At the boat front end in its longitudinal direction is a concertina barrier which can be drawn in and out, and whose barrier components (8) represent shears with rotary points (9) and are joined to each other by hinges (10). At the rear end of the concertina barrier is a drive oar blade (1) fixed by means of a hinge (2).With the boat in the water, the barrier components of the concertina barrier with the enclosed virtual surfaces of the barrier are vertical to the water surface and parallel to the direction of the force of gravity. The person stand surface is connected with the upper end piece (6) of the front concertina barrier via a hinge (11).
