Stable ships for smooth servicing of offshore wind farms

There is a rapid increase in the number of offshore wind farms in European waters to help meet renewable energy targets. Wind turbines are being installed in progressively more exposed areas of the North Sea and the Irish Sea, with the eventual aim of placing them in the Atlantic Ocean. As offshore wind farms require regular maintenance, being able to access the wind turbines during rough sea conditions is a key issue for profitable operation. The operation involves transferring personnel from the service ship to the wind turbine. The current wave height limit for this is 1.5 m, slightly less than 5 feet, increasing this results in significant savings over the lifetime of the wind farm. Each wind farm service ship has 12 maintenance crew. Imagine you are one waiting on port for the sea and weather conditions to be right so that you can head out to the wind turbine. You’ve been waiting for two weeks, you can see the wind turbine from land but the sea is so rough that stepping from the ship to the turbine is impossible. The only way to transfer the maintenance crew to the turbines is from the front (bow) of the ship, out at the wind farm this is the best way for the ship to maintain position. Standing at the bow of a ship is much like standing on the end of a seesaw; which means that accessing the wind turbine can only occur during reasonably calm conditions. Quantitatively, this results in the average of the highest one-third waves being 1.5 m, which is described as a sea state code of slight to moderate. This research aims to develop designs that can operate in the sea state code of rough, with an average height of the highest one-third of the waves being 3 metres or more