Barnacle Repelling Tech Protects Ship Hull
An antifouling biotechnology developed by I-Tech AB has reportedly protected the hull and other areas of the world’s largest hospital ship in a recent successful test.
According to the release from Selektope, the test was the company’s toughest challenge and protected the ship while it was docked for extensive periods of time in warm waters.
About the Challenge
The release stated that though Global Mercy spent over 22 months stationary, at risk from barnacle fouling, since delivery to Mercy Ships in August 2021, the vessel’s hull and "niche areas" have remained completely free of barnacle fouling.
Uncoated surfaces of the vessel, the azimuth propellers and bow thrusters, were reportedly found to be covered with biofouling, both soft and hard fouling species. Additionally, it was noted that Barnacle fouling was present in areas where the coating surface was damaged, including the bulbous bow and where anchor damage had occurred.
The findings reportedly confirmed the elevated hard fouling pressures in waters that Global Mercy regularly encountered while delivering medical help from the Port of Dakar, Senegal, or while docked for maintenance at the Granadilla de Abona Port in Tenerife, Spain.
Selektope’s release also stated that it is an active agent ingredient added to marine coatings in nano-molar concentrations—about 0.1% per wet weight of paint—that is characterized by its first-of-its-kind bio-repellent mode of action, which can help keep a ship’s hull free from barnacles with a non-fatal effect on the target organism.
When released from the antifouling coating, the organic, non-metal compound reportedly temporarily causes the barnacle larvae to begin "swimming," making it harder for them to attach to the hull and transform into the calcareous adult stage of their lifecycle.
“The past 32 months have served as the ultimate trial for Selektope, to protect a ship that is static in the barnacle fouling hotspots for many months at a time. The most recent hull inspection has confirmed that our technology is doing its job as a key component of the hard fouling protection delivered by the antifouling coating system,” said Philip Chaabene, CEO of I-Tech AB.
“We are proud partners to the Mercy Ships organisation and grateful that we have the opportunity to help them to eliminate costs associated with hard biofouling accumulation in support of the charity’s incredible mission to help humanity.”
The release added that the vertical sides and flat bottom hull areas of Global Mercy were coated with the antifouling coating SEAQUANTUM PRO ACE, which contained Selektope, back in 2020.
When floated, the vessel reportedly underwent outfitting for 300 days. If the vessel’s idling time during outfitting was also considered, the barnacle fouling protection delivered by Selektope reportedly spanned over 32 months of static performance in total.
Selektope was developed in 2022, when I-Tech AB and RISE Research Institutes of Sweden announced they had developed a new method for introducing its barnacle repelling active agent into marine antifouling coatings.
Selektope, or medetomidine, is an active agent developed, patented and registered by I-Tech for use in antifouling coatings, reducing hard fouling on vessels and other underwater structures. The latest findings will reportedly expand the ways paint manufactures can work with the technology and pave the way for enhanced future hard biofouling prevention.
I-Tech and RISE collaborated over a period of five years on a series of projects to improve the use of Selektope in biocidal antifouling coatings for its barnacle fouling prevention characteristics. With the success of biocidal coatings dependent on the sustained control of biocide released at the coating surface, the team looked at previous elements that made antifouling coatings successful.
Selektope was delivered to the surface of self-polishing copolymer (SPC) antifouling coatings due to being held in the coating matrix via electrostatic interactions with metal pigments, allowing the technology to be evenly dispersed throughout the coating matrix and released at a sustained rate as the paint erodes or polishes.
However, the success of biocidal coatings is reportedly dependent on the sustained control of biocide release at the coating surface across the entire intended lifespan of a coating system. For large merchant ships, this period could be up to sixty months.
In other research, superior antifouling efficacy was achieved when a biocide was attached to a polymer chain with a covalent bond that was hydrolysable upon contact with water. Before the ban of tributyltin (TBT) use in 2008, this release mechanism is reportedly what gave TBT-containing coatings their success.
Researchers from I-Tech and RISE then began to look at ways of attaching Selektope to a co-polymer chain via the creation of Selektope-containing monomers that could be polymerized.
To test this idea, several coating SPC copper-free formulations on control panels were tested off the west coast of Sweden for 10 months, including:
Following this experiment, I-Tech and RISE reported that the control panel displayed heavy barnacle fouling whereas the panels coated with paints containing Selektope, both introduced via the traditional method and via the new method of attachment to a co-polymer chain, were barnacle-free.
The researchers said these results provided proof of concept that attaching Selektope to a co-polymer for use in SPC antifouling coatings is possible.
The research findings were presented at the International Antifouling Conference earlier this year in Gothenburg, Sweden. The companies report that Selektope in SPC coatings has been used on over 1,000 vessels to-date.