A boat’s heading is the direction her bow is pointing, expressed as a compass direction in degrees from 000 to 359. It is not the same as the course you are trying to make good, nor the track you actually make over the ground, and the difference between the three is where most navigational errors live. The word has a second use:
- A boat’s heading: the direction the bow is pointing at any moment, read from the steering compass or a heading sensor.
- A current’s heading: the direction in which a tidal stream or current is flowing, also called its set. Note the convention – a current is named by where it goes, while wind is named by where it comes from.
A beginner learns to hold a heading on the compass. An experienced sailor watches the heading constantly for what it reveals about the wind: on a close-hauled boat the compass heading is the most sensitive wind-shift indicator on board.
Heading, Course, Track and Bearing
These four words are often used loosely and should not be. Heading is where the bow points. Course is the direction you intend to travel, which you may achieve by heading a few degrees up-tide or up-wind of it to allow for set and leeway. Track, or course over ground, is the direction you actually travel, as shown by the GPS. Bearing is the direction from you to something else – a headland, a mark, another boat. A boat heading 045° in a cross-tide setting 135° might be tracking 055°, while the harbour entrance bears 060°.
True, Magnetic and Compass Heading
A heading is only meaningful with its reference. True heading is measured from the geographic North Pole and is what appears on charts. Magnetic heading is measured from the magnetic pole and differs from true by variation, which is printed on the chart’s compass rose and changes slowly year by year. Compass heading is what your steering compass actually shows, which differs from magnetic by deviation – the error caused by the boat’s own metal and electrics. The traditional sequence runs True, Variation, Magnetic, Deviation, Compass, and the old reminder “variation west, compass best” tells you to add westerly variation when converting from true to magnetic.
Heading as a Racing Tool
Upwind, a sailing boat cannot choose her heading freely – she sails as close to the wind as her sails allow, so her heading follows the wind. This turns the compass into a wind instrument. Before the start, sail close-hauled on both tacks and note the headings; the difference is your tacking angle, and the mid-point is the wind direction. During the beat, watch the heading against those numbers. On starboard tack a veering wind lifts you and the heading number climbs; the same shift on port is a header and the number falls. Tack on the headers, sail the lifts, and you are playing the shifts with hard data rather than a feeling.
Heading and the Cruising Sailor
For the cruiser, heading is about arriving where you meant to. Leeway pushes the boat downwind of her heading, typically a few degrees close-hauled and more in a chop or with a shallow keel. Tidal set pushes her across her heading. The traditional method was to lay off a course to steer that allowed for both, hold that heading and check the track by fixes. Today the GPS shows course over ground directly, but the discipline is the same: if heading and track diverge by more than you expected, something – tide, leeway or a compass error – is not what you thought.
Common Mistakes
- Steering to the GPS course: the course-to-waypoint number on a plotter is a bearing, not a heading. Chasing it in a cross-tide produces a curved track and a longer passage.
- Ignoring deviation: a phone left beside the compass or a new speaker in the bulkhead can change deviation by several degrees.
- Confusing wind and current conventions: a southerly wind comes from the south; a southerly current heads toward the south.
Frequently Asked Questions about Heading
What is the difference between heading and course?
Heading is where the bow is pointing right now. Course is the direction you intend to make good; you may deliberately steer a heading that differs from your course to allow for tide and leeway.
Why does my GPS show a different heading from my compass?
Most GPS units show course over ground, which includes tide and leeway, rather than heading. The compass shows where the bow points. In slack water with no leeway they agree; otherwise they should not.
How do I use heading to spot a wind shift?
Sail close-hauled with the sails trimmed the same way and note the compass heading. If the number moves and your trim has not changed, the wind has shifted. Compare with your pre-start numbers to decide whether you are lifted or headed.
Heading is the simplest number on the boat and the most revealing. Learn to read it against course and track when navigating, and against the wind when racing, and the compass becomes an instrument for sailing well rather than a dial you glance at when the fog comes in.