Field operations for this hydrographic survey were conducted under the direct supervision of the then Chief of Party, Commander Marc S. Moser, 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 and Specifications Deliverables Manual, 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.Chief of Party2016-05-04LCDR Briana Welton, NOAAField Operations Officer2016-04-28LT Nicholas Morgan, NOAASenior Survey Technician2016-04-28HSST Patrick BerubeAll sounding systems were calibrated as detailed in the DAPR.All data reduction procedures conform to those detailed in the DAPR.Raw Backscatter was logged as a 7k file and is included in the submission to the Processing Branch. Backscatter was processed by the field unit.During acquisition on sheet H12841 several sound speed artifacts were observed. As shown in figure 10, most artifacts were within total vertical uncertainty standards for the survey. Soundings were rejected by the hydrographer to make the grid best represent the sea floor.Sound Velocity Artifactsfile:///Q:/2015/OPR-D304-FH-15_Approaches_to_Chesapeake/Surveys/H12841/Survey_Files/DR_Images/H12841_SV_Artifact.jpgH12841 Sound velocity artifactThroughout the acquisition of H12841 there were several instances where accurate sea floor detection was by the outer most beams. Generally there was enough overlap to compensate for the loss of sea floor detection. Erroneous sea floor detections were rejected.Loss of sea floor detectionfile:///Q:/2015/OPR-D304-FH-15_Approaches_to_Chesapeake/Surveys/H12841/Survey_Files/DR_Images/H12841_Loss_of_BDetection.jpgH12841 Loss of sea floor detectionA density analysis determined that over 99.9% of all nodes in the only finalized surface contain five or more soundings. The density analysis was executed on nodes which were populated by at least one sounding and did not account for holidays located within the surface.Data Density Analysisfile:///Q:/2015/OPR-D304-FH-15_Approaches_to_Chesapeake/Surveys/H12841/Survey_Files/DR_Images/H12841_MB_2m_MLLW_Final_Density.pngH12841 Data density analysis for 2-meter finalized surface.On the north west edge of survey H12841 several holidays occurred near the northern most 14 fathom sounding on chart 12200. These holidays occurred due to not enough overlap on pre-existing coverage. The ship left the project area without an opportunity to acquire data over the holidays.Holidaysfile:///Q:/2015/OPR-D304-FH-15_Approaches_to_Chesapeake/Surveys/H12841/Survey_Files/DR_Images/H12841_Holiday.pngH12841 HolidaysOne junction comparison was completed for H12841 as shown in Figure 8. The junction survey, H12840, was completed by NOAA Ship FERDINAND R. HASSLER in 2015.The area of overlap between sheets H12841 and its junction sheet, H12840, shown in Figure 8, was reviewed in CARIS Subset Editor. The functioning 2-meter surface was subtracted from the 2-meter surface from H12841 to assess sounding consistency. Survey H12840 was conducted by NOAA Ship FERDINAND R. HASSLER in 2015 during the course of project OPR-D304-FH-15. A difference surface analysis between the H12841 and H12840 2-meter resolution surfaces showed H12840 to be on average 0.01 meters shoaler then H12841, with a standard deviation of 0.09 meters. Ninety five percent of all differences are less than 0.17 meters from the mean.ENOAA Ship FERDINAND R. HASSLERH12840201540000file:///Q:/2015/OPR-D304-FH-15_Approaches_to_Chesapeake/Surveys/H12841/Survey_Files/DR_Images/B2_H12841_Junction.jpgJunctioning area between surveys H12841 and H12840file:///Q:/2015/OPR-D304-FH-15_Approaches_to_Chesapeake/Surveys/H12841/Survey_Files/DR_Images/H12840_vs_H12841_2m_Diff_Stats.pngH12841 H12840 Junction statisticsA total of 576 sound speed measurements were taken within the boundaries of survey H12841. Sound speed casts were performed using the MVP 200 at intervals ranging from 5 minutes to 30 minutes. The shorter intervals were necessary due to high stratification of the water column and high variance between the consecutive sound speed profiles. Sound speed corrections were applied in CARIS using Nearest in Distance Within Time (NDWIT) of 1 hour for the entire survey.file:///Q:/2015/OPR-D304-FH-15_Approaches_to_Chesapeake/Surveys/H12841/Survey_Files/DR_Images/H12841_E_to_W_Lines.jpgH12841 Survey line overviewSurvey coverage was run from east to west to decrease the distance between consecutive sound speed profiles. This mitigated the high sound speed variability observed between casts and resulted in better data quality with fewer sound speed artifacts.A geographic