A cutter suction dredger is a combination of mechanical and hydraulic dredgers. To ensure the quality of underwater excavation depth (i.e., the flatness of the underwater seabed after excavation and the depth of the dredged material), it is necessary to use steel piles and their lifting devices or a three-line positioning device installed on the hull for positioning and the ship's forward and backward movement. The lateral swing of the hull is achieved by the two lateral swing anchors connected to the cutter suction bridge, one on each side.