All waters in survey areaObject Detection CoverageSections of H13298 were surveyed to object detection coverage by complete object detection multibeam echosounder (MBES) coverage (Figure 8) and by 200% side scan sonar (SSS) coverage with concurrent MBES (Figures 9 and 10), as specified in the Project Instructions (PI) and the Hydrographic Surveys Specifications and Deliverables (HSSD) dated March 2019. Sections of H13298 were also surveyed by 200% SSS coverage with concurrent singlebeam echosounder (SBES) (Figures 11 and 12) (see Appendix II for documentation in regards to use of the SBES). Six holidays exist in SSS coverage (Figures 13 and 14). Four of the holidays exist in the 100% coverage and two of the holidays exist in the 200% coverage. Five of the holidays are covered only once by SSS coverage and no indications of significant features were observed. The sixth holiday was not covered by either SSS coverage or MBES coverage; it is the southernmost holiday shown in Figure 13 and is located at 36°56'21.73"N 076°25'43.33"W. There are 26 holidays in the VR surface that covers the area of 100% MBES coverage. Twelve holidays are covered once by either 100% SSS or 200% SSS coverage, six are covered by both 100% SSS and 200% SSS coverage, and no indications of significant features were observed. The remaining eight MBES holidays are not covered by SSS (Figure 15). Four holidays were observed in SBES data. Two are located at 36°56'23.45"N 076°25'43.60"W where a barge was anchored during survey operations (Figure 16). The other two are located at 36°55'48.66"N 076°25'05.98"W and 37°00'39.66"N 076°29'44.12"W (Figures 16 and 17). Other data deficiencies exist in both the SSS and MBES due to equipment effectiveness and environmental factors; see sections B.2.5 Equipment Effectiveness and B.2.6 Factors Affecting Soundings for a complete discussion.SupportFiles\A.4_MBES_Coverage.pngAreas outlined in blue represent 100% object detection MBES coverage for H13298.SupportFiles\A.4_MBES_SSS_Coverage_South.pngArea outlined in blue represents the southern portion of H13298 covered by SSS with concurrent MBES.SupportFiles\A.4_MBES_SSS_Coverage_North.pngArea outlined in blue represents the northern portion of H13298 covered by SSS with concurrent MBES.SupportFiles\A.4_SBES_SSS_Coverage_South.pngArea outlined in blue represents the southern portion of H13298 covered by SSS with concurrent SBES.SupportFiles\A.4_SBES_SSS_Coverage_North.pngArea outlined in blue represents the northern portion of H13298 covered by SSS with concurrent SBES.SupportFiles\A.4_SSS_100_Holidays.pngHolidays in 100% SSS coverage. SupportFiles\A.4_SSS_200_Holidays.pngHolidays in 200% SSS coverage. SupportFiles\A.4_MBESHolidays.pngHolidays in complete coverage MBES not covered by SSS coverage.SupportFiles\A.4_SBES_Holidays_South.pngSBES holiday in the southern portion of H13298.SupportFiles\A.4_SBES_Holidays_North.pngSBES holiday in the northern portion of H13298.11.4400702019-07-092019-07-102019-07-112019-07-142019-07-152019-07-162019-07-172019-07-192019-07-222019-07-292019-07-302019-07-312019-08-012019-08-022019-08-042019-12-192019-12-210352.91136.060081.46011.041.9400352.912.36000000290300133.70096.69011.0402904This project is located in the Chesapeake Bay in Virginia. The Chesapeake Bay is the largest of 130 estuaries in the United States. The Coast Guard is currently conducting a Waterways Assessment and Management Survey of the lower James River. This data will be used to assess if ATONs are correctly placed. Without recent hydrographic data, USCG lacks confidence that charted shoals are accurately positioned and is having a hard time producing a comprehensive report, and is thus looking forward to new data in the lower James River to update the latest surveys from 1945. This project will provide critical data for the updating of National Ocean Service (NOS) nautical charting products and services to increase maritime safety in the region. Survey data from this project is intended to supersede all prior survey data in the common area.The Navigable Area Limit Line (NALL) was met within the limits of H13298 in the southern region around the Nansemond River Channel (Figure 2). Some areas were not surveyed to the NALL because the conditions within those areas were deemed too dangerous for survey operations (Figures 3 and 4, Areas A, B, C, and D). An area of the assigned survey limits was not surveyed due to the restriction of survey operations within a security area around Newport News Shipbuilding (Figure 5, Area E). Some areas of the assigned survey limits were not addressed due to operational time constraints (Figures 6 and 7). SupportFiles\A.1_NallArea.pngArea where the NALL was met within the limits of H13298. 