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    Re: SNO-T/CHO-M + Freiberger info
    From: Doug Royer
    Date: 2003 Oct 7, 10:33 -0700

    Courtney,I suggest you go out and start useing your sextant,becoming
    familiar and comfortable with it.For now don't take what you read on the
    list concerning the fine points of Cel. Nav. and get frustrated trying to
    match results.That will come with time and with continued practical use of
    your sextant.Only practice will hone your skill.
    As for the "Sextant Handbook" I hear it is a good book.I don't have a
    copy.Yes there are tests one can do to check for errors.I don't know about
    collimation(someone on list may) but for I.E. use the diam. or semi diam. of
    the Sun or Moon.This procedure I know is accurate for finding I.E.Bowditch
    has the procedure for this if the sextant handbook doesn't.
    I forget if the scopes on the SNO-T type sextants use a collar that you
    screw the scope into or not thus mounting it to the frame.If so there may be
    a screw adjustment on the collar used to align the scope and frame.Bowditch
    also has a procedure to accomplish this adjustment.
    The optics will be outstanding.I beleive you have both a 4x and 9x
    scope.Objects(stars etc.)should be very crisp and clean viewed with your
    sextant.Do yourself a big,fat favor for now.When taking observations at 1st
    use only the 4x scope.It's easier to use for taking practical cuts while
    learning the actual methods you will employ to get LOPs.Later you will see
    the benefit of useing the greater mag. scope for certain shots.
    As for your last question,I don't really know which sextant I was
    useing(SHO-T or SNO-M) nor have I used either enough to answer your
    question.All I know is I was very impressed by the quality of the optics and
    the sextant as a whole.
    If I may be of further help just ask.
    
    
    -----Original Message-----
    From: Courtney Thomas [mailto:ccthomas{at}JOIMAIL.COM]
    Sent: Monday, October 06, 2003 20:53
    To: NAVIGATION-L{at}LISTSERV.WEBKAHUNA.COM
    Subject: Re: SNO-T/SNO-M + Freiberger info
    
    
    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
    
    
    

       
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