Study on the safety investigation of the free-fall lifeboat during the skid-launching test

Abstract

Recently, free-fall lifeboats are becoming popular due to the fact that many life threatening accidents have occurred with conventional lifeboat systems. Most of the accidents happened during launching and after lowering the boat into the rough seas in high wind. During launch, the lifeboat may hit the sides of the distressed vessel, become severely damaged and occupants may fall into the sea causing injury and even death. It is impossible to launch the lifeboat if the parent vessel is listing significantly or if the falling becomes tangled. After lowering the boat into the water, it may be unable to move away from the distressed vessel if high seas and winds continually push the lifeboat towards the parent vessels or due to the inability of the engine to start. These situations become even more dangerous during fire or when the potential for an explosion exists. Many of the risks associated with conventional lifeboat systems have been substantially reduced by the free-fall lifeboat system. These problems are minimized with the free-fall lifeboat because it is not lowered into the sea. The free-fall lifeboat falls freely into the sea, generating kinetic energy as it does so. The kinetic energy, which is developed, propels the lifeboat away from the distressed vessel during and immediately after water entry. The lifeboat moves away from the danger even if the engine does not operate. This paper presents safety investigation of the free-fall lifeboat (FFLB) through the result of skid-launching free-fall test in the four falling phase, i.e., sliding phase, rotation phase, free-fall phase and water entry phase. In case of water entry phase, the damage of free-fall lifeboat has been remedied structurally, not only reduced top deck impact area and impact pressure but also increased the modular factor of the roof deck in order to modified structure of the deck shape.