3.5m depth contour shown in black.SupportFiles\A.1_South_Danger_Areas.pngSurvey limits were not met in areas A and B due to proximity to the Monitor Merrimac Memorial Bridge Tunnel. SupportFiles\A.1_North_Danger_Areas.pngSurvey limits were not met in areas C and D due to proximity to hazardous features.SupportFiles\A.1_Security_Area.pngSurvey limits were not met in the security area surrounding Newport News Shipbuilding in Area E.SupportFiles\A.1_Time_Constraints_South.pngSurvey limits were not met in the south east section of H13298 due to operational time constraints.SupportFiles\A.1_Time_Constraints_North.pngSurvey limits were not met in the northern section of H13298 due to operational time constraints.36.92176.41237.05476.588Survey H13298 is located in the White Shoal are of the Chesapeake Bay, VA (Table 1 and Figure 1). SupportFiles\A.1_SurveyLimits_Overview.pngSurvey layout for H13298, plotted over ENC US5VA15M and UA5VA25M. Black outline represents the survey limits set forth by the Project Instructions. Object detection coverage for H13298 was accomplished using three methods. These three methods are 100% bathymetric bottom coverage, 200% side scan sonar (SSS) coverage with concurrent multibeam, and 200% SSS coverage with concurrent single beam. See section A.4 Survey Coverage, B.2.8 Coverage Equipment and Methods, and B.5.2 Surfaces for a complete discussion.The survey is partially adequate to supersede previous data.No Horizontal and Vertical Control Report (HVCR) is required for this survey.Mean Lower Low WaterOPR-E350-TJ-19_NAD83-MLLW_Geoid12BERS via VDATUMAll soundings submitted for H13327 are reduced to MLLW using VDatum techniques as outlined in the DAPR.HSLs 2903 and 2904 experienced losses of Primary DGPS mode in the POS/MV system on multiple days during survey acquisition. Below is a list of days on which this issue occurred and how many times losses were experienced. These losses were detected while reviewing the SBET's AutoQC graphs (Figure 47). All losses of Primary DGPS mode were less than one second in length and were correllated with losses of satellite coverage across both the primary and secondary GNSS receivers (Figure 48). The cause of this coverage loss is unknown. Neither MBES or SBES data quality appear to be affected by these brief drop outs. Below is a list of days on which this issue occurred and how many times losses were experienced. 2903 DN197- 2 losses 2903 DN198- 1 loss 2903 DN203- 2 losses 2903 DN210- 1 loss 2903 DN211- 3 losses 2903 DN212- 1 loss 2903 DN213- 2 losses 2903 DN214- 1 loss 2903 DN217- 5 losses (Figures 47 and 48) 2904 DN192- 4 losses 2904 DN211- 1 loss 2904 DN214- 2 losses 2904 DN216- 2 losses 2904 DN353- 1 lossLoss of Primary DGPS fix.SupportFiles\C.3_2903_217_1.pngLoss of Primary DGPS mode seen on HSL 2903 DN217.SupportFiles\C.3_2903_217_2.pngLoss of satellite coverage see on HSL 2903 DN217.Trimble-RTX service was used with an Applanix POS MVv5 GNSS-INS system to obtain highly accurate ellipsoidally referenced position data to meet ERS specifications for H13298 MBES and SBES data.North American Datum 1983The Wide Area Augmentation System (WAAS) was used for real-time horizontal control during data acquisition.Projected UTM 18OPR-E350-TJ-19NOAA Ship Thomas Jefferson (S222)Southern Chesapeake BaySouthern Chesapeake Bay, Virginia10000VirginiaH13298United States2White ShoalNOAA2019-07-05Navigable AreaUTCAtlantic Hydrographic Branch2019-12-212019-07-09CDR Briana Hillstrom, NOAASide Scan SonarMultibeam Echo Sounder BackscatterSinglebeam Echo Sounder Multibeam Echo Sounder2019Any 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 18N, MLLW. All references to other horizontal or vertical datums in this report are applicable to the processed hydrographic data provided by the field unit.metersThree platforms exist for this survey, but were not investigated.Shoreline was not assigned in the Project Instructions or Statement of Work.No abnormal seafloor and/or environmental conditions exist for this survey.The hydrographer recommends further investigation of charted underwater features and shoal areas not fully addressed by current MBES coverage.Overhead features exist for this survey, but were not investigated. There are two bridges and one overhead cable. 