Trailing suction hopper dredgers

Trailing suction hopper dredgers

Trailing suction hopper dredgers (TSHDs) are used on a wide variety of maritime construction and maintenance projects. These range from maintenance dredging of ports and access channels to remove sand to bring them to necessary depths to capital dredging projects such as giant land reclamation projects that require millions of cubic meters of sand.

Our company has brokered a large number of TSHDs sale and purchase transactions and is able to find the buyers for your TSHD or find the right TSHD to be acquired by you. To enable us to locate for you the right TSHD, please inform us your requirements:

  • Hopper capacity
  • Maximum dredging depth
  • Suction pipe diameter
  • Pump power (trailing)
  • Pump power (discharging)
  • Any limitations on the Draught loaded?
  • Required discharge/offloading system(s)?
  • Is pump ashore system needed or not?
  • Is rainbowing system needed or not?

TSHDs vary widely in size. Their size is usually expressed in the hopper volume capacity, length and pump power. They can range from between a few hundred m3 up to 45,000+ m3. Recently several international dredging companies have commissioned some very large TSHDS. For instance, one of the largest in the world has a hopper capacity of 46,000 m3, a deadweight of 78,500 tons and is approximately 223m long, with a loaded draught 15.15 m. She has a maximum dredging depth of 155 m with suction pipes having a diameter of 1,300 mm. Her trailing pump power is 2 x 6,500 kW, a discharging pump power of 16,000 kW and a propulsion power 2 x 19,200 kW. Her total installed diesel power is 41,650 kW and she can sail at a speed of 18.0 knots.

TSHDs are very flexible and can operate independently of other equipment and, since they are self-propelled, are able to transport the dredged material over long distances. Once fully loaded, the vessel sails to the unloading or placement site where the dredged material is offloaded. Depending on the type of project, the dredged material will be offloaded/discharged in one of three ways:

  • material is either deposited at the placement site by opening the hatches in the bottom of the ship;
  • it may be pumped ashore through pipelines, which may be submerged or floating; or
  • the material may be propelled by heavy duty pumps into the air, a process known as rainbowing.

The method of offloading or discharging is directly related to the type of project.

 Trailing suction hopper dredgers

When material is dredged out of a harbour or access channel and the material is clean, the TSHD will sail out to sea to a designated location and deposit the dredged sediment by opening its bottom doors (hatches). Discharging through bottom doors allows quick, direct and total offloading of dredged material at a selected location. This is a reliable and effective method, but only in certain specific circumstances.

 

Rainbowing is the name given to the technique by which a TSHD pumps the sand that has been claimed from the seabed in a high arc placing it at the reclamation site. These locations can vary from a beach which is being shored up to prevent erosion for coastal protection or recreation (or both) to a reclamation site where new land or islands are being built for port expansion, recreation or multiple other purposes. Rainbowing is often the best method for discharging huge quantities of sand in shallow locations close to shore, for land reclamation projects or beach replenishment.

Since rainbowing does not require floating or submerged pipelines, boosters or landlines, it is often the most economical method.

 

Please inform us your requirements to the dredger to be acquired or details of your dredger for sale and we will render you quick efficient support.