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    Re: Sextant accuracy with short distance to horizon
    From: Dan Allen
    Date: 2001 Jun 21, 9:59 AM

    I've spent more time on land standing on 300' cliffs than on boats, hence
    my remembering 20 miles.
    
    I also remember from many years ago driving many times across the Salt Flats
    of
    Western Utah: there is a single stretch of road that is 40 miles long, dead
    straight.  I could see the lights of Wendover UT/NV from about 18 miles away
    when
    I drove it at night.
    
    Dan
    
    -----Original Message-----
    From  Navigation Mailing List
    [mailto:NAVIGATION-L{at}LISTSERV.WEBKAHUNA.COM]On Behalf Of Richard B.
    Emerson
    Sent: Thursday, June 21, 2001 7:47 AM
    To: NAVIGATION-L{at}LISTSERV.WEBKAHUNA.COM
    Subject: Sextant accuracy with short distance to horizon
    
    
    Dan Allen writes:
    [...]
     > This led me to think more about possible inaccuracies of using a horizon
     > that is very close rather than naturally far away.  That is, typically
    you
     > use a horizon that is at the limit of your vision, perhaps 20 miles away.
    [...]
    
    While you're in Bowditch, check out table 12, "Distance of the
    Horizon".  Assuming you're 6' tall and standing on a deck 4' off the
    water, for a total height of eye of 10', the horizon is 3.7 miles
    off.  A twenty mile horizon requires a height of eye of something like
    300'.  And clear air.  [grin]
    
    Rick
    S/v One With The Wind, Baba 35
    

       
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