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: Still on LOPs
    From: Rodney Myrvaagnes
    Date: 2002 Apr 18, 12:43 -0500

    George, I think you need to do better. The probability of the true
    position lying on a measured LOP is higher than it is on either side,
    not zero (Newton and Leibnitz took care of that when they invented
    If you want to simplify a normal distribution, a triangle would be a
    better approximation than two squares. And, to avoid cluttering the
    problem with intercepts, assume LOPs from bearings, rather than sextant
    The width of the distribution, whether gaussian or triangle, must
    overlap those from the other sights, and, if the three sights are
    similar in difficulty, the width of the distribution should be the same
    for all of them.
    Even if you use your rectangular distributions, they overlap only at a
    point inside the cocked hat at the narrowest possible size. Since the
    cocked hat is itself your only measure of the error width, that is as
    far as you need to go. Ergo, the way we have been doing it is correct.
    On Thu, 18 Apr 2002 20:45:30 +0100, George Huxtable wrote:
    >Well, I must admit to getting some enjoyment from confounding the
    >conventional wisdom, but it is not entirely mischief-making. There are many
    >navigators around who firmly believe that when they draw a cocked hat,
    >their true position must lie inside it. If they can be convinced of the
    >truth, that the true position is three times more likely to be outside the
    >triangle than inside it, they will reinterpret their plots with greater
    >understanding. And that can only do good.
    Rodney Myrvaagnes                                  J36 Gjo/a
    "Curse thee, thou quadrant. No longer will I guide my earthly way by thee."  Capt. Ahab

    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