Posted on June 23, 2025
The Royal Navy has announced that maintenance dredging operations are about to begin at the HMNB Devonport.
According to the Navy and the King’s Harbour Master, maintenance dredging will take place at various places throughout HMNB Devonport, starting on June 20, 2025.
The scheme will comprise trailing suction hopper dredger (TSHD) Shoalway, plough dredger Obervargh and survey vessel Smit Neyland working for approximately 10 days to complete the dredging.
These three vessels play complementary roles in a dredging project, working in coordination with various types of dredging hoses to ensure efficient material handling and transportation:
Pre-Dredging Phase:
The survey vessel conducts an initial hydrographic survey to determine seabed conditions, identify high spots or shoals, and help plan the dredging strategy.
Dredging Phase:
The TSHD performs the bulk of the dredging work, sucking up sediment through suction hoses and storing it in onboard hoppers. When the hopper is full, the dredged material is discharged either through discharge hoses connected to HDPE pipes or directly onto the shore via submerged discharge hoses.
The plough dredger supports the TSHD by redistributing sediment from hard-to-reach or shallow areas into the suction path, increasing efficiency and minimizing the need for TSHD repositioning. Flexible rubber hoses play a critical role here, especially in tight or shallow spaces where maneuverability is limited.
Post-Dredging Phase:
After dredging, the survey vessel performs follow-up surveys to verify that the target depths have been achieved and to detect any remaining high spots, which may require additional ploughing or spot dredging.
At this stage, floating hoses with integrated wear indicators are often used for re-check or light-duty sediment relocation tasks. The data also guides the safe retrieval and dismantling of hose systems, ensuring minimal environmental impact.
All dredged material will be disposed at Plymouth Deep (PL035) licensed disposal site.
