Dynamic Analysis of Launching and Recovering ROV

Abstract During operation and maintenance of the offshore wind farms, some regular inspections for the wind turbines are performed by remotely operated underwater vehicles (ROV) and service operation vessels (SOV). However, the ROV often experiences excessive motions as it passes through wave zone due to wave-ROV interaction combined with free surface effects. These movements can cause rope slack and sudden loading, which may damage umbilical components and endanger ROV operation. This study focuses on experimental measurements and numerical prediction of the dynamic tension in the umbilical during launch and recovery of ROV passing through wave zone under different environmental conditions combined with winching process and ship motions. A coupled offshore vessel, umbilical and ROV hydrodynamic analysis for launching and recovering ROV, which is a typical offshore wind farm service operation, is carried out with coupling characteristics being examined. The numerical results are validated by the 1:10 scale model test measurements on the ROV. The numerical simulation shows ROV experiences larger umbilical tension in recovery process than that in launch process in general. It is found that the tension in the cable is primarily determined by the strength and direction of wind and wave, and the change of winch speed does not significantly impact on the maximum tension in umbilical within the operational range examined.