Crew member fatigue has been reported as one of the causes of marine accidents. In our previous study, it was found that human energy expenditure increased in a small marine craft because of the standing postural motions, such as motions of the head and the hip. The purpose of this study is to analyze the relationship between standing postural motions and energy expenditure, assuming that these motions are one of the causes of physical fatigue. Three orientation sensors capable of measuring

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... ar accelerations and angular velocities were placed on the head and hip of each participant, and on the floor of the marine craft, to analyze the postural motions. Energy expenditure was measured using a calorimeter. The relationship between the standing postural motions and their energy expenditures was analyzed by multiple regression analysis of the following variables: energy expenditure, height, weight, and root mean square values of surge, sway, heave, roll, pitch and yaw motions at the head and hip of each participant, and on the floor of the marine craft. It was determined that weight and the pitch motions at the hip were especially affecting energy expenditure. The coefficient of determination was 0.71. Thus, it was suggested that the pitch motions at the hip affect the energy expenditure in the small marine craft.