NOAA Ship Thomas Jefferson 2016 SAT

Executive Summary

A Kongsberg EM2040 multibeam and an EM710 MKII multibeam were installed aboard NOAA Ship Thomas Jefferson during an extended shipyard period at the Coast Guard yard in Curtis Bay in Baltimore, MD during the spring and summer of 2016. After a short stay at the Atlantic Marine Operations Center in Norfolk, VA, the ship proceeded with acceptance testing of the new survey systems in the areas between Norfolk and Hudson Canyon during the third week of October, 2016, with the assistance of Office of Coast Survey and Kongsberg personnel.

All portions of the Office of Coast Survey Sonar Acceptance Procedures were addressed, but the value of some tests were limited by the physical oceanography during testing. While working to confirm proper integration and operation of the new survey systems some important limitations to the installation were uncovered and characterized.

Key findings:
  1. Both the EM2040 and EM710 are properly integrated with the supporting sensors.
  2. A significant artifact presents itself in the outer beams of both multibeams. This artifact is transient and not motion correlated. While troubleshooting of this artifact is ongoing, at this time it is believed to be associated with the specific installation and not a defect in the hardware. Efforts to solve this problem include:
        -- Bringing the paint covering both transducers to Kongsberg specifications.
        -- Removing the fairlead forward of the transducer installation.

      It is not yet known if these efforts will resolve this artifact. In the interim it is recommended that the ship limit the survey swath to 45 degrees on either side by running in Single Sector mode, although the problem still persists at times even within the reduced swath.

  3. A backscatter artifact persists on the port side as a small section of depressed backscatter and at 45 from vertical in the 200 kHz mode of the EM2040. Efforts to solve this problem include:
        -- Bringing the paint covering the EM2040 transducer to Kongsberg specifications.
        -- Removing filler material added during the previous shipyard to smooth the surface around the transducer.
        -- Lowering the EM2040 transmitter to meet current Kongsberg specifications.

      It is not yet known if these efforts will resolve this artifact.

  4. A recommended Caris HIPS workflow had been provided to the ship. This recommended workflow is recognized as restricted to specific steps and integrating specific data to avoid post processing pitfalls.
While preliminary steps have been taken to remedy the problems described above, testing is still ongoing. Coast Survey plans to stay engaged in finding and implementing a solution to the described artifacts such that the survey systems can be used to their full potential.
TJ EM2040 and EM710 Acceptance (PDF)10.88 MB