22 Aids to Navigation (ATONs) were investigated while conducting survey H13298. One ATON was found to be leaning and an ATON Discrepancy Report was submitted to the Coast Guard Navigation Center in accordance with HSSD requirements. Reference the Final Feature File and Appendix II for relevant ATON Discrepancy Report documents for further information. An image of the leaning Nansemond River Channel Light 2NR is included in the Final Feature File.No new insets are recommended for this area.A portion of the Monitor Merrimac Memorial Bridge Tunnel is contained within H13298. The area was covered with 100% object detection MBES coverage and is in agreement with the charted representation of the tunnel (Figure 56). SupportFiles\D.2_15M_MMMBT.pngMBES coverage of the Monitor Merrimac Memorial Bridge Tunnel within H13298.No ferry routes or terminals exist for this survey.No present or planned construction or dredging exist within the survey limits.There is one charted dangerous wreck with a status of "Existence Doubtful" within the limits of H13298 near Rocklanding Shoal Channel located at 37°03'13.75"N -076°34'48.76"W. The source of this feature is Chart 12248 with a source date of 19990828. The location was not covered by MBES or SBES and was only covered by 100% SSS coverage. Little evidence of a dangerous wreck can be seen in the SSS imagery (Figure 51), however, coverage is insufficient for disproval.SupportFiles\D.1_25M_ED_Wreck.pngCharted dangerous wreck near Rockland Shoal Channel.There are nine new obstruction features identified in the survey in addition to the two reported DTONs. Reference the Final Feature File for more information. Additionally, due to operational time constraints, many of the identified SSS contacts were not able to be further developed by MBES coverage (Figure 52). It is possible that some of these contacts could be charted as new features. See side scan contacts file for images and locations. SupportFiles\D.1_SSSContacts_NotDeveloped.pngSSS contacts not covered, or partially covered, by MBES.One DTON was found and reported on Aug. 7, 2019 for US5VA25M and appears on the most recent ENC edition (Figure 53). The danger was initially identified in both 100% SSS and 200% SSS and was further developed using object detection MBES. The least depth was found to be 2.8m with nearby soundings of 6.4-7m. A second DTON was reported on March 18, 2020 for US5VA15M (Figure 54). It was initially reported as a point obstruction but after further analysis, it is suggested that the feature be represented as an area obstruction. The obstruction area was initially identified in both 100% SSS and 200% SSS coverage and was further developed using object detection MBES. The least depth was found to be 3.4m with nearby soundings of 6.4-7.6m. Due to operational time constraints, the NALL was not met over most of the survey, so most charted shoals could not be addressed, particularly for ENC US5VA25M.SupportFiles\D.1_25M_DTON.pngDTON reported for chart US5VA25M.SupportFiles\D.1_15M_DTON.pngDTON reported for chart US5VA15M.Sounding sets derived from H13298's bathymetric surfaces generally agreed with soundings from ENC US5VA15M. However, there are two areas with soundings observed of approximately 1m up to 1.6m shoaler than charted soundings (Figures 49 and 50). One DTON was reported on March 18, 2020 (see Appendix II for relevant documents).SupportFiles\D.1_15M_Shoal_Area_1.pngArea of shoal soundings in the southern reaches of H13298. Charted soundings in black and SBES soundings in red.SupportFiles\D.1_15M_Shoal_Area_2.pngArea of shoal soundings in the mid-region of H13298. Charted soundings in black and SBES soundings in red.200002020-01-28false2020-02-2854US5VA15MSounding sets derived from H13298's bathymetric surfaces showed general deepening of US5VA25M particularly in the most northern region surrounding White Shoal. One DTON was