Joint venture propels new ‘Rock Star’ onto centre stage

A Canadian/Dutch joint venture has launched the first of two purpose-built rock installation vessels to help meet growing demand for specialist subsea rock installation work for offshore wind.

Rock Star is the first of two vessels being developed by the Canadian CSL Group (CSL) and Dutch Offshore Wind Logistics (OWL), who announced their build programme in 2024.

Rock Star has a rock-carrying capacity of 17,500 tonnes and is designed to operate in water depths of up to 100 metres. She can install rock through a tremie pipe fitted with active motion compensation, which allows rock to be accurately placed on the seabed for applications including scour protection around offshore-wind foundations and protection or burial of subsea cables.

The vessel can handle a broad range of rock sizes, including material graded from 60-300kg kilograms and individual rocks of up to 450kg, with provision for larger armour rock. Its propulsion and power systems are designed to operate on marine gas oil as well as methanol, supporting the owners’ ambition to provide more flexible and lower-emission options for offshore construction.

“Our vessels are designed to bring greater flexibility and cost efficiency to subsea rock installation in and around bottom-fixed wind farms and associated cables,” said Maarten van der Giessen, CEO of CSL OWL SRI. “By optimising offshore renewable energy logistics, we aim to help make green energy more affordable.”

With the launch of Rock Star, the two companies are moving from the development and construction phase towards operational deployment.

Build of the second unnamed vessel has begun, with delivery scheduled for February next year.

Growing specialist need

The two vessels are just two of a new generation of vessels specifically designed for offshore wind projects, with several installation vessels already operating.

Van Oord operates Bravenes, Nordnes and Stornes, using flexible fallpipe technology to place rock accurately around pipelines, cables and offshore-wind foundations. Bravenes can carry about 14,000 tonnes.

Boskalis operates Seapiper, Seahorse and Rockpiper, with capacities ranging from 15,000 to 23,500 tonnes and installation depths reaching 1,500 metres.

In 2026, Boskalis also introduced Windpiper, a converted vessel carrying 45,500 tonnes.

Rock Star, at 17,500 tonnes, entering an established but evolving specialist market.