The Art of Dredging

At the height of the Singapore dredging boom 1998-2003, Dutch and Belgian dredging companies invested frantically in a new size of hopperdredgers, so-called "jumbo's"; with hopper capacities ranging between 17.000 and 25.000 m3.

The trend was started in 1991 with the "Pearl River", 17.000 m3, followed 7 years by the "Gerardus Mercator" (18.000 m3), "Amsterdam", "Rotterdam", "WD Fairway", "Queen of the Netherlands", "Queen of Penta Ocean", "Volvox Terranova"  and others.

In 2000 "Vasco Da Gama" (33.000 m3) was commisioned. This ship was the early bird of yet another breed of trailers, "mega" sized.

"Vasco Da Gama" has proven its worth in landfill projects, but has also pioneered in less common jobs, like diamond mining in Southern Africa and deepdredge offshore, with the "Glory Holes", off Newfoundland.

Now, 8 years on, "Vasco Da Gama" finally gets some competition in his class.

WD FAIRWAY was commisioned 2000, lengthened 2003, and went C.T.L.  (constructive total loss) in a collision in Tianjin, China in 2007.

It was indeed the largest trailer in the world (measured in hopper volume, not in deadweight).

QUEEN OF THE NETHERLANDS is sheduled to be lengthened likewise in 2009; the extra section is prepared in a Thai shipyard. 

This conversion is the complete "megatrailer" program of Boskalis.

Leaflet before lengthening

"Queen of the Netherlands" before and after ...

DEME expressed intentions early 2008 to invest in a megatrailer, with a capacity of +30.000 m3. Being a megatrailer, this vessel will have a limited draught of max 12 m, allowing for versatile employment.

These plans finally found follow up in an order to IHC, on January, 2nd, 2009.

Delivery of the vessel would be 2011.

Read:  http://www.sandandgravel.com/news/article.asp?v1=11548

Cristobal and Leiv are two sisterships, and the largest trailers projected.

Their outfit comprises two suction pipes, a 46.000 m3 hopper, and 41 MW installed engine power.

They are simply the biggest and most powerfull dredgers entering the market, having a 50% larger hopper than competitors, and a loaded ship's speed -at 18 knots- a notch higher than other mega's. 

Launch of Cristobal; read:  http://img77.imageshack.us/img77/8/hopperenbaggercristbalcfu8.jpg

An order with the "Naval" shipyard in Spain; this "BN8035" (not yet named) is probably the last (?) in a long row of newbuildings within the Jan De Nul Group, including 3 megatrailers.

There is an option for a sistership, still open at this moment.

VOX DUBAI is the new megatrailer of Van Oord ACZ.

Capacity is 31.000 m3, with 31 MW installed, and the -VOA trademark- single suction pipe with a 6 MW underwaterpump. 

Together with the lengthening of HAM 318 in 2008, this is the entry into the mega-class by Van Oord.

 Newbuilding underway: http://img70.imageshack.us/img70/4163/hopperenbaggervoxdubaizm0.jpg

Leaflet VOX DUBAI

Update (March, 21nd 2009): Van Oord ACZ got second thoughts on this ship's name and changed it to "VOX MAXIMA", to be launched and christened March, 24th 2009. 

 HAM 318 has been lengthened in 2008, turning a good looking ship into a stretched out version.

HAM 318 before and after some major surgery.

Lengthening has some obvious disadvantages; degrading manoeuvrability and stability. The final result is mostly not optimalised for deadweight, speed, draught, etc...

Nevertheless, DEME, Van Oord and Boskalis have lengthened trailerdredgers as a quick fix to upscale hopper capacity for the high demand dredging market of the past 8 years, avoiding capital costs for newbuilding.

 Leaflet Ham 318

Following table compares core figures of the new mega dredgers. 

(*) Commisioned in the actual configuration

Jumbo dredgers (17.000-25.000 m3) were built with a clear market opportunity in sight (Singapore).

For megadredgers, the opportunities are less clear. Due to the ongoing global financial crisis, projects in the Persian Gulf may be delayed, curtailed or cancelled.

These ships tend to create their own markets, by offering possibilities which were technically unfeasible before, or by supplying sand at lower rates than previous.

Long distance sand transport becomes another possibility for deployment.

Design of these mega trailers does not exclude them from smaller projects, normally done by jumbo's or smaller units. The trend is definitely towards wider ships, with limited draughts.

There is also a clear interest in deepdredge installations. Jan De Nul and Boskalis were ahead of the pack around 2004, but Van Oord and DEME are clearly entering this niche.

Dredging equipment has not been scaled up, in ratio with the hopper capacity. Dredge pipe diameters do not go beyond 1300 mm, underwaterpumps are not powered beyond 6 MW, and discharge pump power is comparable to what can be found on jumbo dredgers.

01 /  2009

Marc Van de Velde