Abstract
An experiment on board an actual vessel was carried out with cadets, who were boarding a training ship for the very first time, as the subjects of the ex-periment. The pattern of motion sickness incidence was one in which the incidence increased sharply during the periods the cadets were on watch, and sharply de-creased during their free, off-watch periods. The vertical acceleration (rms) in-cluding heaving, rolling and pitching of the ship was taken as the magnitude of the periodic motion. The motion sickness incidence was divided into three Grades, I (slight), II (moderate), and III (serious). Percentages of incidences in Grade I or above, Grade II or above and Grade III were obtained, and the linear relationship with the acceleration was found. Grade I or above would consist of the total of Grade I, II, and III (I+II+III), Grade II or above would consist of the total of Grade II and III (II+III). In those cases where there was not much fluctuation in the acceleration, the incidence ratio attained its maximum 2 to 3 hr after exposure. It was also observed that acclimatization effects to periodic motion made them-selves apparent by a reduction in the proportion of incidence ratio of motion sickness to acceleration as the number of aggregate days of the cruise increased. Hiroshi, KANDA;Daizo, GOTO;Yukio, TANABE
