OPR-O190-FA-15West Prince of WalesWest Prince of WalesNOAA Ship FAIRWEATHERH127433San Adrian Island to Diver Point AlaskaUnited States200002015CDR David J Zezula, NOAANavigable Area2015-03-022015-09-242015-11-08Multibeam Echo SounderMultibeam Echo Sounder BackscattermetersUniversal Transverse Mercator (UTM)UTC -8Pacific Hydrographic BranchNOAAThe survey area is located in West Prince of Wales, AK, within the sub-locality between San Adrian Island to Diver Point.55.3303688333133.30487911155.2147230556133.223442833H12743 Survey LimitsSupportFiles\Survey Limits.pngSurvey limits were acquired in accordance with the requirements in the Project Instructions and the 2014 Hydrographic Surveys Specifications and Deliverables (HSSD).The purpose of this project is to provide contemporary surveys to update National Ocean Service (NOS) nautical charting products. This area is considered navigationally significant.The entire survey is adequate to supersede previous data.Data acquired in H12743 meets multibeam echo sounder (MBES) coverage requirements for complete coverage, as required by the 2014 Hydrographic Surveys Specifications and Deliverables (HSSD). This includes NOAA allowable uncertainty (see Section B.2.2), density requirements (see Section B.2.9), and crosslines (see Section B.2.1). Inshore limit to 8 meters water depthEither complete MBES coverage with backscatter, or set line spacing SBES/MBES (100m spacing in restricted areas and around rocky points, 200m along open coasts)Greater than 8 meters water depthComplete MBES with backscatterThe entirety of H12743 was completed with complete MBES coverage with backscatter meeting the requirements listed above and in the HSSD, see Figure 2 for the survey outline. Some areas were not surveyed to the 4 meter inshore limit of hydrography as required by the Project Instructions due to the risk of maneuvering the survey vessel in the proximity of rocky and steep shoreline or surface debris. See Figure 3.H12743 Survey OutlineSupportFiles\Survey outline.pngH12743 Example of an area not acquired to the 4m Depth ContourSupportFiles\missed 4m curve.pngFA 28050131.010000000FA 2806018.660000016.210FA 2807048.850000000FA 2808080.490000000S22008.4900000000287.500000016.210012010010.572015-09-242015-09-262015-09-272015-09-282015-10-092015-10-112015-10-122015-10-132015-10-142015-10-202015-10-282015-11-042015-11-08Refer 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.S22070.44.728058.641.1228068.641.1228078.641.1228088.641.12KongsbergEM710MBESRESON7125MBESApplanixPOS/MV V4Positioning and Attitude SystemRolls RoyceMVP 200Conductivity, Temperature, and Depth SensorRESONSVP70Sound Speed SystemRESONSVP 71Sound Speed SystemSeaBirdSBE 19plusConductivity, Temperature, and Depth SensorCrosslines were collected, processed and compared in accordance with section 5.2.4.3 of the HSSD. All crosslines were filtered 45 degrees from nadir on the port and starboard sides with the exception of 2015X_2691843 whose outer beams are accepted to augment coverage and prevent a holiday (see Figure 4). To evaluate crosslines, an 8-meter CUBE surface using strictly mainscheme lines, and an 8-meter CUBE surface using strictly crosslines were created. From these two surfaces, a difference surface (mainscheme - crosslines = difference surface) was generated at an 8-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 0.12 meters (mainscheme being deeper/shoaler) with a 95% of nodes falling within 1.37 meters (Figure 6). For the respective depths, the difference surface was compared to the allowable NOAA accuracy standards (Figure 7). In total, 97% of the depth differences between H12743 mainscheme and crossline data are within allowable NOAA accuracies (Figure 8).H12743 Holiday Covered Using Crossline DataSupportFiles\Xline Holiday.pngH12743 Mainscheme and Crossline Difference SurfaceSupportFiles\Crossline Sep.pngH12743 Mainscheme and Crossline Difference StatisticsSupportFiles\H12743_Crossline Comparison 45 filter.pngH12743 Crossline Difference VS. Allowable NOAA Uncertainty SupportFiles\XL noaaness.pngH12743 Crossline Difference VS. Allowable NOAA Uncertainty StatisticsSupportFiles\Crossline diff NOAAness.png00.25TCARI00TCARI280520.5280620.5280720.5280820.5S22010.5In addition to the usual a priori estimates of uncertainty, some real-time and post-processed uncertainty sources were also incorporated into the depth estimates of survey H12743. Real-time uncertainties from both the EM710 and Reson 7125 data