CSL OWL SRI has launched the first of two purpose-built subsea rock installation vessels being developed for offshore wind projects.
The vessel is equipped with DP2 dynamic positioning and can operate on marine gas oil or methanol. It has a rock carrying capacity of 17,500 tonnes and is designed for subsea rock installation in water depths of up to 100 m.
Construction of the first vessel began with a steel-cutting ceremony on 12 September 2025. The vessel is one of two newbuilds ordered by CSL OWL SRI, a partnership between The CSL Group and Offshore Wind Logistics.
The vessel measures 166.8 m in length and 40 m in breadth, with deadweight of approximately 21,000 tonnes. Its maximum sailing speed is 12 knots.
The rock installation system can handle material up to the 60/300 kg grading, including individual rocks weighing up to 450 kg. Transport belts are designed for rocks weighing up to 1,500 kg, while a side chute can be used for larger armour gradings.
For seabed installation, the vessel uses a tremie pipe with active motion compensation. CSL OWL SRI states that the vessel can install up to 2,000 tonnes of rock per hour, with a maximum installation depth of 100 m.
CSL OWL SRI announced the two-vessel construction programme on 21 November 2024. Both vessels were ordered for subsea rock installation work in the offshore renewable energy sector.
