A critical aspect of operating and maintaining an offshore wind turbine is turbine access. By facilitating crew access to turbine in most any weather, repair and maintenance tasks can be performed in a timely manner. This enhances turbine availability which in turn increases annual energy production yielding an overall reduction in the levelized cost of energy. Most personnel and equipment transfer systems developed to date comprise of a rigid gangway which is deployed from a vessel and which makes hard contact with the tower. With these systems, the need to maneuver the vessel in close proximity to the tower and make a hard contact renders the operation difficult in higher sea states. Therefore a new concept is proposed in which the vessel is stood off the tower, and a highline system, comprising an enclosed gondola running on a set of wires between the vessel and the tower, is used to transfer personnel and equipment. The vessel uses dynamic positioning and a constant-tension winch to ensure safe and smooth gondola deployment and recovery. The gondola is designed as a lifeboat for added safety. The system can be developed as a stand-alone technology and deployed from a range of vessel classes or types. The overall objective of phase I and II is to develop the design of such a highline system and establish the maximum wave conditions in which it is technically feasible to operate it. It is anticipated that the technology, if proven, could be applied in similar systems for accessing other types of offshore installations like oil platforms.
