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Old 23-12-2010, 08:56   #1
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Russian Sextants

This thread has probably been beaten to death but I can't seem to navigate the search function. But what can I say; I have old guy computer skills. My question is; are these sextants worthy of consideration since they seem to be priced right and there are a fair few for sale on e bay.
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Old 23-12-2010, 09:40   #2
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Old 23-12-2010, 10:47   #3
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Off hand, Russian sextants are of generally good quality and fairly small size, the latter being a good point for boaters. They are, if in good condition, a viable alternative to the more expensive western sextants such as Plath and far superior to the inexpensive plastic sextants. On the debit side, the Russians, for reasons best known to themselves, often used astronomical type telescopes on their sextants, rather than the usual navigation types used by everyone else. This has a narrow field of view and presents the image inverted, meaning the user has to bring the horizon up to the sun instead of the other way around as in Western sextants. If one has a Russian sextant of this type, one can replace the telescope with one that presents the image in the manner one has been taught in celestial navigation. The CHO-M sextant is pretty much a copy of the C. Plath sextant of the 1930s.
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Old 23-12-2010, 10:50   #4
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I drool over the $2K plath model. As soon as I take the celestial nav course and need a real one I'm pulling the trigger.
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Old 23-12-2010, 10:58   #5
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I don't have experience with Russian sextants, but I do with Russian optics (for my telescope). Solid as a rock and very good quality. Overall, excellent value for money.

As for sextants in general, the important thing is to avoid "quandrant error" - which essentially means that arc thingy at the bottom (the quandrant) is bent. You can hold the sextant horizontally and look in the index mirror. If you don't see a "step" between the two sides of the quandrant, you're probably Ok. Index and side error are easily corrected by the user, so not much to worry about there.

Hope that helps.
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Old 23-12-2010, 11:13   #6
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While we are on the sextants and accuracy issue, I have a couple of questions.
As my primary use of sextant is to back up the GPS. My main consideration is that it is capable of locating me to within visual distance of major landmass, (I.E. 5-10 miles). Since sextant errors can be corrected for, and some are self correcting, (with multiple sitings), how important is it that you get the super expensive, super accurate ones? I have a super cheap $20.00 I found at a yard sale. As far as I can tell, I should be able to find Hawaii with it if need be.
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Old 23-12-2010, 23:30   #7
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Originally Posted by capn_billl View Post
While we are on the sextants and accuracy issue, I have a couple of questions.
As my primary use of sextant is to back up the GPS. My main consideration is that it is capable of locating me to within visual distance of major landmass, (I.E. 5-10 miles). Since sextant errors can be corrected for, and some are self correcting, (with multiple sitings), how important is it that you get the super expensive, super accurate ones? I have a super cheap $20.00 I found at a yard sale. As far as I can tell, I should be able to find Hawaii with it if need be.
G'Day Bill,

As it happens, Ann and i actually found Hawaii in 1983 on our very first offshore passage (form SF), and we used a moderately priced plastic sextant (not the very cheapest one with no optics at all).

IMO, when taking sights from a small yacht, the accuracy of the sextant is far from your biggest error source. Your very low height of eye coupled with sometimes considerable motion provide much greater chances of stuffing it up.

So, for a backup system, a plastic sextant is quite adequate. You must learn how to check index error each time you take it out of its box, but that's a simple and quick adjustment.

ON the other hand, nice instruments are really... nice!

Cheers, and good onya for even thinking about this issue. Few do these days.

Jim and Ann s/v Insatiable II lying Towlers Bay, NSW, Oz
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Old 24-12-2010, 02:28   #8
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Originally Posted by capn_billl View Post
As my primary use of sextant is to back up the GPS. My main consideration is that it is capable of locating me to within visual distance of major landmass, (I.E. 5-10 miles).
In my experience, unless you are really good and really experienced, that's about as accurate as you are going to get with a sextant in a small boat at sea anyway-- after spending hours a day working on that one running fix. I'm sure this subject has been beaten to death elsewhere, but for the amount of money you're getting ready to spend, you could buy three handheld GPS's and a buttload of AA batteries. Then you would know where you were.

I used to LOVE celestial navigation. It is a beautiful art, and the sport of sailing was altogether different when that was the way you did it. But there's no sextant on my boat now, and I have no plans to get one.
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Old 28-12-2010, 08:50   #9
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G'Day Bill,

So, for a backup system, a plastic sextant is quite adequate. You must learn how to check index error each time you take it out of its box, but that's a simple and quick adjustment.

Jim and Ann s/v Insatiable II lying Towlers Bay, NSW, Oz
Thanks alot. I'm interested in learning more.
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Old 28-12-2010, 09:15   #10
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I have a Celestaire Astro IIIB sextant which was about $500 new. I spoke with the rep at the boat show and asked if there would be any advantage to the more expensive models. His response, which agrees with some of the other posters, is that the limiting factor is getting a good sight from a small, bobbing boat and for those conditions the less expensive models work just fine. So unless, you plan on navigating a freighter, the less expensive models work just fine.

As Capn Bill states, the plastic sextants are not as thermally stable as say an aluminum or brass model and for that reason you will need to constantly check index error before each sight.

Rich
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Old 15-07-2012, 03:12   #11
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Re: Russian Sextants

I read in the forum ...
"If one has a Russian sextant of this type, one can replace the telescope with one that presents the image in the manner one" is accustomed to.

Great. Where do I get one of those "replacement telescopes"?
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Old 15-07-2012, 04:30   #12
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Re: Russian Sextants

Here is a great site (heheh) about Russian sextants. It also goes into detail about how to check that your Plath really is from Hamburg, and not simply a Russian model forged to look like one to scam you. The Russian optics are lovely because they got the German optics factories and technicians bequethed to them at the end of WW2. Back in 1990 just after the Wall was let down (it didn't fall) one could buy nifty nightvision scopes for Dragunov SVD's on the Kurfurstendamm for a pittance... anyway, here are the sextants:

The USSR SNO-T sextant The Nautical Sextant
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