WTG & Monopile Seafastening – Nyuzen

TWD assisted Shimizu Corporation in the installation of the Nyuzen OWF for which TWD Japan Co.,Ltd. supplied a complete seafastening spread. The project consisted of the installation of three 3MW wind turbines, situated off the coast of Toyama Prefecture, Japan.

Shimizu utilized their flagship SEP vessel Blue Wind, which undertook the solo installation mission in just four trips. The first journey was a foundation campaign [link], requiring seven monopile cradles, six platform seafastenings, and a hammer grillage. The following three journeys transported the WTG installation, with seafastening for two tower sections, a nacelle, and a rotor hub.

All seafastening structures were present on deck simultaneously for both campaigns, which facilitated a fast and hassle-free turnaround. To assemble the rotor hub, TWD designed an additional quayside grillage with a modular counterweight attachment. This helped to balance the hub as each blade was attached, before being transferred to an identical grillage on deck.

TWD also performed dedicated motion analyses to determine accurate accelerations during transit.

Project highlights

• The project had a short lead time, meaning seafastening items would have to be on deck during the trips.
• The design of a ballasting frame to keep the rotor stable during transport.
• First project in cooperation with TWD Japan Co., Ltd. That was responsible