# NavList:

## A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

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Re: New compact backup CELNAV system
From: Martin T
Date: 2009 Mar 18, 21:37 -0700

```Ken, In Gary's defense to laminate entire Nautical Almanac would be a
bit impractical. From what I understand his solution is designed to be
compact and waterproof so it could be used in an emergency  even in an
open boat, life raft etc. It fits in 8 laminated pages and provides
for all practical sights, noon, polaris, sun and star sights with
reasonable accuracy from small boat and plastic sextant. As a bonus
sight reduction capability can also be used to calculate great circle
sailings, check compass, etc.

Also, Andres, I understand you EOT and declination graphs provide fast
way to approximate GHA and dec of sun, but perpetual almanac pages
that Gary provided seem to give better accuracy and even with
interpolation tables fit on same two pages. Of course more
calculations are needed using tables.

Though in this day and age emergency navigation seems to mean drifting
in life raft without any control and praying that coast guard got your
mayday or EPIRB signal and will pick you up before water runs out.
Navigation without mobility is quite useless.

Martin

On Mar 18, 3:10�am, "Andres Ruiz"  wrote:
> 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.
>
> Andr�s Ruiz
>
>
> �http://www.geocities.com/andresruizgonzalez
>
> -----Mensaje original-----
>
> De: NavList@fer3.com [mailto:NavList@fer3.com] En nombre de Ken Gebhart
>
> Enviado el: mi�rcoles, 18 de marzo de 2009 3:50
>
> Para: NavList@fer3.com
>
> Asunto: [NavList 7665] Re: New compact backup CELNAV system
>
> Gary,
>
> 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?
>
> Ken
>
> On Mar 17, 2009, at 6:26 PM, glap...@PACBELL.NET wrote:
>
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