17,500-Tonne Subsea Rock Installation Vessel Launched For Offshore Wind Projects

CSL OWL Subsea Rock Installation (CSL OWL SRI) has launched Rock Star, the first of two new vessels that will install rock on the seabed for offshore wind projects.

The vessel can carry 17,500 metric tonnes of rock and has a DP2 dynamic positioning system. It can work in water depths of up to 100 metres.

Rock Star can use both marine gas oil (MGO) and methanol as fuel.

The vessel will work mainly around bottom-fixed offshore wind farms and their cables. Its work will include scour protection, cable burial, cable protection and other subsea rock installation jobs.

CSL OWL SRI announced the order for the two vessels in November 2024. Construction of Rock Star began in September 2025, when the first steel plate was cut.

The second vessel is expected to be delivered in November 2026.

Rock Star has a tremie pipe with active motion compensation for placing rock on the seabed. Its transport belts can handle rock in the 60-300 kg range.

Individual rocks weighing up to 450 kg can be handled. The vessel can also install larger armour rock used for subsea foundation work. The company said the transport belts can handle rocks weighing up to 1,500 kg. A side chute is also available for larger armour rock.

CSL OWL SRI is based in Rotterdam and specialises in subsea rock installation. It is a partnership between Canada’s The CSL Group and Netherlands-based Offshore Wind Logistics (OWL).

The CSL Group is headquartered in Montreal and works in marine transportation and cargo handling. Its fleet includes self-unloaders, bulk carriers, cement carriers, transhippers and other specialised vessels.

Offshore Wind Logistics was established in 2016 and is based in Rotterdam. The company provides marine logistics services to the offshore wind industry.

Rock Star is the first of the two vessels ordered by CSL OWL SRI. The second vessel is due to be delivered in November 2026.

References: bairdmaritime, offshore energy