Bound for duty on the Dogger Bank

Illustrative of accelerating investment in the offshore market’s commissioning service operation vessel(CSOV) category, Norwegian interests are introducing a new generation intended to raise the bar in wind farm supportwrites David Tinsley

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Source: /Vitalii Bondarenko

Walk-to-work offshore: CSOV operability at the highest level in IWS Skywalker.

Constructed in China to the order of Oslo Stock Exchange-listed Integrated Wind Solutions(IWS), the 90m IWS Skywalker is the outcome of a technical project shaped by a drive for second-to-none, year-round operability, personnel safety and environmental profile.

Encapsulating the walk-to-work concept, the vessel will act as a mothership for technicians attending offshore wind turbines. She has been designed specifically to support commissioning works during the construction of wind farms and to enable subsequent through-life servicing of both bottom-fixed and floating turbines. The industry’s move to increasingly powerful and larger turbines, and the development of field arrays further offshore in demanding environmental conditions, is reflected in IWS’ tailor-made class.

IWS Skywalker made her transit to Europe from the Jiangsu shipyard of China Merchants Industry Holdings(CMI), arriving at the Danish port of Hanstholm during February for final preparations before commencing her initial contract at the Dogger Bank Wind Farm in the North Sea. Five further newbuilds of the class, embodying the Kongsberg UT 5519DE design, are scheduled to be completed by the Chinese contractor over the course of 2024 and into 2025.

Equipped with 3D motion-compensated gangway and motion-compensated crane for safe transfers of personnel and equipment, to ensure operational continuity in the rigours of the central North Sea, the vessel type is also distinguished by a double-ended hull form and novel propulsion thruster arrangement for precise manoeuvring and position holding. Although constructed as a plug-in hybrid, a substantial battery installation will provide for a degree of all-electric, zero-emission operation.

The IWS Skywalker breed is among the first in the sector to achieve the DNV Silent(E) notation, which acknowledges measures implemented to reduce underwater radiated noise so as to minimise impact on marine life.

The vessels are built around a technological backbone afforded by a comprehensive equipment solution supplied by Kongsberg Maritime. This includes permanent magnet(PM) azimuth thrusters, generators, electrical and control systems, a fully integrated bridge with navigation, dynamic positioning(DP) and automation systems, and deck machinery.

Main propulsion is provided by four Kongsberg US255-series azimuth thrusters, two forward and two aft, each with a top-mounted PM electric motor. The three main generator sets are driven by rugged, high-speed engines from the Caterpillar portfolio, in the shape of 12-cylinder, vee-type 3512E diesels.

The shipowner attributes its new breed with “the largest battery packs in the industry”, in an offshore service context. Supplied by Corvus Energy, the installation is understood to amount to a capacity of 2.2MWh. Solar panels are fitted on the vessel as an additional charging source. While allowing for limited all-electric propulsion, such as navigation in port areas, the energy storage system is on a scale that provides a usable reserve with the scope to facilitate transition to more extended electric operation. An offshore charging infrastructure would open up new opportunity in this regard.

IWS Skywalker can accommodate up to 120 personnel, comprising 30 crew and up to 90 clients, in a total of 92 cabins. The motion-compensated, electrical gangway system affords technicians a direct connection between the ship’s superstructure and each turbine, and can be positioned at reach heights of 10m to 32m. Deployment will be generally assured in conditions of up to 3m significant wave height.

The 3D compensated, Colibri knuckle boom crane can lift equipment and material from the deck to a fixed or floating turbine at up to 32m height, and may potentially also be used for subsea operations. Both crane and gangway were designed and supplied by Cargotec’s MacGregor division, whose contract included a remote control station on the bridge.

The 400m2 open deck area aft is complemented by 420m2 of warehousing, with temperature- and humidity-controlled storage, IMDG stores and workshops.

The stern is fitted with a special structure for stepless boat landing from crewboats working with personnel on the wind farm. The ship also carries a 12.5m daughter craft, launched and recovered by davit, and and which has capacity for 12 technicians plus two crew. The 25-knot craft can also be used to ferry material or equipment for turbine upkeep and repair. The heli deck mounted forward gives added dimension to the ship’s capability for personnel and spare part transfers.

The interior spaces have been configured to comply with DNV’s COMF(V-2, C-2) notation, acknowledging the fundamental importance of habitability and comfort to the ultimate efficiency and wellbeing of personnel onboard. Such considerations also have longer-term implications for factors such as crew retention and charterer favour.

IWS Skywalker has been chartered by the Dogger Bank Wind Farm development consortium for service during the first two phases of construction(A and B), involving commissioning of 13MW turbines of GE’s Haliade-X type. This will engage the ship until the end of the first quarter of 2025, and possibly beyond if an option on an additional period is exercised. In addition, IWS has a 304-day CSOV charter contract for the C-phase, effective from the third quarter of 2025. Dogger Bank C will have arrays of the more powerful 14MW model of the Haliade-X series.

Underscoring the considerable role of offshore wind in the UK’s energy transition strategy, completion of the three phases of the major scheme on the isolated sandbank in the southern North Sea will provide a total 3.6GW of renewable energy capacity. At its closets point, the wind farm will be 131km(about 80 miles) off the Yorkshire coast in eastern England.

Besides the early endorsement by the Dogger Bank wind farm development consortium, consisting of SSE, Equinor and ENI, IWS’ investment programme and bespoke vessel design has found market approval through a raft of further contracts.

A three-year frame agreement, beginning in 2025, has been signed with Siemens Gamesa Renewable Energy, calling for the use of IWS Skywalker-class vessels to support offshore turbine commissioning works across multiple projects in Europe. Moreover, a timecharter contract has been secured from Greek undersea cable specialist Asso.subsea, which will entail deployment of a CSOV in French waters for up to eight months.

In the meantime, a charter deal with Dutch Government-owned European transmission system company TenneT will provide a minimum four months’ employment, starting at the end of May 2024, for the second ship of the series, IWS Windwalker. The vessel completed sea trials during December, and is scheduled to be delivered in March.

IWS said that the six CSOVs were ordered at an attractive, average fixed yard price of EUR48.2m($52.2m) per vessel, which included specific equipment and features that would add about EUR5m($5.4m) to standard yard prices. Significantly, the contract price has been based on use of about 50% Norwegian equipment and content. The favourable capex offers the prospect of improved yields in a rising market.

Norway’s Ministry of Climate and Environment agency ENOVA has granted EUR1m per vessel to support the environmental technology initiatives in the IWS Skywalker series. Projected energy consumption is estimated to be 20% lower than other newbuild CSOVs.