Dredging is an excavation activity or operation usually carried out at least partly underwater, in shallow seas or fresh water areas with the purpose of gathering up bottom sediments and disposing of them at a different location. This technique is often used to keep waterways navigable.
A cutter-suction dredger’s (CSD) suction tube has a cutter head at the suction inlet, to loosen the earth and transport it to the suction mouth. The cutter can also be used for hard surface materials like gravel or rock. The dredged soil is usually sucked up by a wear-resistant centrifugal pump and discharged through a pipe line or to a barge. In recent years, dredgers with more powerful cutters have been built in order to excavate harder rock without blasting.
The two largest cutter suction dredgers in the world are currently (as at August 2009) DEME’s D’Artagnan (28,200 kW total installed power) and Jan De Nul’s J.F.J. DeNul (27,240 kW).Jan de Nul has by far the most heavy cutters in the market