H13114Northwest of Sanak IslandUnited States40000Alaska3ContractorSouthwestern Alaskan PeninsulaTerrasond, Ltd.OPR-P377-KR-18Southwest Alaska Peninsula2018-06-082018-07-22Navigable Areameters2018Andrew OrthmannPacific Hydrographic BranchUTC2018-04-24Multibeam Echo SounderAll waters in survey areaComplete Coverage (Refer to HSSD Section 5.2.2.3) Acquire backscatter data during all multibeam data acquisition (Refer to HSSD Section 6.2)All waters in survey areaLNM no less than 5715 LNM. Report significant shoaling via weekly progress report. COR may adjust survey prioritization based on observed shoaling.Total project-wide LNM acquired for project OPR-P377-KR-18 totaled 5,738, which exceeded the required 5,715.2018-07-222018-07-212018-07-192018-07-152018-07-142018-07-132018-07-122018-07-112018-07-052018-07-042018-06-302018-06-292018-06-262018-06-212018-06-142018-06-132018-06-092018-06-087086.200ASV-CW5045.2398.3000000Qualifier 105061.8471.3000000010712.30869.600000Only bottom samples were acquired on 7/21 and 7/22.The purpose of this project is to provide contemporary surveys to update National Ocean Service nautical charting products to support an increase in vessel traffic in Unimak Passage. Unimak Passage is the gateway to the Bering Strait utilized by cargo, fishing, and trans-Pacific vessels delivering goods to the Aleutian Islands, western Alaska, and the Arctic. This passage and area is specifically utilized by the fishing fleet in Bristol Bay and the Bering Sea and this area was specifically requested by the Alaska Marine Pilots, Alaska Fisheries Development Foundation, the 17th District of the United States Coast Guard, and the Alaska Marine Highway. This project was last surveyed using partial bottom coverage techniques in the 1930's. Survey data from this project is intended to supersede all prior survey data in the common area.Survey limits were acquired in accordance with the requirements in the Project Instructions and the HSSD.Survey extents and overviewfile:///M:/OPRP377KR18/Surveys/H13114/Office_Processing/Reports_office/SupportFiles/H13114%20Extents.jpgThe survey area is located in the Aleutian Island region of southwest Alaska. The closest community is False Pass, population 35 (2010), located approximately 13 NM to the north on Unimak Island. The closest major hub is Dutch Harbor, population 4,376 (2010), located approximately 117 NM to the WSW. Field work was carried out in June and July of 2018 under project OPR-P377-KR-18, with final processing and reporting carried out from August through December, 2018. Four additional survey areas located to the west, north, and south were surveyed concurrently during this project. Work was done in accordance with the Hydrographic Survey Project Instructions (dated April 24th, 2018) and the NOS Hydrographic Surveys Specifications and Deliverables (HSSD), April 2017 edition.54.482344163.02999154.653065163.345451The entire survey is adequate to supersede previous data.Survey coverage graphicfile:///M:/OPRP377KR18/Surveys/H13114/Office_Processing/Reports_office/SupportFiles/H13114%20Coverage.jpgWAAS was used for real-time positioning only.Projected UTM 3CORS station geometry allowed for Applanix SmartBase (ASB) processing on this project, with AB06 (False Pass) used as the the primary control station. However, ASB was only used on lines that experienced issues with PP-RTX. Lines using ASB are itemized in the Data Acquisition and Processing section of this report.False PassAB06Smart BaseThe Trimble PP-RTX subscription-based correction service within POSPac was used for final positioning for the majority of lines. Results were good overall, usually at 0.10 m or better vertically.North American Datum 1983Mean Lower Low WaterOPR-P377-KR-18_NSPMVD_EPSG6332_NAD83-MLLW_Revised.csarERS via ERTDMAdditional information discussing the vertical or horizontal control for this survey can be found in the accompanying HVCR.Shoreline was not assigned in the Hydrographic Survey Project Instructions or Statement of Work. The survey area does not intersect shoreline.No new surveys or further investigations are recommended for this area.No platforms exist for this survey.No abnormal seafloor and/or environmental conditions exist for this survey.No submarine features exist for this survey.No present or planned construction or dredging exist within the survey limits.No Aids to navigation (ATONs) exist for this survey.No new insets are recommended for this area.During this survey the Alaska Marine Highway System (AMHS) ferry MV Tustumena was observed transiting the area. AMHS provides ferry service approximately every two weeks during the summer months between Homer, Kodiak, and Dutch Harbor as well as various ports between.No overhead features exist for this survey.The chart comparison was performed by examining the best-scale