Heerema Marine Contractors has made the decision to modify the cranes on its semi-submersible vessel, Thialf, capable of lifting 14,200 metric tons. The vessel is currently moored in the Port of Rotterdam and is undergoing an A-frame modification.

This action is possible as Thialf’s A-frames already have hingable corners that can accommodate the NOV custom-designed semi-permanent adjustment system. Using this system, Heerema can lower Thialf’s cranes and fold the A-frames to create a sufficient air gap when combined with ballasting between the vessel and the Storebaelt Bridge.

The project has been greatly collaborative and was a Heerema Group effort as Heerema Fabrication Group’s Opole Yard completed most of the fabrication work. The team fabricated around 150 metric tons of structures required for the modification.

In 2022, Heerema will be installing 27 wind turbines for Parkwind’s Arcadis Ost I wind farm in the Baltic Sea using its novel Rotor Nacelle Assembly (RNA) installation method. This project will be executed with Thialf, the world’s second-largest semi-submersible crane vessel.

The modification is also being done as between Heerema’s home base in the Port of Rotterdam and the Arcadis Ost project location sits Denmark’s Storebaelt Bridge, also known as the Swan. It connects the Danish islands of Zealand and Funen and has a clearance of 65 meters, not enough for Thialf to clear the top of the vessel’s A-frame is at 105 metres.

The modifications ensure Heerema can unlock the region without compromising the integrity of its 14,200 metric ton cranes.