Heading

The direction in which a vessel’s bow is pointed at any given moment, typically measured in degrees relative to true north or magnetic north.

A vessel’s heading is a critical concept in navigation, as it indicates the direction the boat is currently facing, regardless of external influences such as wind, current, or waves. It is distinct from the vessel’s course, which refers to the intended path over the ground. Heading is measured in degrees on a compass, with 0° or 360° representing north, 90° representing east, 180° representing south, and 270° representing west. The heading can be measured in relation to true north (geographic north) or magnetic north (the direction a magnetic compass points, which can vary based on location due to the Earth’s magnetic field).

A vessel’s heading is constantly monitored and adjusted by the helmsman or autopilot to ensure the boat stays on course. However, external forces such as wind, tides, and currents can cause the vessel to drift off its intended course even if the heading remains constant. This phenomenon is known as “leeway” caused by wind or “set and drift” caused by current. Navigators must account for these forces by adjusting the heading to compensate for the drift, ensuring the vessel follows the desired course over the ground.

For example, if a vessel is heading due north (0°) but a strong current is pushing it westward, the navigator may need to adjust the heading slightly eastward to maintain a true northward course. This adjustment is called “crabbing” or “steering into the current.” The actual track the vessel follows over the ground is called the “course over ground” (COG), and it may differ from the heading due to these external influences.

In modern navigation, heading is often displayed digitally on electronic navigation systems, such as GPS chartplotters, which can show both the heading and the course over ground. However, traditional magnetic compasses are still widely used, especially as a backup in case of electronic failure. When using a magnetic compass, navigators must also account for “magnetic variation” (the difference between true north and magnetic north) and “magnetic deviation” (errors caused by the vessel’s magnetic fields) to ensure accurate navigation.

In summary, heading is the direction the vessel is pointed, which plays a crucial role in navigation. It must be constantly monitored and adjusted to ensure the vessel stays on course, taking into account external forces such as wind and current.