Electronic Navigational Charts (ENCs) that intersect the survey area. The latest edition(s) available at the time of the review were used. The chart comparison was accomplished by overlaying the finalized BASE surfaces with shoal-biased soundings, and final feature file on the charts in CARIS HIPS. The general agreement between charted soundings and survey soundings was then examined and a more detailed comparison was undertaken for any shoals or other dangerous features. In areas where a large scale chart overlapped with a small scale chart, only the larger scale chart was examined. When comparing to survey data, chart scale was taken into account so that 1 mm at chart scale was considered to be the valid radius for charted soundings and features. Results are shown in the following sections. It is recommended that in all cases of disagreement this survey should supersede charted data. USCG Notice to Mariners (NM) and USCG Local Notice to Mariners (LNM) were checked for updates affecting the area. No updates affecting the survey area issued subsequent to the date of the Hydrographic Survey Project Instructions and before the end of the survey were found.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.No uncharted features exist for this survey.Only one potentially hazardous feature (14.241 m sounding at 54-31-18.906 N, 163-14-03.774 W) was found and was discussed previously in this report. Given the scale of the chart this potential hazard is adequately charted, although the chart should be updated with the actual position and depth.Seven bottom samples locations were assigned that fell within the extents of this sheet. Samples were successfully obtained at all locations Black gravel was the most common primary constituent returned in the samples. Black sand and white shells were also common constituents. Two samples corresponded to the location of previously charted nature of the seafloor features: 1. Sample at 54-37-25.713 N, 163-10-30.486 W returning gravel (and shells) agrees well with the nearby charted sample which denotes gravel. 2. Sample at 54-34-13.909 N, 163-10-54.372 W returning gravel (and shells with sand) agrees well with the nearby charted sample which denotes sand and gravel.Soundings from this survey (red) shown on chart US3AK61M (black). Soundings in meters.file:///M:/OPRP377KR18/Surveys/H13114/Office_Processing/Reports_office/SupportFiles/US3AK61M_Overlap.jpgCharted sounding (black) is similar in depth but about 370 m WNW of the actual sounding for the bottom feature here, which is the shoalest part of this project area.file:///M:/OPRP377KR18/Surveys/H13114/Office_Processing/Reports_office/SupportFiles/US3AK61M_sounding.jpgAgreement is poor overall, although there is good agreement in a few cases. There appears to be a slight shift to the northwest for many charted soundings (and countours). In other words, moving the position of the charted soundings (and contours where applicable) to the southeast by 200 - 400 m would create a better match with survey data in many (but not all) cases. Sounding discrepancies of particular note are itemized below. The shoalest charted sounding inside this project area (13.7 m at 54-31-22.619 N, 163-14-23.393 W) appears to describe the seafloor shoaling found by this survey centered on 54-31-18.906 N, 163-14-03.774 W, where this survey found a least depth of 14.241 m. The least depths are therefore roughly equivalent but they are displaced horizontally by about 370 m, with the actual position to the ESE of the charted position. false23US3AK61M2018-08-132018-08-13300000Soundings from this survey (red) shown on chart US4AK5CM (black). Soundings in meters.file:///M:/OPRP377KR18/Surveys/H13114/Office_Processing/Reports_office/SupportFiles/US4AK5CM_Overlap.jpgAgreement is fair to good between this chart and the survey. Most charted soundings have survey soundings nearby that agree to within 1-2 meters, with greatest discrepancies on slopes and areas of rugged seafloor where it is likely the survey technology used to produce the charted soundings did not fully capture the least depths of the area. There is no apparent overall trend of shoaling or deepening. There are no sounding disagreements of particular note.false7US4AK5CM2018-07-062018-07-0680660No Maritime Boundary Points were assigned for this survey.No charted features exist for this survey.All equipment and survey methods were used as detailed in the DAPR.Sea-Bird ScientificSBE 26 plusTide Guage, SubmergedTrimble5700Base StationTeledyne OceanscienceRapidcastSound Speed Deployment SystemValeportRapidSVSound Speed SystemApplanixPOS MV 320 v5Positioning and Attitude SystemApplanixPOS MV 320 v4Positioning and Attitude SystemTeledyne RESONSeabat T50MBESRefer 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.The Qualifier 105 (Q105) is a 32 m