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    Re: sextant without paper charts
    From: Lu Abel
    Date: 2008 Nov 03, 16:00 -0800

    The Wikipedia article Frank points to gives a good summary.  The USS San Francisco ran into the seamount not because of navigational instrument failure, but because the thing was only vaguely charted.   The San Francisco probably knew precisely where it itself was, it just didn't know it was competing with a chunk of rock.  

    Look at a map of the Pacific Ocean.   It is dotted with thousands of islands, because the Pacific is a geologically and volcanically active region.   These islands grow thousands of feet from the ocean floor.   Stop a little early in your growth and you're an underwater mountain or seamount.  Without data to support this assertion, I will nevertheless speculate that there are probably far more underwater mountains than above-the-water islands in the Pacific. 

    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.   I've known a few submariners and they have all talked about a back-of-their-minds fear of collision with an uncharted underwater obstacle.  

    The San Francisco's captain received a career-ending reprimand because another chart (not the one he was using) referred to the possibility of seamounts in the region in which he was operating and the court of inquiry found he was negligent for not using "all available navigational information."

    We don't have to go to the Pacific to see uncharted obstacles -- the QE II got her bottom very famously slashed open in the early 1990s by an uncharted rock off Marthas Vinyard in Massachusetts.    Original speculation was that she was either off course or her speed caused her to "squat" in the water (she was operating with very little water under her keel).   Then NOAA sent out one of its survey ships and they discovered an uncharted rock in the channel -- with stripes of the QE II's bottom paint on it.


    Scott Owen wrote:
    frankreed@HistoricalAtlas.net wrote:
    And while not 100% a navigational error, there's the incredible near-loss of
    the USS San Francisco in 2005 after it plowed into a mountain at 33 knots:
    (be sure to click on that small picture to see the details of the damage to
    her bow section).
    Running into a sea mount at 33 knots can ruin your whole day.  IMHO for
    this to happen there had to be serious issues with the error rate of the
    boats Inertial Navigation System or gross error in the plotted position.
    It would be interesting to know the last time the submarine had been to
    the surface prior to the accident as it would have been very easy to get
    a GPS fix, and then just about as easy to "cross check for INS error".
    Whether they were using paper or digital bathymetry charts for plotting
    was probably not a factor.

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