Modelling of ROV-Operated Disconnectable Mooring Systems in Wave Dominated Environments

Floating offshore wind turbines (FOWTs) hold immense potential for unlocking previously inaccessible offshore wind resources, with recent advancements positioning the technology on the brink of commercial success. Central to the success of FOWT projects is the optimization of operations and maintenance (O&M) procedures, particularly concerning mooring system design and the utilization of Remotely Operated Vehicles (ROVs), This paper presents an analysis of mooring line disconnection activities using state-of-the-art ROV technology, focusing on the impact of mooring connector depth with the Arven Offshore Wind Farm serving as a case study. Utilizing a simplified two degree of freedom dynamic ROV model and hindcast metocean data, the study examines the station-keeping ability of an ROV subject to wave perturbations, evaluating the effect of depth on mooring connector operational availability. Results indicate that deeper mooring connector installations substantially enhance mooring connector availability from less than 10 % at 5 m depth to over 90 % at 20 m depth, thereby reducing weather-related delays and improving operational efficiency. Furthermore, a sensitivity analysis on ROV power highlights potential avenues for enhancing accessibility without necessitating mooring design modifications. These findings underscore the importance of integrating FOWT O&M strategies and installation considerations with mooring design at an early stage by accounting for realistic performance of ROV-operated tasks, ultimately contributing to the competitiveness and success in the offshore wind sector.