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.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.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.2015-10-29Ellipsoidally Referenced Survey Capability Memo2015-11-23H12750_Additional_DTONs_22015-07-23H12750_Additional_DTONs2015-05-31H12750_DTONs2015-05-26Final Tides RequestCommanding Officer, NOAA Ship RAINIEREdward J. Van Den Ameele, CDR/NOAA2016-02-29Field Operations Officer, NOAA Ship RAINIERAdam Pfundt, LT/NOAA2016-02-29Chief Survey Technician, NOAA Ship RAINIERJames B. Jacobson2016-02-29Junior Officer, NOAA Ship RAINIERCalandria M. DeCastro, ENS/NOAA2016-02-29Data were acquired within survey limits set forth by the Project Instructions and the HSSD.The survey area is referred to as Sheet 1: "Security Bay" within the Project Instructions. The area encompasses approximately 12.3 square nautical miles of Security Bay, Frederick Sound, and Chatham Strait.Overlay of H12750 sheet limits (blue) and the acquired survey coverage (red) on Chart 17320. Multibeam coverage did not reach the survey limits due to the unnavigable nature of shoreline areas.SupportFiles\overview.jpg56.9349805556134.45435277856.8065134.287666667H12750 depth-colored MBES coverage overlay on Chart 17320SupportFiles\coverage.jpg28010015.66000000280200235.071.3000000280400164.2325.210000000414.9526.5106.3900002015-05-022015-05-032015-05-042015-05-052015-05-062015-05-132015-05-192015-05-202015-05-212015-05-222015-05-232015-05-242015-05-25123012.319Data acquired on survey H12750 met complete multibeam echosounder (MBES) coverage requirements outlined in Section 5.2.2.2 of the HSSD, including data density requirements. Overall, the required data density was achieved in 99.97% of nodes. This was determined using the Pydro Finalized CSAR Surface Density Tool. Density statistics for H12750SupportFiles\Density_Pydro_A.pngThe entire survey is adequate to supersede previous data.The purpose of this project is to provide contemporary surveys to update National Ocean Service (NOS) nautical charting products. Vessels such as cruise liners, ferries, USCG cutters, US Navy vessels, tugs, and barges use the waterway on a regular basis as do larger ships when avoiding storms in the Gulf of Alaska.Complete multibeam echosounder (MBES) coverage was achieved within the limits of hydrography as specified in the Project Instructions with the following exceptions: Survey coverage did not meet the sheet limits along many portions near the shoreline and islets; these areas were considered unnavigable due to fouling with kelp and rocks (Figure 4). These areas are delineated and attributed in the Final Feature File. Additional Holidays: Five small holidays resulting from inadequate line spacing exist in H12750 survey coverage. An overview of these holidays is shown in Figures 5-9. The largest holiday measures approximately 4 x 12 meters. All holidays were examined to ensure that no navigationally significant features were evident in the surrounding data.Overlay of H12750 sheet limits (blue) and the acquired survey coverage (red) on Chart 17320. Multibeam coverage did not reach the survey limits due to the unnavigable nature of shoreline areas.SupportFiles\coverage_1.jpgHoliday in survey coverage measures approximately 4 x 12 meters.SupportFiles\holiday_1.jpgHoliday in survey coverage measures approximately 4 x 11 meters.SupportFiles\holiday_3.jpgHoliday in survey coverage measures approximately 3 x 8 meters.SupportFiles\holiday_4.jpgHoliday in survey coverage measures approximately 3 x 8 meters.SupportFiles\holiday_2.jpgHoliday in survey coverage measures approximately 3 x 3 meters.SupportFiles\holiday_5.jpgChatham StraitChatham Strait, AKOPR-O322-RA-15NOAA Ship RainierNOAAMultibeam Echo SounderMultibeam Echo Sounder BackscattermetersThe 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 Envitronmental Information (NCEI) and can be retrieved via http://www.ncei.noaa.gov/.Edward J. Van Den Ameele, CDR/NOAA2015-04-132015Navigable AreaPacific Hydrographic BranchUTC2015-05-022015-05-25Universal Transverse Mercator (UTM)1Security BayH1275020000AlaskaUnited StatesAdditional information discussing the vertical or horizontal control for this survey can be found in the accompanying HVCR.Mean Lower Low Water9451054Port AlexanderThe Project Instructions required referencing survey data to the ellipsoid using Ellipsoid Referenced Zoned Tides (ERZT). ERZT was not utilized in reducing delivered data due to the need to use SmartBase for creating some SBETS and the eventual vertical offsets introduced by application of GPS tides in CARIS HIPS and SIPS. See the associated ERZT Capability Memo with recommendation and reasoning for reduction to MLLW using TCARI grid approved as final. 