Do you NEED celnav?

[HenryC]

I learned how to use a sextant to determine my position at sea in the early 90s, about the same time the Global Positioning System (GPS) became widely available.  Since that time, we've all heard the debate: now that a simple, reliable, inexpensive method of electronic navigation is essentially perfected, do we really need to learn celestial navigation? To put it bluntly, the answer is "no". In my opinion, celnav  is obsolete, and prospective blue-water sailors are probably better off spending their  time and money somewhere else.   From a purely practical point of view, you don't need it.  Unless you are really motivated to pick it up as a hobby, as I have, you're probably better off mastering any of the thousand other practical skills you'll need on a yacht. 

We've all heard the arguments:  GPS, like all mechanical systems, is vulnerable to failure;  we need celnav as a backup.  There is some merit to this point of view, after all, machines do break down, especially in the harsh marine environment, and the GPS system and the bureaucracy that maintains it is vulnerable to global catastrophe and war.  But sextants are fragile mechanical devices too, as are the accurate timepieces they are dependent on.  Small, inexpensive hand-held GPS units are now so effective and economical and so mechanically robust, that carrying a few spares aboard your yacht (and batteries to power them) as a backup to your main electronic navigation gear certainly makes more sense than relying on astronomical methods as a fallback.  As far as the long-term viability of the system is concerned, the yearly Nautical Almanac,  the Time Service, and short-wave time signals for resetting your clocks, all essential for celestial navigation, are services of government bureaucracies too and vulnerable to potential interruption.

Celestial has other drawbacks.  It is expensive. Be prepared to spend at least five or six hundred dollars for a sextant, and well over a thousand for a really good one.  And then there are the additional expenses, the Nautical Almanac, sight reduction tables, a star finder, a good programmable pocket calculator to reduce your sights (because those tables are slow and cumbersome to use).  Of course, you'll still have to master the tables, as a backup to the calculator.  Although you can teach yourself the art, most busy people today will opt for professional instruction, and the time you must spend practicing with a sextant and reducing the sights to keep that proficiency also counts as an expense.   If you don't live near the sea, you'll have to go to the additional bother and expense of acquiring an artificial horizon just so you can practice. And you'll have to do at least some of your practice shots under real conditions, at sunrise or sunset while you're out at sea, or you'll never really convince yourself you can do it under realistic conditions. Celnav is more complicated than it first appears: you'll need to keep a chronometer log, too, so you can monitor the long term error characteristics of your timepieces and correct for them should you lose time updates underway.

All of this paraphernalia takes up space too, always at a premium on a yacht, and it all has to be broken out prior to every use, and stowed away securely  when you're done with it.  You're going to need a workspace like a chart table to do your scribbling and plotting on too (about a half-hour's worth of work once you've mastered it, but usually twice as long under field conditions, a rolling, pitching boat under windy, and dark skies).  Yes, unless you're really, really, good, you'll need an assistant to record your observations, and another to sail the boat.

So why bother at all?  There are advantages to learning celestial, both practical and intangible, and the sailor should consider them.  Other than its use as a backup, celestial teaches you navigation.  By the time you are a celestial navigator, you will have mastered piloting, dead reckoning, chart work, plotting, all the skills you will need AFTER you determine your position.  Celestial navigation will provide you with a fix, but so will visual sightings or GPS.  It's what you do with that lat/lon to plan the next few hours of sailing  that matters. To be fair, you don't need to know celestial to pick up these skills, but you can't do celestial unless you've mastered them.  Unfortunately, you can't say the same about GPS.

Celnav will teach you the sky, you will understand timekeeping, the calendar, the celestial sphere and how it shifts and rolls about us throughout the night, the year, and as you move on the surface of the earth beneath it.    I suppose you could memorize celestial navigation as a procedure, (I do this, then I do that, then I write it down here).  This is how we operate a GPS unit, we push certain buttons in a certain order, we get a number that we plot on a chart.  But if you take the trouble during your training to understand how it all fits together, you will emerge  with an understanding of how the process, and you, relate to the real world around you.  Never again will the stars just be lights in the sky, and as you travel long distances across the sea, you will actually see the sky move above you to reflect that motion.  Only then will you truly understand just how big the earth really is.

