Leg distance

Leg distance is the distance along one segment of a passage plan, measured between two consecutive waypoints in nautical miles. The track between the waypoints is a rhumb line on a Mercator chart or a great-circle leg on an ocean passage, and the leg distance is the length of that track. Summed over all legs it gives the total passage distance; divided by the planned speed it gives the steaming time and feeds the running ETA at each waypoint. The navigator measures it on the chart against the latitude scale, since one minute of latitude equals one nautical mile, or computes it by the sailings. Leg distances are the backbone of the plan’s time and fuel estimate.