Industry is being readied for a safe, efficient and environmentally sustainable cleaning standard
Shipowners’ association BIMCO is leading an industry working group to formulate global standards for hull and propeller cleaning. Besides BIMCO, the group includes stakeholders such as paint manufacturers, companies that offer cleaning services, as well as ports. The industry-wide standards will set out how to evaluate the effectiveness of hull and propeller cleaning, how to handle cleaning products and seawater discharge, as well as a permitting process for companies that offer the cleaning service. The standards will also describe shipboard documentation of the cleaning regime adopted by the ship.
The document will be published online by the end of the year and feedback will be sought from the industry. The standards aim to enable ports across the world to allow in-water hull and propeller cleaning.
There is an industry need for greater availability of hull and propeller cleaning, says HullWiper general manager Laurance Langdon, pointing to the increased stress on fuel efficiency as part of efforts to cut greenhouse gas emissions. “In addition, countries such as Australia and New Zealand are saying that ships coming into their ports are demonstrably ‘clean’, i.e., free of invasive species,” Mr Langdon adds.
While hull and propeller cleaning can potentially rid the hull of invasive species that latch on to the hull, many ports have taken a not-in-my-backyard view towards cleaning. A particular concern is that the hull’s performance coating may be removed during hull cleaning, leading to the release of metals such as copper.
In the absence of a global standard, the options for in-water hull and propeller cleaning are divided between parts of the world where there is a more relaxed approach to these issues, such as in Asia and ports where stringent standards are in place, such as in Europe. Some European ports such as Southampton and Gothenburg have qualified companies performing hull and propeller cleaning, following rigorous scrutiny of their processes. Ecosubsea is one of the approved vendors in Southampton. The company chief executive officer, Tor M Østervold, says cleaning is performed using a battery-operated submarine; adding a soft jet ensures that none of the painting is scraped out during the cleaning process and no metals are released. “When cleaning is underway, substantial volumes of seawater from the cleaning are pumped to the surface where they are filtered in several steps and then discharged to the sea. The biological material is diligently collected and becomes feedstock for biodiesel at a nearby plant in Southampton,” adds Mr Østervold.
Mr Østervold says Ecosubsea has been offering in-water hull and propeller cleaning at Southampton since 2008. Recently, the company has been permitted in ports in Sweden and Denmark besides Antwerp and Ghent, he adds. Mr Østervold is aware of the BIMCO standards and believes that very soon there will be a rapid increase in the number of ports allowing hull and propeller cleaning services.
Coating over the issue
The prevention of hull fouling began with anti-fouling paints introduced in the 1960s. However, these were found to contain tributylin, which contaminates seawater and sediments, killing marine life.
IMO took up the issue in 1988 and these paints were phased out completely by 2008. Since then, new paints have been formulated that claim to act against fouling on the hull but are not harmful to sea life. In-water hull and propeller cleaning removes fouling and reduces hull resistance, which can build up between dry dockings.
Source: Marine Propulsion & Auxillary Machinery | October/November 2019