To avoid the danger of a collision by gripping an operation rod integrated with an oar in the course direction, operating it by the same rowing method as before, horizontally operating the oar in the dog-legged inverse shape while a spindle serves as a fulcrum, and advancing a boat interlockingly with the vertical action by a set pin.

An operation rod 1 is gripped in the course direction of a boat, an oar is rowed by the conventional motion, the spindle 6 of the operation rod 1 and the oar 4 serves as a fulcrum, and dog-legged inverse continuous actions are repeated on the horizontal line via the principle of lever. The operation rod 1 and the oar 4 are symmetrically operated in the same direction via the principle of lever, and the boat is advanced forward. The oar 4 is connected to an oar receptacle 9 fixed to a hull by a set pin 8, and the water entrance angle of the oar 4 can be invariably kept constant without being unstabilized according to the gripping way of the operation rod 1.