PURPOSE: To contrive to secure a stern working space and to realize a small size lightweight driving device and the like by a structure wherein a reducer- reverser, which contains a trawling mechanism and equipped with a forward- backward change-over clutch, is provided within an intermediate shaft bearing device.

CONSTITUTION: An engine 3 is installed at a fixed distance ahead the driving device 1 in the stern of the vessel and the intermediate shaft bearing device 5 is arranged in the middle of the driving device 1 and the engine 3. Connecting shafts 6 and 7 respectively connect the engine 3 to the intermediate shaft bearing device 5 and the intermediate shaft bearing device 5 to the driving device 1. Furthermore, the reducer-reverser, which contains the trawling mechanism and equipped with the forward-backward change-over clutch, is provided within the intermediate shaft bearing device 5. Because the reducer-reverser is not provided yet the small size lightweight driving device 1 can be realized.