I live in Fort Lauderdale.  If you'd like a celnav teacher, get in touch with me. Maybe we can work something out.  I won't take your money, but you can let me crew on your boat.

[kchunk]

Now that's insightful and seriously appreciated! Thanks for the inspiration...

[newt]

Henry,
I put up such a big post on this yesterday that the public wireless I was on would not bring it to the forum. Your original question- do we need C-nav? I think you made a convincing argument for "NO". Allow me to take the other side...
I am still quite new to bluewater cruising, being captain to  boats larger than 20 ft or so for only 5 years. My bluewater yacht, which I am slowly making into my world voyager has redundancies. Not just redundancies, but redundant systems. Propulsion for example, can occur by two sets of sails, diesel axillary or by outboard. Navigation- eyes, with line of sight, paper charts, chartplotter and finally I want c-nav. Why- because when I am halfway between Seattle and Kauai I want two systems for navigation. I guess I could get a cheap directional AM antenna, but I was hoping for a bit more accuracy. Now in your argument you stated that GPS basically will not fail, and if it does, it is the fault of the unit (ie you all you need to backup GPS is another GPS) I have had brief times when multiple GPS's did not work, and have heard of a time when they went blank along some of the east coast (during a offshore fishing derby- I heard it was a nightmare). With everything from solar flares to micrometeorites and increasing space junk pelting them, do we want to be dependent on a technology we cannot fix from down here? Plus ( and for me this is the most beautiful part of it) C-nav does not rely on outside power. No radio signals, city lights, satellites- you get my drift. I think it teaches me to be in sinc with the natural world.
You say that you need electronics anyway, to reduce the sight etc. Cannot all this be done by math? If we have one set of reduction tables and a almanac, can't I adjust for the year (for the stars, not the planets or moon) If I know the date and take a noonsite, can I not get a latitude? I do need a bulletproof accurate watch, but these are available.
Finally, I have heard that a sextant can be used to get quick fixes by measuring the angle of a object- it you know the height of that object from the charts. This would be useful to me in my running fixes along the coast.
I would be a willing student- please teach me when I pass by the Caribbean in 4 years. Money and or adventure time (from there I am heading to Europe) will be gladly exchanged. Thank you for your kind offer.

[HenryC]

You're preaching to the choir, Newt, I still am very glad I know celestial, it's just that as GPS proves itself over the years, the need for an alternative becomes less obvious, and certainly less critical.  For starters, there is quite a bit of redundancy already built into GPS, There are many more satellites available than necessary (I believe a dozen are usually accessible at any time while only 3 or 4 are actually needed) to determine your position, so even a massive degradation of the constellation  would not be crippling.  The Russians also have a parallel system, and the Euros are considering one, so even the unlikely total failure of GPS would leave us with alternatives.  Future receivers might be available to pick up these  multiple systems, breaking the US monopoly and the dreaded selective availability issue. 

Neither is celestial foolproof.  You not only need a clear view of a celestial body, you also need a sharp horizon to get a good sight. You rarely get both simultaneously.  And that still only gives you one Line of Position.  For a fix you need at least 2, and preferably 5.  Of course, even one LOP is better than nothing.  Another problem is that if it's too rough, you might not be able to get a decent observation from a small boat.  I'm terribly farsighted, if I lose my glasses, I can't read, write or figure.  Now that's scary!  Also, remember some fixes are more important than others.  In the middle of the Atlantic you can afford a couple of weeks of solid overcast.  In a northwesterly gale off the lee shore  of Ireland you need a posit NOW.

Celestial does give you flexibility, which is why I like it in my toolkit. Yes, you can use last year's Almanac for stars, but you'd be surprised how few navigators know about the necessary corrections or limitations of that tactic. Even a couple of LOPs  from separate days can be folded into a running fix, and a noon sun can get your latitude, even if your clocks are all dead.  If you're really good, you can teach yourself lunars and get the time from the moon.  Still, this kind of expertise usually means you do it conscientiously, all the time, and are really checked out and practiced up for any emergency.  Is this realistic if you've got a GPS aboard? We do tend to get lazy when we have a simple alternative at hand.

