On the conceptual design of large Cutter Suction Dredgers; Considerations for making choices
Type:
Presented during:
WODCON XVII: "Dredging in a Sensitive Environment" - 2004, Hamburg, Germany
Authors:
Jaap L. van Overhagen, Marcel Boor, André Kik and Caspar H.M. Kramers
Abstract: In December 2003 a milestone was reached when the first Jumbo self-propelled cutter suction dredger, "J.F.J. de Nul" was commissioned. This happened 17 years after the delivery of "Leonardo da Vinci", one of the last of the foregoing series of self-propelled CSD being delivered. As she is in all aspects larger and more powerful than all its predecessors, "J.F.J. de Nul" is called a Jumbo Cutter Suction Dredger. In the same year 2003 D.E.M.E. also ordered the design of a Jumbo self-propelled CSD. Although she should be very competitive with De Nul's Jumbo, she is in many aspects a completely different concept.
Of course there are more roads leading to Rome.
In order to make a distinction between the concepts, competing dredging Contractors want to search the outmost competitive design for future new building dredgers. Although she should be versatile, capable to perform well in a range of future, unknown, dredging jobs, she should perform best in one unique well chosen design point.
This all is leading to a wide range of different design specifications.
This paper considers all the choices that are generally made during the specification and conceptual design phases of a large CSD, such as:
· Design aspects dependent on kind of soils and operation area(s)
· Dredging depth, capacities
· Degree of self-sufficiency, self-propelled or stationary?
· If self-propelled: which cutter ladder position (bow or stern oriented)
· Seaworthiness in sailing conditions, seagoing dredging capability?
· Type and stroke of spud carriage (flexibility required)
· Spud handling and hoisting system(s)
· Cutter type, diameter, speed, power
· Pump characteristics
· Diesel-direct or (semi or fully) diesel electric
· Requirements related to noise and vibrations (incl. construction fatigue)
· Degree of automation
There is no doubt that all those aspects have their interrelations, which ask for tuning. Besides, a lot of developments are going on, which have to be balanced carefully in respect of pros and cons. And, of course, all solutions and choices have their impact on the building price as well as on the exploitation costs.
Keywords: Large cutter dredger, design aspects, cutter dredger development, workability, self-propelled, dredging work requirements.