OPR-P183-RA-12Shumagin Islands, AKShumagin IslandsNOAA Ship RAINIERH124732 Vicinity of Simeonof HarborAlaskaUnited States400002012Richard T. Brennan, CDR/NOAANavigable Area2012-05-162012-08-122012-09-30Multibeam EchosoundermetersMean Lower Low WaterfathomsMean Lower Low WaterUniversal Transverse Mercator (UTM)UTCPacific Hydrographic BranchThe project area is referred to as Sheet 2: Vicinity of Simeonof Harbor within the project instructions. The area surveyed is in the waters west of Simeonof Island, the eastern-most island of the Shumigan Islands, approximately 48 nautical miles southeast of Sand Point, AK. 54.8208444444159.50663611154.8261694444159.294951H12473 survey limits.file:///K:/Projects/2012_Projects/OPR-P183-RA-12,%20Shumagin%20Is/Surveys/H12473/Descriptive_Report/Report_Body/Images_DR/H12473_coverage.jpgThis project was conducted in support of NOAA's Office of Coast Survey to provide contemporary hydrographic data in order to update the nautical charting products and reduce the survey backlog within the area. The need for nautical chart updates is due to an increasing number of passenger vessels, tour vessels and large fishing fleets in the area. In addition, the data would be used to create DTM maps in support of efficiencies in longline and pot fisheries, while minimizing habitat disruption. The entire survey is adequate to supersede previous data.Data acquired on survey H12473 met complete multibeam coverage requirements, including the 5 soundings per node data density requirements outlined in section 5.2.2.2 of the HSSDM, in 99.9% of the nodes. 2Survey H12473 data density.file:///K:/Projects/2012_Projects/OPR-P183-RA-12,%20Shumagin%20Is/Surveys/H12473/Descriptive_Report/Report_Body/Images_DR/H12473_Density_sheet.jpg3Summary table showing the percentage of nodes satisfying the 5 sounding density requirements, sub-divided by the appropriate depth ranges. Note: The final row has a unit of square meters, and sums the number of different resolution nodes into a common unit of area.file:///K:/Projects/2012_Projects/OPR-P183-RA-12,%20Shumagin%20Is/Surveys/H12473/Descriptive_Report/Report_Body/Images_DR/survey%20H12473%20Density%20Table.jpgSurvey Limits were acquired in accordance with the requirements in the Project Instructions and the HSSD.4Survey H12473 coverage.file:///K:/Projects/2012_Projects/OPR-P183-RA-12,%20Shumagin%20Is/Surveys/H12473/Descriptive_Report/Report_Body/Images_DR/H12473_Suvey%20Coverage.jpgComplete multibeam echo sounder (MBES) coverage was achieved within the limits of hydrography as defined in the Project Instructions with three exceptions. Three small areas due: to the shallow nature of the seafloor; thick bands of kelp; and safety concerns, a small area (measuring 175 by 575 meters) in the northeast section of the survey, and two areas in the central eastern section (measuring 250 by 135 meters and 130 by 50 meters). These areas were unsafe to approach and are represented in the H12473 Final Feature File. One holiday exists for survey H12473, located at 54-53-06.1N 159-27-10.5W and measures 80 by 40 meters in 40 meters of water. No navigationally significant items were found; additionally, the least depths were represented.5Survey H12473 coverage deficiencies.file:///K:/Projects/2012_Projects/OPR-P183-RA-12,%20Shumagin%20Is/Surveys/H12473/Descriptive_Report/Report_Body/Images_DR/H12473%20coverage%20deficient%20areas.jpg6Holiday located at 54-53-06.1N 159-27-10.5W in 40 meters of water, deemed non-navigationally significant.file:///K:/Projects/2012_Projects/OPR-P183-RA-12,%20Shumagin%20Is/Surveys/H12473/Descriptive_Report/Report_Body/Images_DR/H12473_3_Node%20Holiday.jpg2012-08-122012-08-282012-08-292012-09-092012-09-132012-09-152012-09-262012-09-292012-09-3060033.68S-2210325.100000002801080.900000002802059.200000002803031.600000002804094.00000028.800590.80000028.804.8Shoreline