Great Circle Navigation Suite
Great Circle & Composite Sailing
Plot great circle tracks, meridian intersections and composite routes directly on the chart.
Orthodrome • Loxodrome • Vertex
Chart Display
Hint: Click once for departure, again for arrival. If you do not enter etmal (daily run) or meridian intersection interval I will use 10° for meridian intersection and 360 nm for etmal (daily run).
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📱 Neptune's Route for Android

Looking for a professional route planner? Neptune's Route calculates Great Circle routes using spherical and WGS84 (Karney) methods and supports Composite Sailing with user-defined maximum latitude. Route calculations are performed on your device. An internet connection is only required for Google Maps.

Get it on Google Play
Route Definition
Enter departure and arrival positions as chart latitudes/longitudes.
φD – Departure Latitude
Example: 45°12.5'N
λD – Departure Longitude
Example: 007°12.5'W
φA – Arrival Latitude
Example: 55°12.5'S
λA – Arrival Longitude
Example: 125°23.7'E
Sailing Parameters
Define meridian intersection spacing, daily run (etmal), maximum latitude and average speed.
Meridian Intersection Interval
Δλ in degrees, default 10°
Etmal (nm)
Daily run, default 360 nm
Maximum Latitude
For composite sailing, e.g. 60°0.0'N
Average Speed (kn)
For time estimation
Options & Composite Sailing
Control what is calculated and displayed on the chart and in your PDF.
Composite Sailing
Show Meridian Intersections on Map
Show Great Circle Positions on Map
PDF Name
Unique name for your exported PDF
Advanced Composite Parameters
Optional meridian intersection and etmal settings for segments around the vertex.
MIntersection Departure → Vertex 1 (Δλ)
MIntersection Vertex 2 → Arrival (Δλ)
Etmal Departure → Vertex 1 (nm)
Etmal Vertex 2 → Arrival (nm)
Calculate Meridian Intersections
Calculate Great Circle Points
Computed Route & Tables
Results will appear here after calculation (distance, courses, vertex, intersections, composite legs, etc.).