A trailing suction hopper dredger [1] is a ship that has a full sailing capacity used to maintain navigable waterways, deepening the maritime canals that are threatened to become silted, to construct new land elsewhere or to replace sand eroded by storms or wave action on the beaches. This is made possible by large powerful pumps and engines able to suck sand, clay, silt and gravel. [2]
A trailing suction hopper dredger is self-loading/unloading and sometimes equipped with a pressurized discharging system.
From the side of the ship one or two suction pipes descend to the bottom of the seabed. On the end of the pipe a so-called trailing drag head is connected. This head is comparable to a large vacuum cleaner and is trailed along the seabed. In the head there are nozzles connected to a high pressure water installation that are capable of loosening the material on the seabed. Due to lower pressure in the pipe, the material will be sucked inward and discharged in the hopper.
The vessel should always have a positive speed over the ground. It is possible to regulate the density of the sucked substance. If the head is lowered, more material will be sucked but this risks damaging the installation because the material can get stuck inside the pipes. Once the mixture is loaded inside the hopper, the substance will sink and the water is discharged overboard, saving on storage space. A trailing suction hopper dredger can only suck relatively loose substance because the steel teeth are not so big. Harder substances such as rock or ironbased rock must be destroyed by a cutter.
There are several ways to discharge a TSHD. The most common way is dumping the material.
A trailing suction hopper dredger is equipped with the following equipment:
A dredging vessel [3] and particularly a TSHD is mostly used for
Dredging is the excavation of material from a water environment. Possible reasons for dredging include improving existing water features; reshaping land and water features to alter drainage, navigability, and commercial use; constructing dams, dikes, and other controls for streams and shorelines; and recovering valuable mineral deposits or marine life having commercial value. In all but a few situations the excavation is undertaken by a specialist floating plant, known as a dredger.
A hose is a flexible hollow tube designed to carry fluids from one location to another. Hoses are also sometimes called pipes, or more generally tubing. The shape of a hose is usually cylindrical.
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A dredge drag head is used by a trailing suction hopper dredger to collect sand from the sea floor.
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USAVYaquina is a hopper dredge of the United States Army Corps of Engineers. Her primary mission is to maintain the entrance bars, rivers, and harbors along the coasts of California, Oregon, and Washington. She is assigned to the Portland District of the Army Corps of Engineers. Her homeport is Portland, Oregon. She was launched in 1980 and remains in service.
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Miss Katie is a hopper dredge owned by EJE Dredging Service, LLC. Her primary mission is to maintain the channels through Oregon Inlet and nearby Hatteras Inlet in the Outer Banks of North Carolina. Keeping these navigable waterways open is important to local fishing, recreational boating, and other maritime interests.
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