What it boils down to is a tradeoff.  Are you better off having a spare $200 GPS handheld or a spare sextant in case you drop your $2500 Tamaya  over the side?  If you rely on a calculator and it dies, how well will you be able to fall back on tables?  Sure, the math is all in the Almanac, but most people won't remember their trig, if they ever knew it in the first place.  These are all judgment calls.  It depends on what's best for you. This is not a yes or no kind of question.

Having said that.  I'm glad I took the time to learn how, it's one of the things I'm proudest of. And I'd be delighted to teach anyone of you guys what little I know.  Contact me through my email address

gutmancaspar
at yahoo
dot com


PS: You might also want to read my articles on "Morning Sights" and the "Pepperday S-Table" at

http://www.qmss.com/articles.html

There's a craftsman's side to celnav that you don't get  from just taking a course.

[newt]

Talking to you makes me want to learn c-nav even more. I guess I am a hopeless addict. I am in the hunt for a sextant right now. I will learn as much as possible on my own, then bother you with the finer points. Thank you for your time.

[HenryC]

I have an Astra, and highly recommend it.  It shoots straighter than I can, and is very reasonably priced.  It may not be the most accurate or the most durable sextant, but it stays in adjustment very well and it certainly is the best value.  It also has big mirrors, which means it is easy to use. Stay away from those plastic ones, except maybe for training.

http://www.celestaire.com/Astra-III-Professional/View-all-products.html

I see prices have gone up from when I bought mine 20 years ago, although not as fast as general inflation might suggest!  You can probably pick up a real bargain if you look for a used sextant, but learn how to adjust one before you go shopping.  One of the best indicators of quality in a sextant is the ease of adjustment, there are a handful of basic user alignment and calibration procedures common to all these instruments.  They should be easy to do and not have to be done too often. More advanced adjustments are best left to a qualified sextant repairman.

I highly recommend "The Sextant Handbook" by Bruce Bauer as a good general introduction to the instrument, regardless of which kind you eventually get.

[brackish]

HenryC, I wish I lived close enough to take you up on your offer.  When I took a coastal navigation course too many years ago to count, we were only offered an overview.  I would like to learn how if for no other reason than knowledge inventory.

[HenryC]

I was taught to navigate as a Navy Quartermaster, (piloting, dead reckoning, compass and chartwork, Decca, RDF, radar and Loran-A)  but we only received the briefest introduction to celestial techniques.  Even in the late 60s, celestial was on the way out, most navigation offshore was by Loran, with celestial relegated to gaps in the coverage, mostly in mid-ocean where an accurate position isn't really critical anyway.

Many years later I decided to teach myself, directly from the Nautical Almanac.   Yep, everything you need to know is in there, although not necessarily organized for the convenience of a beginner.  I had a great job and was making good money and was considering buying a real blue water boat and following the dream. I  programmed my new HP 28S calculator to do sight reductions, and as I dug deeper and deeper into it, I was motivated to pick up the whole nine yards.  I still have that pocket calculator software (if you send me an HP48 RAM Card I'd be happy to burn you a copy of it) although there are now far superior commercial calculator sight reduction packages available.

There are many good books to teach you celestial, but I'm glad I learned it "from the inside out", so to speak. It gave me a really good understanding of WHY I was doing what I was doing, not just HOW.  I was soon going through some personal changes at the time, too.  I was laid off from my job as a Silly Valley computer programmer (for over a year, as it turned out) and teaching myself celestial and how to program it helped me keep my sanity, and self-respect.  I had studied  math, astronomy and geography in college, and with my Navy and computer mapping experience, I felt if I couldn't teach myself celnav from scratch, then there had to be something wrong with me. Besides, I lived in the San Francisco Bay area at the time, and I had a lot of yachty friends that gave me lots of opportunities to practice it. I had this fantasy I could earn my living as a navigator on ocean races.

The real irony is I never did buy my own ocean-going boat, I spent all my life savings getting through my jobless year, instead.  And by the time I had moved back to Florida, got a job, and started putting my life back together, GPS was starting to take over. My journey to the stars was for nothing.  Maybe someday I'll write a book about it.

[newt]

Your journey was not for nothing...You are the holder of an ancient language (and skill). We of the next generation will coming looking for you.