The Noon Sight: An Anachronism?

[seanpatrick]

Hello!

I took up celestial navigation as a hobby recently. Don't ask me why...I don't own a boat. I can barely even swim. But nonetheless I find it fascinating.

Anyway, for my birthday this year I got the book "100 Problems in Celestial Navigation" by Leonard Gray. Up to this point I have been teaching myself by reading the Nautical Almanac, Pub. 229 and whatever I can find online. I've even shot a successful Lunar with my Davis Mk 15. But I was reading through the "Procedures" in Appendix B of "100 Problems..." and on page 94 the author states:

"The noonsight is an anachronism - it is not recommended as useful for practical navigation."

And a few lines later:

"If you want to do it anyway, as a connection with your pre-chronometer ancestors[...]here's how."

My question is: Why would the noon sight not be useful? Using it you can fairly accurately obtain your Latitude and Longitude. And why would it connect you with "your pre-chronometer ancestors" when you need an accurate chronometer set at GMT for the process?

Thanks,
Sean

[killarney_sailor]

Perhaps the author is dismissing it as being unworthy of his talents (serioiusly). You don't really need to use a chronometer for it since you can just start a few minutes before local noon and keep taking sights until the elevation stops increasing and starts to increase. The maximum angle you get is noon at your longitude. With a few simple calculations the noon site will give you your latitude.

[cb32863]

I wouldn't worry too much about it. As Killarney said, maybe the author is "above" it for some reason. I took a celestial nav class back the spring, they used David Birch's book, Amazon Link, I found it very informative and a great learning too. Get a general navigation book too and you can have some good fun. One thing to try too... If you have a hand held GPS, get your self some waypoints, then go out there with your sextant and see how accurate your sights and calculations are. I am going to be doing that over the winter. Have fun doing it "Old School".

[seanpatrick]

Thanks!

[AdamLein]

Originally Posted by killarney_sailor:784000

Perhaps the author is dismissing it as being unworthy of his talents (serioiusly). You don't really need to use a chronometer for it since you can just start a few minutes before local noon and keep taking sights until the elevation stops increasing and starts to increase. The maximum angle you get is noon at your longitude. With a few simple calculations the noon site will give you your latitude.

You still need the time at Greenwich if you want to know your longitude.

The noon sight isn't any more an anachronism than using wind for propulsion.

[St Anna]

Originally Posted by killarney_sailor

Perhaps the author is dismissing it as being unworthy of his talents (serioiusly). You don't really need to use a chronometer for it since you can just start a few minutes before local noon and keep taking sights until the elevation stops increasing and starts to increase. The maximum angle you get is noon at your longitude. With a few simple calculations the noon site will give you your latitude.

Absolutely.

Also at noon, the sun is due north of us (south for you)