were recorded and applied in post-processing. Tidal uncertainties are calculated by the TCARI grid and are applied during post-processing. Applanix TrueHeave files are recorded on all survey vessels, which includes an estimate of the heave uncertainty, and are applied during post-processing. Finally, the post-processed uncertainties associated with vessel roll, pitch, gyro and navigation are applied in CARIS HIPS and SIPS via an SBET RMS file generated in POSPac.The areas of overlap between surveys were reviewed with CARIS HIPS and SIPS by surface differencing the 8 meter combined surface for H12742, H12744 and 16 meter combined surfaces for surveys H12292 to assess surface agreement. The junction agreement is generally within the total allowable vertical uncertainty in their common areas and depths for all surfaces. Data overlap between all surveys was achieved. See Figure 9 for all areas of overlap.Junction between H12743 and H12742, H12744, and H12292SupportFiles\Junction Surveys.pngH12292200002011NOAA Ship RAINIERNSurface differencing in CARIS HIPS and SIPS was used to assess junction agreement between the 8 meter combined surfaces from H12743 and the 16 meter combined surface from H12292. The statistical analysis of the difference surface shows a mean of -1.00 meters with 95% of all nodes having a maximum deviation of +/- 3.37 meters, as seen in Figure 11. A detailed graphical overview can be seen in Figure 10. In addition, a comparison surface was created between the difference surface and the allowable NOAA uncertainty (See Figures 12 and 13). It was found that 75% of nodes are within allowable NOAA uncertainty. The largest differences are located along steep inclines and rocky areas near shore and are most likely attributed to differences in tidal data and horizontal positioning.Junction Between H12743 and H12292SupportFiles\H12292 difference.pngDifference Statistics Between H12743 and H12292SupportFiles\H12743_H12292_Difference.pngJunction H12743/ H12292 VS. Allowable NOAA Uncertainty SurfaceSupportFiles\Junction12292 NOAAness graphic.pngJunction H12743/ H12292 VS. Allowable NOAA Uncertainty StatisticsSupportFiles\Junction12292 NOAAness.pngH12742200002015NOAA Ship FAIRWEATHERSSurface differencing in CARIS HIPS and SIPS was used to assess junction agreement between the 8 meter combined surfaces from H12743 and the 8 meter combined surface from H12742. The statistical analysis of the difference surface shows a mean of -0.08 meters with 95% of all nodes having a maximum deviation of +/- 2.48 meters, as seen in Figure 15. A detailed graphical overview can be seen in Figure 14. In addition, a comparison surface was created between the difference surface and the allowable NOAA uncertainty (See Figure 16). It was found that 92% of nodes are within allowable NOAA uncertainty. The largest differences are located along steep inclines. Junction H12743 and H12742 SupportFiles\H12742 Diff.pngDifference Statistics Between H12743 and H12742SupportFiles\H12743_H12742_Difference_Diff.pngJunction H12743/ H12742 VS. Allowable NOAA Uncertainty SurfaceSupportFiles\H12742 NOAAness.pngH12744200002015NOAA Ship FAIRWEATHERESurface differencing in CARIS HIPS and SIPS was used to assess junction agreement between the 8 meter combined surfaces from H12743 and the 8 meter combined surface from H12744. The statistical analysis of the difference surface shows a mean of 0.04 meters with 95% of all nodes have a maximum deviation of +/- 0.84 meters, as seen in Figure 18. A detailed graphical overview can be seen in Figure 17. The largest differences are located along rocky areas near shore and to the west of Meares Island. Given these statistics, the junction analysis between H12743 and H12744 shows as strong correlation. In addition, a comparison surface was created between the difference surface and the allowable NOAA uncertainty. It was found that 99% of nodes are within allowable NOAA uncertainty. The largest differences are located along steep inclines and rocky areas near shore and are most likely attributed to differences in tidal data and horizontal positioning.Junction Between H12743 and H12744SupportFiles\H12744 Difference.pngDifference Statistics Between H12743 and H12744SupportFiles\H12743_H12744_Difference.pngSonar system quality control checks were conducted as detailed in the quality control section of the DAPR.Operational Survey Depths Exceded for RESON 7125During survey acquisition on H12743, Launch 2805 ran north- south