OPR-O190-FA-22 Vicinity of West Prince of Wales Island West Prince of Wales Island, AK NOAA Ship Fairweather (S220) H13668 8 Reserved for OHSL testing 2 NM South of Kupreanof Island Alaska United States 10000 2022 CDR Meghan McGovern Navigable Area 2022-08-11 2022-10-02 2022-10-12 Multibeam Echo Sounder Multibeam Echo Sounder Backscatter meters UTC Pacific Hydrographic Branch Any 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 8N, MLLW. All references to other horizontal or vertical datums in this report are applicable to the processed hydrographic data provided by the field unit. CC0-1.0 (NOAA Field Units) CC0-1.0 https://creativecommons.org/publicdomain/zero/1.0/ https://creativecommons.org/publicdomain/zero/1.0/legalcode These data were produced by NOAA and are in the public domain within the United States. NOAA waives any potential copyright and related rights in these data worldwide through the Creative Commons Zero 1.0 Universal Public Domain Dedication (CC0). NOAA The survey are is located in South of Kupreanof Island, Alaska. 133.35528480555556 56.47879588888889 133.073125 56.381372694444444 Data were acquired to the survey limits in accordance with the requirements in the Project Instructions and the 2022 NOS Hydrographic Surveys Specifications and Deliverables (HSSD). Coverage acquired in H13668 is shown in the figure below. H13668 sheet limits (dotted line) and survey coverage overlaid onto ENC US3AK3CM. SupportFiles\Coverage Graphic.jpg The area surrounding Prince of Wales Island is navigationally complex and home to communities that are inaccessible by land, relying instead on the sea as their primary means of travel. Waterways along the project area of Prince of Wales Island are marked by pinnacles, rocks, islets, and complex tidal currents. These hazards would not have been identified during prior surveys due to limitations of the technologies and techniques used at the time. These waterways are critical to the economic success of local coastal communities on Prince of Wales Island, as they are actively used for fishing and are the primary means for transporting goods throughout the region. Survey vintage in the southwestern Prince of Wales region dates back to 1916. Additional work on this project will occur in the vicinity of Sumner and Clarence Straits, AK, on the northern side of west Prince of Wales Island, in support of uncrewed Hydrographic Survey Launch testing. Sumner and Clarence straits are an important confluence of the Alaskan Inside Passage, handling a significant amount of commercial, recreational and fishing vessel traffic. Survey vintage in this portion of the survey dates back to 1971. This project will provide contemporary data to update National Ocean Service (NOS) nautical charting products and services, improving the safety of the maritime traffic and services available to these communities by reducing the current risk that is present due to unknown bathymetry. The entire survey is adequate to supersede previous data. Data acquired in H13668 meet multibeam echo sounder (MBES) coverage requirements for complete coverage, as required by the HSSD. This includes crosslines, NOAA allowable uncertainty, and density requirements. Uncertainty requirements were not met due to extensive sound velocity errors throughout the survey area. All waters in survey area Complete Coverage (Refer to HSSD Section 5.2.2.3) Survey coverage was in accordance with the requirements listed above and in the HSSD. H13668 survey coverage overlaid onto ENC US3AK3CM. SupportFiles\Coverage Graphic.jpg 2808 0.0 13.731 0.0 0.0 0.0 0.0 0.0 0.0 0.0 2807 0.0 142.9 0.0 0.0 0.0 0.0 0.0 19.6 0.0 2806 0.0 210.0 0.0 0.0 0.0 0.0 0.0 10.0 0.0 2805 0.0 104.9 0.0 0.0 0.0 0.0 0.0 0.0 0.0 S220 0.0 0.0 0.0 0.0 0.0 0.0 0.0 5.3 0.0 0.0 467.6 0.0 0.0 0.0 0.0 0.0 34.9 0.0 7.5 0 0 0 0 21.1 2022-10-02 2022-10-03 2022-10-04 2022-10-05 2022-10-06 2022-10-07 2022-10-08 2022-10-10 2022-10-11 2022-10-12 Refer to the OPR-O190-FA-22 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. 2808 8.6 1.1 2807 8.6 1.1 2806 8.6 1.1 2805 8.6 1.1 S220 70.4 4.8 MBES Kongsberg Maritime EM 712 MBES Kongsberg Maritime EM 2040 Conductivity, Temperature, and Depth Sensor Sea-Bird Scientific SBE 19plus V2 Sound Speed System Teledyne RESON SVP 70 Sound Speed System Teledyne RESON SVP 71 Positioning and Attitude System Applanix POS MV 320 v5 Conductivity, Temperature, and Depth Sensor AML Oceanographic MVP200 The equipment was installed on the survey platform as follows: S220 utilizes the Kongsberg EM 712MBES, a POS M/V v5 system for position and attitude, SVP 70 surface sound speed sensors, and AML Oceanographic MVP 200 for conductivity, temperature, and depth (CTD) casts. All launches utilize the Kongsberg EM 2040 MBES, a POS M/V v5 system for position and attitude, SVP 71 surface sound speed sensors, and Sea-Bird SBE 19plus v2 CTDs for conductivity, temperature, and depth. Crosslines were collected, processed and compared in accordance with Section 5.2.4.2 of the HSSD. For adequate comparison, 7.47% of crossline to MBES data was acquired.To evaluate crosslines, a surface generated via data strictly from mainscheme lines and a surface generated via data strictly from crosslines were created. From