It's not as bad as it seems - at least not with the right instructor. I passed the Power Squadron's Junior Navigator course (basic celestial) and even if I never use it, it was worth it. I've never looked at the sky quite the same way since. And yes, even the basic is a good back-up for an ocean crossing for when your GPS batteries get wet.

I tried the advanced course twice, but the conceptual trigonometry was just too much for me. Maybe I'll try again when I get older and wiser. I don't know about videos, but there are plenty of good books. Just hang around a bookstore (not a website) and you'll see.

 

It's not necessary, but the prudent mariner etc.

I think the more important question is, do you want to learn it? If not, you can get away without it. If so, it's a lot of fun. However there are a million threads on this site that give pointers to how to get started; I recommend using google to search.

 

These days I think there is very little case to be made that celestial navigation is necessary or prudent. (I think the prudent mariner should have a backup GPS unit)

That is: assuming that the GPS system (NAVSTAR) does not go down for an extended period of time - and even then there are GLONASS and GALILEO systems as backup.

Electronics on board of course can fail, but at the current price of handheld units, having several back-ups is no longer an issue (be sure to put one in your ditch bag or even in your life raft). These will be battery powered and of course it's possible the whole electrical systems fails, but a baggy of batteries will allow you a fix a couple times a day for months.

That being said, there is a charm and a certain sense of accomplishment to do it the old fashioned way. It can get quite complicated, but some of the basics like a noon shot are certainly not too hard for anyone to master.

 

The bottom line is that if you want to have a full understanding about how the whole celestial thing works mathematically then you have a task ahead of you.

However, if you can grasp the fundamentals about taking a sight, filling in a basic form, using a plotting sheet and looking up data in manuals, the physics of getting a fix are not difficult to master.

Forms and plotting sheets have been posted on this board several times and a search should locate them. If not, I can help with some, PM me if you wish.

My advice is take a basic course on celestial which will help you understand the terminology and process but don't try to master all the (as others have rightly called it) conceptual trig and other mathematics that go with it. I would advise against trying to learn from a book.

 

really a very simple answer
Buy a cheap sextant and learn how to take a noon shot
you will be amazed at how simple it is
by doing this then you will begin to see that there are instances when only you can save your bacon
this will also require that you keep up with where you are and how fast you are travelling (DR)
and two GPSs do not work if there is a failure of the system
when one takes off into the ocean be prepared to take care of yourself

 

and two GPSs do not work if there is a failure of the system

Are there still people who believe that the GPS system is going to go down? A hundred or more satellites would simultaneously have to fall out of the sky for the system to fail.

How long does something have to keep flawlessly working before it is universally trusted?

People die due to aircraft falling out of the sky at a rate of a million to one compared to those dying due to GPS "failure" yet we all still trust commercial airlines but not GPS.

Go figure.

Let's face it, celestial navigation is a recreational pastime.

 

GPS system failure is a distant possibility, excepting the potential for localized jamming or the USG deciding to once-again implement "selective availability".

However, the possibility of onboard GPS units failing is much greater. Power failures, battery depletion, unit malfunctions, and EMF due to nearby or direct lightning strikes are much more a possibility.

Celestial is a good backup, and it's very good exercise for the brain. I agree that one needn't "master" the spherical trigonometry involved. The noon sight is very easy to learn. So, too, is the noon sight for longitude, which involves taking equal altitude sights before and after meridian passage. Learn these, and if you're interested and so inclined, continue on from there.

Not sure about the plastic sextants. I like good equipment. Good sextants cost a bit, but they're worth it. Get a good used Plath or Tamaya or Freiburger or Simex or Aires sextant. For heaven's sake, don't waste your money on any of the many "replicas" available on the market....they are strictly for show, not serious use.

Bill

 

I have had more than one occasion where my Garmin handheld picked up zero satellites when I had a clear view of the horizon. At least once was while sailing in open waters, and the condition lasted a couple of hours that time. I gave up waiting, but it worked again the very next day (no change of batteries or anything).

 

Please note: I was navigating commercially across the Oceans long before they had GPS. And really don't need a GPS to get me from point A to Point B.

 

Me too but now that I have GPS . . . . . it's a little like trying to find a call box when I could have a satellite phone in my hand.

 

The OP asked for any book recomendations.

Celestial Navigation for Yachtsmen by Mary Blewitt demystifies the process.

I liked it and know of many others who also learned from it.

BTW GET A PLASTIC SEXTANT TO LEARN ON! Lots on fleabay. You might even find one is a marina skip!

 

Back to the original question:

Ya - if you feel like it - it is not hard to learn. Trig is NOT my strong point, but, you don't need to understand trig to do elestial nav.

My wife and I both took Celestial Nav (and both passed it) with the Canadian Power Squadron group - and it was fun. Taking sites is not all that hard to do and neither is working out the positions. Just takes patience, practice and someone who can teach it to you.

