Applying a Needs Analysis to Promote Daughter Craft for Year-Round Access to Far-Offshore Wind Turbines
S. Brans (Siemens Gamesa)
Andre Rinne (Siemens Gamesa)
A.A. Kana (TU Delft - Mechanical Engineering)
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Abstract
Service Operation Vessels (SOVs) are purpose-built maintenance vessels that provide high accessibility to far-offshore wind turbines, but they lack multitasking capabilities. Its daughter craft (DC) is a valu-able asset for unplanned maintenance in the summer when it can operate safely, but it is often not deployable during rough weather conditions. The main research question is: What are the deficiencies of current DCs, and how can these access vessels be modified to operate year-round at far-offshore wind farms? The results show that the current DC’s deficiencies lie in its current operational require-ments. Also, performance in oblique waves is currently riskiest since that is when there are higher vertical accelerations or a combination of vertical and lateral accelerations. Furthermore, wave steep-ness has significantly more effect on accelerations than wave height. Lastly, future DC designs should be focussed on stable seakeeping performance during transfers rather than high-speed transit. An anal-ysis into the seakeeping performance of four prototypes showed that it is feasible to increase the transfer requirement from Hs ≤ 1.5 m to 2.0 m ≤ Hs ≤ 2.5 m. The catamaran type DCs have a high potential to realise year-round accessibility to far-offshore wind farms due to their resulting performance in oblique wave conditions.