On Apr 4, 2:57 pm, Sam Wormley wrote:
wrote:
On Apr 4, 8:57 am, "Jim" wrote:
More importantly - can anyone list a website that explains:

1. how \ where to find those 57 stars and
2. how to use them for navigation

I was only aware of polaris, the southern cross and orion's belt as
navigational stars.

Get a copy of Bowditch
The American Practical Navigator.

Joe

Or read it athttp://www.irbs.com/bowditch/

For a student working on a class project I agree.

For a sailor it's not the same, any sailor worth his salt has a copy
of bowditch aboard.

Joe

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On Apr 4, 2:57 pm, Sam Wormley wrote:
wrote:
On Apr 4, 8:57 am, "Jim" wrote:
More importantly - can anyone list a website that explains:

1. how \ where to find those 57 stars and
2. how to use them for navigation

I was only aware of polaris, the southern cross and orion's belt as
navigational stars.

Get a copy of Bowditch
The American Practical Navigator.

Joe

Or read it athttp://www.irbs.com/bowditch/

For a student working on a class project I agree.

For a sailor it's not the same, any sailor worth his salt has a copy
of bowditch aboard.

Joe



Even if they don't carry, or know how to use, a sextant. Right? ;-)

On Wed, 4 Apr 2007 18:15:34 -0500, "KLC Lewis"
wrote:

Even if they don't carry, or know how to use, a sextant. Right? ;-)

There's a lot in there other than celestial.

On Apr 4, 6:54 pm, Wayne.B wrote:
On Wed, 4 Apr 2007 18:15:34 -0500, "KLC Lewis"
wrote:

Even if they don't carry, or know how to use, a sextant. Right? ;-)

There's a lot in there other than celestial.

Indeed Wayne, it's one of my treasured items passed down in the
family.
And if you want to learn celestial, you will not find a better
publication.

As I said, and KLC shows, any sailor worth his salt has a copy of
bowditch aboard.

Joe

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On Apr 4, 6:54 pm, Wayne.B wrote:
On Wed, 4 Apr 2007 18:15:34 -0500, "KLC Lewis"
wrote:

Even if they don't carry, or know how to use, a sextant. Right? ;-)

There's a lot in there other than celestial.

Indeed Wayne, it's one of my treasured items passed down in the
family.
And if you want to learn celestial, you will not find a better
publication.

As I said, and KLC shows, any sailor worth his salt has a copy of
bowditch aboard.

Joe


Ain't much salt in the Great Lakes. But I also didn't say that I didn't have
a copy, did I? Cute dig, though.

On 4 Apr 2007 17:05:26 -0700, wrote:

Indeed Wayne, it's one of my treasured items passed down in the
family.

I bought my copy back in the 70s when an RDF was a hi tech navigation
device. Duttons also.

On Apr 4, 8:12 pm, "KLC Lewis" wrote:
wrote in message

oups.com...





On Apr 4, 6:54 pm, Wayne.B wrote:
On Wed, 4 Apr 2007 18:15:34 -0500, "KLC Lewis"
wrote:

Even if they don't carry, or know how to use, a sextant. Right? ;-)

There's a lot in there other than celestial.

Indeed Wayne, it's one of my treasured items passed down in the
family.
And if you want to learn celestial, you will not find a better
publication.

As I said, and KLC shows, any sailor worth his salt has a copy of
bowditch aboard.

Joe

Ain't much salt in the Great Lakes.

Not much sailing either since you are frozen in half the year...sorry
to hear it.
But the saying " Worth his salt" refers to the amount of salt in your
body, not the amount of salt in your local lake.

But I also didn't say that I didn't have
a copy, did I?

If you did have a copy... you would have known of all the other great
subjects Bowditch covers besides celestial navigation.
Unless you never read it, you would see it value beyond using a
sextant.

Joe

Cute dig, though.- Hide quoted text -

- Show quoted text -

"Jim" wrote:

More importantly - can anyone list a website that explains:

1. how \ where to find those 57 stars and

Finding the stars comes from knowledge of the heavens. It's not
difficult to learn the minimum amount needed to identify 5 or 6 bright
stars in any heaven that would be above you. You could also use a
planisphere or with sight reduction tables you could work out more or
less where the star would be at the time you want to use it for
navigation. You look in that direction at that altitude and then the
brightest one in that area is likely to be your navigation star.

