Analytic assessment of the effect of varying schedules, trade routes and sea states on navigation bridge crew

The present study attempted to understand the effect of different maritime work-rest schedules, types of trade routes (with different number of port entries) and ship motion on incidence and severity of fatigue accrual among navigation watchstanders. Different scenarios were simulated using task network simulation technique. Simulation models were built using Micro Saint simulation software and included different combinations of maritime work-rest schedules, trade routes and sea states. Resulting fatigue was represented as a numerical value and was plotted against time (in days) for the entire length of travel (about 14 days). Fatigue score due to circadian desynchronization and sleep deprivation was further increased by 25% in the presence of ship motion. Results showed statistically significant difference in fatigue accrual for different schedules with schedules providing longer and continuous sleep yielding least fatigue. Route with intermediate port entries showed higher fatigue accrual than that with no intermediate port entry. Ship motion caused significantly higher fatigue accrual. Fatigue scores were further categorized in to Acceptable, Marginally Acceptable and High Risk zones and expected performance in each zone was explained.