The Art of Dredging

Dredging and shipping

Fallpipe vessel "Simon Stevin"

While "Leiv Eiriksson" is being outfitted at "La Naval" shipyard in Sestao, Spain, another specialised vessel "Simon Stevin" is nearing completion on the same yard.


"Simon Stevin" fully opens up the niche of deep rock placement for the JDN group.

Similar vessels are already in operation for Boskalis, DEME and Van Oord.  

                                      (see also )

 However, "Simon" is the first purpose built fallpipe vessel, has a larger carrying capacity than any other  fallpipe-vessel on the market today, and a higher power output.



"Simon Stevin" is capable of transporting quarry rock in two hoppers on deck, for a total of 33.500 tons.

These stones (with a mx. diameter of 400 mm) are discharged by means of two hydraulic excavator cranes, feeding conveyor belts, at a max. rate of 2000 ton/hour. Stones can be discharged through a fallpipe; steered by a large 600 kW R.O.V., to a max. depth of 2000 meter below sealevel.

Another 100 kW ROV can be deployed for e.g. QA-work.

Classification: I / Hull / Mach / AUT-UMS    DYNAPOS AM/AT R    Cleanship 7+  by Bureau Veritas

Main particulars:

      Length overall 191.5 m

      Breadth moulded 40 m

      Depth to main deck 13.2 m

      Max. draught 9.25 m with 33.500 tons of rock loaded

Speed, loaded 15 knots


      AC diesel driven main generator sets 5 x 4500 kW

      AC diesel driven aux. gen. set             1 x 1500 KW

      Emergency gen. set                             1 x 350 kW

      Aft azipods:                                           4 x 3350 kW

      Forward azipods - retractable               2 x 2000 kW

      Bowthrusters                                         2 x 2000 kW

 The ship is further equipped with a heli-deck, able to take the largest helicopters used in the offshore industry today.

An anti-roll system with two 1180 m3 ballastwatertanks is also installed.

Accomodation is provided for 70 persons.

The ship is designed to be able to operate in a significant waveheight of 3.5 to 4.5 metres, depending on period  and direction.


General arrangement



Fall pipe vessel operating principle


Stones, carried onboard are fed into a conveyor belt, feeding in its turn a vertical suspended fallpipe.

The fallpipe is dynamically positioned over the area to be dumped with stones (subsa pipes, cables, constructions, mainly for the oil- and gas industry.)


Bottom of fallpipe, with remotely operated vehicle (ROV), capable of steering the pipe, delivering quarry into an exact location at the seabed.



Sidedump vessel "Willem De Vlamingh"

The JDN-group has an additional -smaller- side-dump vessel "Willem De Vlamingh" on order.

Both vessels can be seen as a fleet, amongst them able to handle most stonedump jobs.


 october 2009

Marc Van de Velde



                           All illustrations courtesy of Public Relations Dept. Jan De Nul N.V.

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