was investigated in accordance with the Project Instructions and the HSSDM.Six of the seven assigned bottom samples were collected for survey H12473 using a small traditional clamshell sampler and a small Ponar sampler. This sheet had no previously charted bottom characteristics. The common characteristic of the samples examined were sand and shells. Only one sample, #2, (Figure 7) failed to produce any measurable material to determine the bottom characteristics. All bottom samples have been included in H12473 Final Features.hob file.7Survey H12473 bottom sample locations.file:///K:/Projects/2012_Projects/OPR-P183-RA-12,%20Shumagin%20Is/Surveys/H12473/Descriptive_Report/Report_Body/Images_DR/H12473_Bottom%20Sample%20Locations.jpgRefer 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.S22123116.52801283.52802283.52803283.52804283.5ResonSeaBat 7125MBESApplanixPOS MV V4Positioning and Attitude SystemApplanixPOS MV V5Positioning and Attitude SystemReson SVP70Sound Speed SystemResonSVP71Sound Speed SystemKongsbergEM710MBESRolls Royce-Odim-Brooke OceanMoving Vessel Profiler 30Conductivity, Temperature and Depth SensorRolls Royce-Odim-Brooke OceanMoving Vessel Profiler 200Conductivity, Temperature and Depth SensorSeabird SBE 19 plusConductivity, Temperature and Depth SensorMultibeam echosounder crosslines totaled 28.79 nautical miles comprising 4.8% of the mainscheme MBES hydrography. Mainscheme bathymetry was visually compared to the crossline nadir beams in CARIS Subset Editor for consistency and agreement. In addition the Hydrographer created a 2-meter CUBE surface using strictly the mainscheme lines, and a second separate 2-meter CUBE surface using only crosslines. A difference surface was then generated in CARIS (Figure 8), and descriptive statistics were then compiled in excel. (Figure 9). The average difference between the depths derived from mainscheme and crosslines was -0.03 meters (mainscheme being deeper) with a standard deviation of 0.12 meters.8Survey H12473 crossline comparison at a 2-meter resolution surface, differences in meters.file:///K:/Projects/2012_Projects/OPR-P183-RA-12,%20Shumagin%20Is/Surveys/H12473/Descriptive_Report/Report_Body/Images_DR/mog_Crossline_surface.jpg9Survey H12473 crossline-to-mainscheme difference surface statistics in meters.file:///K:/Projects/2012_Projects/OPR-P183-RA-12,%20Shumagin%20Is/Surveys/H12473/Descriptive_Report/Report_Body/Images_DR/mog_Crossline_statistics.jpg10Vessels S221 & 2804 on survey H12473 comparing crossline and mainscheme bathymetry.file:///K:/Projects/2012_Projects/OPR-P183-RA-12,%20Shumagin%20Is/Surveys/H12473/Descriptive_Report/Report_Body/Images_DR/H12473%20cross-line%20comparison%20subset_new_no%20orange.jpg00.065S221110.05280130.15280230.15280330.152804330.15Uncertainty values of submitted, finalized grids were calculated in CARIS using the "Greater of the Two" of among total propagated uncertainty and standard deviation (scaled to 95%). To visualize the locations in which accuracy requirements were met for each finalized surface, a custom "IHOness" layer was created, based on the difference between calculated uncertainty of the nodes and the allowable IHO uncertainty (Figure 11). To quantify the extent to which accuracy requirements were met, the preceding "IHOness" layers were queried within CARIS and then analyzed in Excel. Overall, 100.0% of survey H12473 met the accuracy requirements stated in the HSSDM. Post-processed uncertainties of the survey vessels' position and attitude were produced using