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    Re: sextant without paper charts
    From: Lu Abel
    Date: 2008 Nov 03, 16:47 -0800

    Peter Fogg wrote:
    > Lu continues:
    > Consider then the crudeness of our charting capabilities.   Satellites
    > can't spot stuff below the water like they can above the water.   Side
    > scan sonar is great -- if you've got the time and money to scan the
    > ocean a few hundred yards at a swath.  Bottom line:  we really don't
    > know what's out there in the great oceans.
    > Response:
    > Although this is changing, at least in our waters.  Australia claims a
    > vast swathe of underwater territory (in the guise of 'economic
    > interest') and has set about charting this realm in a systematic way.
    > All sorts of interesting  things are bobbing to the surface .. of our
    > understanding.
    There's more than that, too.  It's one thing to slash the bottom of the
    QE II, quite another to do it to the bottom of an oil tanker or to an
    LNG tanker.  On more and more charts, I'm seeing symbols for channels
    where commercial ships operate having been swept for obstacles by drags,
    rather than merely having been scanned with sonar.   It's interesting to
    look at the chart for that particular region -- whilst there's one tiny
    region where surveys date back a century, most of the shallower areas
    transited by commercial ships have been charted with side-scan sonar
    since the QE II incident.
    If anyone wants to take a look for him/herself, here's the image of the
    chart:   http://www.charts.noaa.gov/OnLineViewer/13218.shtml
    There are a westward running string of islands eminating in the
    northeastern corner of the chart, off the western tip of the westernmost
    island is Sow and Pigs Reef, the QE II was sailing just south of that
    and I rather suspect some of the shallower rocks are recent discoveries.
    We have people from all around the world on this list and since I gave a
    weblink above, I'd like to mention that all charts of the US are
    available for on-line viewing.   Starting point is
    Navigation List archive: www.fer3.com/arc
    To post, email NavList@fer3.com
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