Abstract: In connecting a bow of a pusher boat having a driving power source with a stern of a barge having no driving power source at a recessed portion formed at the stern of the barge, a plurality of freely projectable connecting pins provided at positions in the vicinity of center part of both sides as well as at the bow of the pusher boat are inserted into connecting pin receiving ports formed at corresponding positions in the recess of the barge so as to make both pusher boat and barge to be unified into a single navigable body, and the connecting pins at both sides of the pusher boat and the connecting pin receiving ports provided at the recessed portion at the stern of the barge are arranged in a backward obliquity, or swept back direction, with respect to the lengthwise direction of the boat hull.