Applanix POSPac processing software (in addition to improved estimates of the position and attitude values themselves). For RAINIER (S221) only position uncertainties were applied, while the launches updated both position and attitude uncertainties.11Survey H12473 IHO uncertainty. Green nodes pass and red nodes fail IHO Order 1 compliance.file:///K:/Projects/2012_Projects/OPR-P183-RA-12,%20Shumagin%20Is/Surveys/H12473/Data_to_Submit_DO_NOT_USE/Processed/Multimedia/IHOness_Figure.png12Summary table showing the percentage of nodes satisfying the indicated IHO uncertainty level, sub-divided by the appropriate depth ranges.file:///K:/Projects/2012_Projects/OPR-P183-RA-12,%20Shumagin%20Is/Surveys/H12473/Data_to_Submit_DO_NOT_USE/Processed/Multimedia/IHOness_Table.pngThree junction comparisons were completed for survey H12473 (Figure 13). Two junctioning surveys (H12472, H12475) were acquired concurrently with this survey. The remaining junctioning survey, H12103, is a lidar survey completed in 2009 by Fugro LADS. Depth comparisons were performed using the CARIS difference surface (at the 4-meter resolution), from which descriptive statistics were generated. For the contemporary surveys, multibeam data was also examined in CARIS Subset Editor, along with the cursor Tool Tip for consistency and agreement.H12472400002012NOAA Ship RAINIERNSurvey H12472 was acquired concurrently with survey H12473 during project OPR-P183-RA-12. On average there is 150 meters of overlap between the two surveys which spans the entire length of the junction (Figure 14). Difference surface analysis showed depth differences averaging -0.09 meters, making survey H12473 shoaler, with a standard deviation of 0.15 meters (Figure 15). The junctioning overlap contained a rocky feature with significant relief which was used to compare the two surveys. The feature located at 54-55-17.410N 159-22.12.350W shows an agreement of soundings over the shoalest point with a difference of 0.01 meters (Figure 16). 13Survey H12473 junction locations.file:///K:/Projects/2012_Projects/OPR-P183-RA-12,%20Shumagin%20Is/Surveys/H12473/Descriptive_Report/Report_Body/Images_DR/Survey%20H12473_Junctions.jpg14Survey H12473 and junction H12472 difference surface in meters.file:///K:/Projects/2012_Projects/OPR-P183-RA-12,%20Shumagin%20Is/Surveys/H12473/Descriptive_Report/Report_Body/Images_DR/H12473_H12472_Junction_difference_new.jpg15Survey H12473 and junction H12472 difference surface statistics in meters.file:///K:/Projects/2012_Projects/OPR-P183-RA-12,%20Shumagin%20Is/Surveys/H12473/Descriptive_Report/Report_Body/Images_DR/H12473_H12472_Junction%20statistics.jpg16Survey H12473 and H12472 sounding comparison over feature contained in both.file:///K:/Projects/2012_Projects/OPR-P183-RA-12,%20Shumagin%20Is/Surveys/H12473/Descriptive_Report/Report_Body/Images_DR/H12473_H12472_junction%20feature%20comparison.jpgH12475400002012NOAA Ship RAINIERSESurvey H12475 was acquired concurrently with survey H12473 during project OPR-P183-RA-12. On average there is 120 meters width of overlap between the two surveys for a length of 400 meters (Figure 17 and 18). Depth differences in the areas of overlap averaged -0.04 meters, making survey H12473 shoaler, with a standard deviation of 0.49 meters (Figure 21). The junctioning overlap contained a rock feature located at 54-49-36.157N 159-17-27.892W showing an agreement of soundings over the shoalest point within 0.03 meters (Figure 20). 