As offshore wind turbines and their foundations become ever larger, contractors across the industry face growing challenges with their vessels’ limited capacities. To stay efficient and competitive with their current fleets, they require innovative installation concepts and daring engineering solutions.
One such example is the recent ‘upgrade’ of GeoSea’s heavy lift jack-up vessel INNOVATION. To prepare HLJV INNOVATION for handling the large foundations of the Galloper offshore wind farm, in a configuration of four foundations per journey, TWD designed a range of advanced structures to:
In the initial stage of the project, TWD analyzed the foundations of several forthcoming projects to be installed with the INNOVATION. To choose an optimal deck layout suitable for all these projects, this team looked into the number of foundations that could be taken per journey, the installation sequence of each journey and the time it would take, as well as the size and cost of the seafastening and handling tools.
The chosen layout foresaw four foundations per journey. For the large monopiles, positioned transversally between the vessel’s jacking legs, this meant that three could be positioned in one level while the fourth one had to be stacked in the most forward position. Furthermore, the two stacked forward monopiles were out of the crane’s reach.
To overcome this challenge TWD proposed to GeoSea a system utilizing skidding, vertical rotation and horizontal rotation of cradles in order to bring all monopiles within the crane’s reach, in what is now the first ever skidding monopile seafastening on an installation vessel.
Built for heavy loads and easy operation, this system combines robustness with smart mechanical solutions and interfaces that are easy to maintain.
To make the skidding possible, and to efficiently spread the loads of these heavy monopiles, we designed two bull rails for the INNOVATION, one above each side shell. Although the bull rails are not vessel reinforcements in the standard sense, they considerably increase the vessel’s capacity for the upcoming projects, and can be used to seafasten monopiles, but also other large and heavy items.
Besides the monopile handling structures, TWD also designed seafastening frames for transition pieces and the hammer, as well as a tower for stacking four anode cages.
The transition piece frames are built as modular structures, consisting of a core, radial beams and clamps which slide along these beams.
The beams are bolted to the core, making it possible to use the frames in any location on deck, and for various purposes. The clamps are hydraulically actuated and provided with rollers for easy movement along the beams by hand. The frames can therefore support transition pieces of different diameters, as well as other items, and are easy and safe to use.
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On behalf of GeoSea, TWD’s fabrication services department assisted during the fabrication phase by performing weekly site visits to assure working products which meet high-quality standards. We helped meet the fabrication’s challenging deadlines by detecting and preventing errors during fabrication and proposing practical solutions on the spot.
With these new structures on HLJV INNOVATION, GeoSea and TWD made a step towards the future, where deck layouts are flexible, seafastening structures more active and possibilities for vessels expanded by smart design solutions.
TWD would like to congratulate GeoSea on the successful ‘upgrade’ of HLJV INNOVATION and the installation of the first Galloper foundations. We are committed to supporting GeoSea in ensuring that these machine-like structures can easily be used in as many future projects as possible.