Solutions that can better manage and protect hull surface from fouling attachment are highly sought after because they could improve operational efficiency, reduce fuel consumption, cut carbon emissions as well as reduce maintenance costs.
At present, fouling has been dealt with by biocidal or non-biocidal coatings. Biocides are substances that can keep aquatic lives from attaching to the surfaces. The concern over the eco-toxicity and the bioaccumulation of certain biocides may lead to usage restrictions enforced by statutory bodies. Apart from the IMO’s global ban on the tributyltin (TBT), some governments are under pressure to impose stricter control on copper or even biocidal coatings as a whole, especially for small leisure crafts staying idle for long periods in harbours or in environmentally sensitive areas. Some of the early adopters include Sweden, Denmark and Washington State, USA. Meanwhile, non-biocidal coatings offer non-stick surfaces for fouling organisms to settle onto but are easily washed away once the ships move. But there are other disadvantages associated with such coatings. For example, they may require more complicated application processes or are less resistant to external mechanical impact.
A multidisciplinary European consortium, the CLEANSHIP project, was established back in 2012 to investigate ultrasonic technology developed towards fouling monitoring and fouling prevention or delay in the marine environment. The ultrasound wave is designed to travel through the hull below the waterline. The ultrasonic technologies for cleaning other applications may have arrived more than 60 years ago, but adapting such technologies for superyachts or even larger commercial vessels has only emerged recently. Ultrasound sent into water at certain conditions is found to create cavitation (bubbles) and pressure waves that may deter or delay fouling attachment. One benefit of such technology is that it deploys kinetic and physical means, instead of chemical or biological measures, in a proactive approach to tackle fouling on the hull surface. The detection of fouling growth at an early stage can also allow just-in-time and cheaper removal.
In the CLEANSHIP project, Lloyd’s Register’s Strategic Research and Technology Policy Group works together with the Materials and NDE department in offering advice on the practical challenges in the marine industry. The overall objective is to better manage the performance of waterborne vessels and the operational efficiency for the marine industry. But the complexity of a ship’s structure and the material properties found on larger commercial vessels means that scaling up such technology for commercial vessels are difficult to simulate.
“It was suggested then that the performance of the device should be investigated further afield after the project completion in order to persuade the mass marine market. Ultrasonic system is a developing technology that is certainly worth watching closely,” said Ivy Fang, Senior Specialist, Strategic Research and Technology Policy Group, LR.
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