The marine curse of fouled hulls has generated a thriving industry of toxic paints which release self-polishing copolymers. But the European Biocidal Products Regulation (BPR) calls into question even the less harmful copper-based antifouling paints. Leading companies are updating their lines to meet the upcoming deadlines.
The new regulations require that all key biocides used in antifouling yacht paints in the EU be assessed. Applying and maintaining these paints is costly for recreational vessels, and can be huge for large ships. The combination of environmental concerns, rising costs, and technological changes has spurred the search for better solutions.
“Addressing hull fouling is a crucial step in protecting marine biodiversity.”
Poisoning the ocean is not the only problem posed by organisms adhering to hulls. International Maritime Organization (IMO) director Stefan Micallef explained: “The IMO has been at the forefront of the international effort to tackle the transfer of invasive aquatic species by ships. Addressing hull fouling is a crucial step in protecting marine biodiversity. The treatment of hulls to reduce fouling by aquatic organisms has the additional benefit of reducing greenhouse gas emissions, since [it also reduces] drag.”
In 2017, the IMO announced it was allocating $6.9 million to its new GloFouling Project, covering both commercial and recreational vessels. All available approaches will be examined, including improved ultrasonic waves, nanotechnology and robotic solutions.
A Range of Technologies
Antifouling paint prevents rust on metal hulls and reduces marine growth on all hulls. In addition to high cost, it has only limited ability to combat barnacle growth inside hull fittings. This is spurring efforts to modify or completely change the system.
New approaches include metal-free, low-friction alternatives, enzyme-based green products and silicone liquids, among others. Selektope from pharmaceutical giant AstraZeneca is one example. The collaborative EU eSHaRk project that includes non-eroding silicone filament from Mactac is another. A third possible solution is a low-friction nanotechnology being developed by Nanotech Marine.
Applying these paints and filaments remains onerous, creating a need for robotic applicators and cleaners. Robotic hull cleaners, such as the Italian-designed Keelcrab, is a solution aimed at recreational boaters. Commercial shipping already uses robots for hull inspection, one reason the US Coast Guard commissioned an extensive report on the subject in 2016. Robots used magnetism to stick to hulls or negative pressure fields, though shipowners questioned both approaches. The report concluded that “In terms of the effectiveness of the technologies, we continue to see a lack of conclusive testing.”
The Ultrasonic Alternative
In the 1950s, the US Navy found growth-free areas on hulls near sonar signal sources and used the phenomenon to complement antifouling paint. Critics of the technology note that power output was substantial—perhaps 2 kW—whereas consumer versions operated at 20-100 kHz. Ironically, ultrasound is also used to promote plant growth, making it a somewhat controversial solution. However, manufacturers such as CMS Marine and Harsonic point out that the amount of power required to destroy algae at single cell level is significantly lower than that required to destroy molluscs. Another company, NRG Marine, told visitors to METSTRADE 2017 that its Sonihull ultrasonic product has 15,000 users.
A variation comes from Australia’s Barnaclerid, which creates a copper ion electronic field around the boat’s hull. Unlike ultrasonic systems, no hull installation is required. Instead, it consists of a wiring harness holding several electrodes that hangs from the boat when moored. “Also, Barnaclerid does not cause electrolysis or galvanic corrosion, as shown in independent tests. This report is available on request,” CEO Shane Gillard told NauticExpo e-magazine.
Read more about antifouling coatings on NauticExpo website.