The technology behind hull coatings has come a long way. In the 18th century, antifouling was a mix of oil, tar, and sulphur. The goal back then was the same as it is now: to decrease the resistance on vessels as they travel through water by preventing ship hulls from accumulating plants, animals, and bacteria.
Here’s a look at some innovative new approaches to coatings that might help the industry increase efficiency while decreasing biofouling.
From swimming pool to open sea
Developed by a consortium of companies with EU funding, the eSHaRk project draws inspiration from the swimsuits that every competitor seemed to wear during the 2008 Olympics. Swimmers wearing the suits broke so many records that the suits were eventually banned. PPG and other partners in the research consortium wondered if they could apply similar body-hugging hydrodynamic technology to ships.
eSHaRk is based around a self-adhesive foil that contains a biocide-free fouling release coating. Part of the innovation is the application to a large vessel using robotic laminators. The self-adhesive fouling release foil for ship hulls provides a coating method that reduces speed loss and lowers the amount of greenhouse emissions on every journey. The foil system has self-cleaning properties that contribute its extended life span and also help increase operational profitability for ship owners by reducing maintenance costs. As the coating does not degenerate over time, there is reduced need for repeat applications. The low environmental impact also enables the foil to be applied to vessels operating in the most ecologically delicate environments, such as research vessels and cruise ships that need to leave minimal impact on surroundings.
In 2019, the eSHaRK consortium partners, PPG and Avery Dennison Graphics Solutions, announced an agreement to further commercialise the patented self-adhesive fouling release foil for ship hulls. Avery Dennison markets the foil solution to the leisure sector under the brand name MactacⓇ MacGlide™. PPG markets the product as PPG SIGMAGLIDE® Foil to the commercial marine sector, focusing primarily on smaller vessels that suit the foil’s manual application. The process of expanding this into the larger, commercial vessel market is under development.
Inspired by tuna
The Japanese government recently presented Nippon Paint with its 2020 Award for Global Warming Prevention Activity. The recognition was for Nippon Paint’s LF-Sea hydrodynamic coating that is based on the mucus layer on tuna’s skin. Tuna trap a microscopic layer of water between their skin and the ocean’s water, enabling them to reach speeds of 100 km/h.
LF-Sea’s coating uses the same water trapping principle to cut down on resistance. It has already been applied to nearly 3,000 vessels. It reduces fuel consumption by between four and 10 percent compared to regular self-polishing copolymer antifouling coatings. An updated version of this technology, with greater antifouling properties, will be introduced in 2021.
Could thin air be the answer?
In what may be the most unorthodox solution to date, fleets of ships could float on a thin layer of air to help meet efficiency and biofouling goals.
AIRCOAT is a foil coating solution that uses the biometric Salvinia effect to reduce underwater drag. The Salvinia effect traps tiny air bubbles between the ship and the water. The technology could decrease fuel consumption by an estimated 25 percent.
Like eSHaRk, this project also uses adhesive foil technology and is funded by the EU. The AIRCOAT consortium, which includes Danaos Shipping, received 5.3 million euros as part of the Horizon 2020 project topic: Innovations for energy efficiency and emission control in waterborne transport. Testing is underway in Malta and Germany.
Meeting the IMO’s targets on reducing both greenhouse gases and biofouling will depend on solutions from all sectors of the marine industry. Ship coatings are one example. They sit at the crossroads of the UN’s biofouling and emissions goals. They increase hydrodynamics and are more difficult for organisms to adhere to, increasing vessel efficiency and reducing the spread of invasive species.
Projects that combine public and private funding, like eSHaRk and AIRCOAT, are examples of the kind of partnership needed to solve some of the challenges facing the marine industry. It’s these publicly incentivised research projects, and other cooperative approaches, like Getting to Zero Coalition, that will drive the marine industry toward the lofty goals set out by the IMO and help drive the European economy out of the economic slump caused by the COVID-19 crisis.