Abstract: A cylindrical drum is mounted for rotation about its axis on laterally opposed horizontal crossbeams of an open rectangular frame which crossbeams, in turn, bear on at least one end thereof, lift beams, slidable within vertical guide rails for varying the vertical height of each crossbeam and its drum relative to a barge supporting the dredging apparatus. A plurality of closely spaced radially directed pairs of guide plates extend outwardly from the axis of the drum to the drum outer periphery at given drum slots, permitting the projection of blade assemblies radially from the drum periphery. Each blade assembly includes a planar blade member bearing elongated rectangular bucket cut-out areas. To the opposite edges of the cut-out areas are hinge-mounted, interengaging main and auxiliary bucket plates which overlie each other when closed and which open to form generally right angle troughs or buckets.