identified and reported on Aug. 7, 2019 (see Appendix II for relevant documents).400002020-01-08false2020-02-1930US5VA25MChart comparisons were conducted between survey H13298 soundings and previously charted ENCs US5VA15M and US5VA25M using procedures outlined in the DAPR.No Maritime Boundary Points were assigned for this survey.A set of SBES soundings was compared to published controlling depths of the Rocklanding Shoal Channel and was found to be in agreement. A set of MBES soundings was compared to published controlling depths of the Channel to Newport News and was found to be in agreement. Bottom samples were assigned, investigated, and are included in the Final Feature File. See Figure 55 for a generalized view of H13298's bottom sample locations.SupportFiles\D.1_BS_Locations.png General location of bottom samples investigated within the sheet limits of H13298.Multibeam/single beam echo sounder/side scan sonar crosslines acquired for this survey totaled 1.89%* of mainscheme acquisition. *1.935% Hydrographic Survey Launch 2904 collected 11.04 linear nautical miles of MBES crosslines in the southern portion of H13298 (Figure 18) which accounted for 3.35% of mainscheme acquisition in this area. Additional crosslines over the northern portion of the survey area were not collected due to operational time constraints. A 50cm single resolution Combined Uncertainty and Bathymetry Estimator (CUBE) surface of mainscheme data and a 50cm single resolution CUBE surface of crossline data were differenced. The resulting mean was -0.01m and the standard deviation was 0.03m (Figure 20). Visual inspection and statistical analysis of the difference surface indicated no systematic issues. There were no crosslines acquired by the single beam echosounder. Agreement in observed depths between the MBES and SBES systems was evaluated by creating a 4m single resolution CUBE surface of SBES data and a 50cm single resolution CUBE surface of MBES data (including crosslines). See Figure 19 for a sample area where SBES coverage overlaps MBES coverage. The entire MBES surface was used in order to maximize the number of nodes being compared (10,242 nodes versus only 1,274 nodes when using only MBES crosslines). The two surfaces were differenced and the resulting mean was -0.02m and the standard deviation was 0.05m indicating acceptable agreement between the systems (Figure 21).SupportFiles\B.2_XLines_MBES_Overview.pngH13298 MBES crossline data, shown in color, overlaid on mainscheme MBES data, shown in greyscale.SupportFiles\B.2_MBES_SBES_Overview.pngExample area of SBES lines, shown in color, overlaid on mainscheme MBES data, shown in greyscale.SupportFiles\B.2_MBES_Xline_Stats.pngH13298 crossline/MBES mainscheme comparison statistics.SupportFiles\B.2_MBES_SBES_Stats.pngH13298 SBES/MBES comparison statistics.There are no existing surveys that junction with H13298 at this time. H13298 is located in a tidal river area that frequently exhibits stratification due to temperature and salinity differences. This layering greatly affects sound speed and results in refraction in the SSS imagery. The side scan towfish are hull-mounted on HSLs 2903 and 2904 and therefore cannot be lowered below the thermocline or halocline. Figures 29 and 30 show a representative area of refraction with associated profiles from a CTD cast. The CTD cast was conducted on Julian day number 190 at 1800 UTC and the section of side scan data started on Julian day number 190 at 1808 UTC. This area is located at 36°57'09.18"N 076°25'57.37"W. Areas of refraction were seen in the data from both vessels and on multiple days, particularly in the middle to northern extents of the survey. The refraction observed throughout the survey area was not severe enough to impede the detection of a 1m x 1m x 1m object. Figure 31 was taken from line 20190717174533H collected by HSL 2903 and shows a crab pot visible through an area of refraction. The crab pots encountered in the survey area were smaller than 1m x 1m x 1m. Refraction seen in SSS data.SupportFiles\B.2_Refraction_1.pngExample of refraction seen in SSS imagery. This example is from HSL 2904 line 20190709180922H and is located at 36°57'09.18"N 076°25'57.37"W. SupportFiles\B.2_CTD_Refrac_Location.pngOverview of location of SSS refraction and associated CTD