Strange Russian Sextant - Question

[tefkiac]

Hey,
This is my first post, I just started into getting into sailing, and since I have an interest in astronomy since childhood, I find celestial navigation appealing.

So, I was browsing ebay for old sextants, and saw this one:

Vintage Soviet CCCP/USSR Russian Marine Navy SEXTANT No.90310 Boxed c.1969 | eBay

Now from what little I gathered so far, this has a similarity to the CHO-M, but for one it has a different name on the box and manual, lacks the illuminated lupe and most importantly, has only one index and horizon shades. Even in the manual page listed there, the sextant appears to have only one shade. Does anyone know what type of sextant that is, and most importantly, is it safe with just that shade?

I'd love to hear back from you, a lot of experienced people here!
Thanks!

Tef

[Vasco]

As far as the shade goes, if it only has one strong one that's fine. The lighter shades are only used on overcast days when the sun might peep out of the clouds and is very weak. If you do eventually use this sextant it'll be on a sunny day as, in most cases, it'll be used for practice or fun.

[Bestathook]

I looked at several Russian sextants. They were cheap, mostly under $100.

Check the error card in the box. Most I looked at had some pretty large errors. Some sextants are beyond salvage.

American Practical Navigator, by Bowditch will tell you a lot about sextants and their errors, and anything else you need to know to navigate. You will also need an accurate timepiece.

Any Master, Mates, and Pilots Union hall has a board full of good sextants for sale. With modern electronics, sextants have way more sellers than buyers.

But do it! What you have to learn to navigate with a sextant will give you a great knowledge of navigation of almost all types.

I took a course from Bill P, a writer from Rudder magazine 35 years ago in San Diego, and what I learned has navigated me around the world.

[tefkiac]

Thanks guys!
I'll just have to wait for the sextant and see. I naively didn't pay much attention to the error card of the sextant, which seems pretty significant at some angles. But I guess at the price it will suffice for practice! Unfortunately where I live, the people who own or can use a sextant can be measured with one hand! So, many things to learn!

[tropicalescape]

I used to import russian military surplus and those sextants were some of the stuff I brought in,I would buy them at the bazaar along with SLR camaras,night vision goggles,watches and swords etc..havent seen one in years but I have an info sheet (russian and chezh) if your interested in trying to get it translated...good luck

[Jim Cate]

FWIW,

I know nothing about Russian instruments, but have the following comment:

When thinking about doing celestial from a small yacht, instrument error is not often a big factor in observational error. Rather factors like low height of eye, big seas and an unstable platform are the main sources of error.

Consider the folks (like us some years ago) who use inexpensive plastic instruments such as the Davis Mk 20 or 25 and successfully navigate our way across the seas. These instruments are quite unstable with temperature change and simple handling stresses, and I suspect are much less accurate than the metal Russian devices.

I think that it will serve you well enough, so enjoy!

Cheers,

Jim

[tefkiac]

This sounds good!
I'll get a bit more study on celestial navigation till it arrives and try to review the sextant once it arrives!

Thanks!

[gjordan]

Instrument/index error are something you would normally figure into every shot anyway. It is the rare sextant that has no error, so I would not worry about the small step of figuring it in. I did my first 15K miles with plastic sextons, and I am sure your Russian one will be better than the plastic ones. 25 cents worth of advice! Dont learn to do a noon sight at first.(People will say that my advice is blasphemy), because a noon sight is one of the most difficult to get any accuracy on, and also if you have cloud cover at noon, you are SOL for 24 hours. It only takes a couple of more steps to do a proper sun line, and that gives you many more options. I met too many sailors that once having figured out a noon sight, never learned more. In reality, once you can do a sun line/line of position, the stars, moon and planets are not much more difficult. Celestial is a dying art, but it is a good skill, and can be a lot of fun. Best of luck to you. ____Grant.

[JPA Cate]

Noon sights are good; star sights are better! Loved those three star fixes. Which Jim took.

Ann

[tefkiac]

Wow lots of good advice, I really appreciate it!
To be honest star sights is what I had in mind, since I'm already a bit of a romantic with the night sky, so I guess if all works well, the blasphemy will spread!

[gjordan]

Go for it! Once you can do a line of position with the sun, the rest is just a bit more. Some of the best is being able to cross a sun line with a moon shot during the day. The moon can be used for celestial during the day on almost a third of the month. Much of the rest of the month the moon can be figured into a round of sunset/sunrise sights. I took a formal course in celestial from an astrophysasist (sp?) and he confused the hell out of me. An ex Navy quartermaster straightened me out and it all made sense. Dont let anyone tell you it is too tough to learn. If you are really into the romance of the stars, you might want to pick up a book by Dr David Lewis called We The Navigators. I was given this book at Christmas one year and didnt sleep until I was finished with it. A truly wonderful read. Best of Luck to you. _____Grant.

[tefkiac]

Originally Posted by gjordan

Go for it! Once you can do a line of position with the sun, the rest is just a bit more. Some of the best is being able to cross a sun line with a moon shot during the day. The moon can be used for celestial during the day on almost a third of the month. Much of the rest of the month the moon can be figured into a round of sunset/sunrise sights. I took a formal course in celestial from an astrophysasist (sp?) and he confused the hell out of me. An ex Navy quartermaster straightened me out and it all made sense. Dont let anyone tell you it is too tough to learn. If you are really into the romance of the stars, you might want to pick up a book by Dr David Lewis called We The Navigators. I was given this book at Christmas one year and didnt sleep until I was finished with it. A truly wonderful read. Best of Luck to you. _____Grant.

That book seems awesome, I ordered a copy!

[robert sailor]

Star sights and sun shots are great, moon shots are for those boring people who when asked what time it is tell you how to build a watch.

[carstenb]

Get a copy of

Celestial Navigation, by H.O 249. Best teaching book there is.

Not hard to learn, and hell you've got nothing else to do out here -s o you might as well spend some time learning.

[tefkiac]

I have received the sextant. It is indeed a CHO-M, but with the following differences:

- The 4 index shades have been replaced by a single shade, as have the horizon shades. I'm not sure the index filter is as dark as it should, since I can see through it like a pair of dark sunglasses. I have ordered a replacement from Russian CHO-M spares . I should have asked about opinions first, but the site looks OK. I suppose the horizon shades are not as critical, am I right?

- The illuminated magnifier is missing. However, the numbers on the scale are properly phosphorescent. I'll try to find a replacement magnifier somewhere.

- There is no inverted 6x30 scope, however it's scope is an amazing 3.5 or 4x40 erect scope, the optics are crystal clear and it's condition is nearly pristine.

There is a replacement index mirror, but no replacement half-mirror. Both installed mirrors are in excellent condition, with the index mirror showing two very small desilvered spots on two of its corners.

The micrometer works fine and is very smooth and accurate. No corrosion on the sextant, it even had a very thin film of protective oil on it.

I think it's a pretty good deal for the price I paid. Now i can start learning! Of course I'll stick to the night sky until I get filters strong enough, or just modify the existing one with some solar filter!