Modifying Thialfs 14200 metric ton cranes

Heerema Marine Contractors is committed to delivering solutions for our clients worldwide, which means sometimes we must think creatively to get there! With Heerema Fabrication Group fabricating the required structures, we are now modifying Thialf's cranes capable of lifting 14,200 metric tons. 

The gate to the Baltic Sea

In 2022, Heerema will be installing 27 wind turbines for Parkwind's Arcadis Ost I wind farm in the Baltic Sea using our novel Rotor Nacelle Assembly (RNA) installation method. We will execute this project with Thialf, the world's second-largest semi-submersible crane vessel (only Sleipnir is bigger).  


Sounds straightforward, except between our home base in the Port of Rotterdam and the Arcadis Ost project location sits Denmark's Storebaelt Bridge. It connects the Danish islands of Zealand and Funen and has a clearance of 65 meters, while from Thialf's floaters to the top of the vessel's A-frames is a huge 105 meters!

Driving above, building below

The nearly 240-metre-long ASTRA Bridge will be built above the roadway to be resurfaced. The traffic will be diverted above it in two lanes and can drive on it at 60 km/h. Around 100 metres are available under the bridge for the actual construction work. Once the work under the bridge is finished, the mobile bridge is moved a further 100 metres by remote control for the next construction section.


Making the impossible possible

We have a bold vision that we want to make the impossible possible offshore. This commitment translates into all of Heerema's activities and drove the decision to modify Thialf's A-frames to access the Baltic Sea. This action ensures we can unlock the region without compromising the integrity of our 14,200 metric ton cranes.

A-frame modification for Thialf

At the moment, Thialf is moored in the Port of Rotterdam 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.