一物標の方位線三本によるRunning Fixの等精度曲線について(日本航海学会第41回講演会)

抄録

We consider that the Running Fix obtained by a bearing and two transfered position lines is equal to the fix by cross bearings from S_1 and S_2, S_3 which are advanced object S_1 and exist in the error boundary of estimated position when ship's running course or distance is wrong. (see Fig 1-b) So, we constructed contours of constant probability density for Running Fix and considered as follows ; (1) When ship's course is set, the closer the object to the ship the better and, since the dotted lines make an angle of about 70 degrees with S_1S_3, it is recommended that the first observation be made at the close angle from the ship's head, while the third bearing of the same object is observed about 20 degrees abaft the beam. This result is common with the Running Fix by two position lines. (2) When ship's course is altered at the time getting the second bearing, the first bearing should be observe at the point to see the angle between the object and ship's head to be ∠S_1 S_3S_2 in Fig.5, while the third bearing of the same object should be observed about 20 degrees abaft the beam.