Abstract
This paper describes a new concept for launching free-fall lifeboats proposed by Yokohama National University. Using the conventional single-skid free-fall system, as the fall height of the lifeboat increases, the potential for increasing incidence of dangerous lifeboat motions, in which the lifeboat moves backward or stumbles on the surface after entering the water, has been pointed out. One of the principal causes of this undesirable motion is rotation of the lifeboat during its restricted fall at the edge of the launching skid. Thus a new “double- skid” launching concept is proposed to effectively eliminate the rotation of the lifeboat at the skid end and to enable the lifeboat to move smoothly after entering the water. In order to confirm the performance of the proposed method a series of numerical simulations and model experiments are carried out in which two lifeboat models with overall lengths of 1 meter and 6 meters are used. The effects of design parameters such as skid angle, skid height, etc., are investigated and an example of the implementation of this new system at the stern of a large merchant ship is illustrated.
