One of the causes of accidents at sea involving small boat is not enough lookout. However, there have been few studies on behavior of boat’s operator such as lookout and safety checks on boat.

This research had a purpose which was to compare the behaviors of beginner and expert operators when maneuvering a boat and to reveal the differences between them. We conducted a maneuvering experiment of the operator’s behavior on straight line and altering course on 14 operators. As a result, we found that there was no difference in the number and duration of gaze in straight line course, and expert operators had many gazing time and duration for the 5 seconds before altering course. Begginers were found to be able to lookout when maneuvering, but they cannot found the danger.

These results suggest that boat’s operator keep lookout with understanding of dangerous objects to accidents at sea and contribute to safety navigation.

The horizontal distance between the two masthead lights or between the sternlight and the second masthead light abaft of the forward one are enlarged with the specialization and the increasing size of vessels. As an example, the navigation lights exhibited on TI-class supertanker (380 meter in length, the horizontal distance between the two masthead lights are approximately 300 meters) are taken up as a sample of a vessel and her navigation lights are displayed on the screen of a ship-handling simulator in a moonless night situation. Seafarers watching her masthead lights and her sidelights from a small craft in the simulator have mistaken one large tanker as two small ships and have also misunderstood her heading direction. As a similar problem, navigation lights of very large container vessels constructed in recent years and of towing vessels are discussed and necessities of drastic measures on navigation lights including a revision of Colregs are pointed out.