Sextant navigation made simple(r)

manual titleJust before we left South Africa I asked Kris to teach me how to navigate using a sextant. We have a distrust of electronics on the boat (salt water and electronics do not love each other) because we have seen too many people rely on these gadgets, and then flounder when the gadgets malfunctioned.

Besides, there is romance in navigating using an old-fashioned sextant that modern-day GPS’s don’t seem to possess. As one sailor we met put it, what is these days referred to as “the science of astronavigation” was, once upon a time, called “the art of atronavigation”. We’ll take the art over the technology, anytime.

Kris has only ever navigated using a sextant and an accurate timepiece, and when we are sailing he uses it every day, so he’s got the operation of this beautiful piece of equipment down to a simple and functional process. When he was trying to teach me how to use it he wrote a short manual, because lots of other people have expressed the desire to learn from him, and he hasn’t got the time to sit with them all. So we’ve fixed this file up, added a few diagrams and some (admittedly poor photographs of) pages of a nautical almanac to assist with the equations, and it’s up for sale as a PDF file in my ETSY shop.

fig 1 sextant schem

A lot of people ask me to teach them sextant navigation. While the actual process is simple and easy, to become a confident navigator requires time and practice. I’ve seen so many people discouraged by the technical jargon used to explain celestial mechanics, that I have decided to write a simple how-to manual, leaving out anything that is not essential. You do not really need to understand the underlying spherical geometry to become a proficient navigator. If it takes your fancy, you can fill in the gaps later, but in the 1970ies when I learned the sextant myself, most skippers just did the trick without bothering about the theory, and it still worked.

The only mathematics involved in this manual are addition and subtraction of angles…6th grade algebra. The first man to circumnavigate the globe using a sextant and reliable clock, Captain James Cook, only had two years of formal education. When he joined the Navy at the age of 12 he could barely read and write…roughly the equivalent of a High School Certificate, these days.

I will assume that you are familiar with the concepts of latitude and longitude; namely that the Equator is designated as zero degrees of latitude, the North Pole lies on latitude 90° north and the South Pole is on 90° south.

Sections included in this manual:

  • Introducing the Sextant
  • The Nautical Almanac
  • Latitude
  • Longitude
  • Position Line
  • Finding Your Position and Some Dirty Tricks

19 pages, with 15 illustrations/figures.

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6 thoughts on “Sextant navigation made simple(r)

  1. I also get your blog posts direct to my email and don’t always comment but I just love it when I see you show up in my email. You are the most well written interesting person on the whole of the blog world in my opinion (of course I have not read anywhere near ALL). I just want you to know how you brighten my day with such interesting facts, whimsical pieces and beautiful art work. Through you I live a dream, thank you so much! 🙂 🙂 🙂

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  2. I get your blog posts direct to my email these days and relish reading every single one. Howver I don’t always comment as it involves opening a browser etc etc and I don’t always have time. But I am LOVING your journey and this particular post is really cool. I love this stuff and as my dream is to one day live on a boat then this is the kind of stuff I want to learn. Thank you and carry on being so interesting and amazing X

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    1. Loulou! I can’t believe you bought that manual! I was expecting the first customer to be a middle-aged guy with a new boat and a taste for the old-fashioned! LOL Thank you for your continued support and encouragement. Glad you enjoy the blog, and don’t feel that I am wasting your time. I wish it could be so much more…working on it, slowly, slowly! N

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