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Celestial Navigation

3887 Views 22 Replies 13 Participants Last post by SVAuspicious, Feb 1, 2015

TheNauticalAlmanac

Discussion Starter · Jan 31, 2015

Are any of you sailors doing Celestial Navigation?

1 - 20 of 23 Posts

MarkofSeaLife

· #2 · Jan 31, 2015

Not since Myan 2012. The end of the world stuff was a total crock of codswallop but they were correct in saying the axis of the earth is moving at about .5 degree per year, so now its 2.5 years later you will always be miles out in your LP.

Its clearly shown in the graphic attached.

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captbillc

· #3 · Jan 31, 2015

i would think the nautical almanac which you get each year corrects for this, so your fixes are still ok.

Don L

· #4 · Jan 31, 2015

I'm not, never have, don't plan on learning!

No one will ever call me a Luddite

SVAuspicious

· #5 · Jan 31, 2015

I think it's fun.

MarkofSeaLife

· #6 · Jan 31, 2015

SVAuspicious said:
I think it's fun.

I think chasing hot chicks while swilling beer is fun.

Reactions: 4

TheNauticalAlmanac

Discussion Starter · #7 · Jan 31, 2015

captbillc said:
i would think the nautical almanac which you get each year corrects for this, so your fixes are still ok.

Yes, through corrections to precession and nutation found in HO-249 Vol. 1
TABLE 5 - CORRECTION FOR PRECESSION AND NUTATION.

Puddin'_Tain

· #8 · Jan 31, 2015

I have a couple of cheap sextants, and I've learned to use them well enough that (if need be) I could probably manage to find my way to Hawaii or some other fairly large target. It's kind of fun, and a bit frustrating at times.

But, let's face it, CN is a bit like being able to paint a pretty picture. I could invest in oils, canvas, brushes, an easel, etc., and sit down for hours and paint away. It would be fun, and probably a bit frustrating. In the end (and after a lot of practice) I would probably be able to paint something that looked pretty much like the subject at hand. OR, I could whip out my iPhone, take a digital pic, and have something that looked exactly like the subject.

Reactions: 1

Minnewaska

· #9 · Jan 31, 2015

Noon shots are fun. Particularly if you have an app or program that converts the data to position. Just like sailing itself, showing a newbie how its done is like revealing how the wizard does their magic. It's just not as hard as some think. Triangulating the constellations, that's not fun.

Beer and pretty women. Also fun.

Reactions: 1

TheNauticalAlmanac

Discussion Starter · #10 · Jan 31, 2015

Usually, on board I have a certain amount of time to spare and find CelNav very enjoyable and easy. Minimization of electronics is important to me. Dead batteries and I go hand in hand.

You can get The Nautical Almanac for free at- TheNauticalAlmanac.com

The site offers the Almanac up to the year 2020 plus a lot of other CelNav info.

Reactions: 1

Gary M

· #11 · Jan 31, 2015

It has been years and I just used a cheap Davis but enjoyed doing it and best shots were within a mile of so doing a three point.

Sailing the BVIs in a weeks time and just went to the boat and got dividers, parallel rules and hand bearing, will get both adult kids to lay out courses and running fixes etc. They are quite interested to learn.

TheNauticalAlmanac

Discussion Starter · #12 · Jan 31, 2015

Nice to teach your kids.

Do you have the Mark 15? They certainly are corrosion resistant!

Also, paper based navigation (charts) is much more interesting than a chart plotter and it certainly makes you more aware of your surroundings when in a coastal situation. You have to be!

I have an Astra III-B and typically get fixes within a 3 to 4 miles. Last night I shot Jupiter and Sirius 6 times each and got a nice fix.

Gary M

· #13 · Jan 31, 2015

It is a 25 and you are right, not a spot of rust on it anywhere

Always thought I would like to pick up a Plath or something nice, they are so shiny

My one mile shot may have been luck

killarney_sailor

· #14 · Jan 31, 2015

Haven't met a serious cruiser who uses CN at all. Very few even have a sextant onboard, let along the rest of the stuff you need. I used celestial for real 30+ years ago - don't miss it.

TheNauticalAlmanac

Discussion Starter · #15 · Jan 31, 2015

Gary M said:
It is a 25 and you are right, not a spot of rust on it anywhere

Always thought I would like to pick up a Plath or something nice, they are so shiny

My one mile shot may have been luck

Nah, call it "skill".

Face it- when offshore anywhere within a 2 mile radius is excellent.

A Plath is very nice. I really hope this doesn't turn into a collection of sextants for me! It'll get expensive fast.

Have fun.

Minnewaska

· #16 · Jan 31, 2015

I would love to pick up a used Astra IIIB in good shape.

TheNauticalAlmanac

Discussion Starter · #17 · Jan 31, 2015

They're the most common sextant around. Tamaya is pretty good too.

Caribbeachbum

· #18 · Jan 31, 2015

MarkofSeaLife said:
I think chasing hot chicks while swilling beer is fun.

But, but ... what if you can't find your way to the beer or the chicks? Then you need a sextant! And some sight reduction tables. And math. Chicks dig math.

Jiminri

· #19 · Feb 1, 2015

I apologize in advance for what is likely a dumb question. Can you do CN and noon shots in an enclosed body of water like the Chesapeake? My crude understanding of how a sextant works is that you adjust the sextant until the sun appears to touch the horizon...which you wouldn't really observe at sea level because of the nearby land...and then record the angle and make the necessary calculations. If this is all true, how does one practice CN when not in the middle of the ocean?

Even though CN is no longer common or necessary, I think learning some bit of it...even just to better appreciate how navigation was once done...would be satisfying.

TheNauticalAlmanac

Discussion Starter · #20 · Feb 1, 2015

Jiminri said:
I apologize in advance for what is likely a dumb question. Can you do CN and noon shots in an enclosed body of water like the Chesapeake? My crude understanding of how a sextant works is that you adjust the sextant until the sun appears to touch the horizon...which you wouldn't really observe at sea level because of the nearby land...and then record the angle and make the necessary calculations. If this is all true, how does one practice CN when not in the middle of the ocean?

Even though CN is no longer common or necessary, I think learning some bit of it...even just to better appreciate how navigation was once done...would be satisfying.

You're correct about close areas with no horizon- only land. Typically in the Chesapeake once the Sun is South then you can take good shots but not much later or earlier than that. On most of the Chesapeake you really don't need fancy navigational equipment when the weather is good....but if it's late at night...a GPS really does help and makes life a bit less stressful. Being realistic- CelNav on the Chesapeake isn't done. You already know where you are and a chart simplifies everything.

If you use an Artificial Horizon (AH) then you can take shots any time. An AH is simple to make and easier to use. Take water in a dish, bowl or puddle and find the Sun's reflection in it. Adjust your sextant so that you bring the Sun from the sky down to rest on top of the reflected image sun which is in the dish of water. Then record your time and altitude taken- Hs (Height of Sextant). Then you do the math to get a LOP (Line Of Position). It's much more complicated than that but those are the basics.

On land, without all extra complexity of fancier equipment, an AH is the best choice to taking shots and makes sights very simple.

The key issue with an AH is stability. The wind mustn't disturb the liquid surface. You can make a "tent" of glass panes or plastic to enclose the AH.

However, I've taken sights using ice as a reflective surface, muddy puddles and coffee. It's not that difficult.

What CelNav does teach, and that very well, is to know your surroundings either by simply looking with your eyes at the position of the stars or land features.

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