17Survey H12473 and H12475 junction location.file:///K:/Projects/2012_Projects/OPR-P183-RA-12,%20Shumagin%20Is/Surveys/H12473/Descriptive_Report/Report_Body/Images_DR/Survey%20H12473_H12475_junction%20location.jpg18Survey H12473 and junction H12475 difference surface comparison in meters.file:///K:/Projects/2012_Projects/OPR-P183-RA-12,%20Shumagin%20Is/Surveys/H12473/Descriptive_Report/Report_Body/Images_DR/H12473_12475_Junction_Surface_Difference_new.jpg19Survey H12473 and junction H12475 difference surface statistics in meters.file:///K:/Projects/2012_Projects/OPR-P183-RA-12,%20Shumagin%20Is/Surveys/H12473/Descriptive_Report/Report_Body/Images_DR/H12473_H12475_Junction%20_stats_graph.jpg20Survey H12473 and junction H12475 showing agreement within 0.03 meter over rock.file:///K:/Projects/2012_Projects/OPR-P183-RA-12,%20Shumagin%20Is/Surveys/H12473/Descriptive_Report/Report_Body/Images_DR/H12473_12475_Junction_feature.jpgH12103100002009Fugro LADSESurvey H12103 was a lidar survey completed in 2009 by Fugro LADS. The average distance of overlap, which varies widely throughout the length of the survey, is approximately 200 meters (Figure 21). In accordance with the H12103 Descriptive Report, the lidar shoal layer was used in the difference surface. Depth differences in the areas of overlap averaged -0.01 meters, making survey H12473 shoaler, with a standard deviation of 0.35 meters. (Figure 22). 21Survey H12473 and junction H12103 using the shoal layer difference surface in meters.file:///K:/Projects/2012_Projects/OPR-P183-RA-12,%20Shumagin%20Is/Surveys/H12473/Descriptive_Report/Report_Body/Images_DR/H12473_H12103_Junction_difference_new.jpg22Survey H12473 and junction H12103 difference surface statistics in meters.file:///K:/Projects/2012_Projects/OPR-P183-RA-12,%20Shumagin%20Is/Surveys/H12473/Descriptive_Report/Report_Body/Images_DR/H12473_H12103_Junction%20Statistics%20graph.jpgSonar system quality control checks were conducted as detailed in the quality control section of the DAPR.Kongsberg Data ArtifactDuring the 2012 Hydrographic Survey Readiness Review, an artifact was identified in bathymetric data acquired with the RAINIER's (S221) Kongsberg EM710. This heave-like artifact amplifies with vessel dynamics; in particular, as the magnitude of the ship's pitch and heave increases (e.g. in heavy weather), so too does the magnitude of the depth errors. Figure 23 shows an example not acquired on survey H12473, of an overhead view of two survey lines acquired in similar depths (~90 meters) on different days. On the left, data was acquired in a more dynamic regime (8 foot seas), while the right was acquired on a calmer day (4 foot seas) -- both lines are gridded at a 4-meter resolution with equivalent vertical exaggerations. The survey lines of Figure 23 are shown in CARIS Subset view in Figure 24. Figure 24 demonstrates the characteristic undulation of the nadir pings of the ship's system, when in heavy seas. By way of contrast, Figure 24 (bottom), acquired in a less dynamic environment, is nearly free of the artifact. While not a absolute rule, every 1-degree of vessel pitch leads to about 0.1 meters of vertical bias. Representatives from Kongsberg, Applanix and CARIS have been contacted with regard to this problem, and ship's personnel are actively investigating a remedy to this issue; however, at the time of this writing, the artifact still persists. Note that Figures 23 and 24 are not of data acquired during survey H12473, but serve as a pictorial representation. The artifact seen on survey H12473 had an error on a magnitude of approximately 0.05 meters. To mitigate problems associated with this artifact, ship's acquisition was only conducted in a sea state that was commensurate with minimizing vessel dynamics. It is in the opinion of the Hydrographer that all data is acquired by the kongsberg EM710 for survey H12473 is adequate to supersede the chart. 