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    Re: How did Sumner navigate in 1837?
    From: George Huxtable
    Date: 2003 May 24, 23:14 +0100

    Among some interesting sea tales, Peter Fogg said-
    >
    >Up until the Second World War sailing ships sailed from Europe in ballast to
    >load grain in South Australia and return (usually) via Cape Horn. The most
    >direct route was through Bass Strait but it is studded with islands and
    >swirling currents. Although its dangers were encountered soon after
    >departure, thus with an accurate enough DR, in practice their masters
    >preferred to avoid it by taking the long detour around the south of
    >Tasmania, even though this meant running a long way to the south while being
    >blown against a lee shore. As Conrad said, the true peace of God is only
    >known a thousand miles from land.
    
    I think Peter should take a look at a globe, rather than an atlas.
    Remember, the islands of New Zealand are slap in the way of that passage,
    from the grain-loading ports of the Spencer Gulf, passing either side of
    Tasmania to aim for the Horn. A mariner would certainly avoid going
    North-about New Zealand; that WOULD be an immense detour and take him out
    of the strong Westerlies. He would also avoid the difficult passage through
    the Cook Strait; and the Foveax Strait, north of Stewart Island, was so
    dangerous as to be a no-no. He would aim to make his Easting around the
    south Pacific toward the Horn in Lat S50?, or perhaps even a bit further
    South still. So his aiming-point, after leaving Spencer Gulf and Tasmania,
    would be to pass well south of Stewart Island, to somewhere near S50?,
    E170?.
    
    Stretching a string on the globe, between Kangaroo Island and that
    waypoint, shows there's very little difference in distance travelled,
    between passing North of Tasmania through Bass Strait, and passing South,
    off Tasmania's Southern capes, in unencumbered waters. If anything, the
    Southern route appears marginally shorter; certainly not a "long detour".
    What these unwieldy ocean carriers needed was clear sea-room, and not
    tricky rock-hopping. So the Southern passage would be the automatic choice.
    The snag was that sometimes the prevailing Westerlies, to the West of
    Tasmania, might have enough South in them to prevent a ship from Spencer
    Gulf making sufficient Southing to clear the Tasmanian coast, and force her
    reluctantly into Bass Srait instead, causing great unease on board.
    
    Peter adds-
    
    >The impression I get is that the kind of precision we worry about here on
    >the Nav. List was largely unknown and unrealistic to expect in practice
    >under most conditions.
    
    Well, I think that the big difference between then-and-now was in the
    different approach to risk: risk to the vessel and risk to human life. In
    the 19th century, the normal way for a vessel to end her career was in some
    sort of mishap, rather than to rot away. There are records of mariners who
    had been through 3 or 4 shipwrecks in their time. The great explorers, such
    as Cook, were prepared to take a chance by sailing on through the night in
    completely unknown waters. The successful mariners, in those circumstances,
    would be those that happened to be lucky.
    
    Sorry if I am diverging too far from the original thread, about Sumner.
    
    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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