plot of crosslines is shown in Figure 4. To evaluate crossline agreement, two 2-meter surfaces were created: one from crossline soundings, the other from mainscheme soundings. These two surfaces were differenced using CARIS HIPS and SIPS. The statistical analysis of the differences between the mainscheme and crossline surfaces is shown as follows in Figure 5. The average difference between the surfaces is 0.06 meters with a standard deviation of 0.10 meters; 95% of all differences were less than 0.19 meters from the mean.file:///Q:/2015/OPR-D304-FH-15_Approaches_to_Chesapeake/Surveys/H12841/Survey_Files/DR_Images/H12841_XLine_Overview.jpgH12841 Crossline overviewfile:///Q:/2015/OPR-D304-FH-15_Approaches_to_Chesapeake/Surveys/H12841/Survey_Files/DR_Images/H12841_MS_XL_Diff.pngH12841 Crossline difference statisticsAll data for survey H12841 were reduced to MLLW via VDatum. This model functioned as a gridded separation model for GPS tide computations with a 0.102 meter uncertainty. Final TPU calculations are derived from the following sources: VDatum separation model, sound velocity (MVP and surface sound velocimeter), HVF uncertainties, and SBET post processed uncertainty. Error data sources applied through CARIS processing software are listed in Tables 6 and 7. Total vertical uncertainty analysis was performed by creating an IHO order one layer and exporting it to ASCII for statistical analysis. This layer yielded an average uncertainty of 0.47 meters, with a standard deviation of 0.04 meters. Ninety five percent of grid nodes were within 0.08 meters of the average uncertainty. Each H12841 finalized surface was processed with the Finalized CSAR Surface QA tool within Pydro to generate TVU statistics. Greater than 99.9% of nodes within the 2-meter finalized surface meet the vertical uncertainty standards of section 5.1.3 of the Hydrographic Surveys Specifications and Deliverables (2015). See H12841_Standards_Compliance report submitted in Appendix III of this report.1.00.10.5S250Discrete Zoning0.160.01VDATUM0.1020.01file:///Q:/2015/OPR-D304-FH-15_Approaches_to_Chesapeake/Surveys/H12841/Survey_Files/DR_Images/H12841_IHO_Overview.jpgH12841 IHO uncertainty layer overviewfile:///Q:/2015/OPR-D304-FH-15_Approaches_to_Chesapeake/Surveys/H12841/Survey_Files/DR_Images/H12841_IHO_Uncertainty.pngH12841 IHO uncertainty statisticsSonar system quality control checks were conducted as detailed in the quality control section of the DAPR.There were no conditions or deficiencies that affected equipment operational effectiveness.None ExistAll equipment and survey methods were used as detailed in the DAPR.7.4.5b 64-bitFMGTFledermausNOAA Profile V_5_39.0.21CARIS HIPSCarisComplete MBES2H12841_MB_2m_MLLWCUBE20.0440.4NOAA_2mComplete MBES2H12841_MB_2m_MLLW_FinalCUBE20.0438.56NOAA_2mAll soundings fell within the 2 meter resolution.Southwest of the 15 fathom sounding on chart 12200 in the vicinity of the sand waves there is an area where the 2 meter surface is not honoring the sea floor. The hydrographer designated the sounding determined to represent the least depth of the sea floor.Surface not honoring sea floorfile:///Q:/2015/OPR-D304-FH-15_Approaches_to_Chesapeake/Surveys/H12841/Survey_Files/DR_Images/H12841_Sand_Wave_Des.pngH12841 Designation3.7737.7S250file:///Q:/2015/OPR-D304-FH-15_Approaches_to_Chesapeake/Surveys/H12841/Survey_Files/DR_Images/Hassler.pngNOAA Ship FERDINAND R. HASSLER alongside pier at Marine Operations Center-AtlanticNOAA Ship FERDINAND R. HASSLER (S250), shown in Figure 3, acquired all data within the limits of H12841.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.7125RESONMBESPOS M/V 320 V5ApplanixPositioning and Attitude SystemMBX-4HemispherePositioning SystemMicroCTDAMLSound Speed SystemMVP-200Brooke OceanSound Speed SystemSVP-70RESONSound Speed SystemSBE 19+Sea BirdSound Speed System2016-06-06527382015-05-06122042012-1280000Surveyed soundings varied in comparison to charted soundings. Most surveyed soundings were one to two feet deeper then charted soundings with some isolated cases of surveyed soundings being shoaler than charted soundings. There are also some extreme examples where surveyed soundings were either four to six feet deeper or shoaler then charted soundings. The largest disagreement between charted and surveyed soundings exists on the southern most 100-foot sounding. Surveyed soundings produced an 86-foot sounding in the vicinity. This can be seen below with other examples of sounding disagreement. Red circles in the figures below show gross