Celestial Navigation? Forget it! - Page 31 - SailNet Community
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post #301 of 330 Old 12-20-2008
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Lapworth,

I have the Bowditch book, Also known as The American Practical Navigator. If you don't have it I recommend you pick one up. There is more information other then CN in there.

Dennis
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post #302 of 330 Old 12-21-2008
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Quote:
Originally Posted by MaryBeth View Post
I notice no other posts from EscapeArtist. Perhaps he/she is either a GPS or sextant salesperson in disguise?

Sorry,
MaryBeth
A few years ago I spoke with guy from a company exhibiting celestial navigation supplies at a trade show. I asked him how GPS had affected his sales. He told me they were way UP, not down! He said that he beleived the reason was that previously only people that NEEDED celestial navigation took the time to learn it. It was also too difficult to learn while actually sailing because you never REALLY knew where you were, and always had the uncertainty of how good your calculations are. However, when your primary means of navigation is GPS, and you are very sure of where you are, then the sextant becomes fun to use. You have an absolute target to measure against, so you are immediately sure of whether you did it right, and can check you calculations right then and there to figure out what you did wrong. You can try different techniques for taking a sight, and almost instantly determine whether it improves your accuracy. So learning is much easier too. So it is likely you will be MUCH better able to actually use the sextant if needed. Interesting thoughts!
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post #303 of 330 Old 12-26-2008
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You do realise that the only real way to check an error on a gyro compass is to take an azimuth. Also there are numerous computer programs which mr electronic i'm assuming you have on board that will work out sights automatically, so your'e argument is flawed.

The United States government has a program in its gps that allows them to change and disconfigure (they say it's disabled but come on) the system, this was used primarily in the cold war.

and also if you're going to lose sextants why not lose anything reasonbly old like learning to tie a monkeys fist (unless your vessel is considerably large, you have no need of a heaving line) e.t.c

We learn these things because one day we might need them.

Finally if you read the nautical almanac it talks you through how to reduce sights.
and this is coming from a person who's only 20 years old.


(ALSO i agree with denby the Bowditch is a brilliant book)

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Last edited by Davidrogerson; 12-26-2008 at 12:45 AM. Reason: I had to put in a smiley face otherwise people don't understand my humour
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post #304 of 330 Old 12-26-2008
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So, I'll apologize for hijacking this thread, and please feel free to redirect me elsewhere on the forum if it's already been discussed.

I'm interested in buying a sextant to learn and practice CN. However I am fairly sure I'm not going to lose interest and therefore would not like to buy a "better" one someday. Finally, I am not wealthy.

So I'm thinking of either getting an inexpensive working reproduction, or finding one in a pawn shop or something. If I go with the latter option, any recommendations for how to examine a sextant to determine whether it's useful and in good condition?
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post #305 of 330 Old 12-26-2008
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Quote:
Originally Posted by denby View Post
Lapworth,

I have the Bowditch book, Also known as The American Practical Navigator. If you don't have it I recommend you pick one up. There is more information other then CN in there.


I try to link this every time i see it come up. American Practical Navigator is available in for free from the NGA:

Maritime Safety Information

Click on the complete version, or you can download each chapter. The complete version is 35 MB.

In adition to that, you can get all nautical publications for free by clicking on the "Publications" link on the left hand side of the screen and then choosing a pub from the dropdown list. You can get American Practical Navigator, Chart No. 1, Sight Reduction Tables, Radio Navigational Aids, Pilot Charts, US Notice to Mariners, etc etc. All are free for download.

Dictated, but not read.

Last edited by Sapperwhite; 12-26-2008 at 03:37 AM.
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post #306 of 330 Old 12-26-2008
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Don't go with a reproduction one, since most aren't made with any sort of accuracy. You can get a decent sextant, either plastic or if your budget affords it, a metal one for less than you'd think. If you have questions about a sextant, the best book to get, is Bruce Bauer's The Sextant Handbook. It has a very good section on how to examine a sextant for specific problems, and whether the sextant is worth purchasing...
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Originally Posted by AdamLein View Post
So, I'll apologize for hijacking this thread, and please feel free to redirect me elsewhere on the forum if it's already been discussed.

I'm interested in buying a sextant to learn and practice CN. However I am fairly sure I'm not going to lose interest and therefore would not like to buy a "better" one someday. Finally, I am not wealthy.

So I'm thinking of either getting an inexpensive working reproduction, or finding one in a pawn shop or something. If I go with the latter option, any recommendations for how to examine a sextant to determine whether it's useful and in good condition?

Sailingdog

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post #307 of 330 Old 12-26-2008
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The United States government has a program in its gps that allows them to change and disconfigure (they say it's disabled but come on) the system...
Something like that. They have the ability to introduce random error into the non-military signal. It's currently turned off and, with todays dependence on GPS, it is considered unlikely it'll ever be turned on again.

Jim
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post #308 of 330 Old 12-26-2008
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Celestial Nav is to GPS Nav what Morse Code is to Radio Communications. Both CN and Morse Code are now art forms practiced by people who truly enjoy using them. When MC was no longer required for an Amateur Radio license the doom and gloomers said the world was sure to end etc.etc. The same is being said of GPS now. Remember one must learn all sorts of interesting things (basic seamanship, basic navigation, using a compass, making sure you have enough fresh fuel for your aux motor, and on and on) before he or she can safely sail across a bay much less an ocean.
Yes I have a chart plotter, several GPS, a few paper charts, a computer filled with electronic charts. My most important tool is between my ears. I can see my compassd or listen for a fog horn if necessary. I know when to drop an anchor and wait out a bad weather situation. Taking unnecessary chances is not macho or wise.
If you believe that CN is a vital tool that you must have, take the time to learn it to proficiency.
Please enjoy your outing today as none of us knows how many more we have.
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post #309 of 330 Old 12-26-2008
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Quote:
Originally Posted by Sapperwhite View Post
I try to link this every time i see it come up. American Practical Navigator is available in for free from the NGA:

Maritime Safety Information

Click on the complete version, or you can download each chapter. The complete version is 35 MB.

In adition to that, you can get all nautical publications for free by clicking on the "Publications" link on the left hand side of the screen and then choosing a pub from the dropdown list. You can get American Practical Navigator, Chart No. 1, Sight Reduction Tables, Radio Navigational Aids, Pilot Charts, US Notice to Mariners, etc etc. All are free for download.
Sapp,

Thanks for the link.

Cam is going to be so happy this thread is still alive.

Dennis
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post #310 of 330 Old 12-27-2008
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Thankyou Jim

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