Backhoe dredgers (BHDs) are stationary dredgers with a hydraulic excavator installed on a pontoon. The backhoe dredgers can dredge a wide range of materials very precisely and they operate mainly in shallow and enclosed waters.
The backhoe dredger is anchored firmly with three spuds. A transport barge is moored alongside the backhoe dredger. The bucket excavates soil in a combined backward and upward movement of the boom, stick and bucket. When the bucket is full, an upward movement of the boom and stick lifts the bucket above the water to start swinging. The filled bucket is positioned above the barge by rotating the excavator on the turntable. The dredged material is discharged into the transport barge. The full barge transports the dredged material to a designated location.
Boskalis has around 20 of these vessels operating on projects all over the world, including the Magnor, the largest backhoe in the world. It can dredge to a depth of 32 meters, and has a bucket with a volume of 40 cubic meters.
Source: Boskalis