profiles. A difference of 20m/s can be seen from the surface to 1m water depth. SupportFiles\B.2_RefracContact.pngCrab pot visible through area of refraction on line 20190717174533H from HSL 2903.Many large schools of fish were encountered in the middle to southern extents of H13298. Some schools were dense enough to create large acoustic shadows that obscured parts of the seafloor and potential contacts (see Figure 32 for an example). This data deficiency could obscure significant features or their shadows. Data for these areas were not re-acquired due to operational time constraints.Schools of fish obscuring the bottom. SupportFiles\B.2_Fish_Schools.pngExample of a shadow from a school of fish potentially obscuring a contact located at 36°58'22.37"N 076°26'21.18"W.A large barge was anchored at 36°56'23.45"N 076°25'43.60"W during survey operations. This created holidays in two side scan lines collected by HSL 2903 (20190710143835H and 20190714113252H) and can be seen in two additional lines (20190710152018H and 20190714120728H) (Figures 33 and 34). The presence of the barge may have obscured significant contacts in the area. Data for these holidays were not re-acquired due to operational time constraints.Anchored barge.SupportFiles\B.2_Barge_1.pngBarge seen in line 20190710152018H from HSL 2903.SupportFiles\B.2_Barge_2.pngBarge seen in line 20190714120728H from HSL 2903.H13298 covers a well-trafficked area and numerous small boats crossed in front of the launches while conducting survey operations. The turbulence from their propellers can be seen in the sidescan data (see Figure 35 for an example). Lines that contain this deficiency are listed below. This data deficiency could potentially obscure significant features. Data for these areas were not re-acquired due to operational time constraints. Lines containing incidents of propeller turbulence: HSL 2903: 20190709153041H 20190710121459H 20190710130605H 20190711132048H 20190711132554H 20190714122540H 20190715180649H 2903_DN210190729161800 2903_DN210190729131300 2903_DN210190729150800 2903_DN212190731141700 2903_DN212190731150400 2903_DN213190801153500 2903_DN213190801174900 2903_DN214190802135200 2903_DN214190802141200 HSL 2904: 20190710142440HPropeller turbulence seen in SSS data.SupportFiles\B.2_Wake_1.pngExample of propeller turbulence seen in sidescan data from 2903 line 20190709153041 located at 36°55'25.08"N 076°26'10.01"W.The launches encountered greater sea states on a few days of acquisition and motion (roll and yaw) artifacts can be seen in the lines listed below. See Figure 36 for a representative example. These motion artifacts can distort significant features. Data for these areas were not re-acquired due to operational time constraints. Lines with significant motion artifacts: HSL 2903: 20190709153041H 20190710164257H 20190710171338H 20190710180152H 20190711143618H 20190711150606H 20190722123540H 20190722130844H HSL 2904: 20190711134905H 20190711145734H 20190711155201HSea state/motion artifacts.SupportFiles\B.2_Motion_1.pngAn example of motion (roll and yaw) artifacts seen in SSS data from HSL 2904 line 20190711134905 located at 36°57'50.83"N 076°26'29.37"W.Sonar system quality control checks were conducted as detailed in the quality control section of the DAPR.HSL 2903 acquired 200% SSS data with concurrent SBES data to meet object detection coverage requirements per the waiver from the Project Manager. Additionally, HSL 2903 collected 100% MBES data over a portion of SSS holidays. SSS data was collected using an Edgetech 4200 system and a Klein 5000 system. SBES data was collected using an Odom CV200 and MBES data was collected using a Kongsberg EM2040. HSL 2904 acquired 200% SSS data with concurrent MBES data as well as 100% MBES data to meet object detection coverage. SSS data was collected using a Klein 5000 system and MBES data was collected using a Kongsberg EM2040. See section A.4 Survey Coverage Figures 8-12 for an overview of areas of coverage using these three methods. SupportFiles\B.2_CTD_Locations.pngOverview of all CTD casts taken on H13298. Casts for 2903 are in red and casts for 2904 are in blue.Sound speed profiles were acquired from HSL 2903 and 2904 in accordance with HSSD 2019 standards using a Sea-Bird Scientific SBE 19plus V2 Conductivity, Temperature, and