lines in the Ulloa Channel in the northern half of H12743. The depth in this area, reaching approximately 140 meters, would normally be acquired using the EM710 sonar on S220 but was not due to the confined space of this channel. These depths exceeded the capabilities of the RESON 7125 MBES aboard Launch 2805 while in the low frequency (200 kHz) mode. This caused excessive noise in the data, which resulted in the CUBE surface misrepresenting the seafloor (Figure 19). Where the noise was present the hydrographer rejected these spurious soundings in order to accurately reflect the true seafloor. The resulting cleaned data is sufficient to supersede charted data. H1273 Noise Rejected in Area Exceeding RESON 7125 (200 kHz) EffectivenessSupportFiles\Deep noise Ulloa.pngH12743 Area Exceeding RESON 7125 200khz EffectivenessSupportFiles\Deep noise area.pngSea Grass and KelpKelp and sea grass were present throughout the survey area and at times, indistinguishable from the seafloor. In areas where they were distinguishable, the soundings on the vegetation were rejected to enable more accurate representation of the true seafloor. In some areas, dense kelp and debris created and unsafe situation which halted acquisition. H12743 Example of Sea Grass in the Soundings. (5x vertical exaggeration) SupportFiles\Sea Grass3.pngH12743 Sheet Limit not met due to Kelp and DebrisSupportFiles\Area not covered due to kelp.pngSea StateDuring acquisition on survey H12743, the survey launches experienced periods of high sea-state due to weather causing excessive pitching and rolling. The result of the pitching were periods of blow-outs in the surface sound speed as air pockets passed under the transducer. Excessive quick rolls caused blow-outs due to launch attitude as the IMU attempted to keep up with the launch's movements. Because of the sea state, data acquired with Launch 2806 on day number 282 displayed excessive blowouts and beam spreading. To ensure higher data quality, on day number 293, Launch 2805 reacquired the areas covered by Launch 2806 on day number 282. All data lines for Launch 2806, day number 282 were rejected with exception of lines to cover holidays and to meet the required inshore limit. This Launch 2806, day number 282 accepted data meets HSSD requirements, and corroborates well with other launch data. H12743 Example of Reacquired and Cleaned Data From 2806 DN282 and 2805 DN293SupportFiles\DN 282 Corrected.pngH12743 Example of 2806 DN 282 Sea State EffectsSupportFiles\2806 roll artifact.pngH12743 Outter Beam Spreading 2806 DN 282SupportFiles\Outter Beam spreading.pngLaunch 2806, DN 282 contains data that exceeds allowable vertical error budgets for depth. Where this occurs, it does not meet HSSD requirements and does not corroborate well with other launch data. Data has been manually edited to remove the affected soundings which exceed total vertical error tolerances.Vertical OffsetOccasional offsets between survey lines are present in the data. Figures 26 and 27 below show one example of this type of offset north of Waterfall Resort. These offsets do not exceed 0.3 meters and meet HSSD specification This same offset occurs a few other times on DN 301 for multiple boats pointing to an issue with the tides as the cause. The hydrographer recommends survey data supersede charted soundings and contours. In high current areas such as Port Refugio and the southern half of Ulloa Channel, some dynamic draft offsets are present in the data. These offsets are small, usually less than 13 centimeters, and do not negatively impact the data in these areas. Due to the low speed of near shore surveying, these vertical offsets can be attributed to varying strong currents throughout the boat days.H12743 Graphical Overview of Vertical offset North of Waterfall Resort (8x vertical exaggeration)SupportFiles\offset waterfall area.pngH12743 Subset view Vertical Offset North of Waterfall ResortSupportFiles\offset waterfall.pngCasts were conducted at a minimum of at least one per every 4 hours during launch acquisition. Casts were conducted more often in areas where the input of freshwater had an effect on the speed of sound in the water column and when there was a change in surface sound velocity greater than two meters per second. MVP casts on S220 were conducted with one cast per line.All equipment and survey methods are detailed in the DAPR.IHO ComplianceUncertainty values of submitted finalized grids were calculated in CARIS HIPS