Although the marine sextant is seldom used these days due to the introduction of satellite navigation systems (ie GPS), it still can be used for the following:
- Measuring the altitude of the stars, sun, moon and planets in order to determine geographical position out of sight of land (ocean navigation).
- Measuring horizontal sextant angles between prominent terrestrial objects to fix position (coastal navigation).
- Measuring vertical sextant angles of suitably positioned high terrestrial objects to obtain distance off (coastal navigation).
- Vertical distances of masts to obtain distance off other ships when steaming in convoy (in times of conflict).
- Hydrographic surveying.