2. how to use them for navigation

All celestial navigation is based on a very simple theory. At any
given moment (exact time) every star in the heavens above has a
zenithal point somewhere on earth. That is a point where it is 90
degrees to the earth below. Directly overhead. At that exact moment
you measure the angle between your position and the star. Then you
can use a giant imaginery compass, with one point stuck into that
zenithal point and with the two legs set at the angle you measured, to
inscribe a giant circle on the earth. Somewhere on this circle you
must be. Do this with three stars and those three imaginary circles
will intersect at a single point. That's where you are on the globe.

That's the theory. In practice it is a little more complicated. As
others have indicated there are very good online and paper resources
which will explain the details.

It is also fairly pricey to do it this way - a good sextant and
reliable chronometer will set you back a bit but they are one time
expenditures. Annually you will have to purchase celestial tables -
and they can be very pricey.

But this is the purist celestial navigator's way. I have a cousin who
during the eighties did a few years delivering yachts around the
world. He had a scanty knowledge of navigation. By using a few
tricks - like a good celestial navigation calculator - and a cheap
plastic sextant he avoided running into anything expensive. Most
navigation is pretty commonsensical - give a clot the most expensive
GPS and he will still run into things, probably while peering at the
GPS, while an expert navigator can make do with very little. I had a
pal who once sailed from Cape Town to St Helena using a cheap
transistor radio for the time and an old war surplus box sextant.
Even those aids were pretty pointless as for the first week he was in
fog and couldn't see a star or the sun. And he made it spot on. He
had been a navigator on an ocean minesweeper during WW2 - and their
navigation had to be pretty good and accurate. His skill made up for
the lack of fancy equipment.

Eugene L Griessel

The basic delusion that men may be governed and yet be free.

On Apr 4, 5:11 pm, " wrote:
On Apr 4, 2:34 am, "John Nagelson" wrote:

Hello, the US Nautical Almanac lists 173 "navigational stars", of
which a shorter list of 57 is sometimes extracted.

I've been unable to find these lists online, although I have found
databases referencing many millions of stars!

Could someone tell me if they know where the lists of 57 and 173 stars
exists online.

Or if it doesn't, and someone has got the two lists in text format,
I'd be very grateful if they could post them in follow-up to this
message!

Bowditch's THE AMERICAN PRACTICAL NAVIGATOR in hardcopy, or
online in PDF form at URL:

http://www.irbs.com/bowditch/

A big thank you to everyone who has posted in reply. Bowditch looks a
fantastic
source on celestial navigation, which I will study.

Unless I am mistaken, though, it gives the list of 57 plus Polaris,
not the 173, although it says the latter is given in the US Nautical
Almanac.

Maybe there is a shareware navigation program somewhere that I can
pick out the
info from???

Cheers,

John

"John Nagelson" wrote:

Unless I am mistaken, though, it gives the list of 57 plus Polaris,
not the 173, although it says the latter is given in the US Nautical
Almanac.

Maybe there is a shareware navigation program somewhere that I can
pick out the
info from???

Any visible star can be used for navigation. The 57 given in
Alamanacs are all bright stars which are not easily confused with
others. The majority of the 173 you will find are sometimes pretty
iffy and any celestial navigator would probaly only resort to them in
fairly awkward circumstances. When you start hitting 3 magnitude and
higher it gets more awkward to distinguish the star one wants from the
background - especially on a ship which may be moving quite heavily.
Brown, for instance, (In the last copy I bought) gives some stars up
to 4 magnitude. But practically, unless you are that rarest of
navigators who can distinguish 173 stars with certainty, anything much
higher than 2 magnitude becomes chancy. Wheras the SHA and Dec of the
57 principal stars are given on the daily pages of nautical almanacs I
don't think I have ever seen the lesser stars listed thus. They are
usually confined to a couple of pages in the back giving the SHA and
Dec for the month only. In principle, unless you plan to sail the
world, you could probably get away with an intimate knowledge of about
sixteen stars in your hemisphere.




Eugene L Griessel

For every person willing to teach, there are 30 not willing to be
taught