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Old 11-02-2016, 16:37   #76
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Re: A sextant for the 21st century?

You can justify your purchase by noting that although it may keep no better time than my cheap digital watch, at least it will not suffer battery failure and is less vulnerable to EMP disturbances.
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Old 11-02-2016, 21:26   #77
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Re: A sextant for the 21st century?

Since much of our continents and coastlines run fairly north-south it appears that just being able to ascertain how far north or south one is using noon sights and working from first principals to enable safe latitude sailing to a landfall would be a capability worth having.

Are the Suns apparent peregrinations north and south a straight line function or does the apparent altitude alter sinusoidaly?
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Old 09-09-2016, 11:59   #78
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Re: A sextant for the 21st century?

I went to the Goodwill outlet and bought a Pocketpc with spare batteries and accessories for$5.00 . Then I bought Pocketstars. It does and has everything. Check it out.


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Old 10-09-2016, 15:43   #79
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Re: A sextant for the 21st century?

Just spent some time down at the Antarctic festival. There was a neat display of the way they track the seabirds with miniture tags that record ambient light and temperature against time over a few years.

The results are post processed when the tags are recovered from the nesting areas to give a length of day type calc, using two methods, old school length of day, and using the shape of the curves for morning and evening.

This infomation is combined with the temperature data and DR calcs to give about 60NM resolution from a device about the size of my fingernail. Pretty impressive.

http://www.geolocationjourneys.com/s...t-and-Location

I cant help comparing it to this case of emergency navigation.

http://boats.duncan.com/caledoniayawl/aegre6.htm
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Old 10-09-2016, 19:43   #80
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Re: A sextant for the 21st century?

Can't help thinking this would be an easy app to develop. Use ambient light to measure length of day and compute a rough position. The thing could be refined with equal altitudes, or even unequal altitudes. Other refinements would be DR and Kamel assist.

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