Salvage trailing suction hopper dredger

THOR R

In the early morning of 26 September 2004, the Danish trailing suction hopper dredger ’Thor R.’, owned by Danish dredging contractor Rohde Nielsen, collided with the construction vessel ’Ocean Ace’, while executing maintenance dredging in the navigation channel to the Port of Esbjerg. The next day the ’Thor R’ sank and subsequently capsized under water, partially impeding traffic into the port.

The contract for the salvage was awarded to the Dutch towage and salvage company Multrahip of Terneuzen, which immediately mobilized the 1500t floating sheerlegs ’Matador 3’. The sheerlegs owned by Bonn & Mees of Rotterdam and designed by Vuyk was collected in Rotterdam by the tug ’Multratug 7’.

 

 

Principal characteristics of the casualty

 

Owner

Rohde Nielsen

Flag state

Denmark

Built by

IHC Sliedrecht B.V., The Netherlands

Built

1984

Gross tonnage

1 995 GT

Deadweight

3420 ton

Hopper capacity

2 507m3

Length overall

79.00 m

Breadth moulded

14.00 m

Depth moulded

6.30 m

Draft loaded

4.90 m

Totally installed power

3 622 kW

 

Vuyk assisted on-site with engineering for preparation of parbuckling and lifting of the vessel.

The salvage of the vessel was complicated by strong tides, which allowed only four hours of diving time per day and by the soft sandy bottom, into which the wreck continually sank. The vessel was lifted on 24 October 2004 and subsequently transported into the port of Esbjerg by the sheerlegs and tugs. To place the dredger in Esbjerg’s local small dry dock (120 x 19.5 m) the sheerlegs had to re-rig the slings.

The ’Thor R.’ re-entered service after completing repairs with new Wärtsilä main engines.

 

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