Trailing suction hopper dredger

A trailing suction hopper dredger (TSHD) is a self-propelled ship that dredges while under way, lowering one or two drag heads to the seabed and pumping the water-sediment mixture into its own hopper. When full it sails to a disposal site or reclamation area and discharges through bottom doors, by pumping ashore, or by rainbowing. It is the main vessel for maintenance dredging of channels and for large sand-fill reclamation, prized because it works in open water without obstructing traffic the way a stationary cutter does.