The cost of maintenance of offshore wind farms currently impacts on the competitiveness of the electricity produced. Current safety requirements and the needs of the service personnel influence wind farm locations and operational flexibility and, consequently, future Service Operation Vessels (SOVs) need to be more efficient and safer in order to meet future demands. NEXUS will deliver an advanced SOV design optimised for efficiency, performance, safety, and working environment which will minimise costs throughout the life-cycle by 20% compared to the current state of art vessels. This will be achieved by designing and validating a reference concept SOV integrating new and emerging technologies. To allow room for design creativity and flexibility, NEXUS will also deliver new safety regulations for windfarm service vessels.