OPR-S313-KR-15Cape Prince of Wales Shoal, AKBering StraitTerrasond LimitedH127531Registry Instructions30 NM North of Cape Prince of WalesAlaskaUnited States400002015Andrew OrthmannNavigable Area2015-05-052015-07-042015-07-26Multibeam EchosounderSinglebeam EchosoundermetersNAD83UTCPacific Hydrographic BranchThe purpose of this survey is to provide contemporary surveys to update National Ocean Service (NOS) nautical charts. All separates are filed with the hydrographic data. Notes in red were generated during office processing. The processing branch concurs with all information and recommendations in the DR unless otherwise noted. Page numbering may be interrupted or non-sequential. All pertinent records for this survey, including the Descriptive Report, are archived at the National Centers for Environmental Information (NCEI) and can be retrieved via http://www.ncei.noaa.gov/.ContractorA navigable area survey (H12753) was conducted in the area 30 NM North of Cape Prince of Wales, Alaska, in accordance with the NOAA, National Ocean Service, Statement of Work (SOW), OPR-S313-KR-15, dated March 13th, 2015, and Hydrographic Survey Project Instructions dated May 5th, 2015. Hydrographic survey data collection began July 4th, 2015 and ended July 26th, 2015. The area is in a remote region just south of the Arctic circle. Sea ice covers the area for the majority of the year, with a limited ice-free season with open navigable water from approximately late June through October. Vessel traffic in the region primarily consists of barges serving communities along Alaska's north coast with fuel and supplies, freighters moving lead and zinc from Red Dog Mine to the north, and research vessels involved in Arctic studies. Traffic is relatively sparse but has been increasing in recent years along with economic and scientific interest in the Arctic. The survey area is centered on Prince of Wales Shoal. This shoal is a relatively narrow ridge of sediment, covered 3 1/2 to 5 fathoms, which extends NNE from Cape Prince of Wales approximately 35 NM. The shoal is built and maintained by sediment transport caused by tidal current flow between the Arctic Ocean and the Pacific Ocean by way of the Bering Strait. The shoal is unmarked because of the ice conditions and remoteness of the locality. Weather during the ice-free season is frequently inclement. The area is fully exposed in most directions and offers no anchorages or other protected areas. Rapidly changing wind and current conditions offshore of the shoal frequently cause confused and choppy seas which can be dangerous for small craft. Multibeam echosounder (MBES) and single beam echosounder (SBES) operations were conducted in the area in accordance with the project instructions, which specified set line spacing SBES or MBES with backscatter. Requirements called for 200 m set line spacing SBES (or MBES) within the project extents, with no inshore limit. 66.163152168.03412265.98975167.674166Survey extents and overview.SupportFiles\1_H12753_SurveyExtents.jpgSurvey limits were achieved.The purpose of the survey, as well as three adjacent surveys completed co-incidentally during project OPR-S313-KR-15, was to update NOS nautical charts in the general vicinity of the Bering Strait, addressing approximately 297 SQ NM of Priority 3 area identified in the NOAA Hydrographic Survey Priorities, 2012 edition. The survey also addresses United States Coast Guard (USCG) requests for defining the extent of Cape Prince of Wales Shoal due to increased vessel traffic in the region. Prior to this survey, the degree to which the shoal may have shifted from the charted position was unknown, especially given that the best scale chart at the time of this survey (Chart 16190) is out of date, with source soundings acquired from 1940 to 1969.The entire survey is adequate to supersede previous data.The 200 m spacing requirement for set line spacing within the survey extents was met. Line splits on charted soundings were not conducted because the nature of the bottom in the area reduced the likelihood of pinnacles or shoals between lines.Line splits are required in for set line spacing surveys in accordance with section 5.2.2.3 of the HSSD. There was no correspondence indicating that this requirement was waived.Survey overview showing coverage.SupportFiles\2_H12753_Coverage.jpgQualifier 105074200000710ASV-CT314600000000146742000007108.090000852015-07-042015-07-052015-07-062015-07-072015-07-082015-07-112015-07-122015-07-142015-07-152015-07-162015-07-172015-07-222015-07-252015-07-26Refer 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.Qualifier 105321.8ASV-CT33.50.3The Qualifier 105 (Q105) is a 32 m aluminum hull vessel owned and operated by Support Vessels of Alaska. The Q105 acquired all multibeam data and provided housing and facilities for on-site data