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Old 24-02-2015, 20:40   #16
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Re: Materials for learning celestial navigation in an emergency

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Originally Posted by Sam Plan B View Post
The DVD is still available on line.
I'm curious.

How will a DVD help on a life raft after "...all electronics fail"?

As a cute little signal mirror?
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Old 03-07-2015, 08:53   #17
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Re: Materials for learning celestial navigation in an emergency

Celestial Navigation in the GPS Age, by John Karl.
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Old 03-07-2015, 17:30   #18
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Re: Materials for learning celestial navigation in an emergency

The Concise Sight Reduction tables in The Nautical Almanac are/is a horrible way to do a sight reduction. They're too difficult to understand, the directions were written by some impersonal "math type" that'll only confuse most people.

Most....most celestial navigation books are written by those very people who can explain why it works but not how it works and salivate over solving the PZX triangle. But they can't explain it to us mere mortals.

Face it- we want to determine our position in the easiest, quickest manner with less reliance upon electronics (as in an emergency) and less ambiguity.

Burch's book, Mary Blewitt's (great name) Karl's book are so confusing as to leave most people lost and helpless. Bowditch is in the same category- too darned hard to understand.

Those inclined to math and abstract concepts will do well with those sort of books.

Most of use just want to know how to do celestial navigation in the simplest terms.

So then, what to do? Buy a sextant. For practicality and cost there are 2 possible choices- the Davis Mark 15 (plastic and not too accurate) and the Celestaire Astra III-B. The Astra III-B is most prolific marine sextant.

Get William F. Buckley's DVD- Celestial Navigation Simplified. Get The Nautical Almanac from- The Nautical Almanac

Learn to do Sun sights and determine Latitude using Polaris. If you learn how to determine LAN (Local Apparent Noon) you can easily figure out Longitude. Here's how to do it-

Formulas

Even if you learn nothing at all- learn to determine latitude using Polaris. Then you can, at least, figure out your Latitude.

Clear skies
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Old 03-07-2015, 17:40   #19
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Re: Materials for learning celestial navigation in an emergency

Without any preparation?

Forget about it. No book can guarantee you will understand how to check the sextant for misalignment, and then figure out how to use the reduction tables.

For 1/4 of the price of a low-priced sextant and a couple of books, you buy an extra cheap GPS and a brick of "ten year storage life guaranteed!" batteries for it.

And you'll have a position you can just read and copy, without spending hors or days trying to figure out how to use a bulky kit. Assuming there's enough clear sky to use it.

Unless you plan to LEARN the sextant and get familiar with it, don't even waste time, much less space and money, thinking about it.
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Old 03-07-2015, 18:00   #20
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Re: Materials for learning celestial navigation in an emergency

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Originally Posted by tominny View Post
What materials should be part of an emergency celestial navigation kit that would allow anyone to chart a current position without any prior knowledge about celestial navigation? For example if all electronics fail or for fun on a ling passage.

Is there a book that explains the practical aspects and the steps very well?
I already bought a used Simek III sextant. Do I need to have it adjusted by someone?

Thanks!
Sextant which you have.

3 cheap Casio water proof watches
small, hip pocket, Rite-in-the-Rain note pad (This is for logging the error rates of the 3 watches, updating once a week while on passage will be sufficient).
Long Term Almanac by Geoffry Kolbe
Plotting sheets, Laminated
Sight worksheets, laminated
erasible drymarker
Small steel metal box to keep the Casios in
You can download Celestial Navigation in a Nutshell for free, though I have no opinion on how well written it is.


I assume this is in case of failure of the electrical system on the main boat.
Potentially you could use this on a lifeboat assuming you had some means to affect your course.
There would be little practical use on a life raft other than morale boosting since there is little ability to affect course on a raft.

I would practice using this equipement once per week when the watch errors are checked and recorded . When you take a sight, hit the MOB button in the GPS, work the sight and then check how close you came to the MOB. Count on errors in the 2-5nm range with practice. When you take sights, it's best to take a series of sights and times over 1-2 minutes and average all of them, this will improve your accuracy.

Regarding the watches don't ever reset them except well before you leave on passage, like at least 4 weeks.

The metal box is to protect the watches in case of a lightning strike.

If you want to go with a competely electronics free system there are a few more things to get. If you want I can give you a short list for that.

How much navigation have you already done? A little understanding of normal visual navigation would help you understand the Celestail.
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Old 03-07-2015, 22:13   #21
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Re: Materials for learning celestial navigation in an emergency

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Originally Posted by tominny View Post
Is there a book that explains the practical aspects and the steps very well?
There are plenty of books. The question is which one will work for you? No way to know without reading several, people absorb, process and think about things differently. Here are a few free on-line PDFs and a PPT you can start on.

http://www.bethandevans.com/pdf/Sext...%20GuideV6.pdf
http://physics.gmu.edu/~hgeller/astr...estNavig19.ppt
http://msi.nga.mil/MSISiteContent/St...N/Chapt-16.pdf


Quote:
Originally Posted by tominny View Post
I already bought a used Simek III sextant. Do I need to have it adjusted by someone?
There are at least 4 types of error you can address yourself: Index error,side error, perpendicularity error and collimation error.

