OPR-P335-FA-16South Coast of Kodiak IslandSouth Coast of Kodiak IslandNOAA Ship FAIRWEATHERH129137Natalia BayAlaskaUnited States400002016CDR Mark Van Waes, NOAANavigable Area2016-04-212016-07-162016-07-31Multibeam Echo SounderMultibeam Echo Sounder BackscattermetersUniversal 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/.NOAAThis survey area is located along the South Coast of Kodiak Island, AK, within the sub-locality of Natalia Bay.57.0912218611153.49936616757.0041960556153.319651444H12913 sheet limits overlaid onto Chart 16592SupportFiles\H12913_Sheet_Limits.pngData were acquired to the survey limits in accordance with the requirements in the Project Instructions and the March 2016 NOS Hydrographic Surveys Specifications and Deliverables (HSSD) as shown in Figure 1. In all areas where the 4 meter depth contour or the sheet limits were not met, the Navigable Area Limit Line (NALL) was defined as the inshore limit of bathymetry due to the risks of maneuvering the survey vessel in close proximity to the steep and rocky shoreline (Figure 2), or kelp (Figure 3).Area where the NALL was redefined due to the presence of rocks SupportFiles\4m_Example.pngArea where the NALL was redefined to to the presence of kelpSupportFiles\H12913_4m_Kelp.pngThe purpose of this project is to provide contemporary surveys to update National Ocean Service (NOS) nautical charting products. This survey area addresses approximately 21 SNM of navigationally significant waters. This survey also supports seismic research for tsunami risk analysis by the United States Geological Survey (USGS) and Alaska Department of Fish and Game (ADF&G).This survey area addresses approximately 14 SNM, not 21 SNM as stated above.The entire survey is adequate to supersede previous data.Data acquired in H12913 meet multibeam echo sounder (MBES) coverage requirements for complete coverage, as required by the March 2016 Hydrographic Surveys Specifications and Deliverables (HSSD). This includes NOAA allowable uncertainty (see Section B. 2. 10), and density requirements (see Section B.2.11). Additional compliance statistics can be found in the Standards and Compliance Review located in Appendix II of this report. All waters in survey areaComplete Coverage accomplished using either: A) Complete coverage MBES depth and backscatter data, or B) 100% SSS coverage with concurrent set line spacing MBES depth and backscatter data. Refer to HSSD Section 5.2.2.2 The entirety of H12913 was acquired with complete MBES coverage with backscatter, meeting the requirements listed above and in the HSSD. See Figure 4 for an overview of coverage. H12913 Survey coverage (4m surface) overlaid onto Chart 16592SupportFiles\Coverage_Graphic.png2805029.9500000002806062.11000002.4202807068.84000001.7102808031.060000000S220042.0100000000233.96000004.1301.77200014.092016-07-162016-07-262016-07-31Refer to the OPR-P335-FA-16 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. 28058.641.1228068.641.1228078.641.1228088.641.12S22070.44.7KongsbergEM710MBESRESON7125MBESApplanixPOS/MV V4Positioning and Attitude SystemRolls RoyceMVP 200Conductivity, Temperature, and Depth SensorRESONSVP 70Sound Speed SystemRESONSVP 71Sound Speed SystemSeabird19plusConductivity, Temperature, and Depth SensorDue to equipment malfunction, Fairweather was forced to halt operations and leave the survey area before the acquisition of the required 4% of crosslines could be completed. The crosslines that were collected (1.77% of mainscheme acquisition) were processed and compared in accordance with Section 5.2.4.3 of the HSSD, and show an exceedingly high level of agreement with the mainscheme surface. To evaluate crosslines a 4 meter CUBE surface composed of strictly mainscheme lines and a 4 meter surface composed of strictly crosslines was created. From these two surfaces, a difference surface (mainscheme - crosslines = difference surface) was generated at a 4 meter resolution (Figure 5), and is submitted in the Separates II Digital Data folder. Statistics show the mean difference between the depths derived from mainscheme and crosslines was -0.06 meters (with mainscheme being shoaler) and 95% of nodes fall within 0.20 meters (Figure 6). For the respective depths, the difference