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course

The Bowditch definition: The direction in which a vessel is steered or intended to be steered, expressed as angular distance from north, usually from 000° at north, clockwise through 360°. Strictly, the term applies to direction through the water, not the direction intended to be made good over the ground.

The course is often designated as true, magnetic, or compass to indicate the reference direction.

Starpath Note: This Bowditch (and Duttons) definition of "course" is not how we use the term. This definition is equivalent to what we (and others) call "course to steer." When we use charts to layout the route we want to take from A to B, which is a series of legs between waypoints along the way, they will call this route the "intended track." We call this route our course, which we do not distinguish from an "intended course."

Under the definition of course, Bowditch includes this note:

TRACK MADE GOOD is the single resultant direction from the point of departure to point of arrival at any given time. The use of this term to indicate a single resultant direction is preferred to the use of the misnomer course made good. A course line is a line, as drawn on a chart, extending in the direction of a course. See also COURSE ANGLE, COURSE OF ADVANCE, COURSE OVER GROUND. HEADING, TRACK.

Starpath Note: In the Bowditch terminology, they do not like "course made good" but in our terminology this is a perfectly good and useful concept. Our different approach to these couple terms is not crucial at all, but our usage matches more closely with modern electronics terms and avoids other awkward communications... one important example of a derived term being velocity made course (VMC), which is used by most modern navigation electronics.

Thus in our simple terms, "course" is the direction we want to go. If we are following a route made up of a series of waypoints, then we can speak of the plot on the chart of that series of line segments as our course, and while sailing on a particular leg of the course, our course would then be just the direction to the next waypoint from the last waypoint.

For longer routes or ocean passages, we would then distinguish between great circle routes and rhumb line routes, which imply different courses between the end points.

Related concepts: course over ground (COG) vs course through the water (CTW). See course to steer and course made good.

See also Tricky Terms in Navigation.





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