For a good drawing of how to detect perpendicularity error see page 268 of: http://msi.nga.mil/MSISiteContent/St...N/Chapt-16.pdf

Removing Error - Ocean Navigator - January/February 2003.

http://www.uscg.mil/auxiliary/public...ec8Sextant.pdf
http://www.suomennavigaatioliitto.co.../mark15_25.pdf
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Old 04-07-2015, 05:48   #22
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Re: Materials for learning celestial navigation in an emergency

Many modern "yachtsmen" have never seen a paper chart, much less had any practical experience in the principles of basic piloting.
If you can't figure set, drift, variation, deviation, current vectors or any of the rest you are wasting your time thinking you pull out your sextant on a heaving small vessel and read your position! I have met several "yachtsmen" who can't even steer by a compass ! Start at the begining with piloting and DR skills. Learn the leeway characteristics of your vessel, to estimate speed, distance on a DR plot. How to contruct a Mercador chart....In other words learn your trade! And yes thr DOD can, will, and has shut down stratigic sections of the GPS constellation for defense purposes. It happened after 9-11 along the eastern seaboard during the G-8 meeting. There are an unpresedented number of hotspots in the world presently and anything might happen.
Modern electronic gadgets while being easy to use, have nurtured a generation of IPad navigators who have a false dependency anf faith in their "preposterous gadgetry".....
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Old 04-07-2015, 18:22   #23
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Re: Materials for learning celestial navigation in an emergency

Hapless yachtsman had to be rescued twice as he tried to sail 300 miles.He used nothing but a mobile phone app to navigate the British coast. Ran into difficulty forcing lifeboats to be launched in two rescue bids




Yachtsman rescued twice after trying to sail 300 miles using APP | Daily Mail Online
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Old 04-07-2015, 23:53   #24
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Re: Materials for learning celestial navigation in an emergency

The OP could probably do worse than download and read through this boring old stuff... Some Celestial Stuff
which was written so that I could understand it...
After the event I met a 13 year old who had succesfully completed the course and been awarded the certificate... one of about 3500 to do so.... can't be too hard... enjoy.
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Old 17-07-2015, 01:07   #25
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Re: Materials for learning celestial navigation in an emergency

Hi Tominny
You'll need

1) Sextant, one with a good scope on it, if you want to sight stars, your looking at $900 to $1200 Australian Dollars.

2) Nautical Almanac for the year your in e.g. 2015, nun of this multiple year stuff.

3) A star finder, so you can identify what star you have taken the sight of, there are only 57 Navigational stars, not including, the Sun, Moon & Planets. You need the stars name so you can Declination & SHA (you don't need to no what that means just where to find it, and that stuff is in the Almanac.

4) a Scientific Calculator, CASIO fx-570MS or latest model 20 bucks should cover that.

5) Pencil, rubber, sharpener & full size note book.


6) A good watch, very easy to read minutes and seconds, it can be set on your local time, and converted to UTC time later when doing the working out. but all reading must be to the second.



Cheers

Shane
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Old 17-07-2015, 20:22   #26
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Re: Materials for learning celestial navigation in an emergency

Hi Tominny

A great little book to have on-board for, all your old school Navigation is,

Practical Navigation for Officers of the Watch, book will cost about $70 Aus.


It has worked examples and quizzes


Cheers


Shane

P.S soon as I work out how to up load a pic on here I will post a of some star sight that I have done, don't let all the numbers scare you, there is a colum for each star/ heavenly body, you need at least 2 sights, but 3 are better, it creates a cocked hat ( triangle) which you will be somewhere in, put your position inside the triangle nearest to danger.

Cheers
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Old 17-07-2015, 22:49   #27
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Re: Materials for learning celestial navigation in an emergency

Hi

Here's what you'll end up with,

you can do extra work if you want and work out what stars you are going to sight, or you can just go out and sight them soon as they become visible, at twilight, the reason for twilight is so you can still see the horizon, as you know, you have to bring the star down to the horizon then take the time to the second.

Once you do the maths, you then know where you where back when you took the sight, as most of us on here will be sighting stars from a slow moving yacht under, there is no real reason to be running each sight up, and complicating things. As Celestial Navigation is for Blue water Navigation, Not coastal the final position only has to be within a few miles.

I have attached some pics, I don't no if they will load up though

cheers
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Old 17-07-2015, 23:19   #28
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Re: Materials for learning celestial navigation in an emergency

try again to up load pics
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Old 17-07-2015, 23:59   #29
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Re: Materials for learning celestial navigation in an emergency

Hi here are some more pics, these are all very accurate sights and vessel position fixes, except for the one dated 29th April 2015,

the DR for the 29th April is the vessels GPS position, so it's not really a DR, you can see that the longitude is pretty good, but because my watch was out and I didn't correct it, the longitude is way out to the East 50nm to be exact. so there's a good example of not taking accurate times of each sight.

Hope this was some help to you



P.S the workings out of these sight have been done 2 different ways one using formulas & the other using Norrie's Nautical tables, the 29th April was done with formulas, you can see this in the A, B, C columns, they go to about 9 decimal points where as Norrie's only go's to 2 decimal points


Cheers


Shane
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Old 18-07-2015, 00:25   #30
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Re: Materials for learning celestial navigation in an emergency

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For 1/4 of the price of a low-priced sextant and a couple of books, you buy an extra cheap GPS and a brick of "ten year storage life guaranteed!" batteries for it.
Best advice so far on this thread.
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