cost and environmental impact.

“It has been calculated that fouling and the mechanical damage caused by hull fouling can increase the engine power a vessel utilizes by up to 20 percent,” Glud said. “One leading cruise ship operator, for example, has estimated that hull fouling can add $5 million (U.S.) in fuel costs over the five-year docking interval due to the resistance created by fouling. So for them, investing in a high-performance hull coating from the outset is always the right step in protecting a vessel, minimizing fuel consumption, maximizing efficiency savings and reducing (their) environmental footprint.”

Philip Chaabane, chief executive officer at I-Tech, a biotechnology company based in Sweden, expanded on environmental drivers of innovation. One is the trickier fouling problems created by an increase in the number of ships trading in warmer waters. That increase is due to both global warming and the fact that many emerging countries are located in warmer climates, so more ships are idling in those ports.

Barnacle clusters, shown here in adult form on a substrate, can rob a ship of speed and efficiency.

Courtesy I-Tech

Chaabane said there is also growing concern about ships bringing invasive species on their hulls to foreign ports. In March 2017, New Zealand turned away a cargo ship from Indonesia when divers found dense clusters of barnacles and tube worms attached to the ship’s hull. In May 2018, New Zealand introduced a nationwide standard requiring all commercial and recreational vessel operators to show that they have managed biofouling on their vessels before they enter territorial waters.

Innovative techniques for today’s market
I-Tech has developed an organic approach to antifouling. The company does not produce hull coatings but owns the intellectual property and regulatory rights to Selektope, an organic non-metal compound that is added in low concentrations to paints, providing manufacturers with an alternative active agent for antifouling.

When barnacle cyprid larvae come in contact with the hull, Selektope temporarily stimulates their octopamine receptor, resulting in swimming behavior that makes it impossible for them to settle on the hull.

That temporary and nonfatal effect has another benefit. Chaabane explained that biology’s natural response is to develop resistance to toxic substances over time. Because Selektope’s effect is only temporary, the chance of barnacles developing a resistance is extremely low.

While Selektope represents a relatively new approach to antifouling, it has been around long enough to develop a track record. Recently, the Laurin Maritime tanker Calypso reported a barnacle-free hull after two years of using an antifouling paint containing Selektope. During that period, the ship spent more than 50 percent of its operating time in areas with a high degree of biofouling, and encountered several long idling periods of up to 25 days.

Small in stature but a monumental problem for shipowners and operators, barnacles have bedeviled mariners for centuries. The challenge in the modern age is repelling them cost effectively without harming the environment. A barnacle is shown above feeding.

Courtesy I-Tech

Independent third-party data analysis verified that added resistance on Calypso’s hull and propeller due to fouling was exceptionally low compared to an untreated ship of the same age and same number of days out of dry dock.

Fouling control is also one of Hempel’s focal points for its coatings. The company has developed a unique approach to antifouling with ActiGuard, the science behind its Hempaguard fouling defense coating.

“ActiGuard works by forming a biocide-activated hydrogel on the surface of the fouling defense coating,” Glud said. “As the biocide diffuses out of the film, it is trapped in the hydrogel layer, which increases its surface concentration and prolongs the time the biocide is retained at the surface of the coating, where it is most effective.”

This means that less biocide is needed, and its effectiveness in preventing biofouling organisms from settling on the hull is greatly enhanced. “Additionally, it also means that the concentration of biocide is maintained at a level where the silicone coating is still able to retain all its antifouling and smooth surface properties,” Glud said.

Hempaguard delivers a 6 percent fuel savings across the entire docking interval with a maximum speed loss of just 1.4 percent over five years, he said. Hempaguard also remains effective when switching between slow steaming and fast steaming, and even if the vessel is idle for extended periods up to 120 days.

Assessing the future of antifouling coatings
Manufacturers will continue to come up with better coating solutions through advances in material science and biotechnology, reducing the impact on the environment while lowering fuel costs for vessel owners. However, these advances may not show the full picture of where the industry is heading.

The hull of the Laurin Maritime tanker Calypso was reported free of barnacles two years after using an antifouling paint containing Selektope. Third-party analysis found that added friction on Calypso’s hull due to fouling was exceptionally low compared to a similar ship that had not been treated.

Courtesy I-Tech

Chaabane said paint manufacturers will have to take on more responsibility for hull performance, a responsibility he feels that they want. Instead of selling a bucket of paint, they will sell value.

“These trends will drive them to a scenario where they will guarantee a certain fuel efficiency or hull performance, or they will guarantee some sort of coating performance and stand by it,” he said.

Glud said that while Hempel will continue to develop more effective hull coatings to help shipowners achieve their economic and environmental goals, he believes they will also want a more holistic solution.

“It is likely we will be developing more initiatives such as our recently launched performance monitoring system SHAPE (Systems for Hull and Propeller Efficiency) to assist shipowners to operate even more efficiently,” Glud said. “SHAPE is designed to follow the principles of ISO 19030 and monitors a vessel’s long-term trends using key in-service performance indicators. This provides detailed data allowing the shipowner or operator to make fact-based operational decisions.”

Whether the next decade sees a move toward a holistic approach in the coatings industry or performance guarantees, stricter environmental regulations will all but guarantee a step away from harmful additives leaching into the world’s waters.

By Professional Mariner Staff