processing. The vessel also collected bottom samples, deployed BMPG tide gauges, and deployed/recovered the ASV-CT3 vessel as necessary. The ASV-CT3 is a 3.5 m aluminum hull Autonomous Surface Vessel (ASV) owned and operated by ASV Global. The ASV was operated in an unmanned but monitored mode, collecting SBES data in close vicinity to the Q105 when weather conditions allowed. The ASV collected a minority of the mileage on this project because weather conditions were usually not conducive to its operations, deployment, or recovery. Note that a general-interest report regarding the ASV titled "ASV_Operations_Summary_Report_TerraSond_2015" was submitted to NOAA separately; it is included in the Appendix II subdirectory.Teledyne OdomEchotrac CV100SBESTeledyne ResonSeabat 7101MBESApplanixPOSMV 320 V5Positioning and AttitudeAML OceanographicMinosX with Xchange SensorsSound Speed ProfilerHemisphereVector V113 GPS CompassPositioning and AttitudeValeportRapid SVT 200BarSound Speed ProfilerTeledyne OceanscienceRapidCASTSound Speed Profiler Deployment SystemTrimble5700Base StationTrimble5700PositioningSea-Bird ElectronicsSBE 26+Submerged Tide GaugeAML OceanographicMinosX with Xchange SensorsConductivity and Temperature GaugesEquipment configurations and operations as well as data acquisition and processing are described in the DAPR.Crosslines were acquired to meet or exceed the 8% of mainscheme requirements required in the HSSD. Effort was made to ensure crosslines were geographically distributed across the survey area. Crosslines were run perpendicular to mainscheme lines whenever possible to ensure higher quality nadir beams crossed lower quality outer beams. Multibeam lines intersected SBES lines as an additional cross-system/vessel check. The crossline analysis was conducted using CARIS HIPS “QC Report” routine. Each crossline was selected and run through the process, which calculated the depth difference between each accepted crossline sounding and a QC BASE (CUBE-type) surface’s depth layer created from the mainscheme data. QC BASE surfaces were created with the same CUBE parameters and resolutions as the final BASE surfaces, with the important distinction that the QC BASE surfaces did not include crosslines so as to not bias the QC report results. Differences in depth were grouped by beam number and statistics computed, which included the percentage of soundings with differences from the BASE surface falling within IHO Order 1. When at least 95% of the sounding differences exceed IHO Order 1, 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.” Agreement between the BASE surfaces and crossline soundings is excellent. All crossline comparisons pass with 95% (or more) of soundings comparing to within IHO Order 1. Note that this sheet included a section of SBES mainscheme, which was intersected by MBES crosslines. The SBES surface versus MBES crossline sounding agreement is also excellent, passing with 95% (or more) of soundings comparing to within IHO Order 1. Refer to Separate II: Digital Data for the detailed Crossline QC Reports.00Qualifier 10502.1110.025ASV-CT302.1110All soundings were assigned a horizontal and vertical value for estimated total propagated uncertainty (TPU). Tidal error (measured and zoning) was computed using the "real-time" values in the tide zone definition file (ZDF). The parameters and methods used for computation of sounding uncertainty are detailed in the project DAPR. The ASV-CT3 uses identical uncertainty values for measured sound speed as the Q105 because the Q105 performed all sound speed casts on the project. The BASE surfaces were finalized in CARIS HIPS so that the final uncertainty value for each grid cell is the greater of either standard deviation or uncertainty. The uncertainty layer of the final surface was then examined for areas of uncertainty that exceeded IHO Order 1. Uncertainty for the SBES surface ranged from 0.28 m to 0.40 m. Uncertainty for the MBES surface ranged from 0.13 m to 0.59 m. Few exceeded IHO Order 1. Highest uncertainties were found in areas of varying bottom topography such as slopes and sand waves 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 exhibiting sound speed or motion artifact error. Despite elevated TPU values for these grid cells, the data is within specifications.Table 6 incorrectly implies TPU values for Tide Measured and Tide Zoning were 0-meters. For this survey, the field unit used a realtime method to apply tide TPU values. All of the tidal uncertainties have been dealt with appropriately and the data is adequate to supersede charted data in the common area.This survey junctions with two contemporary surveys: H12754 and H12752. Both were conducted concurrent with this survey. Junctions were compared by creating difference surfaces in CARIS HIPS. 4-m resolution CUBE BASE surfaces were generated