Chinese Seismic Exploration Require New OBC Vessels

Complete twin-screw medium speed propulsion packages have been ordered from MAN B&W for a twin set of 65 m offshore research vessels. The twins will each be specified and equipped for specific operational tasks, i.e. seismic sourcing and seismic recording. The vessels are designated as an OBC Source Vessel and an OBC (Ocean Bottom Cable) Recorder Vessel, respectively.

The design consulting company for this project is Dalian Shipbuilding Technology Research Center Co. Ltd., located in Dalian, China. Both vessels will be built by Liao Nan Shipyard, also located in Dalian, and the delivery of the first vessel is scheduled to the end of next year. Operator and owner is BGP/CNPC (China National Petroleum Corporation), with its fleet mainly based in Tanggu, Tianjin. The operation areas for these two vessels are not limited to Chinese offshore, but include also overseas exploration.

MAN B&W Diesel’s Four-stroke Propulsion Sales Manager, Jorgen Vinde, said: “Very low levels of vibration and noise from propellers, engines and propulsion systems are key issues for these installations. A very soft resilient seating arrangement of base frame and sandwich mountings has been applied for the dampening of structure-borne vibrations by up 97 percent. Additionally, the ducted propellers have been specially designed and shaped with high priority to low levels of cavitation and noise emission. From an underwater point of view, an absolute decisive factor for the customer is a very silent ship, with minimal noise emission and disturbance in relation to the seismic exploration equipment” The MAN B&W Diesel twin-screw Alpha Propulsion System type 6L23/30A-DVO, which has been specified for the newbuildings, includes:

• Main Engines Two MAN B&W 6L23/30A-D engines are resiliently seated with baseframe and sandwich mountings. Each engine develops 960 kW (1305 bhp) at 900 r/min.