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    Re: Dated Chart Datum
    From: Lu Abel
    Date: 2008 Nov 03, 22:11 -0800

    I totally agree on the "genius" of trying to change NOAA charts to
    metric depths.   Fortunately, that died.  Only two NOAA charts still
    have metric depths.   One is Lake Tahoe on the California/Nevada
    border.   Your challenge, should anyone decide to accept it, is to
    identify the other chart.
    bruce hamilton wrote:
    > I still remember going over the charts when I made my first trip around
    > Newfoundland and seeing that the charts were annotated with, "as
    > surveyed by James Cook, 1775". There was no indication of any updates.
    > The waters were deep enough that we slept well at night, but the Mate
    > told us of meeting with an unmarked sea mount on one arctic trip.
    > Apparently shoring up a steel hull with wood and canvas still does the
    > trick.
    > The work that Cook accomplished is quite amazing especially considering
    > the equipment of the day.  I just realized that I used to know the
    > markings of the lead line, but have forgotten them completely. Was seven
    > fathoms red bunting?
    >   I wonder how many of the world's charts are still quite out of date. I
    > read once of a volunteer program in the UK where mariners submit the
    > soundings from their own GPS linked sounders, and the chart makers use
    > that data to help improve the systems. Is that really happening or was
    > it just a plan?
    > Oh, a little note on situational awareness.  In the early eighty's, some
    > genius in our nation's capital decided that nautical charts should be
    > metric and for a while you could have charts with soundings in meters
    > and feet/fathoms, as they were not replaced all at one time. We never
    > had any groundings, but we certainly had a few unkind words to say about
    > our chart makers as we jumped back and forth from metric to nautical
    > soundings.  I used to do the chart updates from the Notice to Mariner's
    > and burn all the old charts when they were finally replaced.  I wish I
    > had kept them all. I could have quite a collection, and I still love
    > paper charts!
    > Keep a good watch.
    > Bruce Hamilton
    > >
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