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View Poll Results: Keeping celestial nav skills alive
Never learned, too many sight reduction books to haul around 12 26.67%
Learned, but no longer practice 17 37.78%
Learned, practice every chance for that perfect pin wheel 16 35.56%
Voters: 45. You may not vote on this poll

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Old 27-02-2012, 21:55   #46
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Re: Who Still Practices Celestial Navigation ?

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Originally Posted by bobconnie View Post
Sounds like Guuieduck and I do the same things ! LOL still do noon sites and sometimes even a star shot, use a taff log, and carry a lead line, with a wax bottom LOL and even use em a lot! also have a hand held GPS, and use that ! and of course the wife has her laptop with the Capt software and Charts, that I look at also! ya can't have to many ways to find your way home !! I just like the old stuff I guess because its what I learned as a young man ! and has worked for over 50 yrs !! LOL Just my 2 cents Bob and Connie
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I used to dive commercially for them back in my wild & woolly days - averaged 10000 lbs per week. We used to have to keep a 1/4 mile from the beach and I used my old Navy sextant to triangulate a position! (still got my Kirby)
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Old 27-02-2012, 22:29   #47
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Re: Who still practices celestial navigation?

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Originally Posted by Bill S View Post
There is still another choice which is that I am working on lesrning it now. Have all the gear and tables aboard.
I also am in this category.....It is not easy on my own, but I am working at it. My accuracy hasn't been that good yet. I assume I need to sight with the sextant better.
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Old 28-02-2012, 09:35   #48
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Re: Who Still Practices Celestial Navigation ?

Noonsites are pretty easy to learn. Taking them at the equator where the sun's altitude doesn't change much takes practice. There's a PDF from Bowditch to show you a sighting technique on my site linked below.

I have a tool that allows you to generate your own noonsite tables. You can squeeze them into just two sheets of paper. Navigation by Noonsite -- All the Almanac Data and Correction Tables You Need

Also I came up with a quick set of tables that lets you dead reckon just using a lookup table. Navigation Information - Use Dead Reckoning Tables - A New Method

Eric
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Old 28-02-2012, 09:45   #49
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Re: Who Still Practices Celestial Navigation ?

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I also am in this category.....It is not easy on my own, but I am working at it. My accuracy hasn't been that good yet. I assume I need to sight with the sextant better.
Assuming your sextant is in good shape and checked for errors, it is merely a matter of frequent practice. You can try going down to the beach or somewhere you have a good horizon and practice on land, and see how close you come to your gps. Then try it on the boat--you have to develop a feel for it afloat, and usually your shots won't be quite so precise as on land.
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Old 28-02-2012, 13:13   #50
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Re: Who Still Practices Celestial Navigation ?

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Originally Posted by Eric. View Post
Noonsites are pretty easy to learn. Taking them at the equator where the sun's altitude doesn't change much takes practice. There's a PDF from Bowditch to show you a sighting technique on my site linked below.

I have a tool that allows you to generate your own noonsite tables. You can squeeze them into just two sheets of paper. Navigation by Noonsite -- All the Almanac Data and Correction Tables You Need

Also I came up with a quick set of tables that lets you dead reckon just using a lookup table. Navigation Information - Use Dead Reckoning Tables - A New Method

Eric
i sow that your web site and are you shure about that,

After careful observation on November 27, 2004 the LAN was measured 3328.7' to the South and occurred at 14h 11m 30s GMT. Eye height 10 ft, Sextant errors = 0.

Longitude:
  1. According to the tables (see excerpt below), MP is 1147.45 GMT.
  2. Finding the difference is 14:11.30 - 11:47.45
    13:71.30 - 11:47.45 (manipulate the hours to minutes for subtraction)
    13:70.90 - 11:47.45 (manipulate the minutes to seconds for subtraction)
    13:70.90 - 11:47.45 = 2h 23m 45s (resulting difference)
  3. Convert 2 hours to degrees 2*15 = 30
    Convert 23 minutes 23/4 = 5.75 (take the whole part of 5.75 as 5)
    Convert 0.75 *4 = 3 (this is the remainder degrees changed to minutes)
    3 * 60 = 180 (changed to seconds)
  4. Now add this 180s remainder to the 45s from the difference in Step 2
    180+45 = 225 seconds (next divide by 4 to get back to minutes of arc).
    225/4 = 56.25 (converted back to minutes for the solution)
    Now put it all together
    30 + 5 + 56.25' = E 3556.25'
  5. This result is your Longitude. Note that it is East because your local apparent noon (LAN) is later than noon at MP.
english is not my first language and maybe i did not anderstand properly your calculations but, if you are east 3556.25' should not LAN be GMT 10 am, (actualy 09:44:53) instead 14 pm, and i think you forgot equation of time, 12min 34 sec.


if your LAN was 14:11:30, longitude should be 3601.0' W
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Old 28-02-2012, 19:09   #51
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Re: Who Still Practices Celestial Navigation ?

