Buoyancy Budgets for Inherent-Flotation Work Clothing: A Design Study for Fishing and Waterside Workers

Drowning is a leading cause of occupational death among fishers and agricultural workers working near water, groups in which conventional lifejackets are rarely worn during routine work. This paper originates a quantitative design study for work clothing with distributed inherent (non-inflatable) buoyancy, and computes its performance limits from first principles. A garment system of 2.895 kg dry mass displacing 16.30 litres at immersion provides a net buoyancy at immersion of 13.81 kgf (135.5 N) in seawater and 13.41 kgf (131.5 N) in freshwater, falling to a permanent value of 8.18 kgf in seawater and 7.91 kgf in freshwater when all trapped air is lost. Across body masses of 60-110 kg and fat fractions of 0.08-0.40, airway height in a simple vertical-float model is 0.059-0.138 m in seawater and 0.029-0.113 m in freshwater at immersion. A static torque model finds at least 40.0% of net buoyancy must be placed on the chest to turn an 80 kg unconscious wearer face-up in seawater; the design adopts 70% chest. Under exponential trapped-air washout (45-minute time constant), airway height of an 80 kg wearer at 15% body fat falls below 0.05 m after about 46 minutes in seawater and about 14 minutes in freshwater. The design fails for a heavy lean wearer in freshwater from the outset, is degraded by heavy work boots, and does not address cold shock. SIMULATED, NOT MEASURED: no garment has been built, worn, or tested in water.