Sustaining performance at sea: Vessel motion thresholds for physical and cognitive performance

Naval personnel at sea completed daily diaries in which they recorded sleep quality, eating patterns and problems with mental and physical task performance. The ships were fitted with motion sensors to enable root mean square accelerations of the deck to be recorded in three axes. Six-hour RMS accelerations were computed for different parts of the ship using rigid body assumptions. The questionnaire data were factor analyzed enabling summative scales for physical and cognitive performance to be derived. Logistic regression analysis revealed significant effects of vertical acceleration on physical and cognitive performance, with the strongest effects on physical performance. Preliminary RMS thresholds are proposed to sustain human performance at sea. No effects of motion on food consumption were found.