23Overhead view of two survey lines, acquired on different days, using the Rainier's Kongsberg EM710. Data acquired in heavier seas (left) displayed a characteristic undulation in the gridded sea floor, while calmer days (right) yielded a smoother representation of the bottom. file:///K:/Projects/2012_Projects/OPR-P183-RA-12,%20Shumagin%20Is/Surveys/H12473/Descriptive_Report/Report_Body/Images_DR/Kongsberg%20Artifact%201.jpg24Cross section view of data acquired using the Rainier's Kongsberg EM710, over a smooth sea floor, on both dynamic (top) and calm (bottom) sea states. Notice that with increased vessel dynamics, there is an increased artifact in the processed depths. file:///K:/Projects/2012_Projects/OPR-P183-RA-12,%20Shumagin%20Is/Surveys/H12473/Descriptive_Report/Report_Body/Images_DR/Kongsberg_artifact2.pngSound Speed ArtifactsSeveral sound speed casts collected by the ship were not applied to data because of anomalous salinity profiles (Figure 25). The conductivity cell ultimately failed entirely on DN273. Casts where the salinity was significantly less than the historic ranges were rejected. Even with the removal, the master concatenated SV file covers the survey area both temporally and spatially, (Figure 26). In areas where there was still a "slight smile or frown" in the sounding data, the Hydrographer rejected the outermost beams obviously in error in an attempt to best represent the seafloor via the CUBE surface. This technique eliminated many, but not every sound speed-related artifact (Figure 27).25H12473 representative inaccurate salinity profile.file:///K:/Projects/2012_Projects/OPR-P183-RA-12,%20Shumagin%20Is/Surveys/H12473/Descriptive_Report/Report_Body/Images_DR/H12473_salinity_outside_historic.jpg26Sound speed profile locations for survey H12473 depicting total profiles versus those submitted for survey compilation. file:///K:/Projects/2012_Projects/OPR-P183-RA-12,%20Shumagin%20Is/Surveys/H12473/Descriptive_Report/Report_Body/Images_DR/mog_update_SV_locations.jpg27 Example of sound speed artifact in survey H12473.file:///K:/Projects/2012_Projects/OPR-P183-RA-12,%20Shumagin%20Is/Surveys/H12473/Descriptive_Report/Report_Body/Images_DR/survey%20H12473%20Sound%20speed%20frowns.jpgApplication of SBET DataSmoothed Best Estimate Trajectory (SBET) and Root Mean Square (RMS) data were applied to all H12473 survey lines with the following exceptions: Vessel S221 DN257, Lines 0004 and 0040 did not load PPK data due to SBET time extents not overlapping with lines; Vessel 2804 DN225 lines 2804_2012RA2251925,2804_RA2251927, and 2804_2012RA2251954 lines did not load PPK data because it did not exist for these lines. Finally, Vessel 2803, Line 2803_2012RA2572349, did not load RMS data due to the extreme short length (2 meters) of the line. The affected data was examined in CARIS Subset Editor with no artifacts present among overlapping lines.Inconsistent Waterline Measurement for RAINIER on DN259On DN259, data acquired after 1700 UTC with the RAINIER's EM710 exhibited a vertical shift of ~0.25 meters (relative to both data acquired prior to 17:00 and crossline data from other vessels) (Figure 28). Prior to 1700, four survey launches were deployed necessitating a re-measurement of the RAINIER's waterline. The recorded waterline changed from -0.300 to -0.465 meters. A 0.16 meter change in the waterline is not unprecedented with the deployment of all the small boats; however, -0.465 meters is on the edge of the historic values. In light of the observed vertical shift in the data, it is possible that the ship was not stationary while the waterline was re-measured, causing a confounding of the waterline with the dynamic draft. As such, the measured waterline value, -0.465 meters, was replaced with the value measured three days prior (DN256 - with all four launches also deployed), -0.122 meters. With the updated waterline, the vertical offset was removed (Figure 29). All depth estimates meet the accuracy requirements set forth in the HSSDM. 