The Running Fix: Getting Position From One Landmark

When only one landmark is in sight, a running fix could give a position. Take a first bearing: it gives a line of position, not a position. Run the DR by course and speed (distance = speed × time; 12 knots × 0.5 h = 6.0 nautical miles). Move the first line parallel to itself by the run and label it with both times (e.g. 1000-1030). Take the second bearing: where it crosses the transferred line is the running fix, circled and marked "R Fix" with the time of the second bearing. If there is a current, transfer the line by course and speed made good; in our example, ignoring a 1.5-knot set toward the coast would put the fix about 0.57 nautical miles too far offshore. The cut is best near 90°; as a rule of thumb, avoid cuts under about 30°. A running fix is only as good as the run between bearings, so confirm it with another mark, radar or GPS when available. The chart and Light A in the reel are fictional. Source: Bowditch, The American Practical Navigator (NGA Pub 9, 2024), Ch. 11, Art. 1002, 1112, 1113, 1119, 1123.

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