and SIPS using the "Greater of the Two" of uncertainty and standard deviation (scaled to 95%). To visualize the locations in which accuracy requirements were met for each finalized surface, a custom predicted NOAA-compliance layer was created, based on the difference between calculated uncertainty of the nodes and the allowable NOAA uncertainty (Figure 28). To quantify the extent to which accuracy requirements were met, the preceding predicted NOAA compliance layers were queried within Pydro, which produced descriptive statistics for examination (Figures 30-33). Overall 99.95% of nodes of H12743 met the accuracy requirements stated in the HSSD.H12743 IHO Uncertainty Compliance OverviewSupportFiles\IHO Overview.pngH12743 IHO Uncertainty StatisticsSupportFiles\H12743 IHO uncertainty stats.pngH12743 1 Meter Surface IHO Uncertainty StatisticsSupportFiles\H12743_MB_1m_MLLW_Final_TVU_QC.pngH12743 2 Meter Surface IHO Uncertainty StatisticsSupportFiles\H12743_MB_2m_MLLW_final_TVU_QC.pngH12743 4 Meter Surface IHO Uncertainty StatisticsSupportFiles\H12743_MB_4m_MLLW_Final_TVU_QC.pngH12743 8 Meter Surface IHO Uncertainty StatisticsSupportFiles\H12743_MB_8m_MLLW_Final_TVU_QC.pngDensity ComplianceData acquired in H12743 exceeds the five soundings per node data density requirements in section 5.2.2.2 of the HSSD for complete coverage MBES with backscatter. In order to extract descriptive statistics of the data density achievements, the finalized surfaces were analyzed within Pydro and summarized into a table (Figure 35). Overall, the required data density was achieved in 99.6% of the nodes (Figure 34). The vast majority of 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.H12743 Density OverviewSupportFiles\Density overview.pngH12743 Density StatisticsSupportFiles\Density statistics.pngH12743 1 Meter Surface Density StatisticsSupportFiles\H12743_MB_1m_MLLW_Final_Density.pngH12743 2 Meter Surface Density StatisticsSupportFiles\H12743_MB_2m_MLLW_final_Density.pngH12743 4 Meter Surface Density StatisticsSupportFiles\H12743_MB_4m_MLLW_Final_Density.pngH12743 8 Meter Surface Density StatisticsSupportFiles\H12743_MB_8m_MLLW_Final_Density.pngHoliday AssessmentData gaps and holidays are present in H12743 due to the following factors: 1. Unsafe Navigation near Shoal and Foul Areas 2. Kelp 3. Acoustic Shadows in Rocky Areas or Areas of Steep Slope For information about data gaps due to foul and kelp areas, refer to section B.2.6: Sea Grass and Kelp. Figure 40 shows an overview on the west coast of H12743 where the least depth of a feature was unable to be attained due to safety ie. safe maneuverability of survey vessel. The least depths of features are represented by H12743, with the exception of the examples below in Figure 41. The tops of these rocks were not obtained either due to kelp, the lack of a high tide window, or both. Figure 42 shows an example of an acoustic shadow where the sonar beams went over the edge of a steep slope, but did not capture the face of the slope. These data gaps are not usually seen in the surface, but can be seen when using the subset editor in CARIS HIPS and SIPS.H12743 Graphical Overview of Holiday Due to Unsafe Navigation in Ulloa Channel.SupportFiles\Rock no depth.pngH12743 Graphical Overview of Holidays Due to Kelp and Shoal soundings in Meares PassSupportFiles\Rocks no depths.pngTypical Holiday as seen throughout H12743 due to Acoustic ShadowingSupportFiles\drop off holiday post extension.pngAll data reduction procedures conform to those detailed in the DAPR.All sounding systems were calibrated as detailed in the DAPR.Raw Backscatter was logged as .7k file for Reson 7125 data and logged as .all for the Kongsberg EM710. The data was submitted directly to NCEI (National Center for Environmental Information) to be archived, and to PHB where the data will be processed. One line per day of backscatter was processed in the field by the field unit for quality control. Backscatter was not collected on 2806 during DN 282 due to operator error.CarisHIPS/SIPS9.0NOAA Profile V_5_3_3H12743_MB_1m_MLLWCUBE1NOAA_1mComplete MBESH12743_MB_2m_MLLWCUBE2NOAA_2mComplete MBESH12743_MB_4m_MLLWCUBE4NOAA_4mComplete MBESH12743_MB_8m_MLLWCUBE8NOAA_8mComplete MBESH12743_MB_1m_MLLW_FinalCUBE1026NOAA_1mComplete MBESH12743_MB_2m_MLLW_FinalCUBE21852NOAA_2mComplete MBESH12743_MB_4m_MLLW_FinalCUBE436104NOAA_4mComplete MBESH12743_MB_8m_MLLW_FinalCUBE872320NOAA_8mComplete MBESH12743_MB_8m_CombinedCUBE8NOAA_8mComplete MBESThe