Course (navigation)
In navigation, the course of a watercraft or aircraft is the cardinal direction in which the craft is to be steered.
The course is to be distinguished from the heading, which is the direction where the watercraft's bow or the aircraft's nose is pointed.
A navigator determines the bearing (the compass direction from the craft's current position) of the next waypoint.
The helmsman or pilot points the craft on a heading that corresponds to the course to steer.
If the predicted drift is correct, then the craft's track will correspond to the planned course to the next waypoint.
1 – True North
2 – Heading, the direction the vessel is "pointing towards"
3 – Magnetic north, which differs from true north by the magnetic variation.
4 – Compass north, including a two-part error; the magnetic variation (6) and the ship's own magnetic field (5)
5 – Magnetic deviation, caused by vessel's magnetic field.
6 – Magnetic variation, caused by variations in Earth's magnetic field.
7 – Compass heading or compass course, before correction for magnetic deviation or magnetic variation.
8 – Magnetic heading, the compass heading corrected for magnetic deviation but not magnetic variation; thus, the heading reliative to magnetic north.
9, 10 – Effects of crosswind and tidal current, causing the vessel's track to differ from its heading.
A, B – Vessel's track.