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    Re: Accuracy of sextant observations at sea
    From: Jeremy C
    Date: 2010 Nov 27, 05:34 EST
    Alan wrote:
     
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    Having said that, and by the way, most of the discussions above referenced, while academically interesting are quite far over my head, the following questions remain.

    1. What sort of boat or vesssel are the sextant shots made from?
    2. Realistically speaking, standing on a smallish boat, a large ship is another story, what sort of accuracy can be reasonably expected?
    3. How experienced is the "shooter?

     
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    I can answer this and Antoine's question about equipment in one email instead of two.
     
    1) All of my Navlist examples are shot from the freighter I am currently sailing on.  The ship is 650 ft long with 105 ft beam.  Height of eye for my observations is 106 feet.  The sextant is a Tamaya MS-733 aluminum alloy frame with brass arc sextant built in 1984.  It has a traditional half-silvered/half-glass horizon mirror.  The scope is a Celestaire 7x35 monocular (I believe the first one that Ken sold).
     
    2) That is the question for the ages and one I am trying to experimentally determine.  Your fix accuracy varies with conditions (especially with horizon quality) as well as observer.  I am happy with <1.0 miles, okay with 1-2 miles, and generally not happy with anything more than 2.0 miles.  This is from a ship and an experienced shooter.   I don't think that you will get as accurate a position from a small boat bouncing in the waves.
     
    3) I've been shooting stars since 1997.
     
    Jeremy
       
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