Offshore Wind Majors Complete Phase 1 on Bottom-Impact Studies of Wind Turbine Jack-Up Vessels

Norway-headquartered DNV and its partners have completed Phase 1 of a joint industry project (JIP) on Bottom Impact and Partially Submerged Conditions for optimising the installation process of offshore wind turbines.

According to DNV, offshore wind turbine installation is currently done in benign weather conditions to limit the bottom impact of wind turbine installation vessels’ (WTIVs) jack-up legs with the seabed during the set-down phase.

This restricts the vessels’ operability and can lead to high day rates, with delays being costly for operators and charterer. Regions exposed to earthquake risk also require new operation philosophies such as operating the crane with the WTIV in a semi-jacked condition.

“As the industry moves further into new territory with harsher weather, less forgiving seabed conditions and seismic areas, there is an increased urgency to widen the weather window so projects can be completely more efficiently”, said Andries Hofman of GustoMSC, JIP steering committee chairman.

Under Phase 1, DNV developed a numerical model based on the input of all the partners to accurately predict bottom-impact forces and simulate semi-jacked conditions.

The JIP is now open to more partners to join the second phase, with the aim of validating the developed models with full-scale measurements and establishing common best-practice guidelines.

“The market is developing quicker than the rules and the only way to make significant leaps is through sharing knowledge”, said Antonio Goncalves, Business Lead, Technical Advisory at DNV and JIP project manager.

“Through better understanding of the forces are at play and their consequences, we can increase performance and safety in worse sea conditions, enabling more efficient and timely turbine installation, which is a great opportunity for the whole industry.”

The new partners can be energy companies, installation contractors, designers and shipyards, crane fabricators, or wind turbine manufacturers.

DNV said that the lack of guidelines and models to fully understand bottom-impact forces and operations in semi-jacked conditions led to the formation of the JIP in November 2020. At that point, the focus was to investigate operational limits and explore potential new operational practices.

The current partners are DEME Offshore, DNV, EDF Renouvelables, Fred. Olsen Windcarrier, GustoMSC, Huisman Equipment, Jan De Nul, Ocean Winds, Ørsted, RWE Renewables, Seajacks UK, Van Oord Offshore Wind, Yantai CIMC Raffles Offshore.

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Photo: DNV