南極洋航海で得られた航海上の2,3の知見について(日本航海学会第32回講演会)

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During the third Antarctic cruise of the "Umitaka Maru" of the Tokyo University of Fisheries between December 1964 and February 1965, on the waters southward from Australia and New Zealand (Fig.1), we obtained some informations which are available to navigation in the Antarctic. The one is a consideration on opportunity of the observation on the heavenly bodies, particularly the sun, for fixing the ship's position and another is a knowledge concerns to the movement of ice bergs. As shown in Tab.1, in this waters, observations of the sun were carried out in a portion of 66% under cloudy sky, the opportunities on the area I (southward of the parallel of 60°S) and II (between the parallels of 60°S and 50°S) showed about an half of that on the area III (northward of 50°S), approximately 17% and 36% (Tab.2). However, observations of the sun on the meridian indicated greater degree in frequency, that is, 51%, 67% and 80% in the areas I, II and III respectively (Tab.3). Regarding to estimating the chance of the observation of the sun, we made use of the thermo-piled radiation meter, the horizontal radiation obtained by which and converted in mV, the correlation is 14 mV-1 gram cal/cm^2/min. The extreme limit of observation of the sun shows in Fig.2 and Tab.5, Fig.6 shows diurnal curves of mean horizontal radiation and the limit of observation in relating to areas I, II and III. Fig.4 represents the mean values of visibility in the respective areas. At the time when visibility is more than 6 in the scale the horizon is generally seen. According to those materials, it can be said that observation of the sun is comparatively easy between 0800 and 1600. The movements of ice bergs and bergy bit were measured on January 31 and February 1, 1965. Fig.5 shows the observed movements of various ice bergs. Consequently, we got a knowledge on selecting the ice berg which is available for reckoning of the ship's position among scattered ice bergs, particularly, among pack-ice. The large tabular ice berg is the most useful for the porpoise because of depending his steadily movement chiefly upon only the oceanic current.
社団法人日本航海学会の論文
1965-07-25

南極洋航海で得られた航海上の2,3の知見について(日本航海学会第32回講演会)

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