Penta-Ocean signs contract for first-of-its-kind monopile installation vessel

Ulstein HX118 U-Stern installation vessel designed for offshore wind monopile installation.

Ulstein Design & Solutions has confirmed that Penta Ocean Construction Company Limited has signed a contract for the construction of an Ulstein HX118 U-Stern installation vessel

The heavy-lift vessel, to be built at Seatrium in Singapore, will be used to install large monopile foundations for the offshore wind sector. Ulstein first unveiled the U-STERN hull concept in April 2024.

Ulstein Design & Solutions said the vessel for Penta-Ocean will have a 5,000-tonne Huisman main crane and the ULSTEIN U-STERN hullform, which, it said, “enables installation of large monopile foundations.”

Following feasibility and concept studies in 2023, Ulstein proposed the HX118 with the U-STERN to Penta-Ocean, a design that builds on Ulstein’s track record with crane vessels.

“The design offers a well-balanced combination of a flush work deck, lifting capacity, accommodation and DP capability and will be the largest X-BOW vessel to date,” said the company.

The U-STERN is designed for longitudinal storage and upending of monopiles along the ship’s centreline. This enables the installation of longer monopiles without overhanging the ship’s sides and allows the vessel to face into the waves during installation, minimising ship motions and fuel consumption.

Since summer 2024, Ulstein has been collaborating with Penta-Ocean Construction on the basic design of the vessel, including an extensive model test programme. The design is being developed at Ulstein’s Rotterdam office, with significant support from Ulstein Poland during the basic design phase.

Ulstein Design & Solutions lead designer Ko Stroo said, “As the project moves forward, with construction at Seatrium shipyard, Singapore, we remain committed to supporting the parties throughout the construction phase.” 

Source: Rivera, Published: 28.01.2025