1960 年 22 巻 p. 77-84
The position fixed by Decca has correspondingly the same degree of accuracy with that of the triangular survey using landmarks. From this point of view, the following studies in which Decca was utilized were carried out during the hydrographic surveying conducted August through September, 1959, off Tokati, Hokkaido, by the Japanese Hydrographic Office: 1) Measurement of the Survey Ship Takuyo's maneuverability (turning circle and distance of new course). 2) Observation of currents using ship's positions by Decca and dead reckoning, comparing the results with those obtained by G.E.K. 3) Measurement of the accuracy of positions by Loran. As to the result of 1), a considerable accuracy was ascertained in the ship's turning circle obtained. The result of 2) revealed that the values obtained by means of Decca and dead reckoning were approximately the same as those of G.E.K. As to the result of 3), ship's positions by Loran rate 2S1 were obtained within 1 mile error, but when using the rate 2S2, positions could not be obtained so accurately, in some cases with errors ranging from 5 to 7 miles, because of being in the proximity of the base line extension.