Chart Navigation & Plotting · Sailings — Great Circle vs Rhumb Line
For a long ocean passage in the mid-latitudes, a great-circle track compared with the rhumb-line track is:
- AIdentical in distance to the rhumb line
- BLonger in distance but steered as one constant course
- CShorter in distance but requires continual course changes✓ Correct
- DAlways due east or due west
Explanation
A great circle is the shortest distance between two points on the earth, but its true course constantly changes, so it is steered as a series of rhumb-line legs between waypoints. The rhumb line is a single constant course but a longer distance (except along the equator or a meridian).
Authority: Bowditch (Pub. No. 9), Great-Circle Sailing
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