28Cross section of multibeam data shown prior to adjusting the ship's irregular waterline measurement taken on DN259.file:///K:/Projects/2012_Projects/OPR-P183-RA-12,%20Shumagin%20Is/Surveys/H12473/Descriptive_Report/Report_Body/Images_DR/mog_waterline1.jpg29Cross section of multibeam data shown after adjusting the ship's waterline measurement taken on DN259 to match that of DN256.file:///K:/Projects/2012_Projects/OPR-P183-RA-12,%20Shumagin%20Is/Surveys/H12473/Descriptive_Report/Report_Body/Images_DR/mog_waterline2.jpgSound speed profiles were measured in accordance with the HSSDM 2012. On survey launches, casts were taken with a Seabird SBE19 plus, or the MVP 30 at least once every 4 hours while acquiring data. Sound speed profiles were acquired on RAINIER using the MVP 200 approximately every 15 minutes with efforts made to evenly distribute the casts throughout the survey area. All CTD and MVP casts were collected into one survey wide concatenated file and applied to multibeam data in CARIS using nearest in distance within a time of 4 hours. 30Distribution and Application of all sound speed profiles used in survey H12473. file:///K:/Projects/2012_Projects/OPR-P183-RA-12,%20Shumagin%20Is/Surveys/H12473/Descriptive_Report/Report_Body/Images_DR/H12473_Sound%20Velocity%20Applications.jpgAll equipment and survey methods were used as detailed in the DAPR.A Kongsberg Seapath 330+ positioning and attitude system was installed on RAINIER and integrated into the acquisition system on DN260 to troubleshoot the Kongsberg data artifacts discussed in section B.2.5.1 of this report. Because the SIS operating system recorded data from multiple sensors, converting the Kongsberg .ALL files in CARIS HIPS and SIPS on DN270, DN273 and DN274 for survey H12473 differs from the RAINIER 2012 DAPR. To convert the raw data files using only the Applanix POS M/V system, the appropriate positioning and attitude sources must be selected (Figure 31). The same vessel file (S221.Simrad-EM710.hvf) is used for all EM710 data acquired on survey H12473. 31Conversion settings for EM710 data acquired after DN260 on survey H12473 to utilize the Applanix POS M/V.file:///K:/Projects/2012_Projects/OPR-P183-RA-12,%20Shumagin%20Is/Surveys/H12473/Descriptive_Report/Report_Body/Images_DR/H12473_Applanix_Conversion.jpgAll sounding systems were calibrated as detailed in the DAPR.Backscatter data was acquired with all systems, but was not processed by RAINIER personnel. However, periodic spot checks were performed to ensure backscatter quality. Backscatter was logged as .ALL files (Kongsberg) or 7k files (Reson) and submitted to NGDC. NOAA Profile.There were no software configuration changes after the DAPR was submitted.H12473_1MCUBE1080NOAA_1mComplete MBESH12473_2MCUBE2080NOAA_2mComplete MBESH12473_4MCUBE4080NOAA_4mComplete MBESH12473_1M_FinalCUBE1020NOAA_1mComplete MBESH12473_2M_FinalCUBE21840NOAA_2mComplete MBESH12473_4M_FinalCUBE43680NOAA_4mComplete MBESH12473_Combined_finalizedCUBE4080NOAA_4mComplete MBESThe vertical datum for this project is Mean Lower Low Water (MLLW). The operating National Water Level Observation Network (NWLON) primary tide station in Sand Point, AK (9459450), served as control for datum determination and as a source for water level reducers for survey H12473. A complete description of the vertical and horizontal control for this survey can be found in the accompanying OPR-P183-RA-12 