Deep dredging engineering to the extreme
Type:
Presented during:
CEDA Dredging Days 2005 - Dredging: The Extremes, Rotterdam
Authors:
E. Put
Abstract: In recent times the development of custom-build / deep-dredging installations has taken a major step forward, showing particularly in the increased number of deep-sea dredging installations available nowadays. The use of such equipment is successfully demonstrated in special offshore dredging projects such as the excavation of glory holes and pre-trenching for pipelines. Besides these special projects there is also an increasing attention for deep-dredging capabilities for land reclamation works. The ever increasing demand for sand, forces the dredging industry to focus on the exploration of the deep sea international waters, instead of the shallow coastal waters. These kind of operations place high demands on the dredging equipment. High trailing forces, submersible dredgepump units with high powers and the demand for accurate positioning of the draghead require high-quality engineering. To build such installations, known engineering boundaries have to be moved and special high-tech solutions are needed.
This paper describes various aspects of the design process and the technique of custom build deep-sea dredging installations. Before the different parts of a dredging installation can be designed, first the system constraints have to be determined. Design criteria such as load conditions, maintainability, wear management and maximum dredging depth have to be laid down. The maximum dredging depth for a particular ship is traditionally determined by its length. On the drawing board, alternatives to cope with this fixed relation have been developed. After the system constraints have been determined, the engineering process goes to the next level: product design. Specialized engineering tools to determine dynamics and workability help the engineer to design specific deepdredging components such as pressure compensating systems and high tech bearing connections.
Keywords: trailing suction hopper design, deep sea dredging, increase of scale, maintainability, workability, suction pipe dynamics, product design.