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    Pocket sextant
    From: Jim Hickey
    Date: 2006 Jan 25, 10:02 -0500
    Thought I would post this as there are a couple of members who own the small hockey puck like pocket sextants.
     
    I have owned one for a number of years but have not worked with it a great deal in the past but have been playing with it the last month or so.
     
    The instrument has a vernier readable to 1' and hellish small mirrors which make star sights a challenge.
     
    I was having difficulty getting consistent sights with the sextant and seemed to be getting an error proportional to the angle I was measuring. It seems that what was required was very, very carful adjustment of the mirrors and I was off to the races.
     
    Anyway, the results. With an artificial horizon and clear conditions it was easy to get results inside 2' of error consistently. So finally happy and confident in the sights.
     
    Headed off on a 4 night cruise from Jacksonville to the Bahamas and back. Thought I might have a chance to take a sight so I took my Palm Pilot with celestial program, the pocket sextant and my GPS. Turned out Sunday was a whole day at sea and turned out to be a great day to sit on deck, drinking beer catching some sun, watching girls and of course taking a few sextant shots. Oh yes forgot, also more ridicule from my wife! For the 5 sun sights I took, the closest to the GPS was 0.3' with the furthest being 2.4'. All results high due probably to using an incorrect dip. I made an estimate and stayed with it. No matter. To me the results were remarkable for such a small instrument using a real horizon.
     
    Just as an aside to mention in this post. I have owned a Japanese made Oaklet sextant which I bought new about 25 years ago. It seems to compare in quality to an Astra. It has a formal manufacturers certificate indicating the instrument error at various angle ranges. There is an error of 10 seconds indicated for only one angle range (20 to 30 degrees if I recall right) the rest of the ranges indicate 0 error. Having seen the accuracy claims listed for the various sextant manufacturers out there, Oaklet seems to have made a bold claim. Any thoughts? Does anyone else have a certificate that shows such a small amount of error? Just curious and realize fully the instrument error is the least of your worries.
     
    Cheers,
     
    Jim
       
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