Offshore wind farms are currently serviced using Crew Transfer Vessels (CTVs) or helicopters for day operations, and Service Operation Vessels (SOVs) for extended periods.
What if there were a CAPEX-smart design that reduces building costs by over 50% compared to an SOV and supplement the SOVs on most tasks?
The world needs greener energy, but high costs are a barrier. Raw material and equipment prices have more than doubled, halting many projects. Can we reduce the financial risk of developing offshore wind farms and make walk-to-work (W2W) operations more affordable?
SOVs are the most efficient and preferred solution today for servicing offshore wind turbines, outperforming CTVs in safety, availability, and comfort.
However, rising shipbuilding costs and newbuild delivery times threaten their viability. CTVs, on the other hand, face tougher requirements, such as slower speed in protected areas and reduced emissions.
Economies of scale have mitigated costs for SOVs, raw materials, and wind farm development, but relying solely on large wind farms is not sustainable. Designing smaller SOVs alone is insufficient; a new approach to operations and vessel conceptualisation is essential.
Ulstein’s design team aimed to develop a walk-to-work vessel that reduces vessel CAPEX by at least 50% compared to an SOV, reducing OPEX accordingly, while retaining the majority of the key functionalities and operability. The result is the ULSTEIN SX250.
The ULSTEIN SX250 transforms offshore wind farm servicing by bridging the gap between CTVs and SOVs, introducing new service logistics. One or more SX250 vessels can support a full-sized SOV, the latter handling larger tasks while the SX250s manage the smaller jobs.
This setup meets service requirements and maintains the necessary up-time and it allows for more detailed operational planning and distribution of workload. The ULSTEIN SX250 design is best suited as the preferred solution for small and medium-sized windfarms, windfarms located in areas with benign and moderate sea states, or in shallow waters.
ULSTEIN SX250 is also a perfect supplement to cater for the additional maintenance activities typically carried out during the summer campaigns.
The ULSTEIN SX250 is based on the proven TWIN X-STERN solution, which ensures high operability and excellent seakeeping capabilities. It measures 47m in length and 12.5m in width, accommodating between 32 to 40 individuals on board (POB). The vessel has a maximum speed of 10 knots and can operate in conditions of up to 2m significant wave height (Hs).
Safety is a major focus, with people and goods transferred via a basket in an Offshore Passenger Transfer System (OPTS), Bring-to-Work-system, or a conventional gangway.
The vessel can be customised with different arrangements and topside equipment, allowing it to adapt to various operational needs and making it easy to repurpose for new tasks. The vessel concept design relies on existing off-the-shelf hardware and technologies to ensure effective W2W operations.
