Heerema Marine Contractors is committed to delivering solutions for clients worldwide. With Heerema Fabrication Group fabricating the required structures, the company is 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 the novel Rotor Nacelle Assembly (RNA) installation method. The company will execute this project with Thialf, the world’s second-largest semi-submersible crane vessel (only Sleipnir is bigger).  

Sounds straightforward, except between 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.

Making the impossible possible

The Heerema has a bold vision that wants 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 can unlock the region without compromising the integrity of 14,200 metric ton cranes.

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. 

The Baltic Sea is a unique region for offshore operations with a heterogeneous seabed profile that includes sand, mud, hard clay, and bedrock. This variety of potential seabed materials can make installations challenging, but Thialf’s floating vessel capabilities mean that no matter what’s below we can execute projects. 

Now that Thialf will be working in the region the lifting capacity has increased by around 10,000 metric tons, so dare to think bigger. Heerema can deliver a range of solutions for offshore wind installation, including wind turbine generators, gravity-based structures, monopiles, pre-piled jackets, and offshore substations.

Source: Heerema