My Last Article-Lines of Position

[HenryC]

My last entry was about my first article, written in 1995.  This is my last one, written a few years ago but which was finally published in Good Old Boat in the Jul/Aug 2014 issue.  For those of you who might have missed it, here it is...

Lines of Position
by Henry Cordova

I was in my early twenties when I first learned about celestial navigation.  I had always had an interest in astronomy, ever since I was a kid. I was a fairly knowledgeable amateur astronomer as a teenager, and I majored in astronomy in college, so when I joined the Navy I managed to finagle myself into the Navigation Department of a missile destroyer.  I'd never been exposed to navigation before, but I soon fell in love with it--it fit right in with my interests and background.  My shipboard training was in the practical aspects of piloting and dead reckoning, plotting and chartwork, publications, electronics, and aids to navigation.  I was introduced to celestial, and even worked out a position or two as part of my training, although in the modern Navy the sextant is rarely used, and then only by the officers and senior enlisted men.

Still, I loved the work, and after going back to school and finishing my degree, I became an avid sailor and had a chance to sharpen my wayfaring skills further.  But it wasn't until many years later, a married man with a responsible career, that I decided I would buy a proper yacht: one  
capable of crossing an ocean.  I realized I would need more than simple piloting and dead reckoning skills, I needed to master celestial navigation.  I bought a professional sextant,  picked up a couple of books on the subject and taught myself the arcane art of determining my position at sea by sighting distant objects in the solar system and the galaxy.

Celestial is really not that difficult, especially for someone with my background.  It all looks very mysterious and remote, but basically it has been refined to a long and involved procedure of looking up numbers in published tables and adding and subtracting columns of figures.  Knowing the mathematics, (mostly high school trig), is not really necessary.  It has been reduced to a series of numerical recipes that can be memorized.  With my understanding of the math and science, it was a bit more interesting for me than for others, but it is important to keep in mind that we're not talking brain surgery or particle physics here.  Celestial  navigation is just accounting, a lot of rules to learn and some adding and subtracting on preprinted forms that keep you from losing your place and to remind you what comes next.  It's all been designed by geniuses to be done by idiots. I would compare it in complexity to figuring out the taxes for a small business, except navigation doesn't change the rules on you every year. The physical skill of using the sextant to make celestial observations is comparable to firing a rifle. Anybody can do it, and after a few dozen shots you will get good enough at it to not embarrass yourself.  Sharpshooter skill is not really necessary.

But although the practice of celestial navigation can be reduced to a mechanical sequence of steps, it helps to learn it if you actually understand what it is you are doing.  Learning celestial can be much more than simply generating an "X" on a chart, it ties together every aspect of navigation; piloting and dead reckoning, as well as mathematics, astronomy, timekeeping, the calendar, cartography, and geography.  If you can put it all together, it makes sense in such a way that you no longer need to memorize the steps,  it becomes an integrated body of knowledge, you grasp how it all fits, and it gives you an immense confidence and peace of mind that is of great value. You can still get lost, but  being lost will never terrify you again. You and your ship become part of the sea, connected to the world, the heavens themselves.  There is no feeling quite like it, and once you understand how to do it, it fills you with immense pride that is difficult to communicate, but that others can sense in you.  And if you're the only one who can navigate, your crew is not likely to mutiny, either, at least not when you're out of sight of land.  

Every star and heavenly body is located in the sky, and there is a spot somewhere on earth where that star or body is directly overhead at any given moment in time.  (The earth spins around once a day, and flies around the sun once a year, but if you know the time and date you can correct for that.)  The Nautical Almanac tells you where in the sky that body is at any time.  The sextant measures how far away that object is from the horizon, which allows you to calculate how far it is from that point directly overhead, so that allows you determine how far away you are from that spot directly underneath the body.  If the star is 40 degrees away from your horizon (50 degrees away from your zenith), then you are 50 degrees away from its known geographical position, and a degree is 60 nautical miles.  That's all there is to it.

