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Old 20-12-2008, 11:45   #1
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Question Sextant...

Hi folks. I'm brand new here so please forgive me.
Ive decided to learn celestial navigation and Im now looking for a sextant.
I see a small number of expensive ones and some mid priced ones I also see a number of lesser priced ones, some described as 'working models/reproductions' like this one.
http://cgi.ebay.ca/Large-ROSS-LONDON-Brass-10iin-Micrometer-Sextant-w-Box_W0QQitemZ120352165380QQcmdZViewItemQQptZLH_Def aultDomain_0?hash=item120352165380&_trksid=p3286.c 0.m14&_trkparms=72%3A1215|66%3A2|65%3A12|39%3A1|24 0%3A1318
My question is this, would it be worth my time and money to get something like this? Im sure I could learn with it but does anyone know if I could actually use it to navigate? At this point I dont really want to spend a small fortune on one but I also dont want to get one that turns out to be completely useless.
Ive done some searches and the subject has been touched on before. Any help would be appreciated greatly.
Thanks Very Much
Craig
BTW, looks like a great forum
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Old 20-12-2008, 11:54   #2
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You can get some very good inexpensive ones...They're from some sort of plastic but are very good.
Davis Mark 3 Plastic Sextant
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Old 20-12-2008, 12:01   #3
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Craig,

Yes, James is right...the Davis plastic sextants are the low-cost way to go. The "working models/reproductions" are worthless...just ornaments for your desk.

A really good metal sextant (Plath, Tamaya, Freiberger, etc.) will cost at least $400 in very good condition, more in excellent condition. They're worth it, but probably not until you learn a bit and decide if you really dig this celestial stuff.

Good luck...it's a fun pursuit!

Bill
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Old 20-12-2008, 12:36   #4
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Didn't someone here have another Davis Mark 15 in the classifieds? I've sold all mine but I recommend them especially for learning.
Kind regards,
JohnL
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Old 20-12-2008, 12:46   #5
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Thanks gentlemen for the information. I have one more question and that being metal versus plastic. I would truly appreciate any opinions on the subject.
Thanks Very Much
Craig
PS; I apologize, I see Ive still got a bad link up there.

EDIT: link fixed...
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Old 20-12-2008, 12:53   #6
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Have you considered one of these. They were good enough for Christopher & Ferdinand.
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Old 20-12-2008, 13:14   #7
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The metal sextants are more substantial, built to closer tolerances and may be a little more stable because of the extra weight. They are also more prone to corrosion, more tiring to use because of their weight and harder to store because of their size. Personally, I prefer a metal sextant but like the price of the plastic ones.

If I were starting off fresh and just wanted a back-up to a GPS would definitely go for a Plastic one. It's not the worth the extra money for the small advantage of a metal sextant. Might even go plastic if I was using it as my primary means of navigation but buy two with one as a back-up. If money was not an issue, would look to buying a used American, European or Japanese instrument.

Aloha
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Old 20-12-2008, 14:15   #8
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I have been using an Astra IIIB with whole horizon mirrors purchased from Celestaire in 1987 as a replacement for a Tamaya that was stolen from our boat during a break-in. At the time the Astra was only about $400 (USD) and I wondered about the quality given its relatively low cost. It has proven to be an excellant instrument, and, given my skill levels, no less functional than the more costly instrument. Using good equipment makes the learning much easier IMHO. See Celestaire, Inc.: Marine Sextants : Astra IIIB

FWIW...

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Old 20-12-2008, 21:27   #9
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The main thing about the one you are looking at on E-Bay is that while it is a working sextant, it will need to be calibrated and certified. As others have said, you can get perfectly good, certified sextants from a variety of suppliers. If you do purchase the Ross of London one, have it checked for accuracy. I have a 70 year old Plath naval sextant which was recalibrated and certified for accuracy, and it's a very useful tool for when your GPS fails you. I have also used several inexpensive plastic ones while learning how to do things the old way, and they give acceptable results, although they are not quite so accurate.
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Old 21-12-2008, 01:03   #10
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Thanks very much for the information folks. I think I'm going to save some money and get the Astra IIIB I'm thinking it will be the best in the long run.
Where would you get a sextant calibrated?
BTW. I'm in BC too Astrid.
Take Care
Craig
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Old 21-12-2008, 03:18   #11
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I remember reading about Steven Callahan who spent 76 days in a life raft crossing the Atlantic (east to west) after loosing his boat to a catastrophic hole...
I think he used two pencils and a popsicle stick or something like that...Its not that complicated...for a noon shot...its just the angle between the sun and the horizon.
It’s a worth while read, “Adrift” I think it was called.
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Old 21-12-2008, 03:20   #12
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The serious metal sextants are: Plath, Cassens & Plath, Tamaya, Freiburger, Simex, Heath, Aires, Astra. These are all good, and will cost several hundred dollars in good condition.

There's what appears to be an excellent Freiburger on eBay right now, coming up soon. It's currently at $249, and would be an excellent bargain if it sold for as much as $400 or so.

There's also a Simex Mark I which looks interesting, but 6 days to go. It would be fine, too, if under $400 or so.

Don't waste your money on the Ross. It's brassy and pretty and, IMHO, useless as a sextant for serious marine navigation.

Bill
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Old 21-12-2008, 05:52   #13
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Quote:
Originally Posted by blackjack View Post
I see a small number of expensive ones and some mid priced ones I also see a number of lesser priced ones, some described as 'working models/reproductions' like this one...
Craig
Be very careful, those advertised as 'reproduction/model' will be useless for navigation. ANd even some will be for sale without proper caveats.

I bought and use a new "Cho-T" They are from the Russian Naval Service, and there are a large number of new ones that have been released from stockpiles over the years. 4 years ago I paid approx $200 incl shipping from Russia for a new one and had it evaluated at White's in Boston - they thought it an excellent piece and worth many times more than I paid.

In direct comparison (side by side at the shoreside) to the more well know brands it does as well and sometimes better for accuracy.

From the link eBay.com.my: USSR Sextant * Cho - T * Very Nice One *Good Condition (item 270292125782 end time Oct 31, 2008 22:55:45 MYT)
you can see that the are still selling on eBay in that price range - but you do have to bide your time and not get in a bidding war.

Hope that helps,
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Old 21-12-2008, 09:53   #14
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I had mine checked and calibrated at

Sextants and Celestial Navigation - Nautical Plotting Tools and Nautical Supplies
or
Robert E. White Instruments, Inc. | 711 Atlantic Avenue, Boston, MA 02111
Tel: 800-992-3045 (U.S./Canada) Tel: 617-482-8460 (Eastern MA) Fax: 617-482-8304


First of all, though, buy Bauer's book on sextants:Sextant Handbook by Bruce Bauer, ISBN: 9780070052192. You can test your sextant, if used (newly made navigational quality sextants come with certificate of calibration) and see if you even need to have it recertified. You may not need to--just have a good chronometer, nautical almanac and take readings from a known position and you will see, if you do your math right, if the sextant is accurate enough or not.
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Old 21-12-2008, 10:07   #15
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Also consider the difference between taking sites from a ship versus taking sites from a relatively unstable platform like a small boat and where your eye height might only be 10 feet. It may be pointless to own a super accurate and expensive sextant when it might make no difference in the accuracy of your fixes.
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