Drag head

A drag head is the toothed suction nozzle at the seabed end of a trailing suction hopper dredger’s suction pipe, dragged along the bottom to cut and pick up sediment. It mixes loosened soil with water into a slurry that the dredge pump lifts to the hopper. Designs match the soil: a visor head with adjustable teeth and water jets for sand, a California or active head with jet assistance and a grid to exclude large debris. The drag head’s penetration, jet pressure, and trailing speed control the in-situ density of the mixture and therefore production. It works under way, so the dredger keeps moving and does not block traffic the way an anchored cutter dredger can.