In practice its a bit more complex.  First, you make a rough guess of your assumed position.  It need not be accurate, anywhere within a hundred miles or so is good enough. Then you determine the elevation of the body above the horizon with your sextant, noting the exact time of the observation. You then go through a rather involved table look-up procedure to determine where the star is (from the almanac) and another one to determine where it should appear in the sky at that moment.  Comparing the distance you measure from the one you expect tells you how far away you are from your assumed position; you draw a line on the chart, and you are somewhere on that line.  After repeating this process for several stars, your result is several lines on the chart.  Where they intersect is your position.  How closely they intersect gives you a rough idea of the error of your position (which may vary considerably due to conditions, your skill as an observer, and mistakes such as misidentifying a star or mathematical blunder).  Under ideal circumstances, you can locate yourself to within about a half-mile.  In general, your true position will be within several miles of the position you calculate.  

Once you're practiced, the whole operation takes about an hour, most of it spent with your books and tables, scribbling furiously. You go out and identify and observe a half-dozen or so stars with your sextant, noting the readings and the exact time of each observation.  Two observations is all you really need, but several more will allow you to discard any obvious errors. You then do the calculations for each star, drawing the lines of position for each on the chart.  Where the lines cross, corrected for the motion of the ship during the interval, is where you are.  In general, you do this twice a day at sea; at twilight, when it's dark enough to see the navigational stars but still bright enough to see the horizon.  At noontime, you can can get a simple latitude by shooting the sun. Identifying stars is easy, you can use a gadget called a star finder until you learn how to use the star chart printed in the almanac. After a while you will learn their names and they will become old friends.

The question I'm most frequently asked is "What do you see when you look through the sextant?"  The instrument is basically an arrangement of mirrors that allows you to look in two separate directions at the same time, superimposing both images in the field of a small telescope.  A reading involves twisting a knob until the glowing dot of a star or planet, or the edge of the sun or moon, just touches the horizon.  At that moment you note the time to the second, and read the angle marked on the instrument.  

By the time I had taught myself how to do it, I was laid off from my posh Silicon Valley job and had to shelve my plans to go sailing indefinitely.  Over the next year, as I looked for work and went through the money I had saved to buy my boat, celestial navigation became a part of my life.  It kept me going through a stressful time, a time when I came to question my own ability to earn a living and support my family.  But no matter what, I could take some comfort from knowing I could take a ship anywhere on the planet the old fashioned way, by using the stars and a compass.  
I took several offshore trips with my sailing friends so I was able to satisfy myself that I had the practical skills as well as the theoretical knowledge.  I also took the time to develop navigational software that ran on a pocket calculator, a means of digging deep into the intricacies of the spherical trigonometry and nautical astronomy involved.  By the time it was over, I considered myself an expert.

I had hoped to sell my software, and perhaps earn a living as a yacht navigator on offshore races or as an instructor, but the times had changed--while I was learning the craft, inexpensive Global Positioning Systems became ubiquitous on all but the smallest boats, celestial  became as obsolete as Morse code telegraphy, hard-hat deep sea diving, or muzzle-loading firearms.  

No one seriously studies celestial any more, except as a hobby.  The essential skill that carried the world's commerce has now become a pastime for dilettantes, a quaint art for armchair sailors.  Real mariners are better off spending their time learning first aid, or diesel repair, or any of a hundred other essential shipboard skills than they are in investing the time and effort to learn celestial, and the constant practice required to keep the skill current.  Short of total war or a breakdown in civilization, it is highly unlikely the satellites will be allowed to deteriorate while the Nautical Almanac is still faithfully published for the convenience of navigators.

But I still have my sextant, neatly packed away in its polished hardwood felt-lined box.  It is a beautiful instrument, with an indescribable feel and even a smell to it, from the lubricants and the mahogany.  I take it out occasionally and simply admire it, and once a year or so I take it to the beach, shoot some sights and calculate a fix, just to prove to myself that if I had to, I could still guide my ship wherever she needed to go.  It's a good feeling, but a sad one. The sextant has become a memory of my youth, relevant only to me, and a reminder that times change irrevocably. It can take me anywhere in the world, but it can't take me back. Its ties to the past are there, of generations of seamen braced against a bulkhead on a rolling deck, bringing a star down to earth.  I am tied to that past, but it is a past,  I am in the last generation to have used a sextant as anything other than just an amusement.  There is some grandeur to that, but also a great sadness.

