Sun Navigation Basic

Helmut Hoffrichter

About this app

Astronavigation, no thanks, it belongs in a museum a long time ago. But this is wrong. In the museum belongs the extremely tedious and still widespread graphic-based intercept method of Saint Hilaire. It would be stupid and at the same time negligent to surrender completely to a system that although fast, precise and comfortable to use, was created by humans and to completely dispense with the sun as a reliable guide. The sea is not a safe place.

With this app on a tablet or smartphone, astronomical navigation is almost as easy as satellite navigation. However, you need a sextant because the sun does not transmit its distance to the observer's position by radio signal. Only satellites can do that. With satellites, a location can be determined every second and very accurately, which is not possible with the sun. But that is not important on long sea voyages. In the past, ships also sailed and found their destination.

With the sun, navigation is safe because it cannot be confused with any other star. Moreover, it has always been the most important navigation star for sailors, accounting for more than 90 % of all positioning. Stars can only be observed during the short periods of twilight, because only then can the horizon still be seen.

The function of the app is based on a work by the famous German mathematician Carl Friedrich Gauss. Anyone can learn to use it intuitively in a few minutes. Except for the need to use a sextant, it is comparable to satellite navigation on a chart plotter.

A Nautical Almanac is not required and the correction of the sextant reading is done automatically. An upper limit in the altitude of the sun to be measured does not have to be respected and a dead reckoning location is unnecessary. An user does not need to have any knowledge of mathematics or astronomy and he does not need to draw anything or write anything down. To determine a location, it is only necessary to enter the altitude of the sun read from the sextant at two different times. Compared to all other classical navigation methods, the Gauss method has the greatest accuracy. Position deviations are mostly caused by inaccurate data of heights and times.

The app is suitable as a backup in case satellite navigation is not available. With a cheap plastic sextant and this app, every skipper has an emergency navigation system that can be used immediately to safely arrive at any destination.

Anyone who prefers to find their way on long voyages with the help of nature and focus their attention more on their surroundings than on a chart plotter can finally do so with this app, without having to solve complicated formulas, make drawings or search around in tables.


The functions of the app are:

1. Circle of position navigation
2. Taking into account change of locations
3. Sun almanac with <0.4' accuracy
4. Automatic correction of sextant reading
5. Observations over 1 following day
6. Basic world map
7. Observation at the lower sun limb
8. Display of DR the position

The professional version has the following additional functions:

1. Parallel full-fledged second system for any input
2. Inclusion of the noon latitude
3. Dead reckoning module for recording changes of location
4. Sun almanac with 0.1' accuracy
5. Observations over 3 following day
6. Download high resolution maps
7. Observation also at the upper sun limb
8. Measurement of distance and course to a target
9. Scale display at <50 NM zoom level
10. Continuous display of DMG, CMG and VMG