It has been estimated that up to $80\%$ of all marine accidents have human elements as a cause. Out of these, human elements of crew fatigue is one of the main causes of marine accident. Crew fatigue involves sleep, schedule, workload, off-time, alcohol, health and stress. With a ship handling simulator, the effect of alcohol on ship operational performance is studied for each 0.05 and 0.08 $\%$ blood alcohol concentrations(BAC). The main effect of alcohol was found that ship operational performance was significantly impaired by alcohol compared to that in the non-alcohol condition. The results of this research can be used as basic data to minimize marine accidents.