[Bob23]

   As usual, a wonderful write. Each fall I tell myself that I'm going to learn celestial but each spring, I haven't. Maybe this year. I have some books, a reprint of the lessons you published here a number of years ago. This recent article of yours might be the catalyst I need to actually do it.
   It may be obsolete, but I bet it's a nice feeling to know you are anchored to something unchangable and concrete. It's all based on the accurate and predictable movement of the heavenly bodies.
  Thanks again, Henry.
Bob23

[HenryC]

You're right.  Its a romantic and complex experience, and it has had a very profound effect on me I still haven't completely understood.  I hope I communicated this in my article, how learning celestial navigation got me through a very difficult period in my life, when I was questioning my ability to earn a living, work in my profession and take care of my family.  Celestial navigation saved my dignity and self-respect, and that's all I needed for everything else to fall into place. It has changed my life in the way you described, giving me a secret knowledge few others have or are ever likely to get, especially in these days of satellites and computers. But why it has done this, how it has affected me this way psychologically, I still haven't fully grasped.

First off, its not a highly complex and difficult skill, like learning a foreign language, mastering a difficult sport or martial art, or becoming an accomplished musician.  Anybody can do it. And it does not require any physical agility or muscle memory like racing a car or sailing a boat.  It is a procedure, like filling out a tax form or following a recipe in the kitchen.  You just follow a set of of written instructions carefully and you can't go wrong, and if you do it often enough you can memorize them, although that isn't really necessary.

The sense of connection to the natural world, the earth, sea and sky is a factor, although I formally studied mathematics and astronomy so I didn't enter into any new mysteries when I taught myself to navigate.  The spherical trigonometry has already been done for you through the reliance on pre-printed tables, and for simplicity, the navigator uses a simplified model of the solar system, one with the earth at its center, like the ancient Greeks did. 

In short, the math and science part of the exercise makes it more fun for me because it helps me understand what is going on in the background, but it is not necessary to actually do the job.  The publishers of the Almanac and Sight Reduction Tables needed to develop a procedure any seaman could be quickly and easily taught to use, without prior education.  All you really need to know is how to read and write, look numbers up in tables and add up columns of figures.  You don't need to understand economics and tax law to fill out Form 1040, and you don't need to understand chemistry to cook up a decent meal.

I wish you the best of luck in your studies, and I will do whatever I can to help. Just ask.  It was worth the effort for me.  Of all the things I've done with my life, its the one I'm most proud of. 

[Craig]

Wonderful! As an old salt I fear the loss of those skills which have defined sailing. I have never used celestial navigation but connect to the role it has played in the history of the world. As a ham radio operator I have similar feelings about Morse code. It may be obsolete in the context of modern communications but it is a tangible connection with our roots. If one accepts the premises of the "preppers" we may need those ancient skills in the future. All that being said there is something culturally essentially in keeping those old arts alive  just like  so many other "obsolete" technologies.

[Bob23]

   Well, I'm not a ham operator and have yet to learn celestial nav, but another skill being lost is the use of a hammer. Yup, you heard me right- the hammer. Greenhorns entering the construction trades use nail guns and mostly incorrectly. You can tell because where 7 or 8 nails will do, I'll see 25 pneumatically driven nails. It's a waste and there's no art in it. And give 'em a handsaw and they have this puzzled look like you handed them a rotary phone.
I can still out nail most of these kids and, I'd have to admit, I take an almost sinister pride in it!   
    Once in a while we'll get in nailing contests and when I pull out my wood handle framing hammer, I'll get a snicker or two and a comment "Where'd you get that antique" as they arm themselves with the lasted carbon fiber titanium something or other. Truth be told, wood is the best absorber of shock so even though those Estwings look cool, grab the 7 dollar wood cheapo and your wrist will thank you in 20 years. And I'll still kick thier butts!
   Bob23 

[HenryC]

People don't realize how much celestial is tied in to modern technology.

So what happens when the technology goes away?

First, you lose the time, or the ability to check it by radio..  Your clock will not be resettable, so unless you have several clocks and log their errors frequently so you can predict their drift, you lose the exact time, and you can't determine longitude. Eventually, your batteries die out and you have no time at all.

You can still do latitude sailing, but the declination values in your old Nautical Almanac (remember, you're not able to buy a new one every year) will get further and further out of date every year due to precession.  You can correct for precession, but you'll need precession tables, and an astronomer, or at least, have an astronomer explain it to you.  But you won't be able to use Sun, Moon or planets, only stars.

We'll all be navigating like Horatio Hornblower did 200 years ago, except HIS Almanac was up-to-date.