2015-05-262015-06-05FinalO322RA2015Final Approved9451054The Tide Note is attached.TCARIBiorka Island, AK- 305 kHzGustavus, AK- 288 kHzUniversal Transverse Mercator (UTM) Zone 08 NorthVessel kinematic data (POS files) were post-processed with Applanix POSPac and POSGNSS software using Smart Base and Single Base processing methods described in the DAPR. SBET and RMS data were applied to all survey lines. Due to equipment malfunctions, Single Base data were not available for all days, and some data created significant vertical offsets in the multibeam data. Therefore, Smart Base was used as a secondary means for creating SBET and RMS files. Single Base data were used for the following boat days: 2802_126, 2802_141, 2804_122, and 2804_144. The remaining boat days were processed using Smart Base data.Smart BaseSingle BaseKLAWOCKAIRAK2005AB49PETERSBURGAK2005AB51Level Island 6LEV6PORTALEXANAK2005AB48Biroka Island 5BIS5MENDENHALLAK2005AB50GUSTAVUS 6GUS6CAPESPMCEAK2007AB43LEVEL ISLAND 5LEV5JUNEAU WAAS 1JNU1GUSTAVUS 5GUS5SKAGWAYUSCAK2005AB44BIORKA ISLAND 6BIS6Barnacle Rock1066Carroll's Sister9715North American Datum of 1983 (NAD83)The reported 10-fathom shoaling near Kingsmill Point on Chart 17320 was investigated and disproved through inspection of multibeam data (Figure 21). The reported shoaling and obstructions near the junction of Frederick Sound and Saginaw Bay on Chart 17368_5 were investigated and confirmed through inspection of multibeam data (Figure 22).Soundings disprove reported shoaling on Chart 17320.SupportFiles\contour_discrepancy4.jpgSoundings confirm reported shoaling and obstructions on Chart 17368_5.SupportFiles\chartcomp1.jpg All shoal and hazardous features were investigated in accordance with the Project Instructions and the HSSD, and are addressed in the Final Feature File. Several new features were found during shoreline verification. The new features were addressed as required with S-57 attribution and recorded in the H12750 Final Feature File.Chart comparisons were performed using a Caris sounding and contour layer based on the 16-meter combined CUBE surface. The contours and soundings were overlaid on the charts and compared for general agreement and to identify areas of significant change.Overview of derived contours over Chart 17320. Note: The chart has been darkened to enhanced the visibility of soundings and contours.SupportFiles\derived_contours.jpgThe contour legend in Figure 16 has incorrect depth labels. The correct depth labels for each color are shown below. Corrected contour legend for Figure 16.file:///M:/OPRO322RA15/Surveys/H12750/Compilation/Working/SAR/Images/DR_Figure16.pngIn total, 14 DTONs were identified and submitted. Danger to Navigation Reports are included in Appendix II of this report.142015-05-31H12750_DTONs2015-07-23H12750_Additional_DTONs2015-11-23H12750_Additional_DTONs_2Twelve proposed bottom sample locations were identified in the Project Reference File. Collection of samples were attempted at all of the proposed sites; of the 12 locations, 3 locations yielded no sample after 3 unsuccessful attempts. Acquired bottom samples are addressed with S-57 attribution and recorded in the Final Feature File submitted with this report.One maritime boundary feature was assigned for investigation by this survey. The investigation of this feature disproved its existence. Another feature NW of Round Island was investigated as a maritime boundary and is attributed as such in the Final Feature File.The comparison of soundings and contours from Chart 17320 and H12750 showed general agreement. Shoreward of the 10-fathom contour, most soundings showed general agreement within 2 fathoms, with most exceptions being deeper than charted. Seaward of the 10-fathom contour, most soundings showed general agreement within 3 fathoms.173202015-08-181912015-08-222178282013-11The comparison of soundings and contours from Chart 17368_1 and H12750 showed general agreement within 1 fathom.173682015-08-18812015-08-22400002014-09In several areas surveyed soundings were significantly shoaler (up to 15 fathoms) than charted soundings.The comparison of soundings and contours from Chart 17368_5 and H12750 showed significant differences. Shoreward of the 10-fathom contour, many soundings show discrepancies greater than 3 fathoms. Seaward of the 10-fathom