Can you navigate (lat and long) at night with a sextant and a compass, but
without a nautical almanac, sight reduction tables, the time of day, and
without knowing the names of the stars? The sextant has an error, but you
don't know what it is, just that it's off. You can keep your modern watch,
but you just replaced the battery and the time is wrong.

Does someone own a sextant? What model? I'm thinking about picking one up.

--
"j" ganz @@
www.sailnow.com

IDIOT!!!

On Sun, 20 Apr 2008 11:26:00 -0700, "Capt. JG"
wrote:

Can you navigate (lat and long) at night with a sextant and a compass, but
without a nautical almanac, sight reduction tables, the time of day, and
without knowing the names of the stars? The sextant has an error, but you
don't know what it is, just that it's off. You can keep your modern watch,
but you just replaced the battery and the time is wrong.

I assume this is a quiz? You can use a sextant to measure horizontal
angles and take relative shore bearings, other than that I think
you're out of luck. You can not take star sights at night (no
horizon), only at twilight.


Does someone own a sextant? What model? I'm thinking about picking one up.

I've owned this one for years and people have crossed oceans with it:

http://tinyurl.com/6fdkfr

It works but I prefer my GPS chartplotter.

"Wayne.B" wrote in message
...
On Sun, 20 Apr 2008 11:26:00 -0700, "Capt. JG"
wrote:

Can you navigate (lat and long) at night with a sextant and a compass, but
without a nautical almanac, sight reduction tables, the time of day, and
without knowing the names of the stars? The sextant has an error, but you
don't know what it is, just that it's off. You can keep your modern watch,
but you just replaced the battery and the time is wrong.

I assume this is a quiz? You can use a sextant to measure horizontal
angles and take relative shore bearings, other than that I think
you're out of luck. You can not take star sights at night (no
horizon), only at twilight.


Does someone own a sextant? What model? I'm thinking about picking one up.

I've owned this one for years and people have crossed oceans with it:

http://tinyurl.com/6fdkfr

It works but I prefer my GPS chartplotter.



Yes, it's a quiz and it's possible...

Not sure what you mean about not being able to use it at night... What about
the artificial horizon common on modern sextants?

http://en.wikipedia.org/wiki/Sextant

I'm somewhat familiar with the Davis models... thinking about playing around
with the 25.


--
"j" ganz @@
www.sailnow.com

On Sun, 20 Apr 2008 12:51:53 -0700, "Capt. JG"
wrote:

Not sure what you mean about not being able to use it at night... What about
the artificial horizon common on modern sextants?

It might be possible but I doubt it. There used to be a sextant
designed for aircraft navigation in WW II that used an artificial
horizon of sorts but those guys were happy to know where they were
within 20 miles or so.

You can get latitude without accurate time by taking a series of noon
sites and plotting the maximum elevation. Longitude to any reasonable
degree of accuracy is very difficult without accurate time.

"Wayne.B" wrote in message
...
On Sun, 20 Apr 2008 12:51:53 -0700, "Capt. JG"
wrote:

Not sure what you mean about not being able to use it at night... What
about
the artificial horizon common on modern sextants?

It might be possible but I doubt it. There used to be a sextant
designed for aircraft navigation in WW II that used an artificial
horizon of sorts but those guys were happy to know where they were
within 20 miles or so.

You can get latitude without accurate time by taking a series of noon
sites and plotting the maximum elevation. Longitude to any reasonable
degree of accuracy is very difficult without accurate time.



Not only possible, but people take star sightings all the time. Besides the
Sun, how many stars are you expecting to see during the day?

Yes, you can get an LOP with the information/equipment I supplied. I didn't
make this up, wish I did, but it works.

--
"j" ganz @@
www.sailnow.com

On Sun, 20 Apr 2008 16:22:29 -0700, "Capt. JG"
wrote:

Yes, you can get an LOP with the information/equipment I supplied. I didn't
make this up, wish I did, but it works.

Well please enlighten us. Heavenly bodies still hold a certain appeal
in these days of push button navigation.

"Wayne.B" wrote in message
...

It might be possible but I doubt it. There used to be a sextant
designed for aircraft navigation in WW II that used an artificial
horizon of sorts but those guys were happy to know where they were
within 20 miles or so.

That was not a sextant. It was called an octant.

Here's one:

http://www.icarusbooks.com/images/1458.jpg

On Sun, 20 Apr 2008 20:25:09 -0600, "Roger Helio"
wrote:


"Wayne.B" wrote in message
.. .

It might be possible but I doubt it. There used to be a sextant
designed for aircraft navigation in WW II that used an artificial
horizon of sorts but those guys were happy to know where they were
within 20 miles or so.

That was not a sextant. It was called an octant.

Here's one:

http://www.icarusbooks.com/images/1458.jpg

I've got no idea what that thing you referenced is but I can assure
you that the devices carried aboard aircraft, at least until the
1970's was called a "Bubble Sextant" and didn't look a thing like your
picture.


Bruce-in-Bangkok
(correct email address for reply)

"Roger Helio" wrote in message
...

"Wayne.B" wrote in message
...

It might be possible but I doubt it. There used to be a sextant
designed for aircraft navigation in WW II that used an artificial
horizon of sorts but those guys were happy to know where they were
within 20 miles or so.

That was not a sextant. It was called an octant.

Here's one:

http://www.icarusbooks.com/images/1458.jpg
That is not an octant. It looks like a bubble sextant as used on aircraft..
An octant is exactly the same as a sextant except that is is constructed to
read to 45 degrees against a sextant's 60.
A sextant can therefore measure a wider angle than an octant.
.. I have an octant that my grandfather used. It is made of
ebony and has ivory engraved scale read with a vernier, but in all essential
respects is identical to a sextant.