New offshore windfarm vessel designs embrace hybrid-battery technology, bring-to-work transfer systems, and personnel comfort and safety
Global offshore windfarm development continues to spur innovation in offshore vessel design, particularly when it comes to emissions reduction, personnel safety and comfort and vessel workability.
All those elements are built into a new trimaran service operation vessel (SOV) designed by Spanish naval architectural firm Marcelo Penna Engineering (MPE). MPE expects its SOV will reach speeds of 21 knots, while providing full comfort for technicians and transfers with up to 3.5 m waves.
Developed in response to a tender from Equinor for the Dogger Bank windfarm project, the SOV will have battery-hybrid propulsion, with the capability of remaining in dynamic positioning (DP) for up to 12 hours in silent mode.
MPE business development director Marcelo Penna Colom told OSJ batteries are becoming a standard in offshore service vessels, especially in the windfarm sector. While fully electric and hydrogen cells are being developed, “hybrid models must be part of the daily fleet in any case,” he said. Mr Penna said high-speed transfers for the oil and gas sector “cannot rely on hybrid systems, as there is practically no need for DP and battery packs would only add weight where you are trying to save it. But,” he added, “this represents a small percentage of the daily needs of the worldwide fleet and hopefully, every year this percentage will decrease, including more fully electric models which are starting to appear everywhere.”
With an overall length of 64 m and beam of 20 m, the CTV has accommodation for 20 technicians in single cabins, with a multimedia meeting room, and recreational areas for after-work relaxation, a fully equipped gym, warehouse and workshop.
“Batteries are becoming a standard in offshore service vessels”
“The workability with the Safeway (motion-compensated gangway system) has proven to be excellent throughout the year,” said Mr Penna, “and our MSI regarding discomfort on board is extremely low; never reaching discomfort levels even after eight hours at sea in the worst conditions.”
Offering a stable platform, the SOV has a DP class-2 system that allows it to maintain position with up to Hs=4m and a constant transfer flow of technicians with up to Hs=3.5m, according to Mr Penna.
For transferring technicians, the 39-m crew transfer vessel (CTV) MHO Esbjerg is testing a new ‘bring-to-work’ (B2W) offshore access system. Developed by Dutch firm Z-Bridge BV, the fully motion-compensated offshore access system allows the transfer of six people and cargo from the vessel’s deck to offshore structures – increasing workability and improving transfer times.
Built for MHO-Co, MHO Esbjerg and its sister MHO Gurli were designed by Incat Crowther and launched in 2019 from Indonesia’s PT Bintang Timur Samudera.
The two catamaran-hulled CTVs accommodate eight crew, with motion-dampening seating for 24 technicians.
Designed with a three-tier structure-mounted aft, the CTVs have plenty of space for cargo, with the capacity for a 20-foot container aft of the main deck house and five 20-foot containers on the fore deck.
Each CTV has four 746-kW Cummins KTA38-M main diesels that drive KaMewa S50-3/CA jets through Reintjes vLI reduction gears.
Meanwhile, Dutch naval architect OSD-IMT has designed a Z-Bridge B2W access system into a new SOV design for the US offshore wind market. Developed to ABS class notations, the OSD-IMT9660 design SOV has an overall length of 59.2 m, beam of 16.8 m, with accommodation for 80. Equipped with diesel-electric hybrid-battery propulsion and an active roll reduction system, the SOV also incorporates an elevator, linking the covered warehouse and access system to protect technicians during offshore operations.