Backup Cel Nav Online Course

A short course that teaches the basic cel nav needed to find your way across an ocean

Printed materials:
How to Use Plastic Sextants By David Burch ISBN 9780914025245
GPS Backup with a Mark 3 Sextant By David Burch ISBN 9780914025603

Ocean sailors are prudent folks. They know they need a backup to all systems, and cel nav is the solution to the loss of GPS for any reason. But not all mariners desire to know cel nav to the level our parents and grandparents needed. GPS is here now and indeed dependable, although certainly not infallible. This course offers a quick way to gain the knowledge needed to have cel nav as a back up, so you need not worry about the loss of standard aids.

This course covers the basic celestial navigation needed to make your way to safety across an ocean with no special aids except one small book, a watch, and a sextant. The sextant can be the most basic available or any other of your choice. We guarantee that you can learn on your own from our books how to take sextant sights with any sextant you might have... and we can help check your sights in this course.

There are no prerequisites, and the few topics covered are quick and easy to master using our textbooks. The primary text (GPS Backup with a Mk3 Sextant) is a short book, 35 pages of text; 65 pages of tables. The tables are designed to make the process of finding latitude and longitude very fast, and very easy to learn.

We estimate that the course will take 5 to 10 hours to complete, not counting optional materials, exercises, or practice sights.

The course includes the opportunity to submit your sextant sight data to us for analysis if the results are not within specified uncertainties. The beauty of cel nav is its transparency. If the results are clearly wrong, we can almost always figure out why based on a series of sights.

Lesson Plan

1 — USE OF THE MARK 3 SEXTANT
Latitude and Longitude • Nautical miles • Introduction to the Mark 3 sextant • Sextant part names • Reading the dial • Adjusting the mirrors • Sextant height corrections • Understanding uncertainties

2 — TIMEKEEPING AND LATITUDE AT LAN
Standard time • UTC • Watch error • Watch rate • Sextant sights • Declination • Refraction • Finding latitude at meridian passage (LAN) • Understanding uncertainties

3 — LONGITUDE AT LAN
Concepts and principles • Finding peak height and time of Mer Pass • Review timekeeping • Greenwich Hour angle (GHA) • Understanding uncertainties • Shorelines and artificial horizons for practice

4 — LATITUDE FROM POLARIS
Principles of Polaris sights • Regiment of the Pole • Extension to meridian stars in the Southern Hemisphere • Understanding uncertainties

5 — PREDICT LAN TIME & UPS PLOTTING
Universal plotting sheets (UPS) • Make your own UPS • Plotting latitude as a line of position (LOP) • DR plotting • Predicting time of LAN

6 — A DAY AT SEA WITH BACKUP CEL NAV
Review basic sailboat navigation • Combine celestial sights from different times • Evaluate results • How to expand these basic methods

This course meets the ASA Standards for 117 Basic Celestial Navigation and also meets the celestial navigation prerequisite of American Sailing Association's ASA 108, Offshore Passagemaking. ASA certification is an optional add on.

If your goal is to learn the full range of cel nav that offers more versatile and accurate navigation, we recommend our standard Celestial Navigation Course.