Heerema Modifying SSCV Thialf to Enable Work in the Baltic

Heerema Marine Contractors are modifying the two cranes on the world’s second-largest semi-submersible crane vessel, SSCV Thialf, to be capable of lifting 14,200t, with Heerema Fabrication Group fabricating the required new structures.

In 2022, Heerema will be using the SSCV Thialf to install 27 wind turbines for Parkwind’s Arcadis Ost I wind farm in the Baltic Sea using Heerema’s novel Rotor Nacelle Assembly (RNA) installation method.

An artist’s impression of what would happen if they tried getting under the bridge without the modification

However, to get the SSCV Thialf to the Arcadis Ost wind farm site it will have to sail under Denmark’s Storebaelt Bridge connecting the Danish islands of Zealand and Funen, and the bridge has a maximum clearance of 65m. The current height from sea level to the top of the Thialf cranes’ A-Frames is 105m.

In line with their bold vision to make the impossible possible offshore Heerema is currently modifying the A-Frames in the Port of Rotterdam which will allow the SSCV Thialf to pass under the bridge and into the Baltic Sea without compromising the integrity of their 14,200 metric ton cranes. This modification is possible because Thialf’s A-frames already have hingable corners that can accommodate the NOV custom-designed semi-permanent adjustment system.

Using this system, when combined with ballasting the vessel, Heerema can lower Thialf’s cranes and fold the A-frames and create a sufficient air gap to pass under 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 is below Heerema and the SSCV Thialf can execute projects. The region has lots of offshore wind energy projects planned and Heerema will be ready for them with the SSCV Thialf.

The previous maximum lift possibility for the region was around 4,000t and soon it will be 14,000t, making many more solutions to earlier challenges.

SSCV Thialf before modification

Source Heerema