2.2 Special Vessels - Dredgers
Dredgers are specialized vessels designed to excavate material from underwater, typically to deepen or widen waterways, maintain navigation channels, or extract resources such as sand.
Key Components
- Hull: The main structure of the dredger, designed to withstand the stresses of dredging operations.
- Propulsion System: Powerful engines and propellers to maneuver the dredger and maintain position.
- Dredging Equipment: The specific equipment used to excavate material, such as bucket wheels, suction pipes, cutterheads, or grab buckets.
- Pumping System: High-capacity pumps to transport dredged material.
- Hopper: A storage compartment for dredged material.
- Pipeline System: A network of pipes to transport dredged material to a disposal site or for reclamation.
Dredgers come in many different forms and sizes depending on their specific uses and geographical locations.
Backhoe Dredger
Description: Backhoe dredgers are stationary dredgers consisting of a hydraulic excavator mounted on a pontoon. This robust design allows for precise excavation in various water depths and conditions.
Applications: Port and Harbor channels and berths to accommodate larger vessels and maintain navigation depths. Coastal Protection, River and Canal Maintenance, Offshore Construction and Trenching for pipeline installations and removing contaminated sediment from waterways
Description: A large, self-propelled vessel equipped with a rotating wheel lined with buckets. The wheel scoops up material from the seabed and deposits it into a hopper or onto a conveyor belt.
Applications: Used for large-scale dredging projects, such as deepening harbors, creating new waterways, and mining sand and gravel.
Trailing Suction Hopper Dredger (TSHD):
Description: A self-propelled vessel with a suction pipe that trails behind the ship. The suction pipe is lowered to the seabed, and powerful pumps draw up sediment and water. The mixture is then transported to a hopper on the ship, where it is stored until it can be discharged.
Applications: Widely used for maintenance dredging, beach nourishment, and offshore mining.
Cutter Suction Dredger:
Description: A self-propelled vessel equipped with a rotating cutterhead that breaks up the seabed material. The loosened material is then sucked up by a powerful pump and discharged into a hopper or onto a pipeline.
Applications: Effective for dredging hard or compacted soils, such as clay and rock.
Description: A vessel equipped with a large clamshell bucket that is lowered to the seabed, filled with material, and then raised to the deck. The material is then discharged into a hopper or onto a conveyor belt.
Applications: Suitable for smaller-scale dredging projects, such as cleaning canals and harbors.
Dipper Dredger:
Description: A self-propelled or barge-mounted vessel with a large, hinged bucket attached to a boom. The bucket is lowered to the seabed, filled with material, and then swung back to the deck for discharge.
Applications: Versatile dredgers used for a variety of tasks, including dredging rivers, lakes, and harbors.