aluminum-hull vessel owned and operated by Support Vessels of Alaska. The Q105 acquired multibeam data and provided housing and facilities for on-site data processing. The vessel was also used to collect bottom samples, deploy/recover BMPG tide gauges, conduct sound speed casts, and deploy/recover the ASV-CW5 vessel. The ASV-CW5 (C-Worker 5) is a 5.5 m aluminum-hull Autonomous Surface Vessel (ASV) owned and operated by ASV Global. The ASV was operated in an unmanned but monitored mode, collecting multibeam data in close proximity to the Q105.Survey vessels used on this project - ASV-CW5 (foreground), Q105 (background)file:///M:/OPRP377KR18/Surveys/H13114/Office_Processing/Reports_office/SupportFiles/Vessels.jpgASV-CW50.55.5Qualifier 1051.832Note that Table 10 documents processing depth ranges, not surface depth ranges. In review, all single resolution gridded surfaces were replaced with a Variable Resolution surface created using the Ranges method. This surface matches the single resolution surfaces for minimum and maximum depths (14.24m to 117.36m)CARIS Raster Surface (CUBE)H13114_MB_1m_MLLW_FinalComplete MBES1020NOAA_1mCARIS Raster Surface (CUBE)H13114_MB_2m_MLLW_FinalComplete MBES21840NOAA_2mCARIS Raster Surface (CUBE)H13114_MB_4m_MLLW_FinalComplete MBES43680NOAA_4mCARIS Raster Surface (CUBE)H13114_MB_8m_MLLW_FinalComplete MBES872160NOAA_8mThe final depth information for this survey was submitted as CARIS BASE surfaces (CSAR format) which best represented the seafloor at the time of the 2018 survey. The surfaces were created from fully processed data with all final corrections applied. Surfaces were created using NOAA CUBE parameters and resolutions by depth range in conformance with the 2017 HSSD. Surfaces were finalized, and designated soundings were applied where applicable. Horizontal projection was selected as UTM Zone 3 North, NAD83. Non-finalized versions of the CSAR surfaces are also included which do not have a depth cutoff applied. These do not have the "_Final" designation in the filename. An S-57 (.000) file was submitted with the survey deliverables as well. The final feature file (FFF) contains meta-data and other data not readily represented by the final surfaces, including bottom samples and shoreline verification results, if applicable. Each object is encoded with mandatory S-57 attributes and NOAA Extended Attributes (V#5.7). A georeferenced multibeam backscatter mosaic (Geotif format in NAD83 UTM Zone 3N, 1 m resolution) was also produced and is provided with the survey deliverables. Note that backscatter processing and mosaic generation was not a requirement of this survey and the mosaic is provided for interest only. The mosaic may have flaws or holidays which could be addressed through further processing. However, it is of sufficient quality to show the relative changes in seafloor type across the survey area.NOAA Profile V_5_7The hydrographer provided an explained in DR Section B.3 but inaccurately stated that real-time TPU was used in favor of post-processed TPU values. Just to clarify, the HIPS and SIPS processing software provides only two options in their compute TPU dialog box, for source of uncertainty, either 1) post-processed (real-time and dynamic) uncertainty based on vessel kinematics logged in the POS-MV or 2) a priori (static) uncertainty estimates from manufacturer's specifications contained within the HIPS Vessel File. The choice to use a priori uncertainty estimates almost certainly inflated the uncertainty estimates. This is brought up solely as a matter of clarification, and the inflated uncertainties involved do not affect the data's ability to meet and exceed gridded uncertainty specifications. * All ASV lines used real time attitude data (gyro, pitch, roll) as well as real-time TPU instead of the standard applciation of post-processed versions. This was due to roll alignment issues on some groups of lines when using the post-processed versions of the attitude data. Note that post-processed navigation and GPS height data was still applied per standard practice. * Applanix SmartBase was used instead of PP-RTX for the post-processing method for the following sets of lines in order to improve small vertical offsets observed on overlapping data: ASV vessel all lines on JD200 and line with prefix 2051 from JD196 Q105 vessel lines with prefix 404-412 (JD180), all lines on JD192 and JD193, line 0144 from JD165. * Q105 line 0144 on JD165 had a gap in post-processed data because POS file logging was cutoff. Navigation and motion is therefore realtime; GPS height is post-processed but interp'd from known measured values across the gap. TPU was computed from vessel settings instead of real-time. The 2nd segment of this line also does not have delayed heave applied as a result. After the corrections, the line compares well