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Re: SNO-T/CHO-M + Freiberger info
From: Courtney Thomas
Date: 2003 Oct 6, 22:52 -0500
From: Courtney Thomas
Date: 2003 Oct 6, 22:52 -0500
Doug, Thanks so much for the fulsome reply. Are you familiar with The Sextant Handbook ? In it there are tests that a typical user can carry out on his sextant for collimation and index error. Just wonderin' how adequate they are. I assumed when I bought my Russian sextant(s) that, considering what was at stake, surely the Russian Navy powers that were, would have seen to it that their ships had, at least, good..... sextants. I must say I am much encouraged by your experience and observations. Which would you prefer [and why]; a calibrated, with manufacturer's certification [including non-adjustable errors] 1970 SNO-M or a 1980 SNO-T. The SNO-T has a label in the box lid with a sequence of Russian data. But, I don't know if it applies to my sextant. i.e. this might not be the original box for this sextant. But, no non-adjustable error data. What is the distinction between SNO and CHO ? Most appreciatively, Courtney Royer, Doug wrote: >Courtney,welcome to the list.Here is what I know. >I had the opportunity to use both of these types of Russian(I should say >Soviet)sextants.One was owned by a Polish ABS I served with and he >consistantly got outstanding LOPs useing his.He won an $1800.00 pool on one >transit when his final position was less than 0.2nm from the ships GPS pos. >when the evolution was stopped by the master. >Both of these sextants types were manufactured I beleive in Riga,Latvia and >someplace in East Germany between 1947 to 1988.They were built for the >Soviet Navy to rigorous standards.They are clones taken from the Freiberger >Prazisionmechanik Co.The optics in the scopes were Zeiss optics.And as all >Freiberger sextants are of the Drum type.Very good quality machining, >optics, very dependable and easy to use.The Index mirror is standard size >about 52 mm and I think also the silvering is on the front face of the >mirror.You will need to use cal. cylinders,dice or dominoes to check >perpendicularity of the Index mirror if that is the case. >The sextants I used were built in the ' 70's or early ' 80's.I can't say if >there were instrument cal. sheets for these on the lids of the boxes because >I can't remember. >All Freiberger sextants(man.after 1975)come with a cert certifying they are >free of Instument Error for practical purposes as do most sextants >manufactured today.These Russian sextants are clones of German >Equipement.Cassens + Plath and Carl Plath sextants have a max. error spec of >9" of arc over the arc's entire radius.Freiberger is right in there also so >your Rissian sextant should be the same.I would be more concerned about >Collumation Error and Index Error than Inst. Error.I wouldn't waste time >and money trying to have the arc calibrated.I had my MS-733 calibrated years >ago at a good chunk of change to find the whole error was 11" of arc.If you >want it collumated there are many places that will do that service for you. >The Clausen Inst. Co. is the importer for Freiberger sextants in the U.S. >and I am sure they have a website.If you need an owners manual maybe they >can help. >Hope this helps you out and good luck. > > > -- Courtney Thomas s/v Mutiny lying Oriental, NC