ASA 117 Basic Celestial Endorsement | Modern Sailing

ASA 117 Basic Celestial Endorsement

2 days, 9:00am - 3:30pm

Embark on a journey to learn the age-old techniques of celestial navigation, a fundamental skill that connects mariners to the vastness of the cosmos and the traditions of seafaring. While modern vessels are equipped with sophisticated electronic navigation systems, the ability to pinpoint your position using the sun, moon, planets, and stars offers self-reliance and seaworthy preparedness. 

The ASA 117 course introduces sailors to the timeless art of celestial navigation using a sextant and celestial bodies to determine position at sea. This course is designed for those interested in gaining a foundational understanding of how to navigate offshore without relying on GPS or electronic tools. 

What You'll Learn:

  • Basic concepts of celestial navigation
  • Use and care of the sextant
  • How to measure the sun's altitude
  • Use of the Nautical Almanac and sight reduction table
  • Determining latitude and longitude by sun sight
  • Understanding time, time zones, and GMT
  • Plotting lines of position (LOPs) on a nautical chart

Your Celestial Endorsement textbook, GPS Backup with a Mark 2 Sextant by David Burch, is included with the purchase of your course and will be mailed to you. If you prefer to pick up your course materials in person or if you signed up less than a week from the first day of your course, please contact our office. Advance study of these books will enhance your success in this course.

Enroll in ASA 117 to equip yourself with this essential skill. If you're interested in a deeper dive into celestial navigation, look for our ASA 107 course, typically scheduled during the fall and winter months.

Cost for Members: 
$545
Cost for Non Members: 
$725
Prerequisites: 
ASA 104 Bareboat Cruising and ASA 105 Coastal Navigation
Capt. Steve Matles using sextant

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  • Sara Jane G.

    I've taken two classes at MSS&C and was very happy with the program. This is also a great club with lots of opportunities for camaraderie and practice on the water. The boats in the fleet are fantastic and kept in tip-top shape. I highly recommend for all sailors and would-be sailors!

  • Ray Arceneaux

    The vessel was clean and in fine condition - very nice boat for training, well-equipped.

  • Emma & George Stubbs, Sausalito

    We just took our ASA 106 at a school in Rhode Island as we prepare for 6 months of cruising in the Caribbean. The class was great, but more than anything it made us really appreciate the quality of teaching and rigor at Modern Sailing. Even though we were the newest to sailing, the group seemed to think that we had the best fundamentals. We felt very well prepared and we see why Modern Sailing has the reputation it does.

  • Jessica Zittere, Member

    The Full Moon Sail with Skipper Bob Gutsgell was Ah-Mayzing!! The group dynamic was lovely and the views spectacular. I can't say enough good things about the experience. Thanks so much for the wonderful Club Sails, they are really great.

  • Esther C

    I took ASA 101 with them recently. They have the best customer service I've ever seen! I mistyped my address when I signed up online so didn't receive the textbook. I called and the lady immediately sent me another copy! Everyone at the club is super friendly.

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Modern Sailing School & Club

Sausalito Location
2310 Marinship Way, Sausalito
(415) 331-8250
(800) 995-1668

Berkeley Location
1 Spinnaker Way, Berkeley
(415) 331-8250
(800) 995-1668

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