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    Re: Navigation and whaling
    From: George Huxtable
    Date: 2009 Feb 20, 21:26 -0000

    Brad Morris wrote these intriguing words-
    
    "I will even offer up that exemplar of navigation, Frank Worsley, who
    navigated by time sights, on that famous sail from Elephant Island to South
    Georgia island in the 1900's.  His account is offered in his book and in his
    navigation log book which lives in a museum.  Was that appropriate 50 years
    after Sumner provided his method?  Some would argue that it wouldn't meet
    the navigation standard of the day, yet it is hard to argue with success."
    
    ====================
    
    Can Brad tell us more about that "navigation log book which lives in a
    museum", please? Which museum? Has it ever been made publicly available? Is
    it indeed legible, after all it's been through? I would love to discover
    more about that journey.
    
    Worsley's own account, in "Shackleton's Boat Journey" (1933; my edition is
    1940), though thoroughly gripping, is frustratingly short on navigational
    detail, and he offers no maps at all. The same journey is described in
    similar words elsewhere; in Shackleton's "South" (1919; mine is 1983), with
    a few maps; in Worsley's "Endurance; an epic of polar adventure" (1931; mine
    is 1999), no maps; and in "Shackleton's Captain", a biography of Worsley, by
    John Thomson (1999), more (but still inadequate) mapping.
    
    For information on South Georgia today, I can thoroughly recommend
    "Antarctic Oasis" (1998), by Tim and Pauline Carr, who have thoroughly
    explored every nook and cranny in their 100-year-old 28ft. engineless wooden
    ketch, being also curators of the South Atlantic whaling museum there. The
    stunning photographs in this book are a delight.
    
    ===================
    
    Now for the navigation on that amazing journey from Elephant Island. As Brad
    says, it's hard to argue with success. But the voyage, and its navigation,
    were not entirely successful; if they had been, that perilous crossing of
    the island would not have been necessary, because the original intention had
    been to round the NW corner of South Georgia to reach a whaling station
    directly. But Worsley honestly admitted, when nearing the island, that he
    couldn't be sure of his position within 10 miles or so, and Shackleton then
    sensibly concluded that in that case, such an approach would run the risk of
    missing the island altogether, and being swept East past it. Worsley's
    difficulty with his Sun altitudes was partly the fleeting and indistinct
    appearances of the Sun, but far worse, the guesswork in determining the
    horizon, from so low down in such big seas.
    
    On the thirteenth day, Worsley tells us that he had so far been able to get
    the Sun only four times, two of these being mere snaps or guesses through
    slight rifts in the clouds. Yet, after each such observation, he presents us
    with a latitude and longitude, stated to the nearest arc-minute. How could
    he do that, when a single Sun sight can provide only a position line, so one
    can only obtain a longitude by assuming a latitude? Such positions must have
    been heavily reliant on the dead-reckoning.
    
    The most interesting reference to navigation was on the fourteenth day, 7
    May 1916, when at 9:15 am the Sun's limb was clear, though the horizon was
    misty. He continues- "The lateness of the hour, and the misty horizon, made
    a poor observation for longitude. At noon, the Sun's limb was blurred by a
    thick haze, so I observed the centre for latitude. Error in latitude throws
    the longitude out, more so when the latter is observed, as now, too near
    noon."
    
    I would go along with Brad, in presuming that Worsley had gone back to
    navigational techniques of the previous century. He seems to be avoiding
    chart-based position lines by instead directly calculating his longitudes
    from a before-noon Sun observation, using an observed noon-Sun latitude. And
    we may guess why, when we read of conditions aboard the 22ft canvas-decked
    James Caird, when any paper had become sodden, and there was no vestige of
    any sort of chart-table. Not that the alternative, using printed tables,
    would have been easy either.
    
    The whole journey was a remarkable achievement for the six participants, for
    the James Caird, and not least for their Primus stove, which kept them
    alive, and was finally abandoned on the mountain descent into Grytviken,
    after the last of its fuel had gone.
    
    George.
    
    contact George Huxtable, at  george@hux.me.uk
    or at +44 1865 820222 (from UK, 01865 820222)
    or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.
    
    
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