Apparatus for coupling a pushboat to a barge having a notch in its stern for receiving the bow of pushboat. The pushboat has three coupler units, two on the opposite sides and one at the bow end, each of which has an extensible and retractable connecting pin. The side connecting pin has hemi-spherical part at its outer end part which comes into tight contact with the similar hemi-spherical part of the holes in side socket on the side wall of the notch when it is extended out and inserted into the hole for connection. The bow connecting pin has wedge-shaped end which engages with the teeth of the center rack located in the barge's centerline at the deepest point of the notch when it is extended out for connection. The motions of connecting pins are remotely controlled from a control panel located in the navigation bridge.