CSL OWL SRI orders two new-build Subsea Rock Installation vessels to service offshore wind sector

CSL OWL Subsea Rock Installation (“CSL OWL SRI”), a newly formed partnership between The CSL Group (“CSL”) and Offshore Wind Logistics (“OWL”), is pleased to announce the construction of two subsea rock installation vessels tailored for the offshore renewable energy sector.

Each vessel will have a cargo capacity of 17,500 metric tonnes and will be equipped with dynamic positioning (DP2). They will be able to operate on marine gas oil (MGO) and/or methanol, providing a pathway to zero emission operations. Purpose-built for optimal flexibility, these vessels will deliver efficient and cost-effective subsea rock installation services in water depths up to 100 metres.

Vessel Highlights

• Capable of installing rock material up to the 60/300 kg grading, with the option of handling rocks weighing up to 450 kg.
• A Tremie Pipe with active motion compensation ensures precise placement at water depths between 30 and 100 metres.
• The transport belts are designed to handle rocks weighing up to 1,500 kg, with a side chute available for larger armour gradings.
• Excavators can be used to handle larger amour rock.

CSL OWL SRI is an independent marine contractor specializing in subsea rock installation services, dedicated to delivering safe, sustainable and cost-effective solutions for the installation and maintenance of subsea rock. Based in Rotterdam, the company combines OWL’s extensive experience in the offshore marine construction sector with CSL’s expertise as a leading provider of complex marine solutions.

“We are committed to providing tailormade capacity to the fast-growing offshore renewable sector. This will support the sectors’ ambitions of ramping up installed capacity, reducing the levelized cost of energy (LCOE) and minimizing emissions,” said Maarten van der Giessen, CEO of CSL OWL SRI.

“Our subsea rock installation solutions are specifically designed to enhance flexibility and cost efficiency for operations in and around bottom-fixed wind farms and associated cables. We believe in making green energy affordable and are committed to doing our part by optimizing offshore renewable energy logistics.”

The first subsea rock installation vessel is scheduled for delivery from the shipyard in August 2026, followed by the second vessel in November 2026.

The CSL Group is a world class provider of complex marine solutions and the largest owner and operator of self-unloading ships in the world. Headquartered in Montreal with operations throughout the Americas, Australia, Europe and Africa, CSL provides a broad range of shipping and handling services, and delivers millions of tonnes of cargo annually for customers in the construction, steel, energy and agri-food sectors.

OWL is renowned for its top-tier logistics solutions in the offshore wind sector, further enhanced by its industry-leading capabilities. The company was founded to enhance the efficiency of the offshore wind logistics supply chain, both operationally and financially.