a cutter suction dredger's suction tube has a cutter head at the suction inlet, to loosen the earth and transport in to the suction mouth . the cutter can also be used for hard surface materials like grave or rock , the dredged soil is usually sucked uo by a wear-resistant centrifugal pump and discharged through a pipe line or to a barge. in recent years, dregers with more powerful cutters have been bulit in order to excavate harder rock without blasting.