for each survey, and then differenced. Results were extracted and analyzed.Survey junctions with this sheet.SupportFiles\3_H12753_Junctions.jpgH12752400002015TerraSondSAgreement is excellent, averaging 0.003 m, with a standard deviation of 0.069 m, and differences falling in a range of -0.388 to 0.363 m.H12754400002015TerraSondNAgreement is excellent, comparing to within 0.048 m on average, with a standard deviation of 0.072 m, and differences falling in a range of -0.487 to 0.342 m.Echosounder confidence checks consisting of bar checks, lead lines, and acoustic comparisons between vessels were undertaken on this project. Two bar checks were completed for the MBES on the Q105, while one bar check was completed for the SBES system on the ASV-CT3. Bar checks served as a check on both real-time as well as processed depth accuracy, and were also used to determine and refine the sonar acoustic center offsets. Results were excellent, with processed sonar depths comparing on average to 0.033 m (or better) of the actual bar depth for MBES, and to 0.015 m for SBES. Lead line comparisons were also undertaken. Over the course of the project, two were completed for the MBES on the Q105 and one was completed for the SBES on the ASV-CT3. Processed sonar results versus depth measured by lead line were 0.051 m or better for the MBES, and 0.046 m for the SBES. Results were deemed acceptable given the variables associated with lead line checks. During acquisition, care was taken to ensure significant overlap between the two survey vessels for comparison purposes. Q105 MBES lines commonly intersect ASV-CT3 SBES data, and in several instances the Q105 surveyed completely over ASV-CT3 lines, creating ample comparable data. To compare the echosounder data, CARIS BASE surfaces at 4 m resolution were created for each vessel, and differenced from each other. The difference surfaces were exported to text and analyzed. Project wide, the MBES data agrees with the SBES data to 0.012 m on average, with a standard deviation of 0.051 m, with the MBES data slightly shoaler. The maximum difference was 0.426 m, and minimum difference was -0.238 m. Refer to the bar check and lead line logs available in Separate I: Acquisition and Processing Logs for specific results. Refer to the project DAPR for more information regarding QC checks methodology.7101 Beam PatternA distinct beam pattern was obvious in the data set in certain areas, with a fuzziness or “horn” like features on both sides of nadir on multibeam swaths, coinciding with the bottom detection shift from phase to amplitude detection. The pattern is common with Reson 8101/7101 multibeam echosounders in certain bottom types. Power and range settings were adjusted in acquisition to minimize the issue, with little effect. However, the “horns,” which can be as great as 0.20 m in height, appear to be largely ignored by the CUBE algorithm during surface creation, with minimal to no effect on the final surfaces.ASV-CT3 Pitch and RollPitch and roll records were logged aboard the the ASV-CT3 using a Hemisphere Vector V113, but were not applied to the SBES data. Although pitch and roll corrections are not required by the HSSD for SBES data, application to the SBES data was attempted on a test set of SBES data in order to minimize effects of motion (especially pitch) on the SBES soundings, but resulted in no noticeable benefit. Therefore, roll and pitch were not applied to the SBES data by way of setting the sensors to "Apply=NO" in the CARIS HVF.Sound Speed ErrorA general downward or upward across-track cupping in multibeam data, indicative of sound speed error, is present periodically in the data set. The sound speed error adversely affected outer beams by up to 0.20 m in places. To minimize the error, sound speed profiles were collected in sets every two hours during multibeam operations, and filters were used in processing to remove the outermost beams. The effect of sound speed error on final surfaces is relatively minor, normally not exceeding 0.10 m, and is within specifications.The outer beams of the MBES lines were rejected in swath editor to account for the SS errors. In some cases, good data was rejected.Motion ArtifactMotion artifact is occasionally visible in the final multibeam surfaces. This is the result of uncompensated effects of motion, particularly due to roll. Poor sea states (normally seas 1.5 m or greater) were common on this project and were the primary contributor. A survey-grade, high-end Applanix POSMV 320 V5 was used for motion compensation but residual error within the manufacturer specifications for the system remains nonetheless. The problem was addressed in processing by identifying lines with the greatest error and iteratively applying more aggressive outer beam filters, in some instances rejecting beams greater than 50 