surface was compared to the allowable NOAA accuracy standards (Figure 7). In total, 99.81% of the depth differences between H12913 mainscheme and crossline data were within allowable NOAA uncertainties (Figure 8). To assure the data acquired by S220 agreed with the data collected by the survey launches in areas not covered by crosslines, areas of overlap between the ship and survey launches 2806, 2807, and 2808 were assessed by creating a 4 meter surface composed of strictly launch data and a 4 meter surface composed of strictly ship data (Figure 9). Statistics show that the mean difference between depths derived from these surfaces was 0.05 meters (with S220 being deeper) and 95% of nodes fall within 0.35 meters (Figure 10). For the respective depths, the difference surface was compared to the allowable NOAA accuracy standards (Figure 11). In total, 99.89% of the depth differences between H12913 S220 and survey launch data were within allowable NOAA uncertainties (Figure 12). The high level agreement between this difference surface, as well as the difference surface generated between mainscheme and crosslines, suggests that there are no significant systematic errors or blunders in the surveying systems, and the accuracy and reliability of surveyed soundings and positions are adequately verified. See Figure 13 for a spatial overview of the difference surfaces discussed above. This analysis was submitted to the Project Manager, and a waiver of the 4% crossline requirement was granted by HSD OPS. See Appendix II for a record of this correspondence. Overview of H12913 crosslinesSupportFiles\H12913_Crossline_Comparison.pngH12913 crossline and mainscheme difference statistics SupportFiles\H12913_Crossline_Comparison_4m.pngDepth differences between H12913 mainscheme and crossline data as compared to NOAA allowable uncertainty standards for the associated depthsSupportFiles\H12913_crossline_NOAAness.pngCrossline surface statistics showing percentage of nodes meeting NOAA allowable uncertaintySupportFiles\H12913_Crossline_NOAA_Stats.pngDifference surface between S220 (in pink) and survey launches (in blue)SupportFiles\S220_Launch_overview.pngH12913 S220 and survey launch difference statisticsSupportFiles\H12913_S220_Launch_Difference.pngDepth differences between H12913 S220 and survey launch data as compared to NOAA allowable uncertainty standards for the associated depthsSupportFiles\H12913_Ship_Launch_NOAA.pngStatistics showing percentage of nodes meeting NOAA allowable uncertainty for the S220 and survey launch difference surfaceSupportFiles\S220_Launch_NOAA.pngH12913 spatial overview of crossline comparison with additional quality controlSupportFiles\Crosslines&Launch_Difference.png00TCARI00.02ERS via PMVD28052N/A0.528062N/A0.528072N/A0.528082N/A0.5S220N/A10.5In addition to the usual a priori estimates of uncertainty provided via device models for vessel motion and PMVD, real-time and post-processed uncertainty sources were incorporated into the depth estimates of survey H12913. Real-time uncertainties were provided via EM710 and Reson 7125 MBES data, Applanix Delayed Heave RMS, and TCARI tides. Following post-processing of vessel motion, real-time uncertainties of vessel roll, pitch, gyro and navigation were applied in CARIS HIPS and SIPS via a Smoothed Best Estimate of Trajectory (SBET) RMS file generated in Applanix POSPac.H12913 junctions with one adjacent survey from this project, H12911, and one survey from a prior project, H11338, as shown in Figure 14. Data overlap between H12913 and each junctioning survey was achieved. These areas of overlap were reviewed in CARIS HIPS and SIPS through surface differencing to assess surface agreement. The multibeam data were also examined in CARIS Subset Editor for consistency and agreement. The junctions with H12913 meet the NOAA allowable uncertainty in their areas of overlap. For all junctions with H12913, a negative difference indicates H12913 was shoaler and a positive difference indicates H12913 was deeper than the junctioning survey. Overview of H12913 junction surveysSupportFiles\H12913_junction_overview.pngH12911400002016NOAA Ship FAIRWEATHERSSurface differencing in CARIS HIPS and SIPS was used to assess junction agreement between