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: The flat earth notion
    From: Trevor Kenchington
    Date: 2003 Nov 5, 09:16 -0400

    Herbert Prinz wrote:
    > On a spheroidal earth, if you proceed on a rhumb line with constant speed, you
    > will arrive at a pole after a finite time. You won't be able to stop your vessel
    > at this very moment, because of your inertia . This raises the puzzling
    > question: Where will you be a second after you will have passed through the
    > pole? Neither Dutton nor Bowditch has the answer.
    I think that Herbert is quite wrong.
    Following a rhumb line on a spheroidal Earth results in a path which
    follows a loxodrome. A loxodrome only reaches either pole after
    _infinite_ time, gradually spiralling in towards the pole but never
    quite getting there. Hence, you cannot pass through, or even reach, a
    pole while on a rhumb line, though you could get very, very close if you
    were really determined to try.
    There are four exceptions to this. A rhumb line course of 090 or 270
    will carry you around a parallel of latitude and will never approach
    either pole. I guess that that is a special case of a loxodrome, taking
    an infinite time to even approach either pole.
    In contrast, a rhumb line of 000 or 180 will carry you directly to the
    pole. When you get there, however, you cannot pass through the pole
    while remaining on the same rhumb line: At the South Pole, all possible
    headings are 000 and a course of 180 is undefined, vice versa in the north.
    Trevor Kenchington
    Trevor J. Kenchington PhD                         Gadus@iStar.ca
    Gadus Associates,                                 Office(902) 889-9250
    R.R.#1, Musquodoboit Harbour,                     Fax   (902) 889-9251
    Nova Scotia  B0J 2L0, CANADA                      Home  (902) 889-3555
                         Science Serving the Fisheries

    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