Comment by murbard2
7 years ago
If you navigate a ship while keeping the rudder straight, absent current or wind you will be following a geodesic. If you try to follow a parallel you will have to constantly be turning.
Planes follow geodesics too over oceans, not parallels.
Yes the geodesic on an ellipsoids aren't always great circle, but the earth's geodesics are commonly referred to as "great circles" because the earth is very nearly spherical.
Should we ignore wind and current? If you are in a medium that has winds and currents, and you do not touch your yaw controls, how will you know if your course remains on a straight line?
You either adjust your compass bearing (also correcting for magnetic variation), or you adjust course.
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