3.1 Introduction
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Statutory Documents - IMO Publications and Documents - Circulars - Maritime Safety Committee - MSC/Circular.616 – Evaluation of Free-Fall Lifeboat Launch Performance – (22 June 1993) - Annex – Evaluation of Free-Fall Lifeboat Launch Performance - Section 3 – Launch Behavior of Free-Fall Lifeboats - 3.1 Introduction

3.1 Introduction

  3.1.1 The configuration of a free-fall lifeboat at the beginning of a launch is shown in figure 3.1. The free-fall height is measured from the water surface to the lowest point on the lifeboat when the lifeboat is in its launch position. The primary factors that affect the launch performance of a free-fall lifeboat are its mass and mass distribution, the length and angle of the launch ramp, and the free-fall height. These parameters interact to affect the orientation and velocity of the lifeboat at the time of water impact, the acceleration forces experienced by the occupants, and the headway of the lifeboat immediately after water entry.

  3.1.2 The launch of a free-fall lifeboat can be divided into four distinct phases. These are the ramp phase, the rotation phase, the free-fall phase, and the water entry phase. The ramp phase is that part of the launch when the lifeboat is sliding along the launch ramp. The ramp phase ends when the center-of-gravity (CG) passes the end of launch ramp and the lifeboat begins to rotate; this rotation marks the beginning of the rotation phase. The rotation phase ends when the lifeboat is no longer in contact with the launch ramp. This is the beginning of the free-fall phase; the lifeboat is falling freely through the air. The water entry phase begins when the lifeboat first contacts the surface of the water and continues until the lifeboat has returned to the surface and is behaving as a boat.

Figure 3.1 Parameters of a Free-Fall Launch with the Lifeboat in the Launch Configuration

Parent topic: Section 3 – Launch Behavior of Free-Fall Lifeboats
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