Scaldis, the Belgian subsidiary of Jan De Nul Group, Herbosch-Kiere adn DEME, in cooperation with BOA Offshore, successfully completed the salvage of the Norwegian frigate KNM Helge Ingstad last Sunday. Scaldis developed a revolutionary lift method especially for this project, by combining its two heavy lift vessels Rambiz and Gulliver, Jan De Nul said in its release.
On 8 November of last year, the Norwegian frigate collided with the tanker Sola TS in the vicinity of Bergen and sank on the inclined slope of a fjord. The Norwegian marine called on the expertise of Scaldis and BOA Offshore to salvage the shipwreck.
Especially for this project, Scaldis developed a revolutionary lift method by combining its two heavy lift vessels: 'Rambiz', equipped with two cranes and a total lifting capacity of 3,300 tonnes, and the new heavy lift vessel 'Gulliver', also with two cranes and a total lifting capacity of 4,000 tonnes. With this unique “Double Duo Lift” method, Scaldis has a combined total lifting capacity of 7,300 tonnes at its disposal.
This made it possible to lift the 133-metre long and 5,500-tonne heavy frigate in one piece. In fact, the synchronous functioning of the four cranes allows to lift the wreck in one continuous operation and to move it into a horizontal position.
Missiles and fuel were removed from the frigate during the winter months while divers installed 16 hoisting chains under the wreck to be able to lift the ship out of the water.
To lift the frigate safely and completely out of the water, it was transported while hanging from the crane hooks of the heavy lift vessels to the nearest port, where it was placed on a submersible pontoon. This partially submerged pontoon was subsequently de-ballasted, allowing it to re-emerge above the waterline while supporting the 'Helge Ingstad' at its centre. During this operation, the hoisting cranes stabilised the ship until all sea-fastenings had been secured for subsequent transport.