VESSEL CONVERSION | Windpiper – Former deep-sea mining ship rebuilt for rock installation work
Dutch marine contractor Boskalis has begun operating Windpiper, a subsea rock installation vessel that had been converted from an uncompleted deep-sea mining ship. The company said she is the largest vessel of her type in the world.
The vessel was christened in Rotterdam on July 3, 2026. The approximately 18 months of conversion work followed the acquisition Boskalis announced in January 2025.
China’s Fujian Mawei Shipbuilding built the vessel's hull. It was launched in 2018 as Nautilus New Era for the Solwara 1 copper-and-gold project off Papua New Guinea. Vuyk Engineering Rotterdam produced the basic design for the conversion.
Indonesia was the main site of the conversion work. Nearly all mining equipment on deck was removed there, while an offshore crane was retained.
Holds reconfigured for transport of rock and other bulk loads
The Bureau Veritas-classed, Cypriot-flagged vessel has an LOA of 227 metres (748 feet), a beam of 40 metres (130 feet), a draught of 13.2 metres (43.3 feet), a depth of 18.2 metres (59.7 feet), and a deadweight of 70,165. Her class notations include DYNAPOS AM/AT R, AUT-UMS, and HEL.
Four former cargo spaces were combined into two holds with a total capacity of 45,500 tonnes by removing internal bulkheads. Vuyk Engineering said finite element analyses identified which reinforcements the existing hull required to handle bulk cargo loads.
Komatsu excavators feed rock through hoppers enclosed in the hull to two TME conveyors, each rated at 1,250 tonnes per hour. The conveyors handle individual rocks of up to 300 kg (660 lb).
The rock is delivered through a tower-mounted inclined fallpipe with a diameter of 1.8 metres (5.9 feet). The pipe is 25 metres (82 feet) long as standard and extends to 52 metres (170 feet). A moonpool system is due to be upgraded for depths of up to 800 metres (2,600 feet).
Modern systems for more accurate placement
Boskalis said its patented fallpipe jet system will also be fitted on the vessel. Three jet pumps at the pipe outlet move rock up to 1.5 metres (4.9 feet) closer to a monopile than gravity discharge would allow.
"Failure to do so risks exposing the monopile to scour and weakening of the foundation," said Arjen Gossije, Manager of Operations in Boskalis' Seabed Intervention business unit.
Low-emission propulsion capable of advanced positioning
Power comes from six Bergen B33:45L9A medium-speed generator sets, each rated at 5,400 kW and compliant with IMO Tier III NOx emissions standards. Two bow thrusters and five azimuthing thrusters meanwhile provide DP2 capability. The vessel has a speed of 12 knots and a fuel capacity of 10,446 cubic metres (2.298 million gallons). She also offers 100 single-occupancy cabins.
Windpiper’s rock capacity is nearly double the 24,000 tonnes of the purpose-built Rockpiper. Boskalis said this suits projects that are located far from loading facilities, such as on the North American East Coast, by reducing round trips.
On her maiden campaign, Windpiper loaded nearly 45,000 tonnes of rock in Norway. In September, she began protecting export cables at the Bałtyk II and Bałtyk III offshore wind farms in the Baltic Sea off Poland.