these two surfaces, a difference surface (mainscheme - crosslines = difference surface) was generated (Figure 3). Statistics show the mean difference between the depths derived from mainscheme data and crossline data was -0.02 meters and 95% of nodes falling within 0.35 meters. For the respective depths, the difference surface was compared to the allowable NOAA uncertainty standards. In total, 99.5% of the depth differences between H13668 mainscheme and crossline data were within allowable NOAA uncertainties. Overview of H13669 crosslines. SupportFiles\XL_Overview.jpg Closer look at H13668 crosslines. SupportFiles\XL Zoom West.jpg Closer look at H13668 crosslines. SupportFiles\XL Zoom East.jpg H13668 crossline and mainscheme difference statistics. SupportFiles\H13668_MB_VR_MLLW_MS_Final-H13668_MB_VR_MLLW_XL_Final_depth_delta.png ERS via VDATUM 0.0 0.132 S220 0 1 0 0.5 280x (all launches) 2 0 0 0.5 In addition to a priori estimates of uncertainty via device models for vessel motion and VDATUM, real-time and post-processed uncertainty sources were also incorporated into the depth estimates of survey H13668. Real-time uncertainties were provided via EM 712 and EM 2040 MBES data and Applanix Delayed Heave RMS. Following post-processing of the real-time vessel motion, recomputed uncertainties of vessel roll, pitch, gyro and navigation were applied in CARIS HIPS and SIPS via a Smoothed Best Estimate of Trajectory (SBET) RMS file generated in Applanix POSPac. The measured MVP sound speed uncertainty used in the TPU calculation was 2.0m/s. No junctions exist for this survey. Sonar system quality control checks were conducted as detailed in the quality control section of the DAPR. Applanix Logging Dropouts While logging POS data, several IMU discontinuities occurred across multiple vessels and days. These errors displayed in POSPac during post processing, and the issue was not known until acquisition was finished. The multibeam data tracklines associated with the POS data with IMU discontinuity were deleted from HIPS file and not used in creation of surfaces. Applanix was notified of the issue but could not give reasons on why it occurred frequently in H13668. POS dropout area. SupportFiles\H13668_POS_Dropouts.jpg Sound Speed Issues In certain areas, there are significant signs of sound speed errors. Examples of these errors can been seen in the figures below. Please refer to OPR-O190-FA-22 DAPR for more details. Example of an offset caused by sound speed issues. SupportFiles\Sound Speed Issues.jpg Example of the crossed overlap between lines caused by sound speed issues. SupportFiles\Sound Speed Issues 2.jpg Vertical Uncertainty Exceeded TVU Limit Throughout Survey Throughout the survey, there are areas where the vertical uncertainty exceeded TVU limit. The best attempts at cleaning were made. However, it is not possible to determine which offset line is a true representation of the seafloor, so both lines were left in. Additional cleaning would result in significant holidays throughout the coverage. Below shows example of this issue. Example of where the vertical uncertainty exceeded TVU limit SupportFiles\H13668-TVU 1.PNG Casts were conducted at a minimum of one every four hours during launch acquisition. Casts were conducted more frequently in areas where the influx of freshwater had an effect on the speed of sound in the water column and when there was a change in surface sound speed greater than two meters per second. MVP casts on S220 were conducted at an average interval of 240 minutes, guided by observation of the surface sound speed and targeted to deeper areas. All sound speed methods were used as detailed in the DAPR. Cast Locations for H13668. SupportFiles\H13668_Casts.jpg All equipment and survey methods were used as detailed in the DAPR. Holidays H13668 data were reviewed in CARIS HIPS and SIPS for holidays in accordance with Section 5.2.2.3 of the HSSD. Thirty-seven holidays which meet the definition described in the HSSD for complete coverage were identified via HydrOffice QC Tools Holiday Finder tool. This tool automatically scans the surface for holidays as defined in the HSSD and was run in conjunction with a visual inspection of the surface by the hydrographer. Most holidays are attributed to acoustic shadowing in steep, rocky areas and gaps over the tops of features, and underwater rocks. In one instance, a holiday is caused by equipment ineffectiveness relating to an offset caused by sound speed error. See OPR-O190-FA-22 DAPR for more details. H13668 Holidays. SupportFiles\H13668_Holidays.jpg H13668 Holiday attributed to ineffective sound speed equipment. SupportFiles\H13668_Holidays_2.jpg NOAA Allowable Uncertainty The surface was analyzed using the HydrOffice QC Tools Grid QA feature to determine compliance with specifications. Overall, 99.5% of nodes within the surface meet NOAA Allowable Uncertainty specifications for H13668 (Figure 11). H13668 allowable uncertainty statistics. SupportFiles\NOAA_Allowable_Uncertainty.png Density The surface was analyzed using the HydrOffice QC Tools Grid QA feature to determine compliance with specifications. Density requirements for H13668 were achieved with at least 99.5% of surface nodes containing