Realistic Capacity Limits for Marine Passenger Safety: Adult Body Weight Distributions in the United States

Abstract

Transportation and lift systems usually incorporate maximum capacity specifications for design, testing, and operation. Whether maximum capacity is specified directly in kilograms, or indirectly as maximum number of adults, user safety depends on accurate and logical relationships between system specifications and the upper limits of body weight distributions in the user population. This study utilizes recent data from the National Health and Nutrition Examination Survey (NHANES) and bootstrap methodology to establish meaningful weight capacity limits for small (10 person) marine craft, concluding that the average adult weight of 75 kg used to establish capacity limits for small marine craft in several ISO standards is far too low to represent contemporary US adults. This study indicates that a randomly selected group of 10 adult males will exceed the 750 kg capacity 97.6% of the time, and a group of 5 adult males and 5 adult females will exceed the 750 kg capacity 80.1% of the time. In fact, this study suggests that a design and testing assumption of 97.5 kg per adult (975 kg for 10 people) is needed to ensure that groups of 10 adult males (the worst case for small craft design) are within capacity limits 95% of the time.

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