[Bob23]

Henry:
   Have you ever read "The Last Navigator" by Stephen Thomas? Fascinating book on the navigational techniques of the Micronesians. You'd love it.
Bob23

[HenryC]

Yes, I did read it.  And I recommend it to all sailors, it is required reading. Mau Piailug (the last traditional navigator) is a reminder of how resourceful and clever so-called "primitive man" can be.

Think of it, Neolithic men have been able to not only survive but actually colonize the Pacific Basin, in craft constructed with stone tools from the meager natural materials available on their home islands.  They could sail into the wind centuries before Europeans learned how. Stone Age peoples have exploited and flourished in some of the most inhospitable environments on earth; the tropical rain forest, the world's great deserts, the Arctic icecap, the slopes of the Andes.  These are places that when we go we have to bring every single item we need with us, and we rely on constant resupply and support from our home bases in the civilized world.

Please follow this link to one of my favorite pictures, "The Discovery of Hawaii", by Herb Kane.

http://islandbreath.org/2007Year/20-HookahiKauai/0720-11HawaiiDiscovered.jpg

It was much harder for them to do that, than it was for us to do this:

http://anony.ws/i/2013/05/23/NOvJY.jpg

[Elk River]

     Henry:

     What is your opinion of the Davis Mark 3 sextant?  Being plastic, it is probably only good as a learning tool.  I have one of those and an artificial horizon.  I continue to drool through the Celestaire catalog.  I am not sure where a decent used sextant might be obtained for a reasonable price (whatever that is...).

     Another interesting book is Longitude by Dava Sobel.  I imagine you have also read that, along with We, the Navigators by David Lewis.  I did read your article in Good Old Boat and found it to very interesting and thought provoking.

     Thanks,

     Elk River

     

[HenryC]

I never read "Longitude", but I did watch the TV special based on it.  I never read the Lewis book but I looked it up and it sounds excellent.

I've never used the Davis family of sextants, but I have played with them. They are not toys, and like can be said for any tool, (like a pistol!) having a bad one is still better than not having one at all.  But as in selecting any tool, the pro will pick the best he can afford.  It is something he will use every day and he needs to develop confidence in it.  A top quality instrument will be expensive, but it will last a lifetime and require little adjustment and maintenance, and will be more durable.  Also, keep in mind, skill with celestial navigation requires constant practice, and the super high precision and ease of use and adjustment of a good instrument will allow you to monitor your own skill level more easily.  Constant practice is essential to keep up your CelNav skills, which means you'll be using it even when you won't have to.  An easy to use instrument with clear, bright optics and stable in a wind, will mean you won't be coming up with excuses not to practice.

I don't want to put down plastic, each of the Davis line is an excellent value, but you get what you pay for. Plastic sextants are great for learning, and are a good backup to have aboard, either for your metal sextant or for your electronics.  Today, when any sailor can afford to buy several hand-held GPSes for the price of a good instrument, the choice of a sextant is less critical.  I find the image quality and ease of use of a cheaper sextant to be really annoying, but for occasional or emergency use, I can live with it if I have to.

I would suggest using the Mark III for training, but when you get ready to go cruising, rely on your electronics, or a higher quality instrument for your navigation.  Keep in mind, if you ever have to use a cheap sextant to get you home, you're going to be in an emergency situation and high precision will not be an issue.  The Davis won't take up much room, and it will be there if you drop your Tamaya over the side, or if a supernova, nuclear war or alien invaders knock out the satellites.

I paid $400 for my Astra about 25 years ago and it still works just fine, even though it is considered a mid-range, middle quality instrument. I'm sure I could sell it now for more than I paid for it new. As for a used sextant, I'm sure you can find real bargains out there, in an estate sale or from an old salt who will never sail again, (or a yachtsman who got cold feet) but keep in mind, good instruments last forever if well-taken care of, so they will be worth almost as much old as brand new.  If you plan to use yours frequently for the rest of your life, splurge.  I wish now I had bought a top-of-the line instrument when I could afford it.

[capt_nemo]

HenryC,

Just wanted to say "Thank You" for sharing your very well written articles with us.

Those of us who missed them when originally published appreciate your taking the time to post them here for our enjoyment and reference.

Sail safely my friend,


capt_nemo

[HenryC]

It's my pleasure.

Yr most hmbl. & obd't servant, etc. etc.

HRC