New Aft Legs for DEME’s Jack-up Innovation

Heavy-lift jack-up vessel Innovation, one of DEME’s DP2 installation vessels, has left Damen Verolme Rotterdam shipyard following a major refit. The Innovation underwent renewal of its aft leg sections and an overhaul of its jacking motors.

The Innovation measures 147.5 metres in length and operates on an electrical rack and pinion jacking system. The vessel supports offshore construction via the installation of foundations and has worked at wind farms across Europe.

Modification of Aft Legs

The most significant aspect of this refit was the modification and re-installation of Innovation’s aft legs, each measuring 89 metres in length. Reinforcement work was carried out on the legs to enable them to cope with an increased rate of jacking operations, driven by the increased efficiency of the installation works.

Once the vessel was drydocked, the two aft legs were removed and two new middle sections were inserted on the quayside, the refurbished leg finally being assembled from three parts. In total, 47 metres of section per leg were replaced.

48 Gearboxes Overhauled

To overhaul the jacking motors, all 48 gearboxes of the aft legs were removed, overhauled in the shipyard’s workshop, and reinstalled on the vessel. Additional general maintenance work completed the refit, which included a box-cooler renewal, maintenance to the spudcan shoes, replacement of one aft thruster, small steel repairs and the installation of a new pile gripper.

Mammoth Drydock

Damen Verolme Rotterdam was chosen as the location of this maintenance work thanks to the shipyard’s capacity and access to its facilities. Given the height of the Innovation’s leg sections, Verolme shipyard’s mammoth drydock offered the possibility to lift the vessel’s legs with a crane installed inside the drydock while the vessel was sitting on the dock blocks, allowing maintenance to be carried out safely and efficiently.

Following its extensive drydock period, which took several months, the Innovation has set sail to the SeaMade project in the Belgian North Sea to install 58 foundations.

Author: Mariska Buitendijk

Mariska Buitendijk is one of SWZ|Maritime's journalists as well as the magazine's copy editor.