Welcome to the NavList Message Boards.

NavList:

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

Compose Your Message

Message:αβγ
Message:abc
Add Images & Files
    or...
       
    Reply
    Re: Latitude by law of cosines
    From: Chris Caswell
    Date: 2018 Jan 23, 12:07 -0800

    Frank Reed, you wrote:

    Chris Caswell, you wrote:
    "Are you saying John Karl's equations are wrong, or inaccurate?"

    Chris, I thought I was pretty clear on all of this, but let me try to re-phrase:
    First things first: you don't need this! No one calculates latitude this way, except in quite peculiar circumstances. It is never the case that we know the exact hour angle (or equivalently the exact GMT and longitude) and do not know our latitude. This is just one of those little "idiosyncracies" in John Karl's book. There's plenty of good material in there, of course, but also quite a few oddball bits like this that are not properly explained. If you never saw this calculational trick in your whole life as a navigator, you would not be diminished in any way.

    Let me ask you, Chris, do you have any questions about what I have just written in this paragraph? Do you understand what I am saying here? Please feel free to ask for clarification.

    Yes, Frank, got it. I also get noon sights, and have done just a few.

    Frank Reed wrote:

    You talked about wanting to solve a middle-of-nowhere scenario, where a navigator is "dropped" somewhere in the world with no clue about location. I want to assure you, again, that the equations you previously referenced in John Karl's book are not the answer... and they're not an answer. I am not being disingenuous when I tell you that there's no real use for that particular set of equations in a scenario like this (or, indeed, any practical scenario).

    Do you understand what I am saying here? Do you have any specific questions about what I have said here?

    Got that as well.

    Frank Reed wrote:

    But just so you know, there is an algorithm in Karl's book which some people cite as a tool for solving exactly this sort of middle-of-nowhere mystery. It's at the end of chapter 7 on "special sights", his formulas 7.5a-f. There are different printings of this book, and the pagination of yours doesn't match mine (as I have alread discovered) so I won't give a page number. I hope that description is enough to find the formulas in question, and you can explore those as you like. They are straight-forward, though a bit tedious.

    I have found the reference and will look into it.  Thank you for all your time and help.

    Chris in VT

       
    Reply
    Browse Files

    Drop Files

    NavList

    What is NavList?

    Join NavList

    Name:
    (please, no nicknames or handles)
    Email:
    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:

    Email Settings

    Posting Code:

    Custom Index

    Subject:
    Author:
    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