Mariner's Performances and the Fluctuation Affecting on Navigation Safety

This study aims to identify the degree of safety when mariners take their actions in several different situations. We have carried out many experiments in order to observe mariners' behavior, and then measured the safety level that is based on their actions to avoid dangerous collision situations. One of the most important actions that mariners have to take, either as their daily routine or when they are in a collision situation and then want to avoid that situation is the lookout. In this paper, behaviors on the lookout have been defined as a standard sequence of three steps that are "time of first detection", "time of recognition as risky vessel" and "time of starting avoiding action", and the suitability and applicability of the definition have been shown. And also we propose the risk assessment on the collision and the recommendation for reducing the collision at sea. Some analyzing results and the application of the results are reported. The sequence of lookout is also understood. By combining these knowledge and some systematic studies, we propose the risk assessment on the collision and the recommendation for reducing the collision at sea.