NOAA CUBE parameters mandated in the HSSD dated May 2014 were used for the creation of all CUBE surfaces in Survey H12743. The 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 be shoaler or deeper than the reliably measured seabed by greater than the maximum allowable Total Vertical Uncertainty at that depth, the noisy data have been rejected and the surface recomputed. In order to prevent visual data gaps between the finalized surfaces, the 1, 2, 4, and 8 meter surface depths were extended for greater overlap between the surfaces. The surfaces and depth ranges are listed in Table 10. The 8 meter surface depth was extended to include 16 meter surface depth requirements as the area covered by the 16 meters surface was small. A waiver for the extension of depth ranges and no requirement to submit a 16 meter surface was granted from the Hydrographic Survey Division Operations Branch and is located in Appendix II. The 1, 2, and 4 meter finalized surface depth ranges were extended deeper by 6 times the surface resolution. To determine how much to expand the depth range by, the largest gap in coverage that could be found was measured in CARIS HIPS and SIPS subset editor. The distance of the gap was divided by the resolution of the surface that would cover the gap to determine how many multiples of that resolution it would take to cover that gap. This number was then multiplied by 2 to ensure that all gaps would be covered resulting in the extension of the surfaces by 6 times their resolution. All surfaces still meet the density and NOAA uncertainty requirements for their expanded ranges. The Flier Finder tool in Pydro Explorer was used to search for additional noise spikes after gross cleaning. Flier finder was performed several time on each surface each time reducing the flier height. Flier finder was useful with large flier heights, but as the height was reduced the effectiveness of the tool diminished. With smaller heights, flier finder began to flag steep drop offs and the edges of surfaces that occurred on slopes resulting in hundreds of false positives. At this point, the hydrographer determined that the remainder of the fliers found were false positives and no further flier cleaning was required.H12743 Example of Apparent Gap in CoverageSupportFiles\Surfaces don't meet.pngData LogsData acquisition and processing notes are included in the acquisition and processing logs, and additional processing such as final tide and sound velocity application is noted in the H12743 Data Log spreadsheet. All data logs are submitted digitally in the Separates I folder.Critical SoundingsDesignation of soundings followed procedures as outlined in section 5.2.1.2 of the HSSD. Survey H12743 contains 70 designated soundings. Four designated soundings are used to represent DTONs (see section D.1.6 for more information), and the other 66 designated soundings are used to accurately represent the sea-floor. Designated soundings were primarily found in rocky areas of the seafloor, especially north of Waterfall Resort.CARIS Automatic Beam DisablingDuring conversion of the EM710 data in CARIS HIPS and SIPS some soundings were rejected due to the disable beams settings in the Kongsberg EM710. See Figure 44 below where beam disabling was present due to the steep slope of the seafloor. Disabled beams were not re-accepted and there was no effect on the density in this area.H12743 Subset Showing Rejected Soundings due to Disabled BeamsSupportFiles\Beam disable Subset.pngInconsistent Number of HSX, 7k, RAW FilesBecause of numerous Hypack software crashes during acquisition on survey H12743 there are a number of days that have a contrasting number of data files between the .HSX and .7k file types. Additionally, 57 HDCS lines were removed from the project after conversion due to the poor data on day number 282 for Launch 2806. (See section B.2.6, "Sea State" above for more information.) Also on Launch 2806 day 282, snippets were not logged resulting in zero .7k files for that boat day. Refer to H12743_Data_Log, submitted in the H12743 Separates folder for detailed accounting of all data files. Additional information discussing the vertical or horizontal control for this survey can be found in the accompanying HVCR.Mean Lower Low WaterDiscrete ZoningTCARISitka, AK9451600Port Alexander, AK9451054Block Island, AK9450406O190FA2015_Final.tcFinalO190FA2015CORP.zdfPreliminary2016-01-252016-03-11The preliminary zoning was deemed to not be efficient