S-F933-NRT2-18Beaufort, NCBeaufort, NCNavigation Response Team 2F007311N/ABeaufort, NCNorth CarolinaUnited States100002018James KirkpatrickNavigable Area2018-07-022018-07-102018-07-11Multibeam Echo SounderSide Scan SonarmetersUniversal Transverse Mercator (UTM)UTCPacific 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. Any revisions to the Descriptive Report (DR) generated during office processing are shown in bold red italic text. The processing branch maintains the DR as a field unit product, therefore, all information and recommendations within the body of the DR are considered preliminary unless otherwise noted. The final disposition of surveyed features is represented in the OCS nautical chart update products. All pertinent records for this survey, including the DR, are archived at the National Centers for Environmental Information (NCEI) and can be retrieved via http://www.ncei.noaa.gov/.NOAASurvey limits include Town Creek and portions of Gallant's Channel in Beaufort, NC.34.72910276.66992834.71931376.662461F00731 Area OverviewSupportFiles\Area_Overview.PNGF00731 Survey AreaSupportFiles\F00731_Survey_Area.PNGSurvey limits were acquired in accordance with the requirements in the Project Instructions and the HSSD.There have been recent reports of vessels grounding in the Gallants Channel and Town Creek at Beaufort NC. This is a very high traffic area and a key waterway for the local economy. Survey data from this project is intended to supersede all prior survey data in the common area.The entire survey is adequate to supersede previous data.All navigable watersObject DetectionThe assigned survey limits were completed with 200% SSS and concurrent MBES except for the areas listed below. These areas were determined to be too shoal for safe operations.Non object detection area 1SupportFiles\Non_Coverage_Area_1.PNGNon object detection area 2SupportFiles\Non_Coverage_Area_2.PNGNon object detection area 3SupportFiles\Non_Coverage_Area_3.PNGNon object detection area 4 SupportFiles\Non_Coverage_Area_4.PNGF00731 Coverage GraphicSupportFiles\Coverage_Graphic.PNGS30090000015.39803.74400000015.39803.744024.300000.092018-07-102018-07-11Survey operations for F00731 were performed on July 10th and July 11th of 2018.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.S3009302S3009SupportFiles\S3009.jpgS3009 is a 30 foot survey vessel used for inshore and near shore hydrographic surveys, homeported in Fernandina Beach, FL and operated by Navigation Response Team 2.Kongsberg MaritimeEM 2040CMBESEdgeTech4125SSSAML OceanographicMicroX SVSSound Speed SystemApplanixPOS MV 320 v5Positioning and Attitude SystemYSICastAway-CTDConductivity, Temperature, and Depth SensorSee DAPR for system specifications.Survey day number 192 consisted of crosslines and developments which equaled 24% of the mainscheme MBES. A separate surface was created for the crosslines and it was directly compared to the Mainscheme surface using Caris HIPS "Difference Surface" tool. A total count of 69,895 soundings yielded a standard deviation of 0.1 meters, with a minimum difference of -0.5 meters and a maximum difference of 0.5 meters. Overall crosslines were in general agreement with mainscheme data.Crossline difference surface statisticsSupportFiles\XL_Difference_Stats.PNG09.7ERS via VDATUMS3009200.5Tide uncertainty was derived from the VDatum text file included with the project instructions. Sound speed uncertainty was derived from manufacturers specifications.A junction from survey H12266 completed by NRT2 in 2010 overlaps the southernmost portion of the survey. A 3m singlebeam bag was created with the data retrieved from NOAA's Bathymetric Data Viewer. This 3m bag was differenced directly with F00731_MB_50cm_MLLW_Final.csar. Results were in general agreement and no significant changes to bathymetry were noted. Standard deviation between the two surfaces was calculated to be 0.3 meters.Junction overlap area.SupportFiles\Junction_Overlap.PNGJunction Depth Delta analysis.SupportFiles\F00731_MB_50cm_MLLW_Final-H12266_VB_3m_MLLW_1of1_depth_delta.pngSonar system quality control checks were conducted as detailed in the quality control section of the DAPR.None