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    Re: Used Sextant Wanted
    From: Dahlgren P
    Date: 1998 Jan 12, 8:29 PM

    In a message dated 98-01-12 00:02:35 EST, you write:
    <<  Is there any significant difference taking a sight on the
     deck of a pitching 35 foot sailboat with a plastic sextant over a shiny
     metal one.  I realize that on a stable surface the tolerances would be great
     but I would appreciate hearing from someone who has used both on small boats
     and the differences it made.
     thanks, Jim.
    I have used an old Davis (Mark 15 I think) and a new Astra IIIB, both from the
    beach and while sailing (nothing too rough, perhaps 3 to 4 foot swells).  My
    most accurate shots from the beach actually were taken with the Davis, with a
    couple of intercepts of 0.5 miles or better.  It's a little hard to pin down
    the accuracy of the shots from the boat, as the only GPS I own is the Davis
    (gray plastic sextant).   You get a much higher rate of change in the index
    error on a plastic sextant as it equilibrates.  Also, there is much more play
    in the gears.  To some extent you can work around this by only adusting in one
    direction, which is good practice anyway.  Certainly the optics of the scope
    on the Astra are far superior to the Davis.  But, the bottom line is, with
    care you can get good shots with either one.
    Paul Dahlgren
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