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 and Longitude by "Noon Sun"
    From: Robert Eno
    Date: 2005 Jun 5, 19:32 -0400

    An old friend of mine, who passed away a few years ago, and who was an
    experienced navigator for over 60 years, once told me that the noon sun shot
    was overrated; that all you had to do was to take a few shots with an
    interval of 2 - 3 hours then transfer one of the LOPs. Fred and a number of
    other list members seem to agree, and so too, do I.
    
    Mind you the noon sun shot is fun to do and very simple to calculate. For
    this reason, it should remain as one of the basic mainstays of
    astro-navigation, however, taking and reducing a sun shot at any other time
    is painfully easy with calculators and with HO 249 (AP3270 in Britain and
    Canada).
    
    George has a very good point about crossing the ocean without GPS and with
    someone who only knows how to take a noon sight. This is something I harp on
    when discussing GPS with the uninitiated. The argument that some students
    will be detracted from learning astro-navigation if things become too
    complex has merit, however, my response would be that I would not bother
    wasting my time in trying to train someone who is not committed to learning
    it properly. No pain, no gain.
    
    I won't delve into the "what ifs" (what if my watch went overboard etc.).
    
    Robert
    
    ----- Original Message -----
    From: "Fred Hebard" 
    To: 
    Sent: Sunday, June 05, 2005 11:42 AM
    Subject: Re: Latitude and Longitude by "Noon Sun"
    
    
    > On Jun 5, 2005, at 10:50 AM, George Huxtable wrote:
    >>
    >>
    >> I ask nav-L members if they would be happy to cross on ocean, without
    >> GPS,
    >> with a "navigator" who had learned his craft in that way, and was
    >> unable to
    >> handle any other observations than those of the Sun at noon. That's
    >> what I
    >> fear will happen, if such individuals can claim some qualification in
    >> "celestial navigation".
    >>
    >
    > In response, I don't find the intercept method any more difficult to
    > understand geometrically than a noon shot.  The basic flag pole
    > analogy, much derided here, seems adequate to me, only requiring that a
    > spherical surface and infinitely tall pole be substituted to achieve
    > reality.  While building the infinitely tall pole, an instructor would
    > get to talk about parallax.
    >
    > Using pen and paper methods of sight reduction, LOP navigation is more
    > difficult, but not with a calculator or computer.  Also, using the Air
    > Almanac, LOP sight reduction on paper is much easier than the Nautical
    > Almanac/HO-229 or predecessors.  The Air Almanac seeks 1.0' precision
    > while the Nautical Almanac seeks 0.1' precision.
    >
    > George's comments about taking a prolonged series of sights while
    > underway are well taken.  Not only would it take a long time to take
    > the shots, but a clear sky is needed.  Why not take a quick morning,
    > noon and evening shot?
    >
    > One point about a traditional noon shot is that the sun often peaks out
    > from behind the clouds at noon for a few moments even on days with
    > heavy overcast.  There is a story famous to me about a passenger on a
    > ship asking why all the officers had their sextants out under a cloudy
    > sky at noon, only to be informed by the captain that the sun often
    > would peak out for a bit, and sure enough it did.  That's also been my
    > experience at 36N in the mountains.
    
    
    

       
    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