Distance to Waypoint (DTW)

The measured distance, typically in nautical miles, between a vessel’s current position and a predetermined navigational point or waypoint.

The term “Distance to Waypoint” is a fundamental concept in marine navigation, particularly in the context of electronic navigation systems such as GPS or chartplotters. A waypoint is a specific location marked on a nautical chart or within a navigation system, often used as a reference point during a voyage. The distance to this waypoint is calculated based on the vessel’s current geographical position and the coordinates of the waypoint. This measurement is usually displayed in nautical miles, the standard unit of distance in maritime contexts, though it can also be shown in kilometres or statute miles depending on the system’s settings.

Knowing the distance to a waypoint is crucial for route planning, fuel management, and ensuring timely arrival at a destination. It allows mariners to monitor their progress along a planned route and make adjustments as necessary to maintain course or optimise travel efficiency. For example, when navigating through a series of waypoints, the distance to each successive point helps the crew anticipate changes in heading, speed, or other navigational factors. In addition, this information is often integrated with estimated time of arrival (ETA) calculations, providing a comprehensive picture of the voyage’s progress.

Modern navigation systems continuously update the distance to waypoint as the vessel moves, offering real-time feedback to the crew. This dynamic measurement is particularly valuable in scenarios requiring precise navigation, such as approaching a harbour, avoiding hazards, or adhering to a specific route in congested waters.