Large scale mooring line experiments and comparison with a fully dynamic simulation program with importance to WEC installation

Large scale experiments with an 82t vessel moored on a 22mm single chain at a mean water depth of 24m were performed at Scapa Flow (Orkney) to study mooring conditions for the installation of wave energy converters (WECs). Tension and response behaviour were found for various pre-tension conditions using horizontal and axial load measurement techniques and a GPS system for tracking the motion of the vessel. The pre-tension conditions were chosen to provide a slack, fully lifted and taut mooring line arrangement. The study also includes a numerical model of the experiments by applying line properties, installation conditions and the displacement measurements to the simulation and calculating the resulting tensions. The experimental problems that were overcome to obtain meaningful results from large scale experiments under real sea conditions are explained and the importance of mooring line dynamics for WECs is discussed.