If you are inclined - go for it.

Rik

 

CN is really a case of use or lose it. I took the course 20 years ago. Trying to get back into it using Tom Cunliffe's book.

 

If it works....there for it will at some point break.

 

I have often used CN to back up GPS and vice versa. It's a good tool to have in your toolbox. You never know when it might just save your butt.

For me it offers a direct connection to all the mariners that have gone before and that alone makes it worth learning.

Also, I believe as sailor anything increases your connection to environment is a good thing. When I sail long distances I get into a routine of regularly logging such things as sea state, barometer reading, wind direction and strength, clouds, and a host of other variables that affect sailing. CN dovetails very nicely into this more traditional, less automated, mode of navigation and sailing. Taken as whole, this practice has taught me more about the art of sailing and made me much more appreciative of the unique gifts that sailing affords than I believe could ever get from simply pushing a button on a GPS.

Don't get me wrong I have pushed more than my fair share of buttons

Do what you makes comfortable and increases your sense of security and confidence because that is what will help you over the horizon or across the bay. How you do it is often times less important simply doing it.

Just my .02 cents.

 

Not try to change the topic here.

If you need to ditch you SV and climb up to the life raft. Beside the other essentials, what would you rather take, GPS with spare battery or your sextant charts, calculator and etc.

Let here from the both sides.

 

Not try to change the topic here.

If you need to ditch you SV and climb up to the life raft. Beside the other essentials, what would you rather take, GPS with spare battery or your sextant charts, calculator and etc.

Let here from the both sides.

Neither. I'd clutch my EPIRB with a death-grip With or without GPS (the built-in 121.5mhz beacon will pinpoint you when help arrives).

Without this and with a fully functioning portable GPS, at least you'll know your own position with certainty when you die of thirst or starvation!

Bill

 

Mid day sun sights are easy-then all you do is use a sight reduction table and proformat sheet into which you put the numbers and do some simple adding and subtracting.
Of course the most fun is dead reckoning plus a sighting line and stick-the Polynesians got to NZ that way and across the south Pacific.One you have got the angle marked up the next person who wants to find you just sails either north or south until they get the same angle ;placing them on the same longtitude;then east or west to reach you.
I have a couple of GPs s as well and the astro calculator from Pangolin

 

It still befuddles me the "anti" attitude towards learning celestial nav. Both here and on AS. I find it intersting to learn and folks were getting around just fine for a few hundred years, if not more, with it. As the only way to nav thses days, no, of course not but, why not learn it if you want to. If you see no need then don't and you really shouldn't discourage others from doing so.

My 2 cents.

 

When I was in Hawaii I read that the Polynesians would lay in their boats and feel the waves to estimate their location. I think they did it in conjunction with celesitial navigation, but it still is pretty amazing.

 

One point that needs to be made is that if all the electronics on the boat go belly up your sextant might not be much help because the third requirement for celestial navigation (after a sextant and sight reduction tables or a nav calculator) is accurate time. Very few, if any, cruising sailors have a calibrated chronometer, one which has been monitored carefully so that the error is known and can be corrected for, to fall back on.

Almost all celestial navigators I have sailed with, myself included, use a radio time tick to set a stopwatch to get an accurate time on their sights. No radio = no accurate time = one line of position each day at noon of your Latitude - if a cloud doesn't obscure sun at just the right moment. Better than nothing, but far from ideal. If you get hit by lighting, as happened to me on a Bermuda-Halifax many years ago, and all the electronics get fried you are in deep doodoo. We had a good recent fix and weren't that far from land so we were able to stumble our way in by Dead Reckoning but it wasn't easy and I was glad we had a really good navigator aboard.

So you need to keep in mind - if you want to have a sextant aboard by all means do so and learn to use it, but remember it isn't much help without accurate time.

 

One point that needs to be made is that if all the electronics on the boat go belly up your sextant might not be much help because the third requirement for celestial navigation (after a sextant and sight reduction tables or a nav calculator) is accurate time. Very few, if any, cruising sailors have a calibrated chronometer, one which has been monitored carefully so that the error is known and can be corrected for, to fall back on.

Being a cheapskate I bought two £5 quartz watches and established their weekly gain/loss by observation before I left the UK.

As I was using a cheap Ebcco sextant I was happy to get 5 mile accuracy sights but that was good enough to find the Canaries and subsequent destinations. I had a SSB set and did get time checks but the +- allowances were within a second or two anyway.

Mind you I was REALLY glad I had a GPS when I went through the Bahamas, boy did I get fed up reading in the pilot that the island was identified by a conspicious stand of Casuarinas and a house with a red roof! Every island had a conspicious stand of Casuarinas and a house with a red roof!

 

Genieskip,

Very good point.

However, as you point out, you can get an LOP for your latitude each day even without accurate time.