contour, about half of the soundings show discrepancies greater than 3 fathoms, with differences as large as 19 fathoms shoaler than charted. Multibeam data disproves the 3-fathom contour crossing Security Bay between Christmas Island and Cedar Island (Figure 17). Other areas of considerable disagreement are depicted below (Figure 18-20).173682015-08-18852015-08-22400002014-09Soundings disprove charted 3 fathom contour crossing Security Bay on Chart 17368_5.SupportFiles\contour_discrepancy1.jpgConsiderable differences between charted contours and derived contours highlighted on Chart 17368_5.SupportFiles\contour_discrepancy3.jpgConsiderable differences between charted contours and derived contours highlighted on Chart 17368_5.SupportFiles\contour_discrepancy2.jpgSoundings considerably shoaler than charted highlighted on Chart 17368_5.SupportFiles\soundings_1.jpgFigure 17: The charted contour crossing Security Bay between Christmas Island and Cedar Island is a 10 fm contour, not a 3 fm contour. Figure 17-19: Corrections to legend, green lines represent 10 fm contours and blue lines represent 50 fm contours. 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 ferry routes or terminals exist for this survey.No significant features exist for this survey which have not been addressed elsewhere in this report.Shoreline verification was conducted near predicted low water in accordance with the applicable sections of the NOAA HSSDM and FPM. There were 164 assigned features for this survey. All features were addressed as required with S-57 attribution and recorded in the H12750 Final Features File to best represent the features at chart scale.No new insets are recommended for this area.No new surveys or further investigations are recommended for this area.No overhead features exist for this survey.No submarine features exist for this survey.No present or planned construction or dredging exist within the survey limits.No platforms exist for this survey.No comparisons with prior surveys were conducted.Two aids to navigation (ATON) were present in the survey area, Kingsmill Point Light and Roadstead Island Light. Both were noted in the Final Feature File and serve their intended purpose.All sounding systems were calibrated as detailed in the DAPR.All data reduction procedures conform to those detailed in the DAPR.POS-MV V4Positioning and Attitude SystemApplanixSBE 19 and 19plus SEACAT ProfilerConductivity, Temperature, and Depth SensorSea-Bird ElectronicsSeaBat 7125-BMBESResonSeaBat 7125 SV2MBESResonSVP71Sound Speed SystemResonRefer 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.28048.81.128028.81.128018.81.119065.80.319055.80.3NOAA Profile V_5_0CUBEH12750_MB_1m_MLLW1Complete MBESNOAA_1m278.2-1.7CUBEH12750_MB_2m_MLLW2Complete MBESNOAA_2m278.2-1.7CUBEH12750_MB_4m_MLLW4Complete MBESNOAA_4m278.2-1.4CUBEH12750_MB_8m_MLLW8Complete MBESNOAA_8m278.2-1.3CUBEH12750_MB_16m_MLLW16Complete MBESNOAA_16m277.8-1.3CUBEH12750_MB_1m_MLLW_Final1Complete MBESNOAA_1m20-2CUBEH12750_MB_2m_MLLW_Final2Complete MBESNOAA_2m4012CUBEH12750_MB_4m_MLLW_Final4Complete MBESNOAA_4m8026CUBEH12750_MB_8m_MLLW_Final8Complete MBESNOAA_8m16072CUBEH12750_MB_16m_MLLW_Final16Complete MBESNOAA_16m320144Using typical depths for gridding resolutions would result in holidays between layers as parts of this survey were very dynamic with steeply sloping bottom. Per section 5.2.2.1 Object Detection Coverage of the HSSD, the shoaler extent of the coarser resolution grid should be modified to prevent this coverage gap. Designated Soundings were determined based on criteria set forth in Section 5.2.1.2 of the HSSD.Multibeam crosslines were acquired using the Reson 7125 sonars on Launches 2802 (RA-5) and 2804 (RA-6). A 4m CUBE surface was created using only mainscheme lines, a second 4m CUBE surface was created using only crosslines, and a difference surface was generated in Caris at a 4m resolution. This difference surface was compared to the allowable uncertainty values within the HSSD for the observed depths, and statistics were calculated in Excel. In total, 99.26% of the depth differences between H12750 mainscheme and crossline data are within the requirements of the HSSD. Crossline HSSD compliance analysis for H12750SupportFiles\Crossline_Statistics.pngH12750 Crossline HSSD ComplianceSupportFiles\crossline_HSSD.jpgSonar system quality control checks were conducted as detailed in the quality control section of the DAPR.Sound speed profiles were collected, processed, and applied as described in the DAPR.All launch