Abstract
This study shows the physical characteristics of the visual environment and the psychological characteristics of the navigation officers. Author has carried out two kinds of experiments on board. One is the measurement of the illuminance at the fore of the inside in the navigation bridge, another one is the measurement of navigation officer's eye movements. The illuminance at the place of fore inside in the navigation bridge can be standardized by the solar altitude. The characteristics of the lookout on board are based on the measurement of navigation officer's eye movements and are brought together as follows.
(1) Average fixation time in the daytime
(2) The relationship between the number of fixation points and the velocity of eye movements, and lookout in the daytime
(3) Lookout on board at twilight