Moreover, most everyone has a good quartz watch these days. If you are reasonably prudent, this can serve very well. Don't forget, an error of 4 seconds = 1 nautical mile, so even an error of a minute or so only results in an error of 15 nautical miles. In many instances, that would be sufficient.

It would also afford a good opportunity to "run down your latitude".

BTW, I give a "time tick" on the WaterWay Net (7268 kHz LSB daily @ 0745 Eastern time) whenever I'm net control, just in case anyone really cares about time accuracy

Bill
WA6CCA

 

Without an apparent answer, I come to the conclusion that if you can only to either GPS or Sextant, all would take a GPS. However, I am sure there a few whose balls are all hair will take the sextant. All power to you.

 

Have to agree that for 99.5% of sailors, there is no practical need for a sextant in 2011. But then again, if we were simply trying to get from point A to point B, we wouldn't sail to do it.

I own a C-Plath. Seldom use it. But it gives me comfort that if I need it, I have it. And IMHO, given the intense spirituality of an offshore voyage/race at night, connecting with the constellations I'm flying through makes it that much deeper.

 

There are only 24 GPS satellites in orbit, not "hundreds". You need signals from at least three satellites for a fix. Four to five is better.

I use an Android phone with Google Maps running off the phone's GPS. I have lost the GPS signal numerous times while driving to work, often in the rain for extended periods. It's not much of a problem on I-95, but I'd be pretty put off if it happened in the middle of Long Island Sound, forget about off the coast.

We had a kind of GPS "blackout" three years ago. The Long Island Rail Road uses GPS in its train cars to determine position. Something related to the GPS network changed, and the whole destination sign/announcement system went on the fritz. Each train car -- the entire fleet -- had to be individually reprogrammed in the shop. ALL the destination signs, AND the automated on--board announcements, were turned off, and reactivated one car (pair) at a time over several months.

I'd recommend always having a backup in case you lose GPS capability offshore.

 

There are only 24 GPS satellites in orbit, not "hundreds". You need signals from at least three satellites for a fix. Four to five is better.

Actually there are 31 . . . .

From Wikipeadiea . . . . . . "As of March 2008, there are 31 actively broadcasting satellites in the GPS constellation, and two older, retired from active service satellites kept in the constellation as orbital spares."

My simple little hand held almost always finds 8 or 9 sats so we would have to lose 5 or more for the system to "go down". I can't remember an occasion in which I had no GPS at any time.

 

Back to the OP's original question
What books? I found this one and it makes for an easy read and it give you an understanding of the basic concepts "Celestial Navigation for the Clueless".
I do love the banter on this site that comes to almost every post!
Peter
s/v Frayed

 

Back to the OP's original question
What books?

Bowditch has instructions on drawing horizon diagrams, which are awesome and take *all* the math and all of the tables out of sight reduction (and are not accurate below one degree, heh). I haven't seen these instruction's elsewhere, though I understand the Dalton book has them as well. If you're doing CN for fun and you like geometry or drawing pictures, or you think minimizing your use of electronics is fun, you should definitely pick up this skill.

In any case people say Bowditch is heavy reading but I don't see the problem. It reads like a textbook, that's all. Everything is built from the ground up. It also has the benefit of teaching you all the navigation you actually "need" to know; you really only need one book.

 

I just use a sextant for the fun of it.
By the way it is possible to work out longtitude without reference to GMT/UT.
Cook used system along side some of the first accurate marine chronometers.
Its all to do with star and planet plots enabling you to get a 2 d fix same way that satellites do it for you-very complex maths and not that accurate.
As for accurate clocks Slocum back in 1900s and Francis Chichester (of single handed around the world sailing fame)in 1930s in his aeroplane used tinplate alarm clocks.
It has to be said that my Great Uncles pocket watch circa 1900 can be more accurate than my digital Casio watch!
As for satnav when I bought my first Magellan handheld back in 1994 it clearly stated in the manual that the US government reserved the right to switch off the system as and when it felt the need.
I am guessing such a time might have been 9/11 when clearly it was very useful to terrorists.
I can also guarantee that submarines jam it for obvious reasons when coming to the surface-a regular occurence on the Firth of Clyde where I once lived when Trident Missile subs returned off their nuclear deterent patrols!
As they passed by your GPS would go haywire!

 

FWIW: the GPS that we all rely on is not always reliable. The FAA just sent me a notice that they finally got the WAAS satellite working again after a 3 MONTH outage (i used to fly regularly, so I am still on their notification list). Now, a boat doesn't need WAAS, but it's still sobering to realize that with all those satellites, things can still go wrong. I am personally interested in knowing how to do celestial navigation for the same reasons that I still carry a compass when backpacking...you never know when the batteries will run out or an errant splash ruins your gear.

 

Even without WAAS your GPS was faaaaaar more accurate than any CN fix you are going to get.

I don't understand the argument that your batteries could go dead on your GPS, but you are willing to drag a big sextant around in its box. (?) If you can drag that thing around, why can't you take some extra batteries?