disagreement while green circles show minor disagreement. The charted wreck located in the southern portion of the sheet was not seen in the multibeam coverage or the surface. See the charted feature section of the descriptive report for discussion.file:///Q:/2015/OPR-D304-FH-15_Approaches_to_Chesapeake/Surveys/H12841/Survey_Files/DR_Images/H12841_Sounding_Disagreement.jpgH12841 Southern sounding disagreement with RNC 12204file:///Q:/2015/OPR-D304-FH-15_Approaches_to_Chesapeake/Surveys/H12841/Survey_Files/DR_Images/H12841_Sounding_Disagreement_Central.jpgH12841 Central sounding disagreement with RNC 122042015-06-13526512015-06-02122002014-06419706Surveyed soundings agree with charted soundings. The charted wreck located in the southern portion of the sheet was not seen in the multibeam coverage or the surface. See the charted feature section of the descriptive report for discussion. Towards the northern portion of the sheet large sand waves appear between charted soundings. This resulted in a large shoal area in between two correctly charted soundings; with the shoalest sounding being 10.5 fathoms between a 12 and 13 fathom sounding.file:///Q:/2015/OPR-D304-FH-15_Approaches_to_Chesapeake/Surveys/H12841/Survey_Files/DR_Images/H12841_Sand_Wave_Feature.jpgH12841 Sand wave shoal areaUS4NC31M2014-10-0918false2015-06-0380000ENC US4NC31M soundings correspond with RNC 12204 soundings. Refer to RNC 12204 for chart comparison.US3DE01M2015-05-0615false2015-05-3180000ENC US3DE01M soundings correspond with RNC 12200 soundings. Refer to RNC 12200 for chart comparison.The hydrographer has compared a sounding plot from the surveyed area to the charted soundings. There are no charted contours to compare.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 shoals or potentially hazardous features exist for this survey. An uncharted underwater rock was found to the south of the southwest 15 fathom sounding on chart 12200. The rock protruded from the sea floor approximately 3.39 meters and was measured at approximately 6.3 meters across at it's widest point. The hydrographer felt the sounding that was designated was the shoalest point on the rock, and the soundings above appear to be vegetation growth off the top of the rock.file:///Q:/2015/OPR-D304-FH-15_Approaches_to_Chesapeake/Surveys/H12841/Survey_Files/DR_Images/H12841_Uncharted_Feature.jpgUncharted rock One charted wreck exists on both chart 12200 and 12204, but was not found during survey acquisition. The area was covered with 100% multibeam and did not appear in the surface or when examined in CARIS subset editor.file:///Q:/2015/OPR-D304-FH-15_Approaches_to_Chesapeake/Surveys/H12841/Survey_Files/DR_Images/H12841_wreck_disproval.jpgH12841 Wreck disprovalNo Maritime Boundary Points were assigned for this survey.Six bottom samples, chosen from HSD Operations Branch's suggestions and acquired backscatter, were taken within the limits of H12841 and are submitted with the final feature file, as shown in Figure 24. Bottom samples consisted mainly of fine sand.file:///Q:/2015/OPR-D304-FH-15_Approaches_to_Chesapeake/Surveys/H12841/Survey_Files/DR_Images/H12841_Bottom_Sample_Overview.jpgH12841 Bottom sample overviewNo Danger to Navigation Reports were submitted for this survey.No submarine features exist for this survey.No ferry routes or terminals exist for this survey.No Aids to navigation (ATONs) exist for this survey.No new insets are recommended for this area.No prior survey comparisons exist for this survey.No overhead features exist for this survey.No new surveys or further investigations are recommended for this area.Shoreline was not assigned in the Hydrographic Survey Project Instructions or Statement of Work.No platforms exist for this survey.No Significant Features exist for this survey.No present or planned construction or dredging exist within the survey limits.Throughout acquisition of H12841 the preferred base station used for single base processing was DUCK. During acquisition there were outages of the DUCK base station, requiring the use of three other stations. NCBI station was the preferred alternate station, with ship to station distances ranging from 39km to 84km. There were several cases where both DUCK and NCBI were not available, in which case station LS03 was used, with ship to station distance ranging from 149km to 183km. COVX was used as the last option with the ship to station ranging from 48km to 83km An overview of all alternate base stations has been provided below. Though LS03 was far outside the