Chief of Party2021-09-30Allison C Stone2021-09-30Data Acquisition and Processing Report2021-07-26Coast Pilot ReportThe survey data meets or exceeds requirements as set forth in the NOS Hydrographic Surveys Specifications and Deliverables, Field Procedures Manual, Letter Instructions, and all HSD Technical Directives. These data are adequate to supersede charted data in their common areas. This survey is complete and no additional work is required with the exception of deficiencies noted in the Descriptive Report.All field sheets, this Descriptive Report, and all accompanying records and data are approved. All records are forwarded for final review and processing to the Processing Branch.As Chief of Party, field operations for this hydrographic survey were conducted under my direct supervision, with frequent personal checks of progress and adequacy. I have reviewed the attached survey data and reports.There were no conditions or deficiencies that affected equipment operational effectiveness.None ExistAll equipment and survey methods were used as detailed in the DAPR.Survey H13451 uncertainty values (Tables 7 and 8) were evaluated in both CARIS HIPS 10.4 and via Pydro QC Tools v3.4.7. The finalized 8m (Figure 7) bathymetric grid meets uncertainty standards with 100% of nodes passing.N/AN/A0.420.25R/V Woldstad0.101ERS via VDATUM0.13Static draft uncertainty values differ slightly from what is reported in the DAPR, the value for the Static Draft Uncertainty for H13451 is -0.03m. file:///M:/OPRQ350KR21/Surveys/H13451/01_HDR/Reports/Descriptive_Report/Components//H13451_MB_8m_MLLW_Final.QAv6.tvu_qc.pngH13451 8m finalized grid TPU QCSound velocity profiles were acquired approximately every two hours from the R/V Woldstad using a Teledyne Ocean Science Rapid Cast.Refer to the DAPR for additional information.There were no other factors that affected corrections to soundings.None ExistCrosslines for survey H13451 were acquired in accordance with section 5.2.4.2 of the HSSD 2020 (Figure 5). Mainscheme to crossline mileage percentage across H13451 is 8.18%. Of the 140,288 grid nodes compared between H13451 mainscheme MBES and MBES crosslines, 100% were within 1m difference. The mean difference is 0.0m, with a standard deviation of 0.13m (Figure 6).file:///M:/OPRQ350KR21/Surveys/H13451/01_HDR/Reports/Descriptive_Report/Components//H13451_XL_dist.pngH13451 MBES mainscheme and MBES crossline distributionfile:///M:/OPRQ350KR21/Surveys/H13451/01_HDR/Reports/Descriptive_Report/Components/H13451_XL_diff.pngH13451 MBES mainscheme differenced from MBES crosslines statistical outputTwo contemporary surveys are available for comparison to H13451: H13448 and H13452 (Table 9 and Figure 8).Survey H13448 was acquired by Fugro USA Marine, Inc. in 2021 as a part of OPR-Q350-KR-21. Of the 91,845 grid nodes compared between H13451 and H13448 the mean difference is 0.08m; 99.9% agree within 1m (Figure 9).S2021H13448Fugro USA Marine, Inc.40000file:///M:/OPRQ350KR21/Surveys/H13451/01_HDR/Reports/Descriptive_Report/Components//JNX_51_48.pngSurvey H13451 junction with Survey H13448Survey H13452 was acquired by Fugro USA Marine, Inc. in 2021 as a part of OPR-Q350-KR-21. Of the 18,256 grid nodes compared between H13451 and H13452 the mean difference is 0.12m; 100% agree within 1m (Figure 10).E2021H13452Fugro USA Marine, Inc.40000file:///M:/OPRQ350KR21/Surveys/H13451/01_HDR/Reports/Descriptive_Report/Components/JNX_51_52.pngSurvey H13451 junction with Survey H13452file:///M:/OPRQ350KR21/Surveys/H13451/01_HDR/Reports/Descriptive_Report/Components//H13451_JNX.pngJunction surveys to H13451Sonar system quality control checks were conducted as detailed in the quality control section of the DAPR.CARIS Raster Surface (CUBE)8NOAA_8mMBES Set Line Spacing97.17124.77H13451_MB_8m_MLLWCARIS Raster Surface (CUBE)8NOAA_8mMBES Set Line Spacing97.17124.77H13451_MB_8m_MLLW_FinalNOAA Profile Version 2021All data reduction procedures conform to those detailed in the DAPR.All sounding systems were calibrated as detailed in the DAPR.No backscatter deliverables are submitted with survey H13451. One line of data per vessel, per day was processed to ensure quality control. All equipment and survey methods utilized in the acquisition and processing of backscatter are detailed in the DAPR.Refer to the Data Acquisition and Processing Report (DAPR) for a complete description of data acquisition and processing systems, survey vessels, quality control procedures and data processing methods. Additional information to supplement sounding and survey data, and any deviations from the DAPR are discussed in the following sections.SeaBat 7125 SV2Teledyne RESONMBESSVP 70Teledyne RESONSound Speed SystemPOS MV 320 v5ApplanixPositioning and Attitude SystemrapidCASTTeledyne OceanscienceConductivity, Temperature, and Depth SensorFor a detailed listing of equipment, refer to the DAPR submitted with this report.12121R/V Woldstadfile:///M:/OPRQ350KR21/Surveys/H13451/01_HDR/Reports/Descriptive_Report/Components//woldstad.jpgR/V WoldstadR/V Woldstad (Table 5 and Figure 4) acquired MBES, MBAB, surface sound velocity, sound velocity profiles, and attitude and positioning data within the survey limits of H13451 (Table 6). For a detailed listing of equipment used to acquire survey data, refer to the DAPR submitted with this report under Project Reports.165.29082777855.0037472222164.98249722254.9663222222Survey H13451 (Figure 1 and Table 1) is located 20 nautical miles North of Dublin Bay on Unimak Island, AK. This area is utilized extensively by vessels involved in diverse fisheries activities in the region, including cod and crab. The R/V Woldstad acquired 500m set line spaced