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    Navigation by soundings.
    From: George Huxtable
    Date: 2009 Dec 21, 09:58 -0000

    I will copy below a short extract from a piece that took my fancy in the
    recent edition of The Journal of Navigation (vol 63 No1, January 2010), in
    case it appeals to other navlist members.
    It explains itself pretty well. Lowestoft is the most Easterly port on the
    North Sea coast of England. An "armed lead", has a tallow or lard smeared
    into a dimple under the lead so that it picks up a sample of the bottom.
    
    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.
    
    ==============================
    
    Heaving The Lead
    
    Lt Cdr R W Cooper RN
    
    2. BOYHOOD BACKGROUND. My experience of the practice of heaving the lead and
    navigation goes back to 1937. My father was a North Sea fishing skipper and
    I was the eight year old son who was obsessed with navigation. My bedtime
    reading was Tait's Home Trade Guide, and I knew the Colregs, Morse code and
    flag meanings off by heart. That year I was allowed for the first time to go
    on a trawling trip with my father.
    
    Navigation at that time consisted almost entirely of sounding by armed lead.
    The ship would be stopped and the 16-pound lead cast. The depth was noted,
    and the state of bottom examined closely, and tasted by the skipper and
    mate. I tasted it too. It was foul. This was done several times at hourly
    intervals until suddenly, and for no good reason that I could discern, the
    trawl was shot with the traditional order " Shoot the nets in the name of
    the
    Lord. "
    
    Soundings were taken at half-hourly intervals while trawling. And then after
    hauling, the whole ritual was repeated. We had been trawling on a NNW
    course, and before shooting again, we had moved some six miles to the
    westward. This procedure was repeated several times until my father decided
    to return to the home port of Lowestoft. No attempt had been made to fix the
    position during the 72 hours. It seems that the bottom of the North Sea has
    a fan-shaped pattern of low ridges which do not appear on navigational
    charts. It is in the valleys between these ridges that the best flat-fish
    are found. It is the fan-shaped nature of the ridges that make them ideal
    for navigation, for the distance between the ridges gives the latitude
    accurately enough.
    
    As the trawl was hove in on the derrick out at sea, my father himself cast
    the lead, tasted it, and then ordered something like west-south-west and a
    half west and off we steamed. The lead was cast at hourly intervals without
    stopping the ship. It was swung overhead three times before being slipped
    and only the depth noticed. Perhaps the course would have been corrected by
    half a point. Otherwise we went straight at the Holm buoy.
    
    Note that the chart was never consulted. My father's collection of blue-back
    charts was kept tightly rolled in black japanned-cases closed with a
    padlock. Only he (and I) looked at them. They had originally been his
    grandfather's and were never used for navigation. Certain sea areas were
    covered with minute marks and symbols entered at the end of each trip by
    mapping pen. They represented details of catches and abnormalities of the
    seabed.
    
    --
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