Coastal Skipper and Yachtmaster Quiz · Position fixing
The lighthouse was 45° on the bow when the log read 12.4, and it is abeam now, with the log reading 14.9. How far off is it now?
Seen from above: a yacht on a straight course from left to right, shown twice. A lighthouse lies to one side of her track. At the first position, labelled log 12.4, the line to the lighthouse makes an angle of 45° with her course. At the second, labelled log 14.9, the line to the lighthouse makes 90° with her course and is drawn in gold with a question mark. Caption: steady course, no tidal stream.
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2.5 miles. This is the four-point bearing, a special case of doubling the angle on the bow (45° doubles to 90°). The distance off when the mark is abeam equals the distance run since it was 45° on the bow: 14.9 minus 12.4 is 2.5 miles. The log must be showing distance over the ground, so allow for any tide.
