Sea1 Offshore floats out first of four energy support vessels in China

Norwegian offshore vessel owner Sea1 Offshore has floated out Sea1 Diamond at Cosco Nantong in China, marking the first launch in a four-vessel offshore energy support newbuilding programme, according to Sea1 Offshore. The vessel entered the water on 21 July and will now undergo outfitting and commissioning alongside at the yard. Delivery is scheduled for 30 January 2027. Sea1 Diamond remains uncommitted, leaving the owner open to project work and term charter opportunities. Sea1 Diamond is the first of four vessels based on Skipsteknisk’s ST-245 design. Each ship will be 120 metres long and have a 1,400-square-metre cargo deck. The vessels will provide accommodation for up to 120 people and will be fitted with a 250-tonne crane, an ROV hangar and a moonpool for subsea operations. Sea1 ordered the first two vessels from Cosco Shipping (Qidong) Offshore in November 2024, with deliveries scheduled for the first and second quarters of 2027. Two additional units were contracted in March 2025 for delivery in the third and fourth quarters of 2027. The ships will feature battery-hybrid DC electrical systems, Kongsberg K-Pos dynamic positioning, integrated navigation and control systems, and Kongsberg propulsion and thruster packages. They will be methanol-ready, while their generators will be capable of running on 100% biofuel. Battery systems and high-capacity shore connections are intended to support zero-emission operations while the vessels are alongside. Sea1 Offshore is a Norwegian offshore services provider with activities spanning oil and gas, subsea, renewable energy and research markets. It manages 23 vessels and employs about 800 people. Cosco Shipping (Qidong) Offshore is a Chinese offshore and specialised vessel construction company. Cosco Nantong is the Chinese shipbuilding location handling the vessel’s launch and subsequent outfitting.