five or more soundings as required by HSSD Section 5.2.2.3 (Figure 12). H13668 data density statistics. SupportFiles\Data_Density.png All data reduction procedures conform to those detailed in the DAPR. All sounding systems were calibrated as detailed in the DAPR. Raw backscatter data were stored in the .kmall and .all file for Kongsberg systems. All backscatter were processed to GSF files and a floating point mosaic was created by the field unit via Fledermaus FMGT 7.10.2. See the figure below for a greyscale representation of the complete mosaic. A single backscatter mosaic was created at 2m resolution based on the specifications for a 300kHz system. All equipment and survey methods were used as detailed in the DAPR. A relative backscatter calibration was performed by the field unit via a backscatter calibration site in order to bring the survey systems on each of the launches into alignment. See the figure below for a table of the calibration values entered into the Processing Settings within FMGT. Approximate inter-calibration corrections for offsets between sonar systems were applied to the mosaic. Backscatter mosaic for H13668. SupportFiles\H13668_Backscatter.jpg CARIS HIPS and SIPS 11.4 QPS Fledermaus 7.10.2 NOAA Profile Version 2022 H13668_MB_VR_MLLW_Final.csar CARIS VR Surface (CUBE) Variable Resolution -1.1 121.7 NOAA_VR Complete MBES H13668_MB_VR_MLLW.csar CARIS VR Surface (CUBE) Variable Resolution -1.1 121.7 NOAA_VR Complete MBES The NOAA CUBE parameters defined in the HSSD were used for the creation of all CUBE surfaces for H13668. The surfaces have been reviewed where noisy data, or "fliers" are incorporated into the gridded solutions causing the surface to be shoaler or deeper than the true sea floor. Where these spurious soundings cause the gridded surface to vary from the reliably measured seabed by greater than the maximum allowable Total Vertical Uncertainty at that depth, the noisy data have been rejected by the hydrographer and the surface recomputed. Flier Finder, part of the QC Tools package within HydrOffice, was used to assist the search for spurious soundings following gross cleaning. Flier Finder was run iteratively until the all remaining flagged areas were deemed to be valid aspects of the surface. Remaining 3,892 flagged areas deemed as valid aspects of the surface. SupportFiles\H13668_Fliers.jpg Designated Soundings H13668 contains 25 designated soundings in accordance with HSSD Section 5.2.1.2.3. The figure below shows an overview of the survey area and the location of designated soundings. H13668 designated soundings. SupportFiles\H13668_Critical_Soundings.PNG Additional information discussing the vertical or horizontal control for this survey can be found in the accompanying HVCR. Mean Lower Low Water ERS via VDATUM OPR-O190-FA-22_Sumner_100m_NAD83_2011-MLLW.csar ERS methods were used as the final means of reducing H13668 to MLLW for submission. North American Datum 1983 Projected UTM 8 RTX Vessel kinematic data were post-processed using Applanix POSPac processing software and RTX positioning methods described in the DAPR. Smoothed Best Estimate of Trajectory (SBET) and associated error (RMS) data were applied to all MBES data in CARIS HIPS and SIPS. During real-time acquisition, all platforms received correctors from the Wide Area Augmentation System (WAAS) for increased accuracies. WAAS and SBETs were the sole methods of positioning for H13668. The soundings from H13668 are generally in agreement with the charted soundings of ENC US4AK3MM and US3AK3CM. H13668 Chart Comparison (H13668 soundings in red). SupportFiles\H13668_Soundings_Comparison.jpg US4AK3MM 80000 13 2023-06-30 2023-06-30 US3AK3CM 217828 12 2023-06-30 2023-06-30 Shoals or potentially hazardous features exist for this survey, but were not investigated. Charted features exist for this survey, but not all features were investigated. Only features with 100% multibeam coverage were investigated. No uncharted features exist for this survey. No channels exist within the survey limits. Aids to navigation (ATONs) exist for this survey, but were not investigated. Maritime Boundary Points were assigned for this survey, but were not addressed. Bottom samples were assigned for this survey, but were not acquired. No overhead features exist for this survey. No submarine features exist for this survey. No platforms exist for this survey. No ferry routes or terminals exist for this survey. No abnormal seafloor or environmental conditions exist for this survey. No present or planned construction or dredging exist within the survey limits. No new surveys or further investigations are recommended for this area. No new ENC scales are recommended for this area. 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. 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. The 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. CDR Meghan McGovern Commanding Officer 2023-10-29 LT Michael Card Operations Officer 2023-10-29 LT Taylor Krabiel Field Operations Officer 2023-10-29 HST Benjamin Bryan Sheet Manager 2023-10-29 HAST John Cole Assistant Survey Technician 2023-10-29 LTJG Sara Rollings Assistant Survey Technician 2023-10-29 HSST Sarah Ober Senior Survey Technician 2023-10-29