Depth (CTD) Sensor. CTD casts were conducted from the launches at the beginning of acquisition and then within four hours of each previous cast. Sound speed was monitored by the survey watch to assess sound speed variation in the water column and conduct casts accordingly. MBES and SBES data were corrected by applying sound speed profiles nearest in distance within time (4 hours). All sound speed profile data were concatenated into a master file. A total of 51 sound speed measurements were collected within the survey limits of H13298 with two additional measurements collected outside the data extents (Figure 37). These outside measurements were collected within 500m of survey coverage as specified in the HSSD 2019. All casts provide data representative of the conditions found within the survey area and are appropriate for use.Beginning on Julian day number 192, an anomaly was noticed in the starboard channel of the Edgetech 4200 side scan data for HSL 2903 (Figure 24). This anomaly persisted on all lines collected with the system through Julian day number 198. The Edgetech was then removed and replaced with a Klein 5000 system. During the equipment swap, an area of the Edgetech cable was found chafed with inner wires exposed.Side scan cable chafe.SupportFiles\B.2_SSS_Cable_Chafe.pngExample of data anomaly caused by cable chafe outlined in blue box. At some point during Julian day numbers 193-194, the initialization file for the Edgetech 4200 side scan TPU was updated on both HSL 2903 and 2904. However, the compass settings were incorrect and resulted in the data for Julian day numbers 195, 196, 197, 198, and 203 having a reciprocal heading (180 degrees off true heading). The lines from these days were re-processed using the heading information from the vessels instead of the towfish that resulted in the heading data. The compass settings in the initialization files were corrected within the Edgetech TPU per manufacturer recommendation and data collected beginning on Julian day number 216 was processed using the compass information from the towfish. Backward SSS compass.The location of the side scan mount on HSL 2904 was found to interfere with the MBES swath. This can be seen as a "step" in the data in the outer swath on the starboard side for all lines collected on Julian day numbers 190, 191, and 192 (Figures 25 and 26). Swath Editor was used to filter beams 383-400 to exclude them from the surface. The starboard swath angle was adjusted to 45° for acquisition on Julian day numbers 197-216 so that the MBES swath would not interact with the side scan mount. The side scan mount was removed prior to data acquisition on Julian day numbers 353 and 355, therefore the starboard swath angle was adjusted back to 65°. Starboard MBES swath interacting with side scan mount. SupportFiles\B.2_SSS_Mount_1.pngExample of "step" seen in the outer starboard beams caused by MBES swath interacting with the side scan mount. Example is from line 0056_20190711_155136_2904_EM2040 as seen in Swath Editor.SupportFiles\B.2_SSS_Mount_2.pngExample of "step" seen in the outer starboard beams caused by MBES swath interacting with the side scan mount. Example is from line 0056_20190711_155136_2904_EM2040 as seen in Subset Editor.A subbottom return was observed in the near-nadir region of HSL 2904 MBES data (Figures 27 and 28). This return was present in all lines collected with 2904 and does not appear to affect the surface. Subset Editor was used to reject this data.MBES subbottom return near nadir.SupportFiles\B.2_MBES_Subbottom_Return_2.pngExample of subbottom return in near-nadir region of HSL 2904 MBES data as seen in Swath Editor. Example is from line 0056_20190711_155136_2904_EM2040.SupportFiles\B.2_MBES_Subbottom_Return_1.pngExample of subbottom return in near-nadir region of HSL 2904 MBES data as seen in Subset Editor. Example is from line 0056_20190711_155136_2904_EM2040.0.00ERS via VDATUM0.09040.2290340.22904The MBES and SBES bathymetric surfaces' uncertainty layer is compliant with HSSD 2019 uncertainty standards. Over 99.5% of all nodes pass uncertainty standards (Figures 22 and 23).SupportFiles\B.2_MB_VR_TVU.pngH13298 MBES surface uncertainty standards.SupportFiles\B.2_SB_4m_TVU.pngH13298 SBES surface uncertainty standards.Object Detection coverage