沿岸航法におけるRuning fixについての一考察(日本航海学会第10回講演会)

概要

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A running fix may be in error unless the course and distance are correctly estimated. If there is no current errors inherent in running fix are due to the error of the log, the Compass error and the error of plotting. In above case the relative error of position which is due to the inaccurate distance is equal to the relative error of the log, and the error is due to the inaccurate bearings are given by following formula when considered that errors of two bearings are equal, [numerical formula], where Δa is the error of the position, Δθ is the error of bearing given by radian, l is the distance run and α is ***acute angle of the bearings. If we admit the error of position in one mile, the limitation of the acute angle is 10 degrees. When there is current the errors of the position depend upon the amount of the current and set. If the current is perpendicular to the first bearing the error is greatest and parallel to it, the error is nill. In the Case of 0<θ+φ<π, the actual position is near the object and in the case of 2π>θ+φ>π, the actual position is father out. Here, θ is the bow angle of the first bearing and φ is the direction of the current against the Course. If we admit the error of the position in one mile, it desire to avoid advancing the position line more than 30 minutes when we estimated the current is 2 knots.
社団法人日本航海学会の論文
1954-04-10