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Basic Celestial Navigation Class


Earn Your Basic Celestial Navigation Endorsement! (ASA 117)

This celestial navigation course includes the ASA 117 Celestial Endorsement Test and Certification. This celestial navigation class is a two-day course, so please see calendar for available dates.

Class Times:

Day 1: 7:00 p.m. – 10:00 p.m. / Day 2: 9:00 a.m. – 5:00 p.m.

REQUIRED TEXT: Required text information will be given by the instructor prior to the first day of class.

DESCRIPTION: This basic celestial navigation class teaches the theory and practice to determine latitude and longitude at sea using the noon sun and the star Polaris (a.k.a. the North Star) with just a small eleven-page booklet, a sextant, a watch and simple arithmetic.
Experienced celestial navigators and beginners alike will enjoy this simple alternative to the intercept method-one that doesn’t depend on sight reduction tables and yields latitude and longitude directly without plotting.



  1. Describe the terms and theory of Basic Celestial Navigation using a traditional sextant and Nautical Almanac and without the use of a programmed calculator or computer.
  2. Convert between standard time and zone time to GMT/UT in either direction.
  3. Calculate the zone time at a given longitude.
  4. Determine the times of sunrise, sunset and civil twilight for a vessel’s position.
  5. Describe and identify the parts, principals and operation of a traditional sextant.
  6. Determine altitudes of the Sun and Polaris by a traditional sextant.
  7. Obtain Latitude and Longitude at noon (LAN) by applying the sextant corrections for conversions of the raw sextant altitudes (hs) of the Sun to the true celestial altitudes (HO) of the Sun.
  8. Determine the vessel’s latitude and Estimated Position at morning and evening twilight by means of the altitude of Polaris.
  9. Plot latitudes and EPs on a chart.

*Please note that we need at least three students signed up to confirm a class. Private instruction is available, please call our office at 831-423-7245 to discuss options. Students must be at least 18 years old or must be accompanied by a parent or guardian.