Oceanographical and meteorological investigations at the disaster of the Nankai Maru.

Abstract

The Nankai Maru, a 495-ton ferryboat in the northern areas of Kii Suido, was missed after emergency call at 1830 JST, January 26, 1958, and was found by echo sounding at 40 m deep and 5 km southwest of Nusima at 1600 JST, January 28. The causes of the disaster are considered to be as follows from meteorological and oceanographical standpoints of view: (1) It blew gusty wind of maximum instantaneous speed over instability line in warm sector of a developed extratropical cyclone. (2) Wind waves generated by warm gusty wind were superposed with their reflected waves by coastal cliff. (3) There existed strong ebb current at about the time of the disaster, which collided with small sea-ridge descending from west towards the disaster spot. In general, when southerly wind prevails, pyramidal waves become conspicuous along the course of ebb current from Naruto Kaikyo, and they extend as far as areas off Hinomisaki. These conditions were superposed, and awfully confused seas with pyramidal and mountainous waves caused, sufficient to make the disaster happen.