MAN B&W Diesel has added two new reference plants to the fourstroke order book. Complete twin-screw medium speed propulsion packages have been ordered for a twin set of 65 m offshore research vessels. The twins will each be specified and equipped for their very specific operational tasks, i.e. seismic sourcing and seismic recording. The vessels are designated as an OBC Source Vessel and an OBC Recorder Vessel, respectively. The OBC abbreviation refers to ‘Ocean Bottom Cable’ and the actual seismic exploration equipment applied. The design consulting company for this project is Dalian Shipbuilding Technology Research Center Co. Ltd., located in Dalian, China.