within specifications to overlapping neighbors. All sounding systems were calibrated as detailed in the DAPR.Image showing junctions with this surveyfile:///M:/OPRP377KR18/Surveys/H13114/Office_Processing/Reports_office/SupportFiles/H13114%20Survey%20Junctions.jpgThis survey junctions with three contemporary surveys. All were accomplished as part of the same overall project and surveyed concurrently. NOAA's "Gridded Surface Comparison V18.4" utility was used to complete the junction comparisons. The utility differences the surfaces from the junctioning surveys and generates statistics, including the percentage of grid cells that compare to within allowable TVU.Agreement is excellent. The mean difference between the two surveys in their overlapping area is 0.03 m, with a standard deviation of 0.22 m. Over 99.5% of grid cells compare to within the allowable TVU.Terrasond, Ltd.2018H1311240000WAgreement is excellent. The mean difference between the two surveys in their overlapping area is 0.01 m, with a standard deviation of 0.19 m. Over 99.5% of grid cells compare to within the allowable TVU.Terrasond, Ltd.2018H1311340000NAgreement is excellent. The mean difference between the two surveys in their overlapping area is 0.02 m, with a standard deviation of 0.19 m. Over 99.5% of grid cells compare to within the allowable TVU.Terrasond, Ltd.2018H1311540000SWSound Speed ErrorMild to moderate sound speed error is evident periodically throughout the data set. This is observed as a general downward or upward cupping ("frowning" or "smiling") of the seafloor profiles. The issue was addressed in the field through a relatively high cast frequency and tightening of line spacing. In processing filters were used to remove outer beam soundings most subject to the error, and areas showing excessive "frowning" or "smiling" received additional manual data editing to reject soundings that adversely affected the final surfaces. The effect on final surfaces is relatively minor, generally less than 0.30 m, and within specifications.Sound speed profiles or casts were acquired aboard the Q105 while underway with an Teledyne Oceanscience RapidCAST system, which utilized a Valeport RapidSV sound speed profiler. The interval between subsequent casts was approximately 2 hours. Casts were taken as deep as possible. On survey lines with significant differences in depth, the deeper portion of the line was favored to ensure changes across the full water column were measured. The cast data was used to correct the sounding data for both vessels, using the "nearest in distance within 4 hours" option within CARIS HIPS.2 hoursReal-time (dynamic) error estimates were computed and loaded for the majority of the survey data. This replaced the static error estimates for attitude and navigation during final TPU computation. Exceptions, if they exist, are listed in Section B.3 of this report. Refer to the DAPR for more information on derivation of the values used for TPU estimates. The BASE surfaces were finalized in CARIS HIPS so that the uncertainty value for each grid cell is the greater of either standard deviation or uncertainty. The uncertainty layer of each final surface was then examined for areas of uncertainty that exceeded allowable TVU for the depth (Order 1a for depths less than 100 m, and Order 2 for depths 100 m and deeper). Uncertainty for the surfaces ranges from 0.21 to 2.57 m. Greater than 99.5% of grid cells have uncertainty values within allowable TVU. Highest uncertainties were found in areas of varying bottom topography such as slopes and near bottom features where high standard deviations are caused by the wide depth ranges of soundings contributing to each grid cell, outer edges of multibeam swathes without adjacent line overlap, and areas with unrejected noisy soundings. Despite elevated TPU values for these grid cells, the data is within specifications.ASV-CW5020.025Qualifier 105020.02500.098ERS via ERTDMEffort was made to ensure crosslines had good temporal and geographic distribution, were angled to enable nadir-to-nadir comparisons, and that the required percent of mainscheme LNM was achieved. Crosslines were conducted with both vessels to ensure there was ample overlap for inter-vessel comparisons, with each vessel crossing the other's mainscheme lines. Since the two vessels worked in close proximity and normally ran parallel lines, crosslines were usually collected in sets when both vessels were in simultaneous operation. These lines were often collected when transiting across the survey area to reach a different survey priority. The crossline analysis was conducted using CARIS HIPS “Line QC Report” process. Each crossline was selected individually and run through the process, which calculated the depth difference between each accepted crossline sounding and a "QC" BASE (CUBE-type, 8 m resolution) surface’s depth layer created from the mainscheme data. QC surfaces were created with the same parameters used for 8 m surfaces as the final surfaces, with the important distinction that the QC surfaces did not include crosslines so as to not bias the results. Differences in depth were grouped by beam number and statistics were computed, including the percentage of soundings with differences from the QC surface falling within IHO Order 1a. Note for simplicity IHO Order 1a was used for all comparisons even though the looser IHO Order 2 standard was allowable for depths greater than 100 m. When at least 95% of the sounding differences exceed IHO Order 1a, the crossline was considered to “pass,” but when less than 95% of the soundings compare within IHO Order 1, the crossline was considered to “fail.” A 5% (or less) failure rate was considered acceptable since this approach compares soundings to a surface (instead of a surface to a surface), allowing for the possibility that noisy crossline soundings that don't adversely affect the final surface(s) could be counted as a QC failure in this process. Lines used as crosslines and their % of soundings passing IHO Order 1a, sorted from highest passing to lowest, are listed below. 1054-180-ASV-CW5-BC1XL -- 100.0% pass 0328-177-Q105-B1-XL -- 100.0% pass 0460-185-Q105-B1-XL -- 100.0% pass 1517-186-ASV-CW5-C1_XL4 -- 99.9% pass 0398-172-ASV-CW5-B2-C1_XL1 -- 99.9% pass 0397-172-ASV-CW5-B2_C1_XL1 -- 99.9% pass 0467-185-Q105-C2-XL -- 99.9% pass 0815-177-ASV-CW5-C2-1206-XL -- 99.9% pass 1072-180-ASV-CW5-C2-XL -- 99.9% pass 0816-177-ASV-CW5-C2-1206_XL -- 99.9% pass 0264-172-Q105-B2-C1-XL2 -- 99.8% pass 1384-185-ASV-CW5-C2-XL -- 99.8% pass 1390-185-ASV-CW5-C2-XL -- 99.8% pass 2121-200-ASV-CW5-C_XL1_ASV -- 99.8% pass 0469-186-Q105-C1_XL2 -- 99.8% pass 0478-186-Q105-C1-XL_3 -- 99.8% pass 0327-177-Q105-C1-XL -- 99.7% pass 1073-180-ASV-CW5-C2-XL -- 99.6% pass 0130-164-Q105-C2-XL-1 -- 99.6% pass 0418-180-Q105-C2-Q105-C2-XL -- 99.5% pass 2118-200-ASV-CW5-C3_XL1 -- 99.5% pass 0462-185-Q105-C2-XL -- 99.5% pass 0747-193-Q105-C-C_XL -- 99.5% pass 0874-200-Q105-C_XL1 -- 99.4% pass 0747-193-Q105-C-C_XL -- 99.4% pass 0481-186-Q105-C1-XL -- 99.4% pass 1055-180-ASV-CW5-BC1XL -- 99.4% pass 1505-ASV-CW5-C1_XL -- 99.3% pass 2007-192-ASV-CW5-C2-XL -- 99.2% pass 2120-200-ASV-CW5-C_XL1 -- 99.2% pass 0717-192-Q105-C2-XL -- 99.1% pass 0404-180-Q105-C2-XL -- 98.9% pass 0206-164-ASV-CW5-C2-XL-2 -- 98.9% pass 2119-200-ASV-CW5-C3_XL1 -- 98.8% pass 0873-200-Q105-C3_XL1 -- 97.9% pass Results: Agreement between the mainscheme surface and crosslines soundings is excellent. At least 95% of crossline soundings compare to the mainscheme surface within IHO Order 1a. Refer to Separate II: Digital Data for the detailed Crossline QC Reports.Sonar system quality control checks were conducted as detailed in the quality control section of the DAPR.All equipment and survey methods were used as detailed in the DAPR.Q105 Roll AlignmentIt became evident during operations that a roll bias was periodically present in data collected on the Q105 vessel. This was determined to correlate to deployment and retrieval of the hydraulic multibeam arm, which was not on the same physical mount as the motion sensor IMU on this vessel. Exact cause is unknown but small fluctuations in hydraulic pressure in the arm actuator are suspected. Effect on pitch and yaw, if any, was not discernible. The issue was addressed in processing by systematically examining lines exhibiting trouble and determining new roll alignment values--which was possible due to significant overlap with adjacent survey lines--and applying them via the HVF. There may be remnants of this error remaining periodically in the Q105 data set but the effect on final surfaces is minor and well within specifications. Additional discussion is available in the DAPR.2018-08-28Marine Mammal Observers Training Logsheet and Observation Logs2018-11-07NCEI Sound Speed Data Submission2018-12-17Coast Pilot Review ReportField operations contributing to the completion of this survey were conducted under my direct supervision with frequent personal checks of progress, integrity, and adequacy.The survey data meets or exceeds requirements as set forth in the NOS Hydrographic Surveys Specifications and Deliverables document as well as the Hydrographic Survey Project Instructions and Statement of Work. This data is adequate to supersede charted data in their common areas. This survey is complete and no additional work is required with the exception of deficiencies--if any--noted in the Descriptive Report.This report, digital data, and all other accompanying records are approved. All records are respectfully submitted for final review and acceptance.TerraSond Charting Program Manager2018-12-29Andrew Orthmann, C.H.