Design and numerical analysis of buoyancy-assist airbags for salvage ship

To enhance the roll stability of crane vessels under lateral loads during salvage operations, this study introduces a buoyancy-assist device using flexible airbags. The device comprises cylindrical airbags fabricated from rubber/PVC materials, installed on the sides of the crane vessel. They provide additional buoyancy when inflated, suppressing the motion response of the crane vessel. A numerical model of the crane vessel and the sunken ship is developed using the AQWA hydrodynamic software to evaluate the effectiveness of the buoyancy-assist airbags in improving stability during the salvage process. Results indicate that with buoyancy-assist airbags, the maximum roll angle of the crane vessel reduces from 6.26° to 3.44° in the wreck-surfacing condition and by approximately 30% in wreck-lifting scenarios. The airbags also exhibit a significant roll suppression effect under the 90° wave-current condition in the wreck-on-seabed scenarios. This study confirms that buoyancy-assist airbags are effective in enhancing the operational stability of crane vessels.