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    Re: Latitude and Longitude by "Noon Sun"
    From: George Huxtable
    Date: 2005 Jun 7, 15:09 +0100

    There are some points to pick up from Frank's many recent postings.
    
    I had written, about his proposed method for "noon" longitude, which he had
    said "goes a little beyond the standard procedure for shooting the Noon Sun
    for latitude only"
    
    "It certainly does. It extends the Noon sight to a protracted series of 9 to
    13 observations extending over 40 to 60 minutes  around noon. Can this still
    be described as "a noon-sight"? "
    
    and he replied-
    "It can  easily be as few as five or six sights."
    
    My figure of 9 to 13 observations was deduced directly from his own
    proposal: for observations every 5 minutes over a period from 20 - 30
    minutes before noon to  20 - 30 minutes after noon.
    
    I added-
    "Frank's proposal, though the best way to do the job  of finding longitude
    around noon, is quite a protracted operation. On how  many lightly crewed
    small craft can a crew member be spared for a period of  40 to 60 minutes
    around noon each day while he takes such a series of shots  at 5-minute
    intervals?"
    
    to which came the reply-
    "No, it is NOT a protracted operation."
    
    Indeed it is. "Protracted" means "drawn out in time", which it certainly
    is, at 40 to 60 minutes, when compared with the usual noon-sight for
    latitude.
    
    Frank added-
    
    "There is  no requirement that the
    sights be taken every 5 minutes like clockwork. Every  "five or ten" as
    time (and
    interest!) permit... "
    
    But that doesn't alter the protraction.
    
    As for the suggestion that someone  has to give up 40 or 60
    >minutes of their day, gimme a break. It takes about a  minute to take and
    >record each sight. You could easily make --and eat-- lunch  during that time
    >taking a break every five or ten minutes for a quick sun  sight.
    
    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.
    
    In reply to my-
    "There may be some interesting implications in what Frank  is saying here.
    With this method, he is teaching a way of finding lat and  long that is only
    available if the Sun happens to shine around the moment of  noon. That's the
    position navigators were in prior to Sumner, when if they  lost their noon
    (or near-noon) observation, both lat and long were  unavailable until the
    >next sunny noon."
    
    this from Frank-
    "First, this is inaccurate  historically. Sumner's discovery was considered
    an>"exotic" sight method for  decades. It was rarely used in practice."
    
    Even if that was the case (and he has provided no evidence for that
    sweeping statement), in what way would it make my previous sentence
    "inaccurate historically"?
    
    he continued-
    
    "...Well into
    the twentieth century, many  vessels were navigated by traditional noon
    latitude and afternoon/morning time  sight."
    
    That may be. So what?
    
    Frank-
    "But back to your main point -- yes, of
    course, this method is  limited to those days when it is clear or partly
    cloudy around noon. But so  what? Celestial navigation is NOT a primary
    method of
    navigation any longer."
    
    It seems to me, then, that a teaching programme, confined to around-noon
    Sun observations and no others, will produce pseudo-navigators who may
    delude themselves into thinking that they can determine lat and long from
    celestial observations, but are in fact only safe on a vessel that is
    actually being navigated by GPS.
    
    What would be the name of such a course? If some sort of certificate is
    provided as a result, how would it be worded? Would it form a required part
    of any other qualification?
    
    Referring to position-line navigation, I added-
    
    "If all that has been lost (and I hope  it
    hasn't), it would be a very crippled 19th-century navigator that  would
    emerge from the course."
    
    Frank-
    "Just to be clear,the method I have  described for getting lat and lon by noon
    sun was NOT used in the 19th century.  It is a modern method."
    
    Well, noon by equal-altitudes has been around since long before the 19th
    century, but primarily for on-land use as it was regarded as insufficiently
    accurate at sea. What's so specially new that makes Frank's a "modern
    method?
    
    Frank-
    "Short, easy to
    teach, easy to learn, easy to RE-learn in  one sitting, and requiring no
    special tables beyond four or five pages of basic  almanac data which would be
    valid for decades. It is not a cheat. It is not "fake" celestial navigation. It
    does have some limitations, as do all methods of  celestial navigation.
    
    As for your use of the words "crippled" and "poor" and so on, your are
    engaging in shameless exaggerration."
    
    A phrase Frank used in another posting, "instant gratification", describes
    what is being offered, perfectly. I don't think I used the word "fake", but
    perhaps "facile" would be more appropriate. If without GPS, then I would
    prefer to be guided by a navigator trained in the 19th century, rather than
    by a product of Frank's proposed class. If navigating by GPS, NEITHER is
    needed.
    
    I don't withdraw my description of the man emerging from Frank's proposed
    class as a "crippled" navigator. Indeed, I wonder if he will even be aware
    of what it is he is missing.
    
    Finally, may I say that an important aspect of position-line navigation, to
    me and perhaps to others, is its universal application, together with its
    basic simplicity, and indeed, its intellectual beauty. True, in applying
    it, there's a lot of hard graft with tables, which can be bypassed with a
    pocket calculator if preferred. Nothing that's worthwhile comes easy.
    
    George.
    
    ================================================================
    contact George Huxtable by email at george---.u-net.com, by phone at
    01865 820222 (from outside UK, +44 1865 820222), or by mail at 1 Sandy
    Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.
    ================================================================
    
    
    

       
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