# NavList:

## A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

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Re: Susceptibility of GPS to CME, Rationale for CN?
From: Hewitt Schlereth
Date: 2018 Oct 1, 14:13 -0700
Francis, it's interesting that you and several others have cited fun as a raison d'etre for celestial, because at the beginning of the year, I changed the way I teach.

My course is now called The Joy of Sextant - Celestial Navigation for the Fun of It. Here I emphasize the two fundamental and enjoyable skills - using the sextant and the plotting sheet. The scut work of sight reduction is done with a smart phone app.

To give you the idea, here's the introduction of the booklet I developed and am using:

INTRODUCTION

Seen as a whole, practical celestial navigation is divided into four parts:

1. Taking a measurement of the angle between the sun, the sea horizon and your eye, and noting the time you you did it. This is called "taking a sight."
2. Computing a comparison sight by one of several methods.
3. Comparing the sextant and computed sights.
4. Plotting the difference between your sight and the computed one on a special blank chart called a plotting sheet.

Until our century, doing steps II and III required a navigator to understand a fair amount of astronomy, geometry, trigonometry, math, and do a lot of arithmetic. It was quite a bit like doing a tax return, i.e., tedious.

Nowadays a smartphone app can do the scut work of parts II and III, - "letting George do it," so to speak - leaving you the enjoyable parts.

Too, once the app is in your phone, it does not need internet or satellite connections. It's self contained. So, it's also a first step away from GPS dependence.

Hewitt

On Oct 1, 2018, at 11:15 AM, Ed Popko <NoReply_EdPopko@fer3.com> wrote:

I have to agree with Dave overall point.

I find celestial navigation extremely rich. I don't own a boat (anymore) and never did deep water sailing when I did.  But it doesn't matter. What's important, to me anyway, is the beauty of form of applied obserational astronomy. For me, that's justification enough.  It's a wonderful medium to learn and appreciate the sky as well as the evolution of technique and equipment.

Much of what man does with nature is distructive. We are quite skilled at destroying nature - consuming, extracting, hording, poluting. But CelNav is different. It's all about information - extracting angles, relationships, visibility, timing, direction.  There's something quite elegant here.

And then there is the other dimension, time and history. CelNav opens so many doors to maritime and aviation history, science, innovation and personalities.

But perhaps the simplest reward is the confidence you can figure out where you are and what time it is (Lunars).

So, when my wife sees me in the back yard taking shots and quips "Has the house moved?" I just think of what she misses.

Popko

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