H12913 and H12911. For comparison purposes, an 8 meter surface was generated for H12913 to match the resolution of the data provided from H12911. A detailed graphical overview can be seen in Figure 15. The statistical analysis of the difference surface shows a mean of -0.92 meters with 95% of all nodes having a maximum deviation of +/- 0.71 meters, as seen in Figure 16. In addition, a comparison surface was created between the difference surface and the NOAA allowable uncertainty (Figure 17). It was found that 100% of nodes are within NOAA allowable uncertainty (Figure 18). Difference surface between H12913 and H12911SupportFiles\H12913_H12911_junction_overview.pngDifference surface statistics between H12913 and H12911 (8 meter surface)SupportFiles\H12913_H12911_junction_stats.pngDifference surface compliance between H12913 and H12911 with regard to NOAA allowable uncertaintySupportFiles\H12913_H12911_NOAA.pngDifference surface statistics between H12913 and H12911 showing percentage of nodes meeting NOAA allowable uncertaintySupportFiles\H12913_H12911_NOAA_Stats.pngThe graphical output in Figure 16 above is from the difference surface compared to the NOAA allowable uncertainty, it does not describe the differences between the two surfaces. The difference surface statistics between H12913 and H12911 are shown below. The mean difference between the two surfaces is -0.03 meters with 95% of all nodes having a maximum deviation of +/-0.27 meters.Difference surface statistics between H12913 and H12911file:///M:/OPRP335FA16/Surveys/H12913/Compilation/Report/Final/SupportFiles/H12913_H12911_8m_Diff_Office.pngH11338100002004NOAA Ship RAINIERWSurface differencing in CARIS HIPS and SIPS was used to assess junction agreement between H12913 and H11338 (Figure 19). For comparison purposes, a 10 meter surface was generated for H12913 to match the resolution of the data provided from H11338. For gridding at the 10 meter node size, the CUBE parameters remained the same as the defined NOAA resolutions with the exception that "Capture_Distance_Min" was adjusted to be (1/sqrt(2)) * 10 m = 7.07 m, as this is the only parameter which changes among the standard resolutions. The statistical analysis of the difference surface shows a mean of -0.20 meters with 95% of all nodes having a maximum deviation of +/- 0.82 meters, as seen in Figure 20. In addition, a comparison surface was created between the difference surface and the NOAA allowable uncertainty (Figure 21). It was found that 99.84% of nodes are within NOAA allowable uncertainty (Figure 22). Difference surface between H12913 and H11338file:///M:/OPRP335FA16/Surveys/H12913/Compilation/Report/Final/SupportFiles/H12913_H11338_Diff_Office.pngDifference surface statistics between H12913 and H11338 (10 meter surface)SupportFiles\H12913_H11338_NOAA_Diff.pngDifference surface compliance between H12913 and H11338 with regard to NOAA allowable uncertaintySupportFiles\H12913_H11338_NOAA.pngDifference surface statistics between H12913 and H11338 showing percentage of nodes meeting NOAA allowable uncertaintySupportFiles\H12913_H11338_NOAA_Stats.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.Sea Grass and KelpKelp and sea grass were present throughout the survey area and at times, indistinguishable from the seafloor (Figure 23). In areas where they were distinguishable, the soundings on the vegetation were rejected to enable more accurate representation of the true seafloor. Where vegetation was indistinguishable all soundings were retained. Furthermore, in some areas patches of dense kelp prohibited safe navigation of the survey vessels. The limits of these areas were then used to define the NALL (Figure 24). Documentation can be found in the vessel boat sheets, which are located in the Separates I Digital Data folder. H12913 area where seagrass affected soundingsSupportFiles\H12913_Seagrass.pngH12913 area where kelp redefined the NALLSupportFiles\Kelp_NALL.pngSound SpeedThroughout the survey area of H12913 there are instances of minor vertical offsets that appear to be due to changes in sound speed. These offsets are found primarily in the southern portion of the survey, highlighted in Figure 25, and are generally due to the swath bending downwards, or "frowning." Examination in Subset Editor in CARIS HIPS and SIPS showed the magnitude of these offsets to be within the HSSD specifications for sound speed uncertainty for their respective depths, with a negligible impact on the Finalized CUBE surface. See Figure 26 for a graphical representation of sound speed influence.H12913 area of vertical offsets due to sound speed influence (10x vertical exaggeration)SupportFiles\H12913_Vertical_offset.pngH12913 subset of data "frowning" due to sound speed issuesSupportFiles\H12913_Frown.pngCasts were conducted at a minimum of one every four hours during launch acquisition. Casts were conducted more often in areas where the influx of freshwater had an effect on the speed of sound in the water column, and when there was a change in surface sound speed greater than two meters per second. MVP casts on S220 were conducted at an average interval of 32 minutes as recommended by Pydro's CastTime software, which determines optimum cast frequency based on the observed sound speed variations from previous casts. All sound speed methods were used as detailed in the DAPR. All equipment and survey methods were used as detailed in the DAPR.HolidaysH12913 data were reviewed in CARIS HIPS and SIPS for holidays in accordance with Section 5.2.2.3 of the HSSD. One holiday that meets the 3 by 3 node definition was identified via Pydro QC Tools Holiday Finder tool. This tool automatically scans finalized surfaces for holidays as defined in the HSSD, and was run in conjunction with a visual inspection of all surfaces by the Hydrographer. The holiday is due to acoustic shadowing from a rock in a downward sloping area as seen in Figure 27. This shadow is the result of a lack of coverage on the "back" side of the rock due to a rapid rise and successive drop in the sea floor in conjunction with poor geometry from the sonar head. The area was investigated in CARIS Subset Editor to verify that least depth was found (Figure 28). Although numerous apparent holidays were flagged by Holiday Finder, all others not previously addressed were examined and determined to be either outside of the sheet limits (Figure 29), or areas where an adjoining finalized surface covered the gap. An example of an apparent holiday in the 4 meter finalized surface due to the area being shoaler than the depth range for the 4 meter surface and therefore covered by the 2 meter finalized surface is shown in Figure 30.H12913 holiday due to acoustic shadowingSupportFiles\H12913_true_holiday.pngAcoustic shadow holiday viewed in CARIS HIPS and SIPS Subset EditorSupportFiles\H12913_Holdiay_Subset.pngH12913 apparent holiday outside of the sheet limitsSupportFiles\Holiday_past_sheet_limits.pngExample of an apparent holiday covered by an adjacent finalized surface SupportFiles\H12913_false_holiday.pngOne additional holiday exists in the 1-meter surface due to acoustic shadowing and is located on the northwest side of Natalia Bay.Holiday due to acoustic shadowing in Natalia Bayfile:///M:/OPRP335FA16/Surveys/H12913/Compilation/Report/Final/SupportFiles/Holiday_NataliaBay.pngNOAA Allowable UncertaintyTo verify that all data meet the accuracy specifications as stated in HSSD Section 5.1.3, a child layer titled "NOAA_Allowable_1" was created for each of the 1 meter, 2 meter, and 4 meter (36-100 meters) surfaces, and "NOAA_Allowable_2" for the 4 meter (100-170 meters) surface using the equations stated in Section C. 2.1 of the DAPR. These surfaces were then analyzed using the Pydro QC Tools Grid QA feature to determine what percentage of each surface meets specifications. Figure 31 shows an overview of the NOAA Allowable Uncertainty layers for all surfaces. Figure 32 shows the corresponding statistics for each individual surface. H12913 NOAA Allowable Uncertainty overviewSupportFiles\H12913_NOAA_Allowable_Uncertainty_Overview.pngH12913 NOAA Allowable Uncertainty StatisticsSupportFiles\H12913_NOAA_Allowable_Uncertainty_Stats.pngDensityFinalized surfaces were analyzed via the Pydro QC Tools Grid QA feature, and the results are shown in Figure 33 below. Density requirements for H12913 were achieved with at least 99.86% of finalized surface nodes containing five or more soundings as required by HSSD Section 5.2.2.3. The