Numerical Study of a Method to Reduce Rescue Boat Motions during Launching from a Ship in Waves

Artikel i vetenskaplig tidskrift, 2005

An attempt to improve the launching of evacuation equipment such as rescue boats or lifeboats from a ship with no forward speed in beam seas is numerically investigated in the present paper. Previous studies have shown that the vertical distance between the launch point and the mean water level is an important parameter in the launch process. Therefore, in the present paper an arm follows the evacuation equipment a certain distance to reduce the swing motion, which corresponds to continuously lower the launching point. This situation is simulated using a numerical model that includes the wave climate, the ship motions and the dynamics of the evacuation equipment. In order to keep the weight and dimensions of the arm within reasonable values it is important to have information of the moment at the launching point. Consequently, this moment is continuously calculated. The influences of the length of the arm, the launch position, the initial wire length and the wavelength are investigated by varying these parameters. The results clearly show that the risk when launching rescue boats or lifeboats can be drastically reduced when using this method.