Horizontal and Vertical Control Report (HVCR), submitted under separate cover.Mean Lower Low WaterDiscrete ZoningSand Point, Alaska945-94509459450.tidFinal ApprovedP183RA2012CORP.zdfFinal2012-10-012012-10-18North American Datum of 1983 (NAD83)Single BaseIn conjunction with this project, a GPS base station was established by RAINIER personnel in the vicinity of Simeonof Harbor near the northwest end of Simeonof Island. Vessel kinematic data (POS files) were post-processed with Applanix POSPac and POSGNSS software using Single Base processing methods described in the DAPR. SBET and associated error (RMS) data was applied to all survey lines with the exception of those described in Section B.2.5.1 - Application of SBET Data. Further, in the case of S221, only GPS height and Navigation data were post-processed (real-time attitude was retained).Vessels 2802, 2804 and S221 acquired data on DN225 prior to base station installation. Precise Point Positioning (PPP) correction was applied to this data only.Cold Bay Alaska (289 kHz) Kodiak Alaska (313 kHz)The particular DGPS beacon used during this survey was variable. The USCG DGPS stations at Kodiak (313 kHz), and Cold Bay (289 kHz) Alaska were used for initial horizontal control depending on which provided the best signal reception at the time of acquisition. Refer to H12473 processing and acquisition logs for details. 165402528300000132010-102012-10-162012-10-27Chart comparison procedures were followed as outlined in section 4.5.1.2 of the FPM and section 8.1.4-D.1 of the HSSDM, utilizing CARIS HIPS and SIPS and CARIS Notebook. The majority of the area of survey H12473 was previously unsurveyed and devoid of charted depths or contours except for the northeastern section going into Simeonof Harbor. There are four soundings total charted within survey H12473. A charted 14-fathom sounding at 54-55-12 N 159-22-58W was found to be 6 fathoms deeper at the center of the charted sounding. An 11-fathom sounding located at 54-55-14N 159-20-57W was found to be deeper than depicted by more than 5 fathoms. A 7 1/2 fathom sounding charted at 54-51-24N 159-21-23W was found to be more than 15 fathoms deeper (Figure 32). A charted 30-fathom sounding at 54-49-36N 159-21-25W was found to agree well with the current survey H12473 within a half fathom. The Hydrographer recommends that survey H12473 supersede charted depths and positions. The 10-fathom contour on chart 16450 did not compare well with survey H12473. The current survey found depths exceeding ten fathoms throughout most of the charted ten fathom area. The hydrographer recommends using depths from survey H12473 and H12103 to define the ten fathom contour (Figure 32). 32Discrepancy between the charted (16450) 10 fathom contour and the surveyed depths of H12473.file:///K:/Projects/2012_Projects/OPR-P183-RA-12,%20Shumagin%20Is/Surveys/H12473/Descriptive_Report/Report_Body/Images_DR/H12473_10_fathom_tint_discrepency.jpgUS3AK50M300000172011-06-292011-06-29falseENC US3AK50M coincides with raster 16450. The depths and contours on the ENC match the raster, and the comparison between survey H12473 and the ENC is equivalent to the preceding comparison with Chart 16450.10One AWOIS item is located within the survey limits of H12473, which was charted as an obstruction with a position doubtful (PD). AWOIS feature #54096 was not located in its assigned search radius of 500 meters, (Figure 33). 