Houlder has developed a windfarm Offshore Support Base (OSB) vessel. The concept recreates the convenience of port facilities - but offshore. ts provides superior seakeeping to that of a standard monohull vessel. Motions are comparable to Semi-submersibles in North Sea conditions. Using a proven, highly stable design significantly improves comfort levels onboard for future windfarm maintenance crews. In typical North Sea crew transfer conditions, the Orelia hull design limits roll to +/- 1 degree.