E/V Nautilus Spring 2014 Quality Assessment Report

Multibeam System: 

Summary and Recommendations

  • As it stands now, the EM302 and associated sensors are working well as compared to other EM302s evaluated recently. The patch test revealed very slight residual angular offsets, indicating a successful reinstallation of the MRU and no apparent change to any other component of the system.
  • Refraction did play a role in limiting the ability to best quantify the accuracy of the system through the reference surface cross lines. When the survey site was selected, SVP ‘weather maps’ indicated a relatively stable water mass. Unfortunately, by the time of the test, the water mass had become relatively complex. During normal mapping missions (or future system testing) in regions of high water column variability, it will be necessary to collect XBT casts more frequently in order to collect higher quality bathymetric data with reduced refraction artifacts. This will be especially true for line spacing greater than 1 water depth (+/-­‐ 45° angular swath width).
  • Sensor positions and SIS Installation Parameters should not be changed. A PU Parameters file containing all SIS Installation Parameters and Runtime Parameters was written to disk on the primary acquisition machine at the end of NA040. If any problems or questions arise with any parameters, this file can be reloaded to restore a functional configuration for SIS. Johnson and Jerram have a copy of this file and can provide it if required.
  • Routine BIST collection should be continued as it provides a great resource for examining changes of the system through its lifetime.

Patch Test Results

Angular Offset NA030 Value NA040 ‘Residual’ Post-NA040 Value
Pitch -0.12° +0.00° -0.12°
Roll +0.14° +0.01° +0.15°
Yaw +0.09° +0.02° +0.11°
20140514_Nautilus_Final.pdf1.77 MB