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    Re: How accurate are fixes in practice?
    From: George Huxtable
    Date: 2008 Jul 15, 23:29 +0100

    Jeremy wrote-
    
     For a larger merchant ship (>100 Meters)  good
    | conditions consist of a sky that shows the bodies and, equally
    importantly,  a
    | crisp horizon.  There have been many times when the sky above is very
    clear and
    | many stars are visible, only to have a fuzzy horizon that leads to
    abnormally
    | high errors.
    
    ===============
    
    This could be a case where Jeremy's lofty perch, up on the bridge, is
    actually working against him, and where those of us in small crafr have an
    advantage. From 100 feet up, the horizon is nearly 12 miles distant, so a
    bit of haze in the air could easily spoil its clarity. I don't know the
    height of Jeremy's working-deck level, but if he could descend to 50 feet,
    that reduces the horizon distance to 8 miles, which could well make all the
    difference. From the cockpit of my own small boat, the horizon is little
    more than 3 miles off.
    
    Lecky tells of a time when he needed a good position entering the Plate
    estuary, but his horizon was too hazy to take a sight. So he had the
    accommodation ladder lowered over the side, and took an altitude from its
    bottom step, just above sea level. I doubt if Jeremy would be able to
    persuade his "old man" to agree to that, however.
    
    George.
    
    contact George Huxtable at george@huxtable.u-net.com
    or at +44 1865 820222 (from UK, 01865 820222)
    or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.
    
    
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