degrees either side of nadir. No adjustments to line spacing were made in acquisition to compensate for the rejected outer beam data because as a set-spaced survey, complete coverage was not required. Following the additional filtering the effect on the final surface is 0.20 m or less, which is within specifications.ASV-CT3 Pitch and RollAs described previously, corrections for pitch and roll were not applied to ASV-CT3 data. This sometimes results in downward "spikes" in the SBES data where the sounder erroneously digitized the depth as deeper than actual due to angle of the transducer relative to the seafloor while the vessel was pitching. To a lesser extent roll similarly affects the data. The relatively large (4 m) grid cell size used for the final BASE surfaces smooths and mitigates the effect of the error. Despite the apparent error the gridded SBES data passes crossline analysis, and compares to overlapping MBES data to 0.012 m on average with a low standard deviation of 0.051 m, and is within specifications.Tide ErrorPeriodic vertical offsets or “busts”, indicative of tide error, is present sporadically in the data set. The majority of lines show excellent matchup with crosslines, but busts of up to 0.15 m are occasionally present and attributable to tide error. The observed amount of tide error was deemed acceptable given that it was not possible for the project tide station and zoning gauges to capture all water level changes across the survey area, especially in this wide open region where winds frequently have more effect on water levels than the daily lunar and solar cycles. Despite the error, data is within specifications.2 hoursSound speed profiles were acquired aboard the Q105 while underway with an Oceanscience RapidCAST system, which utilized a Valeport sound speed profiler. Normally two or three profile "casts" were taken along a survey line, with casts near the beginning, end, and middle of the line (depending on line length), in order to capture spatial variance across the area. The set was then repeated on an interval of approximately two hours in order to capture temporal variance. The sound speed sensor was lowered as close as possible to the seafloor, and then retracted to the vessel and downloaded. The ASV-CT3 vessel was not equipped to collect sound speed profiles. Instead, the profile data collected aboard the Q105 was used to correct all ASV-CT3 SBES data. This was possible because the ASV-CT3 worked simultaneously and in close proximity (usually within 200 m) of the Q105 at all times. Up and down portions of the profiles were averaged and a combined profile at a standardized 0.10 m depth increment was output to CARIS SVP format with time and position. Sound speed profiles were applied with the “nearest in distance within time” method in CARIS HIPS, with time set to two hours for multibeam and four hours for single beam.Set line spacing requirements called for 200 m spaced lines within the survey extents. Line plans were defined in CAD software prior to the commencement of survey operations and were executed line by line during acquisition. Two line sets were available, with north-south and east-west orientations, which provided options for line direction depending on prevailing weather conditions. Refer to the project DAPR for additional methods used to meet coverage requirements.Corrections applied to echo soundings are detailed in the project DAPR. No deviations occurred. Calibrations were undertaken as described in the DAPR; no deviations occurred.Multibeam backscatter was logged during this survey, but not processed. The vessel Q105 multibeam DB and XTF files contain the backscatter records.V5.3.2There were no software configuration changes after the DAPR was submitted.H12753_MB_4m_MLLWMBES4040NOAA_4mSet-spaced MBESH12753_SB_4m_MLLWSBES4040NOAA_4mSet-spaced SBESThe final depth information for this survey was submitted as two CARIS BASE surfaces which best represented the seafloor at the time of the 2015 survey. The surfaces were created from fully processed soundings with all final corrections applied. The MBES surface was created using CUBE parameters that ensured a maximum sounding propagation distance of the grid resolution divided by √2. The SBES surface was created as a Uncertainty surface. A resolution of 4 m was selected for both surfaces based on the requirements for set-spaced surveys described in the HSSD. Surfaces were finalized, and designated soundings were applied where applicable. Horizontal projection was selected as UTM Zone 3 North, NAD 1983. Notes: * Any non-final surfaces submitted with the survey deliverables are interim products and are marked with "nonFinal" in their filename(s). * 4 m resolution was used per HSSD requirements for Set Line Spacing. All depths were less than 40 m. A CARIS HOB file was submitted (H12753_FFF.HOB) 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. Each object is encoded with mandatory S-57 attributes, additional attributes, and NOAA Extended Attributes (V#5.3.2). Refer to the DAPR for more detailed discussion of the steps followed when acquiring and processing the 2015 survey data.The first sentence of the second paragraph is simply describing the NOAA 4m CUBE Parameters. The grid resolution is divided by the square root of 2.Additional information discussing the vertical or horizontal control for this survey can be found in the accompanying HVCR.Mean Lower Low WaterDiscrete ZoningOutside Lopp Lagoon94695159469515.tidFinal ApprovedS313KR2015CORP_20151008.zdfFinal9999-01-019999-01-01In addition to the subordinate tide station installed to support the project, submerged BMPG (bottom mounted pressure gauges) were also deployed throughout the survey area to capture zoning characteristics. Data from all stations were used to derive the tide zones.NAD83UTM Zone 3NSingle Base0056Outside Lopp LagoonThe project base continuously logged GPS data at 1 Hz and was utilized to post-process position data in Applanix POSPac software. All real-time positions for both vessels were replaced in processing with post-processed kinematic (PPK) solutions.The chart comparison was performed by examining all Raster Navigational Charts (RNCs) and Electronic Navigational Charts (ENCs) that intersect the survey area. 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. Results are shown in the following sections. It is recommended that this survey supersede charted data where they overlap. USCG Notice to Mariners (NM) and USCG Local Notice to Mariners were checked for updates affecting the area. None were found that were issued subsequent to issuance date of the project instructions.16190235010000012013-052015-10-202015-10-17Sounding agreement is excellent. All charted soundings agree to this survey to 1 fathom or better. See figure below.Example of the excellent agreement between this survey and chart 16190. Soundings from this survey (blue) agree with soundings on the chart (black) to 1 fathom or better.SupportFiles\4_H12753_GeneralChartAgreement.jpgUS4AK8DM10000032015-04-222015-04-22falseThe same differences observed for the RNC apply to the ENC.There were no assigned AWOIS items for this survey.No maritime boundary points were assigned for this survey.There are no charted features labeled PA, ED, PD, or Rep. within the survey extents.No uncharted features were found during this survey.No DTONs were found during this survey.Prince of Wales Shoal, over which this survey was conducted, could be potentially hazardous to vessels of significant draft. However, soundings from this survey compare well to the charted soundings on chart 16190. Therefore, the chart already adequately depicts potential dangers.No channels exist in the survey area.Bottom samples were collected for this survey. Most returned brown silt, with some clay and fine sand. Samples were not retained. Bottom characteristics are encoded as SBDARE objects in the FFF, with photos of each sample in the accompanying "multimedia" directory, included with the survey deliverables.This survey did not intersect shoreline, and shoreline investigation was not assigned.Comparison with prior surveys was not required.No ATONs were observed in the survey area, and none were assigned for investigation.No overhead features existed within the survey area.None to note.Ferry routes and terminals do not exist within the survey area.Platforms do not exist within the survey area.All significant features and conditions encountered have been described previously.No construction or dredging was occurring within the survey extents, nor are there any known future plans for construction or dredging in the survey area.No new surveys are recommended in this area.No new chart insets are recommended in this area.Field operations contributing to the completion of survey H12753 were conducted under my direct supervision with frequent personal checks of progress, integrity, and adequacy.This report, digital data, and all other accompanying records are approved. All records are respectfully submitted and forwarded for final review.The survey data was collected in accordance with the Statement of Work and meets or exceeds the requirements set in the 2014 NOS Hydrographic Surveys and Specifications Deliverables (HSSD) document. This data is adequate to supersede charted data in common areas. This survey is complete and no additional work is required with the exception of any deficiencies, if any, noted in the Descriptive Report.Andrew Orthmann, C.H.TerraSond Charting Program Manager2015-11-20Coast Pilot Review (CPB9_E33_C09_20151016_1817_Recommendations)2015-10-20OPR S313-KR-15 Tide Station Removal Report (9469515 Outside Lopp Lagoon)2015-09-28