Measured Accelerations on Free-Fall Lifeboats

Abstract

During the emergency evacuation of offshore vessels and facilities, free-fall lifeboats represent an improvement in safety over conventional lifeboat systems. Many lifeboat accidents occur during and after lowering into rough seas. If the vessel is listing much, some of the lifeboats may be unusable. The free-fall concept overcomes these problems by allowing the lifeboat to slide down an inclined ramp and fall freely into the sea away from the parent vessel. The free fall provides kinetic energy that is used to propel the lifeboat away from danger after it has entered the water. This paper discusses the measured accelerations at the occupant seats during 28-m free falls at three different launch angles. The accelerations were measured on the full-scale prototype of a current free-fall lifeboat design. Included in this paper are the procedures used to measure and interpret the acceleration data and suggested limits on human tolerance to acceleration.