Inflatable Lifejacket Requirements for Encumbered Military Personnel

Military personnel’s equipment has become heavier in recent years in order to provide improved combat protection. These encumbered personnel are required to wear a lifejacket for operations over water. Yet only limited published research has been identified that addresses the adequacy and efficiency of lifejackets to protect heavily encumbered military personnel from drowning.The research presented in this thesis investigates a buoyancy system, known as the multi purpose lifejacket concept that combines an inflatable lifejacket with additional buoyancy placed lower on the body in order to adequately support encumbered military personnel in the water. A comparison study has been conducted on yoke and bib lifejackets to investigate the effects of temperature and pressure on lifejacket volume, and the expected mouth freeboard tolerances of good and poor fitting lifejackets. The thesis also considers the effect that the shape of the bladder around the head has on face-plane angle and mouth freeboard. These both impact on head tilt angle. Positive head tilt was expected to improve the survival prospects in water.Static pool experiments with the two buoyancy systems have indicated how much load can be supported. This work was reinforced with wave tank experiments to determine the water ingress into a manikin’s mouth under various load and sea conditions, resulting in recommendations for suitable mouth freeboard clearances. This study identified that the particular bib lifejacket supported additional load more effectively than the yoke lifejacket investigated, when used in conjunction with buoyancy worn on the thighs. Computer models were developed to gain an understanding of the buoyancy relationships and what effect the centre of buoyancy had on supporting the encumbered load. An investigation of the three most relevant standards for this study suggested that the ISO standard best addresses the aspects of encumbered military personnel from drowning. However, it is recommended the technical requirements that can support encumbered military personnel should be additional criteria to this standard