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Old 08-10-2014, 23:47   #1
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Basic Celestial

I know it is totally retro, there is no practical reason to so this, but I want to learn how to use a sextant.

I have a Davis model 25 and an artificial horizon, but I think I need tables sun next (and maybe some basic instructions). I hear that Bowditch volume 2 has the tables, but are they available online? How can I get the tables I need (at a reasonable cost) and a set of basic instructions on how to learn the process?

Thanks for any advice you can give me!

Northwest sailor
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Old 09-10-2014, 00:03   #2
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Re: Basic Celestial

The Nautical Almanac is available on line http://navsoft.com/2014_Nautical_Almanac.pdf

Not sure if or where you can get the sight reduction tables ( air tables) though.

And a second hand copy of Nories Norie's Nautical Tables (Nories Nautical Tables): Capt. George Blance: 9780852889459: Amazon.com: Books would be a handy thing to have.

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Old 09-10-2014, 00:54   #3
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Re: Basic Celestial

Got an andriod phone? there is a sight reduction app, that includes the almanac, called StarStruck. Works great!
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Old 09-10-2014, 09:37   #4
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Re: Basic Celestial

Instructions 'for dummies' http://www.bethandevans.com/pdf/Sext...%20GuideV6.pdf

Slightly more sophisticated instructions: http://www.bethandevans.com/pdf/astro.pdf
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Old 09-10-2014, 10:03   #5
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Basic Celestial

Bowditch: http://msi.nga.mil/NGAPortal/MSI.por...2&pubCode=0002

HO229: http://msi.nga.mil/NGAPortal/MSI.por...2&pubCode=0013

HO249: http://msi.nga.mil/NGAPortal/MSI.por...2&pubCode=0012

That's a bunch free stuff that should be useful.

If learning celestial is intended as a backup for electronic nav then consider the $30 odd for http://www.amazon.com/gp/aw/d/091402...&robot_redir=1.
It has long term almanac for sun and stars and a compact sight reduction table. Neither is as convenient as the regular tables but it is much more compact and the almanac is good thru 2050.


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Old 09-10-2014, 10:25   #6
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Re: Basic Celestial

Do you have the owners manual for your Davis sextant? I know the Davis cheapie sextant (Mark 3?) had instructions in the back for shooting a sun sight and I suspect the manual for yours will also. First thing to do is go into your back yard or find a field and start taking sights with your artificial horizon. If you have a tree line or fence in your back yard, you can make a correction for that using your artificial horizon and then just take sights pretending the fence top or bottom is the horizon.

As mentioned, H.O. 229 and H.O. 249 are both available online in PDF form, just do a search.

Have fun!
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Old 10-10-2014, 22:25   #7
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Re: Basic Celestial

I would recommend the book, Celestial Navigation in a Nutshell, by Hewitt Schlereth. It's one of the easier tutorial books to understand.
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Old 10-10-2014, 23:09   #8
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Re: Basic Celestial

Here's a free book you can download:

http://www.teacupnavigation.net/Cele...a_Teacup_u.pdf
which was found at
Celestial Navigation

This uses a calculator for the sight reduction, not appropriate if you want to learn to use the tables for sight reduction.

Has a good chapter at the end about how to use a sextant to determine your circle of position by measuring the horizontal angle between two landmarks.
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