Category: Navigation

What equipment do I need for Astro-Navigation


  • Sextant
  • Watch
  • Nautical Almanac
  • Sight Reduction Tables 
  • Plotting equipment 


Metal (Quality)
New                       £500-£1000
Second Hand           £200 +

Plastic (EBCO / Davies)
New                       £100+
Second Hand           £30+


Digital Watch          £10+

Nautical Almanac                                                                                                   

The nautical almanac is essential for finding the Geographical Position (GP) of the Celestial bodies. It is an annual publication. The data is bought in book form, though is also found on-line. The ethos of Astro is to avoid electronic aids like computers, so even if the data is found on-line, a hard copy should be printed off.

Options are;

Admiralty Publication NP 314-xx (where xx is the current year)
The Nautical Almanac                    NP 314                                   £ 39.20

e.g. NP 314-12 (2012)

ISBN 978-0-70-774-1222 (2012 edition)


Nautical Almanac Commercial Edition (for current year)

American Version:

ISBN 0-939837-67-6 (2006 edition)                                              £16


iNA – Nautical Almanac for IPhone/Touch/iPad

iPhone App Store                                                                       £12 


ICE – American Hydrographic (No longer available)

This is a DOS based program that I can vouch works on Windows XP.
You may be able to get an old copy from somewhere. It’s new replacement is called  MICA.

Back of the Sight Reduction Tables (for Sun only)

There are concise tables for calculating GHA and DEC for many years ahead. They are found in the back cover of the Sight Reduction tables for Air Navigation, though they take some understanding!                                            

Sight Reduction                                                                                                                

Sight reduction tables are used for solving the PZX Triangle. If you are good with maths and trigonometry, they are not required, however, most people use them, and it is what is used in the RYA Yachtmaster Ocean Course.

Most navigators will have both volumes 2 and 3 to cover all latitudes.
Volume 1 is not required unless you plan to use the ‘7 selected stars’ method.

 NB: Sight reduction tables are solving a mathematical equation, and as such last forever.

 Sight Reduction Tables for Air Navigation AP3270

Less volumes required (the preferred option), however does limit you to less stars as only work to a maximum declination of 29 degrees

Volume 1 – Selected Stars                         £29.90 (2012)
Volume 2 – Latitudes 0-39                         £29.90 (2012)
Volume 3 – Latitudes 39-89                       £29.90 (2012)


Sight Reduction Tables for Marine Navigation NPs 401

More books to carry, but slightly more accurate. Covers all declinations, so good for all stars.

Volumes  (1) to (6)                                                   £ 28.65 (each) (2012)


Formulae for calculations using a Scientific Calculator

Found in the back of the Nautical Almanac. Though you can use a standard Scientific Calculator, I would recommend a ‘Programmable’ one to alleviate errors on entry.

Concise tables at back of Nautical Almanac

These are a nightmare! – To be used in emergency only unless you like a challenge!

Charts / Plotting Sheets                                                                           

Ocean Chart for your journey

Plotting Sheets

These special sheets are for plotting your position lines onto, before transferring your position onto a working chart. They all vary slightly, some using fixed latitude and variable longitude scales or fixed longitude and variable latitude scales. Make sure you select a suitable sheet to cover the latitudes you are working at.

Admiralty 5333A – For different latitudes

                        Large chart size sheets

IMRAY NAC0240 – Pad of universal plotting sheets
A book of 25 sheets (A3 size)

Plotting Instruments                                                                                                           

Portland Plotter or similar

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