The invention relates to a suction drag system for dredging vessels which can be placed or removed respectively on an existing vessel, such as a hopper barge (1,2), the system comprising a suction pipe (26,28) with suction head, a suction pump (29) with drive motor (30), an elbow section (25) on deck and derricks (41) to handle the suction pipe (26,28). These components are separate units to be installed on deck and are units each having a frame (8,9,10) which can be installed disconnectably transversely over the hold (4) onto the coamings (5,6) of the vessel, a further frame (7) being possible carrying the drive unit for the dredging system, these frames (7,8,9,10) in case of a split hopper barge (1,2) being pivotably connected (11) to one coaming (6) and pivotably as well as movably in transverse direction (12,13) to the other coaming (5).