Numerical analysis of docking operation between service vessels and offshore wind turbines

Offshore renewable wind energy market is expected to expand dramatically in the next 5-10 years. Reduction of downtime is crucial to the competitiveness of this new sector. One important part of the research efforts is the evaluation of operational limits (weather limits) of different vessel/access concepts for transportation of maintenance personnel, equipment, and spare parts to the offshore wind turbines. This paper gives a brief description of possible types of service vessel and access system. It presents methodologies for numerical analysis of docking operation by an active motion compensated access device and a simple fender. The proposed frequency-domain approach to the analysis of docking operation with fender is new and highly efficient compared to time-domain simulation. The methods have been applied to two vessel/access concepts in this paper and they can be used in docking operability assessments for a variety of vessels that employ an active motion compensated device or a fender as access system to offshore wind turbines.