recommended base station range, the SBETs that used LS03 were only applied on data acquired during days 262 and 290. No adverse effects are seen in the data.Base station outagesfile:///Q:/2015/OPR-D304-FH-15_Approaches_to_Chesapeake/Surveys/H12841/Survey_Files/DR_Images/H12841_NCBI_overview.jpgNCBI Base station overviewfile:///Q:/2015/OPR-D304-FH-15_Approaches_to_Chesapeake/Surveys/H12841/Survey_Files/DR_Images/H12841_LS03_overview.jpgLS03 Base station overviewfile:///Q:/2015/OPR-D304-FH-15_Approaches_to_Chesapeake/Surveys/H12841/Survey_Files/DR_Images/H12841_COVX_Overview.jpgCOVX Base station overviewOn occasion, SBET altitude spikes compromised the data's ability to meet TVU specifications. In these instances, Pydro's POSPAC Automated QC tools were used to delete the altitude spike and interpolate across the gap. (See Figure 19 for an example). The interpolated SBET was exported out of POSPAC Automated QC tool, opened in POSPAC MMS, and exported again to ensure the SBET was in the correct datum (NAD83). The new SBET contains the prefix "interpolated" for easy identification. The following SBETs were interpolated for H12841: interpolated_2015_294_S250S_b.Interpolation of SBETsfile:///Q:/2015/OPR-D304-FH-15_Approaches_to_Chesapeake/Surveys/H12841/Survey_Files/DR_Images/H12811_InterpolatedSBETExample.pngH12841_Interpolated SBET exampleDuring acquisition on H12841 several vertical offsets were observed after GPS tides were applied. The areas affected by the vertical offset were within TVU for the survey and were not investigated further. The POSPAC Automated QC tool was unable to interpolate in these instances.Vertical offsetfile:///Q:/2015/OPR-D304-FH-15_Approaches_to_Chesapeake/Surveys/H12841/Survey_Files/DR_Images/H12841_Vertical_Offset.jpgH12841 Vertical offsetUTM Zone 18NDriver, VA (289 kHz)LOYOLA Virginia Beach, VALS03BODIE ISLAND Bodie Island, NCNCBIDUCK 3 Duck, NCNCDUChesapeake Light, VACOVXSingle BaseNorth American Datum of 1983 (NAD83)All soundings submitted are reduced to Mean Lower Low Water (MLLW) using a VDatum separation model provided by HSD Operations Branch. A VDatum model evaluation was conducted prior to commencing acquisition on OPR-D304-FH-15 by running checklines across the entire project area. This checkline analysis yielded a combined horizontal and vertical position RMS of less than or equal to 0.07 meters. The checkline analysis report has been submitted as an appendix.2015_D304_VDatum_NAD83_MLLW.csarVDatum8651370Duck, NC2015-11-202015-11-06Discrete ZoningD304FH2015CORP.zdfFinal8651370.tidVerified ObservedMean Lower Low WaterAll vertical and horizontal control activities conducted during the course of this survey are fully addressed in the following sections. No separate HVCR is submitted.H1284123 Miles East of Currituck Beach3United StatesNorth Carolina400002015-07-24LCDR Briana Welton, NOAAmetersMultibeam Echo Sounder BackscatterMultibeam Echo SounderUniversal Transverse Mercator (UTM)2015-10-242015-07-29UTCAtlantic Hydrographic BranchNavigable Area2015Approaches to Chesapeake BayOPR-D304-FH-15NOAA Ship FERDINAND R. HASSLERApproaches to Chesapeake BayNOAAThe survey area is located in the approaches to Chesapeake Bay, within the sub-locality 23 miles east of Currituck Beach.75.502327777836.499883333375.396469444436.1993138889file:///Q:/2015/OPR-D304-FH-15_Approaches_to_Chesapeake/Surveys/H12841/Survey_Files/DR_Images/H12841_Survey_Limits.jpgH12841 Survey LimitsSurvey Limits were acquired with the requirements in the Project Instructions and the HSSD with the exception of the Northeast portion of the sheet. Operations were suspended before the Northeast portion could be completed due to mechanical issues with the ship.Survey coverage was in accordance with the requirements listed above and in the HSSD.Complete Multibeam with BackscatterAll waters in survey areaThe purpose of this project is to provide contemporary surveys to update National Ocean Service (NOS) nautical charting products. In addition, this project will improve the chart for traffic navigating the Atlantic Ocean Channel and will support BOEM research in this area.The entire survey is adequate to supersede previous data.700085.022015-09-082015-09-092015-09-102015-09-112015-09-162015-09-172015-09-182015-09-192015-10-172015-10-182015-10-202015-10-212015-10-222015-10-2405.4072.421364.43000000072.421364.4300000S250file:///Q:/2015/OPR-D304-FH-15_Approaches_to_Chesapeake/Surveys/H12841/Survey_Files/DR_Images/H12841_Coverage.jpgSurvey layout for OPR-D304-FH-15 over raster chart 12200