Multibeam Echosounder (MBES) and Multibeam Echosounder Acoustic Backscatter (MBAB) within the assigned survey limits 21-23 July 2021 (Tables 2-4).file:///M:/OPRQ350KR21/Surveys/H13451/01_HDR/Reports/Descriptive_Report/Components/H13451_Overview.pngSurvey H13451 relative to overall sheet limits of OPR-Q350-KR-21Survey coverage was in accordance with the requirements listed above and in the HSSD.500m Set Line Spacing (Reference HSSD Section 5.2.2.4 Option A). Note: Change was made in set line spacing requirement by COR after it was determined original requirement of 320m created more coverage than neccesary for desired level of data acquisition. All waters in Sheet 8008.18022.520275.2300000022.520275.23000R/V Woldstad00072.602021-07-212021-07-222021-07-23500m set line MBES was achieved within the survey limits of H13451 (Figures 2 and 3). The entire survey is adequate to supersede previous data.file:///M:/OPRQ350KR21/Surveys/H13451/01_HDR/Reports/Descriptive_Report/Components/H13451_Coverage.pngSurvey H13451 MBES coveragefile:///M:/OPRQ350KR21/Surveys/H13451/01_HDR/Reports/Descriptive_Report/Components/H13451_MB_8m_MLLW_Final.QAv6.density.pngSurvey H13451 8m finalized set line MBES density QCSurvey limits were acquired in accordance with the requirements set forth in the Project Instructions and the HSSD 2020.This project will provide contemporary data to update NOS nautical charting products; increasing maritime safety and commerce in the region. The waters around the the North side of Unimak Island are an important fishing ground for the Bering Sea Pacific Cod and other Bering Sea fisheries. This area is part of the main route transited by vessels between Bristol Bay and Dutch Harbor, AK. The North shore of Unimak Island commonly serves as a refuge from weather and waves coming off of the open waters from the North Pacific. The area has been identified by the Western Alaska Tanker Lightering Best Practices Committee as a primary location for lightering operations to occur. The project area has also been identified as an area of inadequate coverage by a risk-based model with respect to the desired coverage needed to support modern navigational needs. Unimak, AKOPR-Q350-KR-21Fugro USA Marine, Inc.Unimak Island, AKContractor8United StatesH13451Alaska40000500 meter Multibeam Sonar Set Line Spacing without Concurrent Side Scan Sonar Coverage (HSSD 2020 5.2.2.4, Option A). Note: The requirement to verify or disprove all charted depth falling between sounding lines and shallower than adjacent surveyed soundings is waived. H13451 is an expansion sheet to accomplish LNM requirement. 20NM North of Dublin BayMultibeam Echo Sounder BackscatterMultibeam Echo Sounder2021-07-232021-07-21UTC2021-04-02Allison StonePacific Hydrographic BranchAny revisions to the Descriptive Report (DR) applied during office processing are shown in red italic text. The DR is maintained as a field unit product, therefore all information and recommendations within this report are considered preliminary unless otherwise noted. The final disposition of survey data is represented in the NOAA nautical chart products. All pertinent records for this survey are archived at the National Centers for Environmental Information (NCEI) and can be retrieved via https://www.ncei.noaa.gov/. Products created during office processing were generated in NAD83 UTM 3N, MLLW. All references to other horizontal or vertical datums in this report are applicable to the processed hydrographic data provided by the field unit.Navigable Area2021metersUS3AK61M2019-03-202020-09-2925300000No uncharted features exist for this survey.No shoals or potentially hazardous features exist for this survey.One submerged buoy charted 55-02-49.92N 165-05-40.08W was investigated to full coverage with a radius of 500m from the charted feature. No submerged buoy was located. Refer to the Final Feature File (FFF) for further detail.No channels exist for this survey. There are no designated anchorages, precautionary areas, safety fairways, traffic separation schemes, pilot boarding areas, or channel and range lines within the survey limits.A chart comparison was conducted using the Triangle Rule script within the Chart Review Tool of Pydro QC Tools. A combined s57 file of charted soundings extracted from ENCs listed in the project instructions and an s57 file of surveyed soundings were compared with the following results. Survey H13451 surveyed soundings exhibit 0 instances where surveyed soundings are shoal to charted soundings by greater than 1m.No abnormal seafloor or environmental conditions exist for this survey.No ferry routes or terminals exist for this survey.No Maritime Boundary Points were assigned for this survey.No new surveys or further investigations are recommended for this area.No bottom samples were required for this survey.No new ENC scales are recommended for this area.No present or planned construction or dredging exist within the survey limits.No overhead features exist for this survey.No submarine features exist for this survey.No Aids to Navigation (ATONs) exist for this survey.No platforms exist for this survey.All positioning and attitude data associated with OPR-Q350-KR-21 was post-processed in POSPac MMS using PP-RTX methods. For further discussion, reference the DAPR submitted with this report.OPR_Q350_KR_21_CapeSarichef_ERTDM21-1_NAD83-MLLWERS via VDATUMMean Lower Low WaterNorth American Datum 1983All positioning and attitude data associated with OPR-Q350-KR-21 was post-processed in POSPac MMS using PP-RTX methods. Projected UTM 3No vertical or horizontal control reports were generated for this survey. All data were reduced to MLLW via VDatum model.