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    Re: Full moon sights and lifeboat sextant accuracy
    From: Bruce Cutting
    Date: 2017 Oct 6, 18:20 -0600

    I'd like to see results from a set of runs, one with the MK3 another with
    a "good" sextant under the same conditions.  These results do not seem too
    bad to me.  Certainly good enough to put on a reasonable sized island.
    > Jing,
    > The Davis MK 3  accuracy is in the + or - 8' range out of the box. Better
    > results are possible but you have to earn it. Plastic sextants will warp
    > in direct sun light or if squeezed too hard. I zero the index error before
    > each observation then check again after the observation. Even if
    > everything is done right there will remain large systematic errors. Below
    > is a set of 5 observations using a Davis MK 3 and a liquid artificial
    > horizon today. Good enough in a pinch but not very good as a primary
    > sextant.
    > Intercepts:
    > 3.7' toward
    > 2.0' toward
    > 2.8' toward
    > 3.0' toward
    > 1.4' toward
    > The MK 3 is very good for horizontal sextant angles, and relative bearings
    > off the bow. Sailboat racers can use to see if gaining or losing on a
    > competitor.
    > Greg Rudzinski
    > [plain text auto-generated]
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    > http://fer3.com/arc/m2.aspx/Full-moon-sights-lifeboat-sextant-accuracy-Rudzinski-oct-2017-g40294

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