Rotterdam-based CSL OWL Subsea Rock Installation has launched Rock Star, the first of two methanol-ready subsea rock installation vessels being built for the offshore wind sector, Offshore Energy reported. The business is a partnership between The CSL Group and Offshore Wind Logistics, with the newbuild programme covering vessels designed to operate on both marine gas oil and methanol.
The partnership announced the two-vessel construction order in November 2024. Work on Rock Star began in September 2025 with the first steel cutting, and the vessel is designed for operations in water depths of up to 100 metres. The launch marks the latest reported step in the programme, while delivery of the second vessel is expected in November 2026, according to Offshore Energy.
Both vessels have a DP2 dynamic positioning specification and a cargo capacity of 17,500 metric tonnes each. Their rock installation equipment can handle material up to the 60/300 kg grading, with an option to accommodate individual rocks weighing as much as 450 kg. These specifications form part of the vessels’ purpose-built arrangement for placing rock on offshore projects, rather than simply transporting the material to a work site.
The handling system also includes transport belts designed for rocks weighing up to 1,500 kg. A side chute is available for larger armour gradings, providing a separate handling provision alongside the stated rock installation capability. Offshore Energy reported these equipment specifications for the two-vessel programme, which combines substantial rock cargo capacity with the ability to use methanol as a marine fuel.
In a social media statement cited by the outlet, CSL OWL SRI described the first launch as progress towards bringing additional capability to offshore renewable energy projects. The partnership highlighted dynamic positioning, accurate rock placement and methanol capability as central features of the design, saying the vessels had been developed for demanding offshore work.