Mitsubishi Heavy Industries, Ltd. (MHI) has installed its innovative “Mitsubishi Air Lubrication System” (MALS) for the first time on a ferry and confirmed over 5% improvement in fuel consumption.
The verification experiment was conducted at sea using the ferry Naminoue, a ship owned by Japan’s A-LINE Ferry Co., Ltd. that went into service starting September 27. The experiment results have verified that MALS is also applicable to high-speed, slender ships as an effective way to reduce fuel consumption and reduce environmental burdens, further extending the range of ship types for which MALS is suited.
The ferry Naminoue is an 8,072 gross tonnage (GT) ship 145 meters (m) in length, 24m wide, and with a designed draft of 6.2m. It was built at MHI’s Shimonoseki Shipyard & Machinery Works and plies the Kagoshima-Amami-Okinawa route in southern Japan.
During the speed trial test at sea, fuel consumption improvement (reduction in propulsion power required) exceeding 5% was confirmed even with waves as high as 2.5-3m. These results verified reduction of frictional resistance by MALS even when installed on high-speed, slender ships. The level of fuel consumption reduction suffices to offset the fuel consumption increase such a ship’s marine diesel engine requires to comply with tightened controls on NOx (nitrogen oxide) emissions. As the air bubbles function as a cushion, noise and vibration are also reduced, enabling improvements in passenger comfort.
The verification experiment using the ferry Naminoue was supported by ClassNK (Nippon Kaiji Kyokai) as a joint research project.
Ferries are vessels with a slender hull form, meaning that it has a small block coefficient (Cb). Cb = volume of displacement divided by the volume of the block defined by a ship’s length x breadth x draft. Ships with a comparatively large Cb value are known as “full hull-form ships”.
Source: MHI
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