Sight Reduction Tables
These Sight Reduction Tables have been condensed into as compact a form as possible. Each set of tables covers seven degrees of Latitude, which should satisfy the needs of most people. Simply download the set, or sets, that best matches your cruising latitude.
The files are ~750KB each.
Taking a leaf out of the Air Tables, pub 249, here are a set of sight reduction tables that return Integer values for Hc, d' and Z. They are easier to read and should make the whole sight reduction process a little quicker with minimal impact on accuracy.
Latitudes 7-13 Integer
Latitudes 14-20 Integer
Latitudes 21-27 Integer
Latitudes 28-34 Integer
Latitudes 35-41 Integer
Latitudes 42-48 Integer
Latitudes 49-55 Integer
Latitudes 56-62 Integer
Latitudes 63-69 Integer
Latitudes 70-76 Integer
Latitudes 77-83 Integer
Latitudes 84-90 Integer
Declination in these Sight Reduction Tables is limited to 23 Degrees. The rationale being these tables are for reducing a Sunsight where the declination never exceeds 24 Degrees.
Most of us amateurs sail in the summer when Latitude and Declination are the SAME. These tables make the transition from SAME, at the front, to CONTRARY towards the rear, as seamlessly as I could contrive. No flicking through SAME/CONTRARY/SAME/CONTRARY page after page.
Where in the tables the transition from SAME to CONTRARY occurs depends on your selected Latitude and LHA. It should all become clear when you start using the tables.
It's also worth pointing out that Sight Reduction Tables do NOT go out of date. Download them once, print them, bind them with nice covers and they're yours forever.
These Sight Reduction Tables include pages for GHA minutes and seconds interpolation, Declination interpolation and Sextant corrections.
What's New• 2024 Almanac uploaded.
• Sunsight.xls, improved error trapping and data entry.
• Links page updated.
Sight Reduction & Plotting Sheet.
Print double sided and on one side you can reduce morning, noon and afternoon sights, while on the reverse you will find a plotting sheet adapted from Andrew Evans' Sextant User's Guide. Ideal for that "Sun-run-Sun" sight.
Universal Plotting Sheet
For the more traditional minded here is a universal plotting sheet to try.
The Sextant Simplified
by Captain O M Watts.
Printed in 1947 it is still an excellent introduction to the sextant.