Ulstein Design & Solutions has been contracted to provide the design for a heavy-lift ship for Japanese contractor Penta-Ocean Construction (POC). The vessel will specialise in offshore wind foundation installation work within the country’s waters, and will comprise a customised version of Ulstein’s HX118 design, which features a length of 215m, a 56m beam and a maximum draught of between 7.5-10m.
The customised design includes a tub-mounted, revolving, 5,000tonne-capacity Huisman main crane, permitting heavy-duty monopile installations. The crane comes with a main hoist and a universal quick connector, and has been designed with a compact tail swing, to optimise available deck space. Huisman will also supply the ship’s monopile-handling system, which features a motion-compensated pile gripper.
Ulstein has also incorporated its U-STERN concept into the vessel’s design. The U-STERN enables longitudinal storage of large components, such as monopiles, meaning these components can be stored along the length of the ship rather than across it, thereby maximising space and preventing overhanging.
When it’s time to install these components, the U-STERN enables them to be upended (lifted vertically) directly along the ship’s centreline. The U-STERN design also allows the ship to face directly into the waves during the installation process, reducing the impact of wave motion on the ship, to make the installation process smoother and safer – as well as to reduce fuel consumption by minimising the ship’s need to compensate for wave-induced movements.
Ulstein comments: “Combining the U-STERN with transverse and longitudinal skidding systems, offshore lifts for monopiles are eliminated as the main crane is only used to support the upending and lowering of the foundation.”
Both Ulstein and POC have been tweaking the ship’s basic design since summer 2024, including a round of extensive model tests. The heavy-lifter will be built by Singapore’s Seatrium Group, with completion scheduled for May 2028 and operations set to commence in the autumn of that year, Ulstein tells The Naval Architect.