few nodes that did not meet density requirements are due to sparse data in the outer beams, especially near steep slopes and rocky areas where acoustic shadowing occurred, and at the edges of the survey limits as visualized in Figure 34. For individual graphs (per surface) of density requirements, see the Standards and Compliance Review located in Appendix II.H12913 density overviewSupportFiles\H12913_Density_Overview.pngH12913 density statisticsSupportFiles\H12913_Density_Stats.pngAll data reduction procedures conform to those detailed in the DAPR.All sounding systems were calibrated as detailed in the DAPR.Raw backscatter data were logged as .7k files for Reson 7125 data. The Kongsberg EM710 stores the backscatter data in the .all file. The data have been sent to the Pacific Hydrographic Branch for processing. One line per vessel per day of acquisition was processed by the field unit for quality control. Teledyne CARISHIPS and SIPS9.1QPSFledermaus FMGT7.5.3NOAA Extended Attribute Files version 5.4H12913_MB_1m_MLLWCUBE1NOAA_1mComplete MBESH12913_MB_2m_MLLWCUBE2NOAA_2mComplete MBESH12913_MB_4m_MLLWCUBE4NOAA_4mComplete MBESH12913_MB_1m_MLLW_FinalCUBE1020NOAA_1mComplete MBESH12913_MB_2m_MLLW_FinalCUBE21840NOAA_2mComplete MBESH12913_MB_4m_MLLW_FinalCUBE436170NOAA_4mComplete MBESThe NOAA CUBE parameters mandated in the HSSD dated May 2016 were used for the creation of all CUBE surfaces in Survey H12913, with the exception of the 4 meter surface. Examination of the data revealed that data density and quality supported the extension of the 4 meter surface to 170 meters, eliminating the necessity of the the creation of lower resolution surfaces for H12913. A waiver to extend the 4 meter surface depth range and not submit an 8 meter or 16 meter surface was granted by the Hydrographic Survey Division Operations Branch, and is located in Appendix II. All data within the extended 4 meter surface meet or exceed coverage requirements as defined by the HSSD, including density and NOAA allowable uncertainty. All surfaces have been reviewed where noisy data, or "fliers," are incorporated into the gridded solutions causing the surface to be shoaler or deeper than the true sea floor. Where these spurious soundings cause the gridded surface to vary from the reliably measured seabed by greater than the maximum allowable Total Vertical Uncertainty at that depth, the noisy data were rejected and the surface recomputed. Flier Finder v3, part of the QC Tools package within Pydro, was used to assist the search for spurious soundings following gross cleaning. Flier Finder was run multiple times for each surface, reducing the flier height value for each consecutive run. This allowed Flier Finder to accurately and quickly identify gross fliers, but as the flier height was reduced the effectiveness of the tool diminished. With smaller heights, Flier Finder began to incorrectly flag dynamic aspects of the seafloor such as steep drop offs and rocky areas as fliers resulting in hundreds of false positives. At this point, the hydrographer ceased using the tool and returned to manual cleaning for these dynamic regions of the seafloor. Data LogsData acquisition and processing notes are included in the acquisition and processing logs, and additional processing such as tide and sound speed application are noted in the H12913 Data Log spreadsheet. All data logs are submitted digitally in the Separates I folder. Designated SoundingsH12913 contains one designated sounding used to represent a DTON. See Section D.1.6 for more information.Additional information discussing the vertical or horizontal control for this survey can be found in the accompanying HVCR.Mean Lower Low WaterAlitak9457804Kodiak Island9457292Offshore Sitkalidak Island GPS Buoy945AAAAOffshore Geese Islands GPS Buoy945BBBBTCARI9457292.tidVerified Observed9457804.tidVerified ObservedP335FA2016_Verified.tcPreliminary2016-10-272016-12-02Initial reduction of acquired data to MLLW was accomplished via traditional tidal means using the Tidal Constituent and Residual Interpolation (TCARI) grid provided by HSD-OPS. Following the successful application of SBETs and computation of an Ellipsoidally Referenced Zone Tide (ERZT) separation model, ERS methods were