Ulstein launches new W2W SOV design

Norway’s Ulstein has unveiled a new wind farm support vessel design that combines the functionality of a crew transfer vessel (CTV) with that of a larger service operation vessel (SOV). The aim of the shipbuilder’s design team was to develop a walk-to-work (W2W) vessel that costs up to 50% less than a SOV while retaining many of the same capabilities.

The Ulstein SX250 bridges the gap between CTVs and SOVs and is intended for small and medium-sized wind farms located in areas with benign and moderate sea states or in shallow waters. The new design is intended to handle additional maintenance activities typically carried out during summer months, the company said.

One or more SX250s can support larger SOVs, allowing the more capital-intensive vessels to focus on larger more complex tasks. This approach maximises uptime and makes the most of the SOV’s capabilities while smaller tasks can be handled by SX250s.

The new design is based on Ulstein’s Twin X-Stern arrangement which, the company claims, ensures high operability and good seakeeping. The 47m-long SX250 has a beam of 12.5m and can accommodate up to 40 persons on board.

It will have a maximum speed of ten knots and will be capable of operating effectively in significant wave heights of up to two metres. Personnel and cargo will be transferred via a basket in an Offshore Passenger Transfer System, a Bring-to-Work arrangement, or a conventional gangway.

The vessel can be customised with different arrangements and topside equipment can be easily repurposed for new tasks, the designers said. Options include a daughter craft, a deck storage container, a work or observation ROV, a fast rescue boat or a workboat.

The concept design relies on existing off-the-shelf hardware and technologies to ensure effective W2W operability while reducing first cost and subsequent operating expenses.