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: No sextant, no watch, no almanach, nothing
    From: Trevor Kenchington
    Date: 2004 Nov 5, 23:56 -0400

    Geoffrey's method would need a star catalogue but not necessarily an
    almanac. Since the stars are fixed (at the level of precision of
    instrument-free navigation), the declinations of the brighter ones can
    be learnt with relatively little difficulty. (Equivalent knowledge,
    though not expressed as "declinations", formed a key component of
    traditional Polynesian navigation. It didn't need the support of
    astronomers, telescopes and printed tables of numbers.)
    Determination of the zenith without a sextant is said to be possible by
    lying on deck, sighting up the mast, and visually averaging the position
    of the masthead against the sky. However, I think I would rather
    memorize the stars with declinations equal to my chosen co-latitude.
    When on the intended parallel, those stars should of course be just
    circumpolar, grazing the horizon at each inferior meridian passage --
    something that could be observed with reasonable precision at tropical
    and temperate latitudes.
    Or you can make a kemal suited to the latitude you are planning to sail
    down, particularly if it is in the northern hemisphere and Polaris is
    Trevor Kenchington
    You wrote:
    > Dear Geoffrey,
    > I am not sure that I really understand the details of the method you
    > describe but it seems to be based on the almanac.
    > The people you mention just used the almanac BEFORE
    > their trip to select the stars.
    > In principle, you can memorize some data from the almanac,
    > then leave the almanac at home and use the data from your
    > memory:-)
    > For example, the hero of Mark Twain novel "Yankee at the court of
    > king Arthur" memorized the day and time of a solar eclipse:-)
    > (He just happened to read an almanac before his travel.)
    > I would not call this "navigation without almanac".
    > Second, how do you detect without a sextant when a star it in zenith?
    > I don't think this is easy to do.
    > Alex.
    Trevor J. Kenchington PhD                         Gadus{at}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