GPS Backup with a Mark 3 Sextant: All Instructions and Tables Included; For Any Ocean, on Any Date; No Background in Celestial Navigation Required.

by David Burch, Tobias Burch (Design)

Our guiding principle for this booklet was to provide a means of learning and executing a position fix at sea when a vessel has run out of power and all the batteries have been consumed, so there is no GPS available. We wanted a solution that is compact and inexpensive, using tables and procedures that are easy to learn and use. This goal led to our proposing a minimum kit that mariners would not hesitate to add to their gear to cover the unlikely situation it would actually be needed. Mariners who cross oceans in small boats realize they must be self-reliant and cover all contingencies.
For those who do not have the chance to learn the full range of celestial navigation before departure, this booklet and a Mark 3 sextant provide a minimum backup kit that can be used to navigate across any ocean if needed. 

This book includes a 60-page Almanac of the sun to provide quick and easy solutions for Latitude and Longitude, as well as a unique new method for finding the corrections needed to find Latitude by Polaris, as well as in depth discussion of how to use a Mark 3 plastic sextant with emphasis on reading the angle scales.

Contents
1. OVERVIEW
2. SEXTANT SIGHTS WITH THE MARK 3 SEXTANT
     Reading the Sextant Scales
     Adjusting the Index Mirror
     Index Mirror Adjustment Using Only a Sea Horizon
     Index Mirror Adjustment with a Star
     Index Mirror Adjustment with Cloud Edges
3. TAKING SUN SIGHTS
     Aligning the Sun on the Horizon
4. A COOKBOOK APPROACH TO FINDING POSITION
     Correcting the Sextant Height to get the Observed Height
     Finding Latitude and Longitude From the Sun
     The Recipe
     Finding the Peak Height of the Sun
     Finding the Time of LAN
     Sailing Under the Sun
5. WORKED LAN EXAMPLES
     Latitude Example 1
     Easy LAN Rule
     Longitude Example 1
     Latitude Example 2
     Longitude Example 2
6. LATITUDE BY POLARIS
     Latitude by Polaris Example
7. PLOTTING POSITIONS AND DR TRACKS
     Setting Up a Universal Plotting Sheet
     Using the Plotting Sheet
     Getting by Without Dividers
8. BACKGROUND INFORMATION
     8.1 Timekeeping in Navigation
     8.2 Lat, Lon, nmi, and DR
     8.3 Adjusting the Index Mirror on Land
     8.4 Predicting the Time of LAN From Your DR-Lon
     8.5 Principles of the Noon Sight for Lat and Lon
     8.6 Universal Rule for LAN
9. GPS BACKUP KIT--THEME AND VARIATIONS
10. REFERENCES
11. TABLES
     Sun Almanac
     Refraction Table, Dip Table, Polaris Table
     Increments Table

108 pages, Paperback

Published June 6, 2018

Reviews

[Michael · Rating 5 out of 5]

Sigh of Relief

40 or so years ago I seem to have a read a booklet similar to this, and I would not find it. It is a FABULOUS backup to electronic failure nowadays, but even as recent as 30 years ago when I sailed to Bermuda using HO249, something of this sort could have been worked out solely in the cockpit,should,the other tables have gone overboard ....

[Frank Pernett · Rating 5 out of 5]

Very informative