used for reducing data to MLLW. As ERS methods were successful for the reduction to MLLW, final tides were not necessary for H12913. Processing was completed prior to receiving final tides, and therefore a waiver was obtained from HSD-OPS for the submission of H12913 without final tides applied. The correspondence has been included in Appendix II, accompanying this report. ERS via Poor Mans VDATUMP335FA2016_PMVD_UTM-NAD83-5N_WGS84-MLLW_CompositeERS methods were used as the final means of reducing H12913 to MLLW for submission. Data were initially reduced via traditional tidal means until an ERZT separation model could be calculated. This empirically derived model was then checked for consistency and compared to the Poor Man's VDatum (PMVD) separation model provided with the Project Instructions. The PMVD separation model was then vertically shifted such that the average difference between these two separation models is zero. This vertical shift de-biases the PMVD separation model, correcting for local offsets that cannot be effectively modeled by the PMVD. In areas where the PMVD model did not have sufficient coverage, such as near shore areas, the ERZT separation model was appended to the PMVD model to create the composite ERZT/PMVD separation model listed above and used to reduce H12913 to MLLW. For further information see the ERS Capability Memo, submitted under separate cover. World Geodetic System of 1984 (WGS84)UTM Zone 5 NorthSingle BaseAC34Old HarborVessel kinematic data were post-processed using Applanix POSPac processing software and Single Base Position methods described in the DAPR. Smoothed Best Estimate of Trajectory (SBET) and associated error (RMS) data were applied to all MBES data in CARIS HIPS and SIPS. For further details regarding the processing and quality control checks performed, see the H12913 POSPac Processing Logs spreadsheet located in the Separates folder. See also the OPR-P335-FA-16 Horizontal and Vertical Control Report (HVCR), submitted under separate cover. Hydrographic Technical Directive (HTD) 2016-3, which revises the horizontal datum requirement to NAD83, was released prior to acquisition for OPR-P335-FA-16. The field unit conferred with HSD-OPS and a waiver was received to maintain WGS84 as the datum for submission. This correspondence has been included in Appendix II.Kodiak, AK (313kHz)Differential correctors from the US Coast Guard beacon at Kodiak (313 kHz) were used in real-time for acquisition when not otherwise noted in the acquisition logs, and were the sole method of positioning of detached positions (DP) and bottom samples. A comparison was performed between survey H12913 and Chart 16592, as well as ENC US4AK5NM, using CARIS HIPS and SIPS sounding and contour layers derived from the 4 meter combined surface. The contours and soundings were overlaid on the charts to assess differences between the surveyed soundings and charted depths. ENCs were compared to a 4 meter combined grid by extracting all soundings from the chart and creating an interpolated TIN surface which could be differenced with the combined surface from H12913. All data from H12913 should supersede charted data. In general, surveyed soundings agree with the majority of charted depths. A full discussion of the disagreements follows below. 16592255080728112014-072016-09-102016-02-20The charted soundings and contours of Chart 16592 are identical to those found on ENC US4AK5NM. As such, all discussions regarding comparisons between surveyed soundings and charted depths are covered under the ENC US4AK5NM discussion below. US4AK5NM80728102016-08-192016-08-19falseSoundings from H12913 are in general agreement with charted depths on ENC US4AK5NM, with most depths agreeing within 2 fathoms as shown in Figure 35. To more accurately visualize trends within these differences, a 4 meter TIN surface was interpolated from the ENC sounding layer. This surface was then differenced with a corresponding 4 meter combined surface from H12913, and is visualized in Figure 36. In this difference surface red colors indicate H12913 was shoaler than the ENC US4AK5NM, green colors indicate agreement, and blue colors indicate H12913 was deeper than ENC US4AK5NM. The area of largest variation is