The DP vessel is designed for world-wide operations with a focus on pre-piling and jacket/tripod/transition piece installation for the offshore wind industry in North Europe. Different deck layouts, based upon NorWind Installer’s installation experience from Alpha Ventus, have been developed for the various installation modes on top of the generic vessel platform provided by ULSTEIN.
The approach for this design has been unique in the sense that NorWind Installer and ULSTEIN started this project by going through the ULSTEIN Accelerated Business Development process. Technical and operational options from both NorWind Installer and ULSTEIN were discussed in a transparent process resulting in the most viable option, which met NorWind Installer’s business model and requirements.
”We are pleased with the concept as it is definitely in line with our vision of combining state-of-the-art technical solutions with the speed and seakeeping capacity of DP vessels. It gives us the opportunity to provide our installation services all-year around in up to 2.5m Hs, as well as meeting our client’s cost targets”, states Thorbjørn Hansen, VP Product Development at NorWind Installer.
The vessel is designed aiming for maximum efficiency and cost effectiveness and features an 800t heave compensated offshore crane on starboard side, while a pre-piling template can be located on a support structure at the stern. The vessel can carry four jackets, alternatively at least 24 piles or up to 12 transition pieces on the large open aft deck.
To enhance vessel operability, the anti-heeling system has been designed in such a way that the main crane can revolve over 180 degrees with a full load in its main hook within 5 minutes, which is very favourable having a large jacket in the crane hook.
When operating in the pre-piling mode, the pre-piling template is positioned on the seabed by the main crane, in parallell a pile is picked up by a gantry crane, put in the upending frame on starboard side and upended. The main crane has been modified by ULSTEIN in such a way that it can first pick-up the piling hammer with its main hook and then connect to the upended pile with its auxiliary hook. When the hammer is working on driving the pile into the seabed, the next pile is upended by the upending frame and made ready for crane lift out.
The large aft deck and AHC crane provide flexibility for serving alternative subsea and offshore markets in the future, which is further increased by the two large holds suitable for carroussels located below main deck. A deck layout version of the vessel has also been developed for tidal turbine installations.
Voith Schneider propellers of 3,900 kW each will allow for a cruising speed of 13 knots and enhance the DP capabilities of the vessel. To minimize the environmental footprint an NOx reduction system is installed in the exhaust lines.
“After working closely with NorWind Installer in the ABD process, ULSTEIN started developing the integrated concept for mission equipment and vessel. This project shows the combined strength we can offer to support our clients in realizing their visions”, says Edwin van Leeuwen, project manager at ULSTEIN.
Main dimensions of the vessel are:
Loa 160.3 m
Lpp 145.5 m
Beam (moulded) 32.0 m
Depth (moulded) 12.6 m
Draught (operational) 8.0 m
Service speed 13 kn
Installed power 6 x 4,680 kW
Main crane 800t (AHC)