EVALUATION OF OPTIMUM CONDITIONS OF LAUNCHING A FREE-FALL LIFEBOAT

This paper presents a study on the behaviour of a free-fall lifeboat during water entry and exit corresponding to varying launching parameters. The motion of these lifeboats are considerably influenced by the length and inclination of launch skid, falling angle and effective guide rail length. Attempt is made in this study to identify the optimum launching conditions which will enhance the safety of the boat and also of its occupants. The motion of the lifeboat has first been categorized on the basis of the horizontal velocity and headway at the first phase of water exit. The range of various parameter combination corresponding to these categories have also been evaluated. The values of the falling angle were then evaluated for the lifeboat model resulting in zero horizontal velocity at water exit for different skid lengths and falling heights. The optimum values of falling angle and falling height for safe water travel of the lifeboat have been evaluated for a particular skid length. A criteria for safety of the occupants based on the effects of acceleration is also incorporated in the study. The influence of effective guide rail length on motion of the lifeboat and safety of the passengers has also been investigated. It is found that at a skid length ratio of 0.5, the motion is expected to be the safest one for effective guide rail length ratio of 0.3.