Heading and course describe two genuinely different things, and confusing them is a real, substantive navigation error, not just a vocabulary slip.
Heading: Where the Bow Points
Heading is the direction a vessel’s bow is actually pointing at a given instant, read directly off the compass — a straightforward, instantaneous measurement.
Course: Where the Ship Is Actually Going
Course is the direction the vessel’s actual path over the ground — its track — is heading, which is not necessarily the same as where the bow points, because current, wind, and resulting leeway can push the vessel sideways even while it holds a steady heading.
Why They Differ: Set and Drift
If a vessel steers a steady heading of 090° (due east) through water genuinely affected by a current pushing it northward, the ship’s actual path over the ground — its course — will be somewhat north of 090°, even though the bow never stopped pointing at 090°. This difference between heading and actual course is exactly what “set and drift” calculations in navigation are designed to account for.
Course to Steer vs Course Made Good
This distinction generates two further important terms:
- Course to steer — the heading an officer must actually set (accounting for expected current/leeway) in order to achieve a desired course over ground
- Course made good — the actual course achieved over ground, verified against position fixes, which may differ from what was intended if current/leeway estimates were imperfect
Why This Isn’t Just Terminology
Confusing heading with course in passage planning would mean simply pointing the bow at the intended destination bearing and assuming that’s sufficient — ignoring current and leeway entirely, which in reality can push a vessel significantly off its intended track over a long passage, a genuine, practical navigation error with real consequences.
Exam Relevance
The heading/course distinction, and set-and-drift calculations correcting for the difference between them, are core, heavily-tested Navigation topics in deck officer competency exams.