ExistThere were no conditions or deficiencies that affected equipment operational effectiveness.None ExistThere were no other factors that affected corrections to soundings.Three sound velocity casts were acquired each survey day. An average of 2 hours lapsed between each cast. Sound velocity samples were collected using the YSI Castaway CTD described in the accompanying DAPR. Most casts were intentionally taken in deep water portions of the survey area to more accurately portray the full water column. F00731 Distribution of Sound Velocity SamplesSupportFiles\SVP_Distribution.PNGThe object detection requirement required for F00731 was achieved across the survey limits, with the exception of the areas already discussed. 200% SSS with concurrent MBES, or "skunk-striping" was employed throughout the survey area. Line planning was based on a 50 meter range scale with the SSS. Two line plans with 40 meter spacing were created, one in the North to South direction and one in the East to West direction. The two line plans were intended to reduce turning time and increase survey efficiency. Shoal areas and SSS contacts were developed with 100% MBES where depths allowed safe operation.F00731 Survey LinesSupportFiles\F00731 Survey_Lines.PNGAll data reduction procedures conform to those detailed in the DAPR.All sounding systems were calibrated as detailed in the DAPR.All equipment and survey methods were used as detailed in the DAPR. Backscatter was logged directly in the Kongsberg .all files but not processed per NRB exemption.NOAA Extended Attribute File 5.7F00731_MB_50cm_MLLWCARIS Raster Surface (CUBE)0.50.110.9NOAA_0.5mMBES TracklineSBES Set Line SpacingF00731_MB_50cm_MLLW_FinalCARIS Raster Surface (CUBE)0.50.110.9NOAA_0.5mMBES TracklineSBES Set Line SpacingF00731_SSSAB_1m_400kHz_1of2SSS Mosaic1N/A100% SSSF00731_SSSAB_1m_400kHz_2of2SSS Mosaic1N/A200% SSSAdditional information discussing the vertical or horizontal control for this survey can be found in the accompanying HVCR.Mean Lower Low WaterERS via VDATUMS-K933_Limits_xyNAD83-MLLW_geoid12b.csarNorth American Datum 1983UTM 18NSingle BaseNCBENCBEOnly one CORS station exists within 40km of the survey area precipitating the decision to use a single base solution. Positional accuracy was calculated in POSPAC MMS 8.3.1 on the order of 0.10 meters.Additional Positional Control IssuesAn overhead bridge existed in the survey area and data under and around the bridge displayed some positional degradation. Large spikes were cleaned out of the data using SBET QC tools by interpolating data around the spikes.A sounding layer was created from the survey data in Caris HIPS 10.4 using a 50 meter radius and NOAA rounding. This layer was then directly compared with soundings on the largest scale ENCs available. Each ENC sounding was compared to the nearest survey sounding as well as the bathymetric surface created with survey data. Shoreline features from the supplied CSF were also directly compared to the largest scale ENCs.Overview of chart comparison with F00731 sounding layer in red.SupportFiles\Chart_Comparison_overview.PNGUS5NC17M15000542018-11-052019-01-25falseSoundings compared between F00731 survey data and US5NC17M soundings are in good general agreement. No soundings in this comparison were observed to be different by more than 2 feet, none being shoaler than charted with the exception of a 1 foot sounding found to be 0 feet at the time of the survey.Shoal survey sounding.SupportFiles\Shoal_Sounding.PNGUS5NC18M40000192018-12-102018-12-10falseUS5NC18M unfortunately only contained one sounding in the survey area and it is in agreement with surveyed depths. Recommend new soundings be added to the ENC.Survey area covered by ENC US5NC18MSupportFiles\ENC_18_area.PNGNo Maritime Boundary Points were assigned for this survey.A reported 5 feet exists on Chart 11545 that is not necessary to safe navigation as it is reported under a marina slip. Recommend removing the reported 5 feet and updating bathymetry as needed. The Wreck PA on Chart 11545 and US5NC18M was not surveyed due to the shallow surrounding waters. No visual contact with the wreck was made. Reported 5 feet.SupportFiles\reported_5_ft.PNGWreck PA.SupportFiles\Wreck_PA.PNG 1. A large obstruction was found in the SSS imagery at position 34.723466N / 076.669970W. Due to the shallow surrounding area and potential height of the object a least depth was not determined. Using the closest bathymetry to the object and the shadow height measured in Caris Side Scan Editor an estimated depth of 3 feet was determined. This item is not considered a danger to navigation because of the proximity to shore and distance from charted channel. 