to determine an accurate vertical uncertainty due to data gaps caused by faulty equipment at Block Island 9450406. A final Tidal Constituents and Residual Interpolation (TCARI) grid was issued in order to provide a better uncertainty value for OPR-O190-FA-15. Due to a sensor stability issue at Block Island, AK 9450406, the harmonic constituents and tidal datums from this station are not included in the TCARI solution.North American Datum of 1983 (NAD83)UTM Zone 8 NorthSingle Base9677WaterfallVessel kinematic data were post-processed using Applanix POSPac processing software with SingleBase positioning methods as described in the DAPR. Smooth Best Estimate of Trajectory (SBET) and associated error (RMS) data were applied to all MBES data in CARIS HIPS. For further details regarding the processing and quality control checks performed see the H12743 POSPAC Processing Logs spreadsheet located in the SBET folder with the GNSS data. See also the OPR-O190-FA-15 Horizontal and Vertical Control Report, submitted under separate cover.Gustavus, AK (288kHz)Annette Island, AK (323 kHz)Differential correctors from the U.S. Coast Guard beacon at Gustavus (288kHz) and Annette Island (323 kHz) were used during real-time, and were the sole method of positioning of detached positions (DP) and bottom samples..A comparison was performed between survey H12743 and chart 17407 as well as ENC chart US5AK4DM using CARIS HIPS and SIPS sounding and contour layers derived from the 8-m combined surface. The contours and soundings were overlaid on the chart to assess differences between the surveyed and charted data. All data from H12743 should supersede charted data. In general, there are large discrepancies between all charts and ENC and the survey derived soundings; significant updating of these charts will be necessary.17407272640000162014-122015-01-102014-12-30A majority of the surveyed soundings of H12743 agree with the charted soundings of chart 17407 within one or two fathoms. Discrepancies do occur, however, and are described below. In nearly every case, the survey derived soundings are shoaler where a discrepancy occurs. In the deep sections of H12743, particularly in Ulloa Channel, there are differences between the chart and the survey soundings between 5- 10 fathoms shoaler, see Figure 45 for an example. In shallower areas, such as north of Waterfall Resort or in Port Refugio, some survey found soundings can be found 3-6 fathoms shoaler than charted soundings (see Figure 46). The generated 5 and 10 fathom contours from the survey are generally further inshore compared to the charted 5 and 10 fathom contours. Additionally, the survey generated contours around ridges and rocky areas have changed significantly in some areas, see Figures 47 and 48 for examples. In the southern portion of Meares Pass, a 100 fathom contour has been included to show the extended depth range in this area. Disagreement Between Charted Depths (17407) and Surveyed Soundings East of San Adrian Island.SupportFiles\17407 San Adrian I soudings.pngDisagreement Between Charted depths (17407) and Surveyed Soundings in Port Refugio.SupportFiles\17407 Port Refugio soundings.pngDisagreement Between Charted Contours (17407) and Surveyed Contours near Ridge Island.SupportFiles\17407 Ridge is contours.pngDisagreement Between Charted Contours (17407) and Surveyed Contours near Bocas Point.SupportFiles\17407 refugio contour.pngUS5AK4DM4000012014-03-312014-12-17falseIn general, a majority of the surveyed soundings of H12743 agree with the charted soundings of ENC US5AK4DM within one to three fathoms except where described below. In the deeper sections of the survey, particularly in Ulloa Channel, there are several differences between charted and surveyed soundings ranging from 3 to 11 fathoms, see Figure 50 for an example. In shoaler areas of the survey, such as north of Waterfall Resort, the soundings agree within 5 fathoms, but are shoaler when there is a difference. Near the entrance of Port Refugio, there are several areas where the survey soundings are 10 fathoms or more deeper than charted (see Figure 49). The charted contours on US5AK4DM closely approximate that survey generated contours, usually within 100 meters. The boarder contours around rocky areas and ridges differ from the charted contours by up to 400 meters in some cases. This is most noticeable differences occur north of Waterfall Resort, near the entrance of Port Refugio, and the ridges west of Meares