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    Re: Latitude and Longitude by "Noon Sun"
    From: Frank Reed CT
    Date: 2005 Jun 11, 03:03 EDT

    George H wrote:
    "Well, if I had a crew member  would be devoting the next 40 - 60 minutes to
    such closely-spaced  observations as Frank has suggested, I wouldn't expect
    much useful boatwork  out of him in the 2 or 3 minute free intervals in
    between."
    
    LOL. Well,  maybe if they're so busy manning the oars on that slave barge you
    operate, then  they wouldn't have time for sights!   More
    seriously, as I have already said (and I think it's obvious) there is no
    requirement to take the sights spaced as closely as you are implying.
    
    I  think that if one has time for celestial at all, then this method I've
    described  is no worse than any other approach when it comes to the time
    required. I  haven't the slightest doubt that a navigator could make and eat lunch and
    do  this sight run, too.
    
    By the way, in another post you commented on the  fact that you need speed
    over the ground which means you would need to correct  for any current. That's
    true, of course, and it applies to ALL running fixes.  One recent post pointed
    out that many people using standard celestial at sea  just shoot a couple of
    sun sights during the day, likely separated by quite a  few hours, and then
    bring them together as a running fix. If they're in a 2 knot  current, and the
    two sun sights are separated by six hours, this could easily  lead to an error
    of 12 miles in the fix. That's standard LOP navigation. That  there is a
    moderate error from ignorance of current in the lat/lon by noon sun  technique that
    I have described is not a problem of this method per se.
    
    Also, something like 75% of the world's ocean surface has currents below  1
    knot, and around 90% has currents below 2 knots. Those areas with higher
    currents tend to be fairly stable, e.g. the Florida Current portion of the Gulf
    Stream is basically always in the same place, and anyone sailing those waters
    better know that before they start thinking about sextants and celestial
    navigation.
    
    And just for fun: What's the most famous ocean current? Three  years ago, it
    was probably the Gulf Stream, but that title now almost certainly  goes to its
    down-under counterpart, the East Australian Current or EAC. Thanks  to a
    computer-generated turtle and a couple of little fish in a Disney movie,  this
    ocean current's name has become known to hundreds of millions of people
    worldwide.
    
    -FER
    42.0N 87.7W, or 41.4N  72.1W.
    www.HistoricalAtlas.com/lunars
    
    
    

       
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