An innovative hull design for an offshore wind farm support vessel

A crucial issue for the maintenance of an offshore wind farm is safe access to the wind turbine by the service crew. Current transfer limits are not suited to sites located in more exposed locations further from shore, which are continually being explored by new projects. Weather downtime will increase in these sites if current vessels are utilised. A vessel that can operate safely for a greater percentage of the year is required. This study discusses a new vessel design to meet the changing demand of the offshore wind sector. Optimised hydrodynamic characteristics allow the innovative vessel to access wind turbines significantly above current limits of 1.5m Hs, thus addressing crew health and safety, and comfort. It utilises narrow catamaran hulls to minimise waves load and has a heaveplate at a deep draught to restrict heave and pitch motions. The design was numerically modelled in ANSYS AQWA and experimental trials to evaluate the operational aspects of the design were carried out in Lir National Ocean Test Facility at 1:25 scale. It was demonstrated that the design can access wind turbines up to a Hs of 3.5m at an estimated cost that is less than that of a SWATH.