33AWOIS item #54096, charted as a submerged rock, was not found within the assigned 500 meter search radius. A submerged feature was located approximately 1 kilometer northeast of charted feature. file:///K:/Projects/2012_Projects/OPR-P183-RA-12,%20Shumagin%20Is/Surveys/H12473/Descriptive_Report/Report_Body/Images_DR/H12473%20Awois%20item%2054096.jpg One obstruction with a position doubtful (PD) is located within the survey limits of H12473. Refer to section D.1.3 of this report.No uncharted features exist for this survey.No Danger to Navigation Reports were submitted for this survey.No shoals or potentially hazardous features exist for this survey.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.All assigned features with the exception of one lidar investigation feature (which was inshore of the NALL), were addressed as required with S-57 attribution and recorded in the H12473 Final Feature File to best represent the features at chart scale. As part of survey H12473, 2 features were specifically designated as lidar investigation items. (using BUAARE objects). For clarity, the BUAARE objects are maintained in a separate layer "H12473_Lidar_Investigations.hob" and submitted as reference.No prior survey comparisons exist for this survey.Aids to navigation (ATONs) do not exist for this survey.Overhead features do not exist for this survey.Submarine features do not 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.There is no present or planned construction or dredging 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 and Specifications Deliverables Manual, Field Procedures Manual, Standing and 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.Richard T. Brennan, CDR/NOAAChief of Party2013-03-27Michael O. Gonsalves, LT/NOAAField Operations Officer2013-03-27James B. JacobsonChief Survey Technician2013-03-27Todd A. WalshSheet Manager2013-03-27file:///K:/Projects/2012_Projects/OPR-P183-RA-12,%20Shumagin%20Is/Surveys/H12473/Descriptive_Report/Appendices/IV%20Tides_and_Water_Levels/Request%20for%20Final%20Approved%20Water%20Levels/H12473_tides_request.midfile:///K:/Projects/2012_Projects/OPR-P183-RA-12,%20Shumagin%20Is/Surveys/H12473/Descriptive_Report/Appendices/IV%20Tides_and_Water_Levels/Request%20for%20Final%20Approved%20Water%20Levels/H12473_tides_request.miffile:///K:/Projects/2012_Projects/OPR-P183-RA-12,%20Shumagin%20Is/Surveys/H12473/Descriptive_Report/Appendices/IV%20Tides_and_Water_Levels/Request%20for%20Final%20Approved%20Water%20Levels/H12473_tides_request.pdffile:///K:/Projects/2012_Projects/OPR-P183-RA-12,%20Shumagin%20Is/Surveys/H12473/Descriptive_Report/Appendices/IV%20Tides_and_Water_Levels/Request%20for%20Final%20Approved%20Water%20Levels/H12473_tides_request.zipfile:///H:/OPR-P183-RA-12_Shumagin/H12473/Acquisition_Logs/Copy%20of%20H12473_S221_Acquisition_Log%20(with%20DN270).xlsmfile:///H:/OPR-P183-RA-12_Shumagin/H12473/Acquisition_Logs/H12473_2801_Acquisition_Log.xlsmfile:///H:/OPR-P183-RA-12_Shumagin/H12473/Acquisition_Logs/H12473_2802_Acquisition_Log.xlsmfile:///H:/OPR-P183-RA-12_Shumagin/H12473/Acquisition_Logs/H12473_2803_Acquisition_Log.xlsmfile:///H:/OPR-P183-RA-12_Shumagin/H12473/Acquisition_Logs/H12473_2804_Acquisition_Log.xlsmfile:///H:/OPR-P183-RA-12_Shumagin/H12473/Acquisition_Logs/H12473_S221_Acquisition_Log.xlsmfile:///K:/Projects/2012_Projects/OPR-P183-RA-12,%20Shumagin%20Is/Surveys/H12473/Descriptive_Report/Separates/I_Acquisition_&_Processing_Logs/Detached_Positions/H12473%20boatsheets.pdffile:///I:/SVP/H12473/H12473.svpfile:///K:/Projects/2012_Projects/OPR-P183-RA-12,%20Shumagin%20Is/Project%20Instructions/Final_OPR-P183-RA-12_Shumigan_Islands_AK_%20Instructions.xmlfile:///K:/Projects/2012_Projects/OPR-P183-RA-12,%20Shumagin%20Is/Project%20Instructions/Final_OPR-P183-RA-12_ShumiganIslands_AK_Instructions.pdffile:///K:/Projects/2012_Projects/OPR-P183-RA-12,%20Shumagin%20Is/Project%20Instructions/Final_OPR-P183-RA-12_ShumiganIslandsAK_Instructions_revised_signed_MOCP_cdlWJB.pdf