2. A 9 foot obstruction was found in the SSS imagery at position 34.723677W / 076.669688W. Least depth was confirmed by 2 passes of MBES bathymetry. This obstruction is not considered a danger to navigation because no vessel with 9 foot draft could transit into the area. Recommend charting new 9 foot obstruction. 3. A new awash wreck was discovered with Side Scan imagery and visual contact at position 34.724886 / 076.662287W. This wreck is not considered a danger to navigation because it is located in a dead end portion of a shallow harbor. Recommend to chart new wreck and possibly chart large foul area because of numerous wrecks and debris in the area. 1. Large obstruction estimated 3 feet.SupportFiles\Large_obstn_Chart.PNG1. Large obstruction Side Scan image.SupportFiles\Large_Obstn.PNG2. 9 foot obstruction.SupportFiles\New_obstn_Chart.PNG2. 9 foot obstruction Side Scan image.SupportFiles\New_obstn.PNG2. 9 foot obstruction Multibeam image.SupportFiles\New_obstn_MB.PNG3. New awash wreck location.SupportFiles\New_wreck_Chart.PNG3. New awash wreck image.SupportFiles\20180711_121159.jpg3. New awash wreck Side Scan image.SupportFiles\New_wreck_SSS.PNG One obstruction on ENC US5NC17M at position 34.721332N / 076.669965W had no least depth reported. A least depth of 14.4 feet was confirmed by MBES. This obstruction is included in the Final Feature File as an update to chart the least depth. One DTON was submitted during F00731. The DTON report and submission email are included in the appendices of this report.Obstruction recommended for update.SupportFiles\Update_Least_Depth_chart.PNGObstruction least depth MBES image.SupportFiles\Update_Least_Depth_MBES.PNG Bulkhead Channel Range 6 from ENC US5NC17M was partially included in F00731. Soundings in the charted channel were all deeper than the reported 7.5 feet with the exception of one sounding that measured 7.3 feet. North of the defunct bascule bridge survey soundings are not shoaler than the reported 15 feet in the channel. 7 foot sounding in Bulkhead Channel Range 6.SupportFiles\Bulkhead_Channel.PNGNo bottom samples were required for this survey.All features assigned in the CSF, as well as new and updated features are included in the Final Feature File.Prior surveys are discussed in the Junction Survey section of this report.All ATONs not discussed in this section are on station and serving their intended purpose. New private aids marking the entrance to Homer Smith Marina are included in the Final Feature File and are recommended for charting.1. The bascule bridge on ENC US5NC17M is no longer operational due to the opening of the new fixed bridge to the north. Recommend removing the bascule bridge. The new Highrise Bridge has a reported vertical clearance of 65 feet at MHW and a horizontal clearance of 72 feet at the channel span. An email from North Carolina Department of Transportation is included in Project Correspondence. 1. Bascule Bridge recommended for removal.SupportFiles\Bascule_Bridge.PNGThe North Carolina Department of Transportation email that is referenced above in section D.2.4 has been appended to this document. 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 and/or environmental conditions exist for this survey.Chart 11545 still displays the Beaufort Highrise bridge in the survey area as under construction. Construction has been completed on the bridge and this note should be removed from the chart.Bridge under construction note.SupportFiles\Bridge_under_construction.PNGNo new surveys or further investigations are recommended for this area.No new insets 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.James KirkpatrickChief of Party2020-05-05