I decided that I was going to teach myself celestial navigation as a winter project. I'm trying to weasel my way onto a delivery crew or an offshore racing crew so I can get some blue-water time. I'm hoping that knowing CN along with being able to cook might brighten up my resume a little. What I have discovered surprises me --and bugs me-- a little bit, and that is that Celestial Navigation is easy. I don't mean "not impossible." I mean easy. It took three hours of reading to figure it out. I, like most of us, have started reading articles or books on Celestial Navigation in the past. I usually threw up my hands somewhere between "Right Ascention" and the "Sidereal Hour Angle." The problem is that people trying to explain the stuff can't resist toruring us with 400% of what we really need to know. They want us to know how smart they are, I guess. Who cares about the precise definition of parallax, or nadirs or the celestial sphere when you're first trying to get your arms around something? Well, this time I plowed through it. Here's how to get a fix with a sextant. It's no harder than bleeding a diesel, in my opinion.. 1. Pick out a celestial body. The North Star works great, or the moon. Use the sun if it's daytime. 2. Get three numbers associated with that body. One comes from the sextant, which is a measurement of the body's angle relative to the horizon. The other two numbers come from a book (Reed's almanac). You don't care what the numbers mean for now, just look them up, they're listed under "North Star." 3. Grind the three numbers through three ugly formulas, and you get an azimuth line that you draw on your chart. That's one LOP. Part of this process involves "guessing" where you really are. That always bothered me, but it makes sense now. Don't let it bother you. 4. Repeat 1-3 for a second celestial body. That gives you a second LOP, which means you have a fix. That's it. Of course there's more to it. You have to add three or four corrections to your sextant measurement, which I conveniently omitted. You have to have your watch hacked right to the exact Universal Time, and record the time of your sight. You have to make allowances for the fact that you're just guessing where the center of the sun and moon are (because they're big). Sometimes there's less, but they never tell you that until you've waded through all the muck. For example, you can get your lattitude by adding three numbers (from the almanac) to your sextant measurement of the North Star. And one of the numbers is 1! Measuring the sun at noon is a no-brainer, too. Sun sight calculation is the only thing that many people know how to do. It's OK if you can wait until noon to know where you are. But you don't need to know all this during the first hour that you're trying to learn this. Work it in later when you get the hang of it. Anyway, thought I'd share. Now I can make fun of Celestial Navigation with authority. Buy a GPS, for God's sake. I wish I had a good link to share that would take you to a usable explanation with diagrams and examples, but I don't. I've included a link to some of the stuff I read. Paul sv Escape Artist h336
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Vague memories...
I seem to remember in the distant naval past bringing the edge (limb?) of the sun or moon to the horizon, not the center. I'm glad to hear that you are enjoying shooting the stars. Good on ya! David Lady Lillie
I seem to remember in the distant naval past bringing the edge (limb?) of the sun or moon to the horizon, not the center. I'm glad to hear that you are enjoying shooting the stars. Good on ya! David Lady Lillie
mired in the terms, history, and theories 
Paul Thanks for your post I too bought a sextant and wish to learn how to use the sky to tell me (about) where I am on this fine earth. But as you said EVERYTHING I read about the subject the very first thing the author does is get me mired in the terms, history, and theories. It’s like I say about driving, I don’t need to know how to build a transmit ion in order to know how to shift my truck! I’ll use the link you sent and see if I can get the hang of it without grinding too many gears. Bob SV I Miss Lisa
Paul Thanks for your post I too bought a sextant and wish to learn how to use the sky to tell me (about) where I am on this fine earth. But as you said EVERYTHING I read about the subject the very first thing the author does is get me mired in the terms, history, and theories. It’s like I say about driving, I don’t need to know how to build a transmit ion in order to know how to shift my truck! I’ll use the link you sent and see if I can get the hang of it without grinding too many gears. Bob SV I Miss Lisa
Ever heard of the S table
Hi Paul, I did the same thing some time ago. Found a little book called the S table. Got it from Celestaire. http://www.celestaire.com/ The S table is a complete sight reduction system in 9 pages. It’s small enough that I keep a copy in my sextant case. It works very well and it’s fast and simple. It’s based on the same formulas as the calculator method but uses a sine cosine table in lou of the calculator. It does assume that you do know how to take a sight and is not meant to teach you how. Just thought you might be interested. Tim Bastian Zephyr’s Aura Hixson, TN
Hi Paul, I did the same thing some time ago. Found a little book called the S table. Got it from Celestaire. http://www.celestaire.com/ The S table is a complete sight reduction system in 9 pages. It’s small enough that I keep a copy in my sextant case. It works very well and it’s fast and simple. It’s based on the same formulas as the calculator method but uses a sine cosine table in lou of the calculator. It does assume that you do know how to take a sight and is not meant to teach you how. Just thought you might be interested. Tim Bastian Zephyr’s Aura Hixson, TN
Thanks Paul
A very entertaining and enlightening post. I, too, have been intrigued with learning the subject.... my dad was a B-17 navigator... but have been somewhat intimidated with the subject's density.... all those numbers, terms and formulae! Your comments have made it seem less intimidating.
A very entertaining and enlightening post. I, too, have been intrigued with learning the subject.... my dad was a B-17 navigator... but have been somewhat intimidated with the subject's density.... all those numbers, terms and formulae! Your comments have made it seem less intimidating.
A Link
Welcome aboard. I've been trying to get people interested in celestial nav for years. Here is a neat link to help you along. It has perpetual almanacs and lots of other great stuff. If you need to find a good sextant, try Ebay. There are always a bunch there... For a comprehensive study that will have you working in a few hours try William Buckley's video. He takes you straight to the heart of it all and doesn't talk about spherical trigonometry. And yes, you are right! It is so easy ever sailor who ventures out of sight of land should know how...
Welcome aboard. I've been trying to get people interested in celestial nav for years. Here is a neat link to help you along. It has perpetual almanacs and lots of other great stuff. If you need to find a good sextant, try Ebay. There are always a bunch there... For a comprehensive study that will have you working in a few hours try William Buckley's video. He takes you straight to the heart of it all and doesn't talk about spherical trigonometry. And yes, you are right! It is so easy ever sailor who ventures out of sight of land should know how...
Comment
You are quite right. CN is easy-with respect to the basics. The thing that gets down to the nitty gritty is practice, experience in the art, (and it is an art-not an exact science), and finally, being in a situation where this skill is necessary and the difference between making a successful landfall and missing it. As with most math related teaching you are quite correct --- the generally accepted method of teaching often gets bogged nown with personalities, egos, pride, self-esteem, etc. When reduced to the basic principles it is usually understandable and applicable by most folks. Keep after it, and thanks for posting. CN is fun!!
You are quite right. CN is easy-with respect to the basics. The thing that gets down to the nitty gritty is practice, experience in the art, (and it is an art-not an exact science), and finally, being in a situation where this skill is necessary and the difference between making a successful landfall and missing it. As with most math related teaching you are quite correct --- the generally accepted method of teaching often gets bogged nown with personalities, egos, pride, self-esteem, etc. When reduced to the basic principles it is usually understandable and applicable by most folks. Keep after it, and thanks for posting. CN is fun!!
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