sound speed profiles were acquired using SBE 19Plus V2 SEACAT Profiler CTD probes at discrete locations within the survey area at least once every four hours, when significant changes in surface sound speed were observed, or when surveying a new area. A sheet-wide concatenated sound speed file was created and applied to survey lines using the "Nearest in distance within time (4 hours)" profile selection method.Two junction comparisons were completed for H12750 at MLLW (Figure 13). H12536 and H12537 were completed by NOAA Ship Rainier in 2013. Depth comparisons were performed by creating Caris difference surfaces. For the junction of H12750 and H12536, the 4m finalized surfaces for each survey were used for the comparison. For the junction of H12750 and H12537, the 16m finalized surfaces for each survey were used.Overview of junctions with survey H12750SupportFiles\junction_overview.jpgOverlap with survey H12536 was approximately 200 to 600 meters wide, covering an area of 0.12 square nautical miles along the southwestern boundary of H12750. Depths in the junction area range from approximately 0 to 421 meters. For respective depths, the difference surface was compared to the allowable uncertainty values within the HSSD for the observed depths, and statistics were calculated in Excel. In total, 99.92% of the depth differences between H12750 and junction survey H12536 are within allowable uncertainties.HSSD compliance analysis for junction of H12750 and H12536SupportFiles\H12536_statistics.pngFigure 14 shows the correct percentages of nodes satisfying allowable depth differences. NOAA Ship RAINIERSW5000H125362013Overlap with survey H12537 was approximately 70 to 300 meters wide, covering an area of 0.79 square nautical miles along the western boundary of H12750. Depths in the junction area range from approximately 132 to 731 meters. For respective depths, the difference surface was compared to the allowable uncertainty values within the HSSD for the observed depths, and statistics were calculated in Excel. In total, 99.65% of the depth differences between H12750 and junction survey H12537 are within allowable uncertainties.HSSD compliance analysis for junction of H12750 and H12537SupportFiles\H12537_statistics.pngFigure 15 shows the correct percentage of nodes satisfying allowable depth differences. NOAA Ship RAINIERW40000H125372013There were no other factors that affected corrections to soundings.None ExistAll equipment and survey methods were used as detailed in the DAPR.There were no conditions or deficiencies that affected equipment operational effectiveness.None ExistUncertainty values were measured and applied in accordance with Section B.4 of the DAPR. Total Propagated Uncertainty (TPU) values for survey H12750 were derived from a combination of fixed values for equipment and vessel characteristics, as well as field assigned values for sound speed uncertainties. Tidal uncertainties were provided by NOAA's Center for Operational Oceanographic Products and Service (COOPS), and were applied to depth soundings using a Tidal Constituent and Residual Interpolation (TCARI) grid. TCARI automatically calculates the uncertainty associated with water level interpolation, which is then written into the Caris HDCS. For this reason, no tidal uncertainty values were entered into the Tide Value section of the Caris Compute TPE function. Uncertainty values of submitted finalized grids were calculated in Caris using the “Greater of the Two” of uncertainty and standard deviation (scaled to 95%). To visualize where uncertainty requirements were met, for each surface a custom “HSSD Compliance” layer was created, based on the difference between the calculated uncertainty of the nodes and the allowable uncertainty defined in the HSSD. To quantify the extent to which requirements were met, the HSSD Compliance layers were queried within Caris and examined in Excel. Overall, 99.99% of the nodes of survey H12750 met the uncertainty requirements specified in the HSSD. These HSSD Compliance layers were retained in the submitted surfaces. Additionally, the surfaces were analyzed using the Pydro Finalized CSAR Surface IHO Compliance tool, achieving similar results.IHO compliance to uncertainty standards as calculated using Pydro Finalized CSAR Surface toolSupportFiles\HSSD_Pydro.png28040.153.028020.153.028010.153.0Raw backscatter was logged as a 7k file and has been submitted to NCEI. Backscatter was not processed by the field unit but was periodically examined (one line per vessel per day).