requirements were met using three methods: 100% Object Detection MBES coverage, 200% Side Scan coverage with concurrent MBES, and 200% SSS coverage with concurrent SBES per the waiver from the Project Manager. The bathymetric grid for SBES data (H13298_SB_4m_MLLW) did not meet density requirements per the HSSD 2019 (Figure 44, 92% of nodes pass density requirements). Upon close inspection of the density layer of the grid, it was found that most of the nodes that fail are located at the beginning and end of lines where sounding density is low (Figure 45, failed nodes are colored red). There are also some failed nodes that occur in the middle of lines that is likely due to a combination of the density of soundings and the 4m gridding method (Figure 45, failed nodes are colored red). The bathymetric grid for MBES data (H13298_MB_VR_MLLW) meets density requirements per the HSSD 2019 (Figure 46).SupportFiles\B.5_SB_4m_density.pngH13298 SBES data density standards.SupportFiles\B.5_SBES_Failed_Nodes.pngExample of SBES nodes that did not meet density requirements.SupportFiles\B.5_MB_VR_density.pngH13298 MBES data density standards.Variable ResolutionNOAA_VRH13298_MB_VR_MLLW26.42.4CARIS VR Surface (CUBE)Object DetectionVariable ResolutionNOAA_VRH13298_MB_VR_MLLW_Final26.42.4CARIS VR Surface (CUBE)Object Detection4NOAA_4mH13298_SB_4m_MLLW17.9952.626CARIS Raster Surface (CUBE)Object Detection4NOAA_4mH13298_SB_4m_MLLW_Final17.9952.626CARIS Raster Surface (CUBE)Object Detection1N/AH13298_SSSAB_1m_600kHz_1of4SSS Mosaic100% SSS1N/AH13298_SSSAB_1m_600kHz_2of4SSS Mosaic200% SSS1N/AH13298_SSSAB_1m_455kHz_3of4SSS Mosaic100% SSS1N/AH13298_SSSAB_1m_455kHz_4of4SSS Mosaic200% SSS1N/AH13298_MBAB_1m_2903_300kHz_1of3MB Backscatter MosaicObject Detection1N/AH13298_MBAB_1m_2904_300kHz_2of3MB Backscatter MosaicObject Detection1N/AH13298_MBAB_1m_2904_400kHz_3of3MB Backscatter MosaicObject DetectionNOAA Profile Version 2019All equipment and survey methods were used as detailed in the DAPR. Multibeam echo sounder acoustic backscatter (MBAB) was logged as part of the .all file of the Kongsberg EM2040 systems. Backscatter was processed in QPS Fledermaus GeoCoder Toolbox (FMGT) software, and the exported geotiff's are included in the final processed data package (Figures 38, 39, and 40). There were five holidays identified in the area of 100% MBES coverage (Figure 41). As previously discussed in section B.2, the side scan mount also created interference in MBAB data that can be seen as dark lines on the starboard side of the swath (Figure 42). There are five anomolies in the MBAB data that were caused by blowouts in MBES coverage (Figure 43). SupportFiles\B.4_2903_300kHz_backscatter.pngHSL 2903's 300kHz multibeam acoustic backscatter at 1m resolution.SupportFiles\B.4_2904_300kHz_backscatter.pngHSL 2904's 300kHz multibeam acoustic backscatter at 1m resolution.SupportFiles\B.4_2904_400kHz_backscatter.pngHSL 2904's 400kHz multibeam acoustic backscatter at 1m resolution.SupportFiles\B.4_Backscatter_Holidays.pngBackscatter holidays in the area of 100% MBES coverage. SupportFiles\B.4_Backscatter_SSMount_Interference.pngExample area or MBAB showing dark lines on starboard side of MBAB swath created by interference from side scan mount. SupportFiles\B.4_Backscatter_Blowouts.pngMBAB anomolies caused by blowouts in MBES coverage. All data reduction procedures conform to those detailed in the DAPR.All sounding systems were calibrated as detailed in the DAPR.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.8.51.229038.51.22904Vessel configurations, equipment operations, data acquisition, and processing were consistent with specifications described in the DAPR.MBESEM 2040Kongsberg MaritimeSSS4200EdgeTechSSSSystem 5000Klein Marine SystemsPositioning and Attitude SystemPOS MV 320 v5ApplanixConductivity, Temperature, and Depth SensorSBE 19plus V2Sea-Bird ScientificLidar SystemVLP-16Velodyne LiDARSBESEchotrac CV200Teledyne Odom HydrographicSound Speed SystemSVP 70Teledyne RESONThe 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.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.CDR Briana W. Hillstrom2020-05-18Commanding OfficerLT Calandria DeCastro2020-05-18Operations OfficerJoshua Hiteshew2020-05-18Chief Hydrographic Survey TechnicianErin Cziraki2020-05-18Sheet Manager