Welcome to the NavList Message Boards.


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

Compose Your Message

Add Images & Files
    Re: Susceptibility of GPS to CME, Rationale for CN?
    From: Francis Upchurch
    Date: 2018 Oct 2, 05:41 +0100

    Thanks Hewitt,
     Your writing has always been fun to me, starting with my very first exposure 
    to CN in your "Commonsense" book.(Thanks for that. My wife has other words 
    for you though!)
    You also got me on to using slide rules to do the math, "just for fun", which 
    adds to my fun, sans smartphone (which is great but needs daily charging, a 
    major negative in emergency survival situations).
    My emergency grab bag contains an Otis King slide rule, miniaturised log 
    tables, Greg's compact Daniol, and charts, Quartz watch set to GMT, Davis 3, 
    Casio Fx-365OP programmable calculator with all the main methods 
    pre-programmed in. (Very robust compared to a smartphone and does not require 
    charging). Hope to  never have to use it, but I do practice runs 
    occasionally, just for fun. 
    Keep spreading the Joy Hewitt. 
    Let's all have fun now. It's later than you think.
    -----Original Message-----
    From: NavList@fer3.com [mailto:NavList@fer3.com] On Behalf Of Hewitt Schlereth
    Sent: 01 October 2018 22:31
    To: francis{at}pharmout.co.uk
    Subject: [NavList] Re: Susceptibility of GPS to CME, Rationale for CN?
    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:
    Seen as a whole, practical celestial navigation is divided into four parts:
    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."
    Computing a comparison sight by one of several methods.
    Comparing the sextant and computed sights.
    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 
    On Oct 1, 2018, at 11:15 AM, Ed Popko  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 
    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 
    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.
    View and reply to this message
    View and reply to this message: 

    Browse Files

    Drop Files


    What is NavList?

    Join NavList

    (please, no nicknames or handles)
    Do you want to receive all group messages by email?
    Yes No

    You can also join by posting. Your first on-topic post automatically makes you a member.

    Posting Code

    Enter the email address associated with your NavList messages. Your posting code will be emailed to you immediately.

    Email Settings

    Posting Code:

    Custom Index

    Start date: (yyyymm dd)
    End date: (yyyymm dd)

    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site