Dredgers

A Trailing Suction Hopper Dredger is a self-propelled vessel, used for maintaining or deepening waterways, or to dredge sands to replenisch beaches or to be used for construction purposes on land, thereby using powerful pumps and deploying one or two suction pipes fitted with a draghead, which are lowered onto the seabed, whilst moving slowly forward. The dredged materials are held in its hopper, to be discharged at the intended location, often many miles away from the dredging area, 1) through its bottom-doors, mounted in the keel of the vessel, 2) to pump these ashore, sometimes over distances of more than one kilometer, by means of a quick coupling mechanism, usually mounted at the bow of the vessel, or 3) spraying the material over a short distance, also known as rainbowing.