A study of red and white light on the chart table for navigation at sea

Twelve subjects performed four similar navigation tests under four different light conditions; red at 4 cd/m 2 and a low, medium and high level of white light at 0·5,2·5 and 12·5 cd/m 2 , respectively. It was found that: (i) Red light was disliked most by the subjects and high white was liked most, (ii) One part of the navigation test was virtually impossible with red light, although the remainder was done quite accurately with better performance occurring only with high white. Subjects performed fastest with high white, red was the third slowest, but low white took the longest time, (iii) The time to become dark adapted was fastest with red and slowest with high white.