Great-Circle Sailing

The following form performs the Distance (D) and Bearing (Z0, Z1) solutions of the spherical triangle for great-circle track sailing from a current Position (L0) to a Destination (L1).
The picture on the left below will show the situation and explain the abbreviations and terms used.

Location (L0)   Destination (L1)
Latitude  N/S  dd-mm.m   Latitude  N/S dd-mm.m
Longitude  E/W ddd-mm.m   Longitude  E/W ddd-mm.m

    Distance / Bearing
sail045c_A.gif   D/Z0  Nm      °

D: Great-Circle Distance from L0 to L1
Z0, Z1: Azimuth angles under which the great-circle track intersects with the local Meridian in L0 and L1.

The Agles Z0 and Z1 are measured clockwise from the northern branch of the local Meridian (true North) in L0 and L1 respectively and towards the (shortest) great-cirlce segment connecting L0 and L1. This way the resulting Azimuth angles represent true bearings. These true bearings are the initial courses to be sailed to travel from L0 to L1 (B0) or reverse (B1).

The great-circle track gives the shortest path between L0 and L1, but the course to be sailed is not constant. The Distance-Bearing problem can also be solved for a loxodrome track (track of constant course).