Some dredgers lack self-propulsion and rely on tugboats to move between work positions. The dredged sediment is loaded into waiting barges and towed away. Self-propelled dredgers operate in waterways used by larger vessels, using large hoses to suction up silt. These dredgers store the sediment in their holds and, once full, sail to offshore locations to dump it. Side-boom dredgers are effective tools for clearing narrow waterways; they move steadily at approximately 3700 meters per hour, excavating a channel about 35 meters wide at the bottom of the lake. Pumps then spray the dredged sediment through a long boom back into the water, away from the channel. Large ships with deep drafts particularly rely on this type of dredger.
The task of a dredger is to perform underwater earthwork, specifically: deepening, widening, and clearing existing waterways and ports; excavating new waterways, ports, and canals; dredging the foundations of docks, shipyards, locks, and other hydraulic structures; and disposing of the dredged sediment in the deep sea or using it for land reclamation in low-lying areas.
The working capacity of a dredger is expressed in cubic meters of soil excavated per hour. Dredgers are classified as either self-propelled or non-self-propelled, and according to their construction characteristics, they can be further divided into trailing suction, cutter suction, bucket chain, grab, and dipper types.
