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Survey dates:16 to 20 October 2005
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Area of survey: Inner continental shelf from
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Charleston to Myrtle Beach, South Carolina. The
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equipment arrived in Charleston on October 15,
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and was installed on the ship and tested. All
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was in good working order with the exception of
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the depth sounder. Due to the size of the boat
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it was not possible to install the depth sounder
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head. The ship left the NOAA pier at 10 a.m.
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Sunday, October 17 to steam to the first survey
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site. Upon arriving on site and powering the
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survey gear it was found that the Lowrance GPS
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unit had failed. Because the navigation
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information is an integral part of the survey,
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Emile Bergeron attempted to feed the navigation
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string that was being supplied by the bridge
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into the SuperSting resistivity logging unit.
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This caused the SuperSting unit to behave in a
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very bizarre way. The navigation information
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being supplied was so garbled that it caused all
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data and configuration files in the unit to be
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overwritten with random characters. It took
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several hours to figure out what the root of the
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problem was. Once solved, the SuperSting unit
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was set up to operate without a navigation
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feed, and navigation data were logged remotely
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on a laptop. It was determined after the fact
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that during these adjustments the bad navigation
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string had caused the clock to reset to
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midnight, January 2, 2000. Survey lines L1
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through L5 had this time offset. Navigation
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continued to be a problem when Hypack stopped
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recognizing the navigation information. The
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sonar technician from Coastal Carolina
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University set up an Ashtech GPS unit and this
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data was then fed to both Hypack and the
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SuperSting logging computer. The time and date
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on the SuperSting unit were reset to GMT at this
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point. The survey continued without any major
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difficulties with the exception of battery power
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for the resistivity equipment. Since surveying
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was being done around the clock, the batteries
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used to power the SuperSting unit never had time
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to properly charge causing the unit to shut
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down, sometimes after only a minute of
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surveying. Batteries from the ship and those
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brought by Coastal Carolina were brought into
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use in an attempt to keep going. An
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insufficient number of battery chargers,
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however, made it a battle of diminishing
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returns. In the end 10 batteries were being
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used, all with questionable charge status. Upon
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returning to Woods Hole Emile Bergeron called
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Lowrance about the failed GPS head and was
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informed by them that the particular unit used
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would fail if placed too close to a radar unit.
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The head as installed on the ship was no closer
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than 30 feet to the ship's radar. Lowrance has
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repaired this problem and will replace our unit.
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All the navigation files that were logged
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remotely had to be converted from $GPGGA to
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$GPRMC as the AGI software will only recognize
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$GPRMC. This was a tedious process, especially
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for the files that were logged using the ship's
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navigation, as the files contained not only
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$GPGGA but GPZDA, GPZTG, GPGGL, GPGSV, GPVTG,
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GPZDA, and GPBWC. The files were also corrupt
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which made editing them all the more difficult.
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The survey consisted of two long shore-parallel
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lines with several shorter crossing lines, and a
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small grid further offshore. A total of 326 km
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of continuous resistivity profiling survey lines
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were collected, with a minimum line length of 89
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meters and a long line of 13,398 meters. That
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includes 58 lines over 900 meters long. The
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small mosaic area lines in the offshore area
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where wells have been previously installed by
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Billy Moore (Univ. of South Carolina, emeritus)
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were all about 1000 meters long, but data
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quality was low. Note that CCU scientists
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collected seismic data simultaneously. USGS was
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not involved in collecting or processing these
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data. A post-cruise meeting to review processed
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resistivity results took place in Woods Hole on
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January 10-11, 2006. In attendance were Paul
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Gayes and Rich Viso from CCU, and John Bratton,
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VeeeAnn Cross, and Wayne Baldwin from USGS.
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