the northern portion of the survey, where the sounding spacing of the prior surveys was insufficient to capture depth variations due to limitations of the TIN creation algorithm. Soundings were visually inspected with an average difference between 1 and 2 fathoms. Contours from H12913 are in general agreement with charted contours on ENC US4AK5NM, with a tendency of being inshore of the charted contours, as shown in Figure 37. The largest discrepancy is found in the southeast portion of H12913, where the surveyed 5 fathom contour extends around an area that has been designated as a new kelp area (Figure 38). The Hydrographer recommends the addition of 20 fathom and 30 fathom contours to the chart in an effort to provide necessary detail to the mariner where the deeper areas within H12913 begin to shoal (Figure 39).Overview of H12913 generated soundings in white overlaid onto ENC US4AK5NM, with ENC depths shown in blackSupportFiles\H12913_Soundings.pngDifference surface between H12913 and interpolated TIN surface from US4AK5NMSupportFiles\H12913_ENC_Comparison.pngOverview of H12913 contoursSupportFiles\H12913_Contours.pngContour discrepancy in southeast portion of H12913SupportFiles\H12913_Contour_Discrepency.pngProposed addition of 20 fathom and 30 fathom contoursSupportFiles\Proposed_Added_Contours.pngNo Maritime Boundary Points were assigned for this survey.No charted features exist for this survey.H12913 has 5 new features that are included in the H12913 Final Feature File. Of these features, there are 2 new Seabed Areas, 1 new Underwater Rock that is submitted as a DTON, and 2 new Kelp area features.1H12913 Danger to Navigation Report2016-08-05One Danger to Navigation Report, with one identified danger was submitted on 08/05/2016. The danger is a rocky protrusion from the seafloor with a least depth of 0.98 fathoms in the area of a charted 3.25 fathom sounding, located west of Natalia Peninsula (Figure 40). The DTON Report is included in Appendix II of this report.Overview of DTON found west of Natalia Peninsula in H12913SupportFiles\H12913_DTON.pngThe DTON was submitted with a data gap at/near the shoal point, resulting in failure to reliably capture the least depth of the rock. Rock should be charted with an depth of 'Unknown' and not 0.98fm as stated above. A red lined DTON Report is appended. No shoals or potentially hazardous features exist for this survey other than those addressed in the Dangers to Navigation section above.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.Two bottom samples were acquired in accordance with the Project Instructions for survey H12913. Both bottom samples were entered in the H12913 Final Feature File. See Figure 41 for a graphical overview of sample locations.H12913 Bottom sample locationsSupportFiles\H12913_Bottom_Samples.pngH12913 survey limits extended to the NALL (see Section A.1) and all features within these limits were addressed and attributed in the H12913 Final Feature File. All features inshore of the NALL were attributed in the Final Feature File with the description of “Not Addressed” and remarks of “Retain as charted, not investigated due to being inshore of NALL” as per HSSD Section 7.3.1. Annotations, information, and diagrams collected on DP forms and boat sheets during field operations are scanned and included in the Separates I Detached Positions folder.No prior survey comparisons were assigned for this survey.No Aids to navigation (ATONs) exist for this survey.No overhead features exist for this survey.No submarine features exist for this survey.No ferry routes or terminals exist for this survey.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.No 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, except as noted in this Descriptive Report. These data are adequate to supersede charted data in their common areas. This survey is complete and no additional work is required unless otherwise noted herein.CDR Mark Van Waes, NOAAChief of Party2016-11-28LT Bart Buesseler, NOAAField Operations Officer2016-11-23HCST Douglas BravoChief Survey Technician2016-11-23HST Sam CandioSheet Manager2016-11-23Data Acquisition and Processing Report2016-11-08Horizontal and Vertical Control Report2016-11-14Coast Pilot Report2016-11-10