Feasibility Study on Recovering Human-Occupied Vehicle with An Offshore Crane

Launching and recovering human-occupied vehicles(HOVs)has always been a challenging problem.The current recovery process requires staff to manually complete the tethering task,which is inefficient and endangers the lives of staff.This paper suggests moving the recovery position from the surface to underwater at approximately half the wavelength of the water depth(30−50 m underwater),where the HOV experiences less environmental disturbance.An ROV equipped with a ultra-short baseline beacon(USBL)and a manipulator was used to complete the tethering operation.Additionally,a shackle customized to the shape of the manipulator’s gripper is fitted to the end of the cable to simplify the tethering process.To investigate the dynamic response of recovering the HOV using this suggested method,a comprehensive numerical model is developed in this research.The effects of wind,surface waves,ocean currents,and nonlinear interaction between the installation vessel and the HOV are quantitatively examined.The results show that the proposed recovery method can reduce the motion amplitude of the HOV and that the wave has the greatest influence on the dynamic response of the HOV during the recovery process.This model provides better insight into the proposed HOV recovery method and confirms the effectiveness of the heave compensation system.The proposed approach aims to enhance safety and operational efficiency by reducing direct human involvement in the recovery process and mitigating potential dangers.This finding holds particular significance,especially in environmentally sensitive areas,where reducing the impact on the surrounding ecosystem is crucial.