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    Re: New compact backup CELNAV system
    From: Andrés Ruiz
    Date: 2009 Mar 18, 11:10 +0100

    Yes, I am interested in the Bygrave proyect, and Gary kindly has sent me some information. I have "historical" interest.


    But or backup celnav system or Emergency Navigation I prefer to use the Sun: a Noon Sight. The necessary material is:

    • Annual curve of the Sun’s declination. For Latitude calculation. (pdf for 2009)

    • Annual curve for the equation of time. For Longitude calculation. (pdf for 2009)

    • A watch set to UT.

    • A Plastic Sextant - backup emergency sextant, (Davis Mark 3, …).

    • A table with Dip, Refraction and PA, assuming: HP = 0.14', SD = 16'

    • A copy of a general nautical chart, or a map. You must know where the point of the calculated latitude and longitude is.

    • A pencil and paper


    It is a very simply system, and playing with it I have obtained a position with an error of a few tens of nautical miles.


    Andrés Ruiz

    Navigational Algorithms





    -----Mensaje original-----

    De: NavList@fer3.com [mailto:NavList@fer3.com] En nombre de Ken Gebhart

    Enviado el: miércoles, 18 de marzo de 2009 3:50

    Para: NavList@fer3.com

    Asunto: [NavList 7665] Re: New compact backup CELNAV system





    The interest in your Bygrave project has been great and well 

    deserved.  But when talking about "backup" systems, I think about one 

    who is ill versed in CN, and just wants to make a safe landfall 

    without his failed GPS.  In this situation, I feel that using simple 

    noon sight procedures supplemented by sunrise/sunset longitudes, and 

    polaris Lats would be fine.  All that would be needed would be the 

    Nautical Almanac (for the Sunrise/ Sunset things) and would have the 

    included SR Tables for intermediate sights.  One might not prefer 

    these NA SR tables, but they DO work, and in a backup situation, why 

    be choosey?



    On Mar 17, 2009, at 6:26 PM, glapook@PACBELL.NET wrote:

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