Bearing to Waypoint (BTW)

The direction from a vessel’s current position to a predetermined navigational point or waypoint.

In marine navigation, Bearing to Waypoint is a concept used to guide a vessel towards a specific location, often defined by coordinates or a known landmark. The bearing is expressed in degrees, typically relative to true north or magnetic north, depending on the navigational system in use. A waypoint is a designated point along a planned route, and the bearing to that waypoint helps the navigator or autopilot system determine the correct heading to reach it.

For instance, if a vessel is at sea and its next waypoint is a lighthouse positioned at a specific set of coordinates, the bearing to that waypoint would indicate the direction the vessel must steer to reach the lighthouse. This bearing can change as the vessel moves, especially if it is off course due to currents, wind, or other factors. Modern electronic navigation systems, such as GPS chartplotters, continuously update the bearing to waypoint, providing real-time information to the helmsman or autopilot.

It’s important to note that the bearing to waypoint is distinct from the course over ground (COG), which is the actual path the vessel is travelling due to external influences like tides or wind. Navigators must constantly monitor both the bearing to waypoint and the vessel’s COG to ensure they are on the correct route and adjust their heading accordingly. This concept is fundamental in ensuring safe and efficient passage planning.