Chart Navigation & Plotting · Sailings
A gnomonic projection chart is most useful for:
- APlotting rhumb lines as straight lines
- BPlotting a great circle as a straight line, then transferring waypoints to a Mercator chart✓ Correct
- CMeasuring tidal heights
- DCoastal piloting only
Explanation
On a gnomonic chart, any straight line is a great circle. Navigators draw the great-circle track as a straight line on the gnomonic chart, read off intermediate latitudes/longitudes, and replot those as rhumb-line legs on the Mercator working chart.
Authority: Bowditch, American Practical Navigator (Pub. 9), great-circle sailing
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