Island. A 100 fathom contour line was created to show the extended depth range in Meares Pass. (See Figures 51-53)Disagreement Between Charted Depths (US5AK4DM) and Surveyed Soundings near the Entrance of Port Refugio.SupportFiles\5AK Refugio Entrance.pngDisagreement Between Charted Depths (US5AK4DM) and Surveyed Soundings in the Southern area of Ulloa ChannelSupportFiles\5AK S Ulloa.pngDisagreement Between Charted Contours (US5AK4DM) and Surveyed Contours in Port RefugioSupportFiles\5AK refugio contours.pngDisagreement Between Charted Contours (US5AK4DM) and Surveyed Contours in Ulloa Channel.SupportFiles\5 AK Waterfall contours.pngDisagreement Between Charted Contours (US5AK4DM) and Surveyed Contours in Meares Pass.SupportFiles\5AK Meares Pass Contours.pngNo Maritime Boundary Points were assigned for this survey.All assigned features were addressed and are included in the H12743_Final_Feature_File. Survey H12743 has 18 new features that are addressed in the H12743_Final_Feature_File. Four of these features are the DTONs described in section D.1.6. Seventeen new uncharted piles and two new uncharted dolphins were found in the area of Waterfall Resort. One pile feature in the final feature file is described as the northern most pile in a row of eleven. These rows are immediately north of Waterfall Resort's southern most pier as charted (See Figure 54). An new obstruction was attributed north of Waterfall Resort where two cylindrical objects are submerged next to each other (See Figure 55). A new anchorage area was attributed in Port Refugio where locals suggest for anchoring and S220 confirmed to be good holding bottom. This new anchorage was also added to the H12743 Coast Pilot updates. Two weed/ kelp areas were attributed in the Survey H12743 in the northern reaches of Meares Pass. Also, a new rock feature was attributed in the southern end of Ulloa Channel south west of Pt San Antonio. More information can be found in the detached position forms located in Separates_ I Acquisition & Processing Logs or the Final Feature File.H12743 Uncharted Piles and Dolphins (highlighted) near Waterfall ResortSupportFiles\New piles.pngNew Obstructions North of Waterfall ResortSupportFiles\Waterfall obstructions.png1H12743 Danger to Navigation Report2015-11-10Four Dangers to Navigation were found within the limits of Survey H12743, and were all reported to the Marine Chart Division on 10 November 2015. These DTONs have been placed on the most recent version of the Chart 17407. The Danger to Navigation Reports are included in Appendix III of this report.H12743 DTON 1 Ridge IslandSupportFiles\DR image SRI.pngH12743 DTON 2 Meares PassSupportFiles\DR image SC2.pngH12743 DTON 3 Meares PassSupportFiles\DR image SC1.pngH12743 DTON 4 West Meares PassSupportFiles\DR image WMP.pngNo shoals or potentially hazardous features exist for this survey.No maintained 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.Twelve bottom samples were acquired in accordance with the Project Instructions for survey H12743. All bottom samples were entered in the H12743 Final Feature File.H12743 Bottom SamplesSupportFiles\Bottom_Samples.pngFAIRWEATHER personnel conducted limited shoreline verification and reconnaissance at times near predicted negative or low tides within the survey limits. Due to the lack of day time low tide windows while FAIRWEATHER was at the survey location, specific shore line acquisition and verification did not occur. Hydrographers were supplied with shore line specific boat sheets so that features could be confirmed to exist visually or lines could be run to develop submerged features at high tide by MBES. These boat sheets are located in the Separates I_Acquisition & Processing Logs folder. Annotations, information, and diagrams collected on DP forms and boat sheets during field operations are scanned and included in the digital Separates I_ Acquisition & Processing Logs folder.Prior survey comparisons exist for this survey, but were not investigated.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 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.CDR David J. Zezula, NOAAChief of Party2016-05-14LT Matthew Forney, NOAAField Operations Officer2016-05-14HCST Douglas BravoChief Survey Technician2016-05-14ENS Patrick Debroisse, NOAASheet Manager2016-05-14Data Acquisition and Processing Report2016-04-21Horizontal and Vertical Control Report2016-05-05Tides and Water Levels Package2015-11-20Coast Pilot Report2016-05-03