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2023 R/V Kilo Moana EM122/EM710 QAT Report

Vessel ID: R/V Kilo Moana
Multibeam System: EM122/EM710
Dates: March 21-22, 2023

KM 2023 QAT Executive Summary

  1. The University of Hawaii’s UNOLS vessel R/V Kilo Moana (KM) is equipped with Kongsberg Maritime EM122 and EM710 multibeam echosounders and an Applanix POS MV-320 V5 Ocean Master navigation system
  2. R/V Kilo Moana conducted pre-season Quality Assurance Testing (QAT) for the EM122 and EM710 multibeam mapping systems during gear trials over March 21-22, 2023
  3. Because no hardware changes were made to the mapping systems since the 2022 post-shipyard QAT, the limited time available for the 2023 QAT was used to conduct deepwater accuracy testing and noise testing to build on the 2022 QAT (i.e., no new patch tests)
  4. Pre- and post-shipyard noise testing conducted in March and May 2022 had indicated elevated but stable noise levels the previous field season (see 2022 report)
  5. RX noise testing in October 2022 revealed significant increases in noise levels; additional testing in March-April 2023 confirmed the high (and worsening) noise levels detected in October 2022:
    a. Noise levels perceived by the EM122 and EM710 are higher in October 2022 and March 2023 across all speeds compared to the pre- and post-shipyard 2022 tests; the low-speed levels are similar between October 2022 and March 2023
    b. The high-speed noise levels observed in March 2023 are ~10 dB higher than the October 2022 levels at 100 and 120 RPM, suggesting a major increase in the flow noise component at those speeds
    c. Generator work was performed during the 2023 maintenance period; however, no major differences were
    noted across generator combinations at 120 RPM, likely ruling out any one unit causing the increases KM 2023 QAT Executive Summary
  6. A diver inspection on April 3, 2023 showed significant biofouling on the hulls and arrays
  7. Hull cleaning is necessary as soon as possible to reduce flow noise, providing the following benefits:
    a. probable improvements to swath coverage and accuracy at typical mapping speeds
    b. clearer assessment of machinery noise testing to determine whether recent generator maintenance may
    have had an across-the-board impact on noise levels
  8. Kongsberg performed transducer impedance testing during the winter maintenance period, generally confirming the BIST TX and RX Channels data (see 2022 report); admittance plots have been generated from the impedance analyzer exports and are included in this report for reference
  9. EM122 accuracy testing was conducted opportunistically by running a crossline in Deep mode over an existing 4700 m reference surface (used previously by several vessels); results indicated expected performance with no significant variability since the last test in this mode (2021)
  10. Given the age of the EM122 and EM710 and the end of maintenance support from Kongsberg (e.g., decreasing availability of spare parts), the MAC recommends beginning to consider the replacement/upgrade planning process for the Kilo Moana’s multibeam mapping systems
  11. The MAC is available to assist with additional testing and replacement planning as requested

Attached Documents

Report:

KM_2023_EM122_EM710_QAT_reportDownload

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