So learned friends; I am looking at Sextants. Cassens & Plaith Ultra - 1795; Astra IIIB 659; Davis Master mark 25 - 240; mark 15 - 173. WTF? How much is enough? The top units have 40 mm lense and the lesser units are 27 mm or so. I get that. I've talked tothe Astra guy at the boat shows and I still can't figure out what we need for off shore circumnavigation. ALSO. there are tons of books on how to. I've talked to seveal people about learning, books, classes. Some say it was cake and others say one book made it simple and others made it impossible. Constructive help here appreciated.
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Old 28-02-2012, 20:57   #52
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Re: Who Still Practices Celestial Navigation ?

I still carry a sextant and almanacs, tables... and I get it out every now and then and use it...but as with most folks, my primary nav tool is my GPS chartplotter in the cockpit, backed up by a stand alone GPS at the nav station and a couple of battery powered handhelds....which is all fine as long as the GPS system doesn't go down....and if it does and you're 2000 miles from anywhere, what do you do then ? Sextant and tables .....
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Old 29-02-2012, 05:12   #53
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Re: Who Still Practices Celestial Navigation ?

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if your LAN was 14:11:30, longitude should be 3601.0' W
Yes that should have been W, not E. The idea is for minimal tables, so both Bowditch and Reeds ignore EoT which introduces a maximum error of about 3.75 deg.

I thought about factoring the EoT into the sun's meridian passage right on the tables because I do compute it in the script.
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Old 29-02-2012, 06:50   #54
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Re: Who Still Practices Celestial Navigation ?

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...EoT which introduces a maximum error of about 3.75 deg.
Sorry...meant to type 16.3 minutes of error.

By the way I did add the EoT to javascript just to be complete.

In reality I haven't met anyone who still uses celestial nav. or even the noonsites.
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Old 29-02-2012, 07:39   #55
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Re: Who Still Practices Celestial Navigation ?

i do not know what bowdich or reeds are saing but something is definitely wrong. and that is 3144 miles wrong.




if your LAN was 14:11:30 GMT, you are definitely WEST of greenwich. So...




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Old 29-02-2012, 07:42   #56
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Re: Who Still Practices Celestial Navigation ?

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Sorry...meant to type 16.3 minutes of error.

By the way I did add the EoT to javascript just to be complete.

In reality I haven't met anyone who still uses celestial nav. or even the noonsites.
maby not people like you. who make possition in black sea instead in the middle of atlantic.3000 miles appart.

and, i am still using cel. nav. sometimes even on ancor, just for fun
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Old 29-02-2012, 08:15   #57
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Re: Who Still Practices Celestial Navigation ?

Being at sea is a series of tasks, standing watch, brightwork,sleep, navigating and yes also shooting the stars,planets and sun. Just something else to do on your way to the destination. Try it better than doing nothing. IMHO.
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Old 29-02-2012, 11:40   #58
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Re: Who Still Practices Celestial Navigation ?

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Being at sea is a series of tasks, standing watch, brightwork,sleep, navigating and yes also shooting the stars,planets and sun. Just something else to do on your way to the destination. Try it better than doing nothing. IMHO.
Brightwork?????
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Old 29-02-2012, 11:48   #59
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Re: Who Still Practices Celestial Navigation ?

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maby not people like you. who make possition in black sea instead in the middle of atlantic.3000 miles appart.
I think you must have missed the part where I said it was WEST not east. But thanks for the pedantic response.

I really don't know anyone who really uses their sextant in 8 years of traveling among the people who have been cruising for 4 or more years. I met one guy who bought his first GPS only 3 years ago (he'd been sailing for 30) and he admitted that he hasn't used his sextant since. But granted, it's also not something I go around asking all the time. The topic usually comes up more often in internet forums than on the docks.

You don't have to get defensive about the lack of use of sextants. I enjoy the celestial mechanical models and have written a lot of programs and spent a lot of time comparing different nutation and other algorithms. In fact I have spent quite a bit of time working on a compact version of the Nautical Almanac that you generate and print out, similar to my noonsite tables. However since there has been next to zero interest in it, I've sort of let the project die.

Eric
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Old 29-02-2012, 12:17   #60
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Quote:
Originally Posted by Eric.

I really don't know anyone who really uses their sextant in 8 years of traveling among the people who have been cruising for 4 or more years. I met one guy who bought his first GPS only 3 years ago (he'd been sailing for 30) and he admitted that he hasn't used his sextant ...

... In fact I have spent quite a bit of time working on a compact version of the Nautical Almanac that you generate and print out, similar to my noonsite tables. However since there has been next to zero interest in it, I've sort of let the project die.

Eric
I met a german couple that each were sailing their own boat, thats another story, and the man still used cn as a nav tool even though he still had gps.

In my last passage i turned off the electronics for 4 days and went cn and dr. Was a bit chicken **** since there waa no land mass near but still....

In 93 i naved from acapulco to panama without electronics just to see...

Appreciate the site and the effort. Personally i like the cn and dr just cause every once in awhile i can turn everything off on passage and pretend i am sailing during the golden age when it was harder and there were less boats and less marinas etc

Edit: i did 4 landfalls solely with cn and dr; puerto corinto nicuaragua, puntarenas and golfito bay costa rica, and panama canal
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