French cryogenic containment technology provider GTT has received approval from the China Classification Society (CCS) and DNV for a ballast-free LNG bunker and supply vessel
Called Shear-Water, the ballast-free concept uses a large bilge keel and a Flume anti-rolling tank supplied by German engineering firm Hoppe Marine for its LNG bunker and feeder ship design.
The Flume roll damping tank is designed to operate at maximum efficiency when the vessel is empty, where rolling might be most severe. It can also be operated at design draft condition with slightly less efficiency.
Most merchant vessels worldwide use ballast water to maintain stability and seaworthiness when the bunkers are empty or only partially loaded. However, this requires ballast water to be treated when discharged to avoid contamination of the environment and the release of invasive organisms.
With the solution developed by GTT, this risk is completely eliminated because the Flume tank is operated with fresh water, which eliminates the costly and energy-intensive ballast water treatment process. Additionally, a ballast-free ship also offers advantages in terms of capex and opex, simplifying ship operation, reducing corrosion and extending service life.
The seakeeping behaviour of the Shear-Water design was extensively tested at the Hamburg Ship Model Basin (Hamburgische Schiffbau-Versuchsanstalt GmbH), including different bilge keels and the operation of the ART in various load cases, sea-states and headings.
GTT said the results were in line with expectations and confirmed the efficiency of the installation, with a rate of roll reduction between 15% and 40% for full condition and 44% to 64% for empty condition.
GTT and CCS are also co-operating under a memorandum of understanding (MoU) on the application of membrane containment technology on a wide range of LNG vessel types, LNG-fuelled vessels and onshore applications.
Under the MoU, GTT and CCS will jointly work on the design of Chinese LNG inland waterway transportation, LNG carriers of all sizes, LNG-fuelled vessels and onshore LNG storage tanks.
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