The settlement of marine organisms on vessels underwater surfaces increases drag, fuel consumption (with increased greenhouse gas emissions) and can facilitate the translocation of Aquatic Invasive Species (AIS) into Australian and New Zealand waters. To minimize this threat, in water hull cleaning was banned in Australia and New Zealand in 1997.
In 2011 the Department of Fisheries – Western Australia (DoF) sought a suitable service provider to trial an in water hull cleaning system capable of cleaning and encapsulating marine biofouling from vessels over 40 metres as a counter measure to minimise the treat of introducing AIS into Australian waters.
GRD Franmarine had developed and patented a revolutionary new fully enclosed capture and containment hull cleaning technology the Envirocart. The Envirocart enables soft Silicon based antifouling paints and coatings containing pesticides such as Copper Oxide to be cleaned using a contact less cleaning method. This fully containerised system is now capable of being deployed to remote locations or directly onto a Dive Support Vessel and is rated to offshore specifications. This is the only known method that complies with the new DAFF guidelines.
The primary underwater cleaning tool is a hydraulically powered hull cleaning unit fitted with rotating discs. The discs can be fitted with conventional brushes for glass or epoxy based coatings or a revolutionary new patented blade system which can remove marine biofouling without damaging the antifouling paint (silicone and copper oxide). Additionally there are a patented range of fully enclosed hand cleaning tools for difficult to access niche areas such as anodes and sea chests, providing an innovative total solution that enables in-water cleaning to be conducted in a manner that causes no biological risk to the environment.
In full containment mode or when AIS are present, material is pumped through a multi stage filtration unit on the surface. Solids greater than 50 micron are separated through a 1st stage seperator and deposited into a disposal bin. Filtrate is then pumped through a series of high flow, back-flushable filters that remove particulate material greater than 5 micron. After the 1st and 2nd stage filtration the filtrate is then disinfected by passing through an automated UV reactor where the treated water is then released back into the ocean.
After extensive trials, the GRD Franmarine in-water hull cleaning and filtration system demonstrated the system to be effective in removing, capturing and containing biofouling > than 50 micron, from vessels surfaces without damage to the antifouling paint. Furthermore the chemical contamination assessment indicated contaminants are now able to meet all water discharge quality guidelines when discharged directly into the adjacent water body.
Since these trials, the Envirocart in-water hull cleaning system was deployed under the DoF’s emergency powers to clean a 120 metre barge infected with Asian green mussels. Located near Perth, Western Australia, the barge was cleaned in open water and subsequently passed a DoF biofouling inspection which concluded no Non-Indigenous Marine Species (NIMS) were present. The vessel was allowed back into active service saving the owners millions of dollars in fuel, labour, dry docking and opportunity costs.
Apart from a front line defence to counter the biosecurity risk posed to our tourism and aquaculture industries, the Envirocart will provide many other significant benefits to the maritime industry through:
• Improved marine safety by enabling a thorough in-water inspection of vessels hulls;
• Up to 30% reduction in fuel consumption and GHG emissions;
• Improved steaming times;
• Significant reduction in labour cost;
• Potential certified emission reduction or carbon credits;
• Reduced vessel down-time and schedule delays by enabling the vessels to be cleaned on site;
• Reduced dry-docking cost and lost down time; and
• Regenerated anti-fouling by restoring the biocide leach rate.
