OPR-B370-NRT5-13Eastern Long Island SoundNorth Shore of Long Island SoundNavigation Response Team 5H125081Saybrook Outer Bar to Salt Works BayConnecticutUnited States100002013Andrew Clos LTJGNavigable Area2013-05-162013-07-302014-05-29Multibeam Echo SounderSide Scan SonarMultibeam 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. Notes in red were generated during office processing. The processing branch concurs with all information and recommendations in the DR unless otherwise noted. Page numbering may be interrupted or non-sequential. All pertinent records for this survey, including the Descriptive Report, are archived at the National Geophysical Data Center (NGDC) and can be retrieved via http://www.ngdc.noaa.gov/.NOAAThe survey extends from Saybrook Outer Bar to Saltworks Bay, and to just south of Long Sand Shoal. In addition, as part of a Dton investigation, the entire length of Long Sand Shoal was developed out to the 30 ft contour on the western end, and the 18 ft contour on the eastern end.41.273063027872.476704861141.217182916772.3187357778Area Surveyedfile:///M:/OPRB370NRT512/Surveys/H12508/Compilation/Report/Components/Figure1%20-%20Area%20Surveyed.pngDuring data acquisition it was discovered that Long Sand Shoal had shifted significantly from what was depicted on the chart. In some places depths had changed by over 30 ft. Long Sand Shoal extends past both the west and east limits of the survey sheet. The entire shoal was developed, and submitted as a Dton.This project is being 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. In addition, data from this project will support the Long Island Sound Seafloor Mapping Initiative in New York and Connecticut.The entire survey is adequate to supersede previous data.The portions of Long Sand shoal lying outside the sheet boundaries were developed as part of a Dton investigation. Because of the shallow depth, and large extent of the shoal, it was not practical to develop the shoal to Object Detection Standards. MBES lines were run perpendicular to the shoal to develop the general locations of the contours. The line spacing chosen by the hydrographer was felt to be adequate to delineate the hazards of the shoal for the purpose of the Dton report, but was not intended to meet any HSSD coverage specification. Inside the sheet boundaries, the planned 200% SSS with concurrent MBES lines were acquired over part of the shoal, however, in some areas it was felt unsafe to proceed further with the towfish, so there are some gaps in coverage within the survey limits.Coverage Graphicfile:///M:/OPRB370NRT512/Surveys/H12508/Compilation/Report/Components/Figure2%20-%20Coverage.pngS300200000433.23027.79000000433.23027.7906.42110009.872013-07-302013-07-312013-08-052013-08-062013-08-122013-08-132013-08-192013-08-212013-08-282013-09-032013-09-042013-09-092013-09-162013-09-182013-09-202013-11-202014-05-29382.95 LNM of Mainscheme MS MBES/SSS Combo, 33.82 LNM of MBES/SBES Crosslines and 137.31 LNM of Mainscheme MBES (developments) were calculated during office processing. Crosslines totaled 8.8% of mainscheme.Refer to the Data Acquisition and Processing Report (DAPR) for a complete description of data acquisition and processing systems, survey vessels, quality control procedures and data processing methods. Additional information to supplement sounding and survey data, and any deviations from the DAPR are discussed in the following sections.S3002301S3002file:///M:/OPRB370NRT512/Surveys/H12508/Compilation/Report/Components/Figure3%20-%20S3002.pngApplanixPos MV v4Positioning and Attitude SystemTrimbleDSM 212Positioning SystemKongsbergEM3002MBESEdgetech4125SSSDigibarDigibar ProSound Speed SystemSeabird19 PlusConductivity, Temperature, and Depth Sensor27.8 nautical miles of crosslines were acquired, which amounts to 6.4% of mainscheme mileage. The 8% required for set line spacing was not achieved because the crosslines were planned based on the planned mainscheme lines. During the course of the survey, however, many miles of developments were acquired which caused the percentage to fall below the target of 8%. Overall, the mainscheme/crossline agreement is good, however, there are some intersections that have a noticeable vertical shift. The crossline/mainscheme agreement was evaluated by creating a base surface using mainscheme lines only. A Caris QC report was then generated, comparing the crossline data to the reference surface. Beam-by-beam statistics were computed. The standard deviation of the crosslines beams with respect to the mainscheme reference surface shows the expected curve, with standard deviation increasing as the beams move away from nadir. The standard deviations indicate that the sounding TVU fall well within IHO Order 1a uncertainty requirements. A plot of the beam-by-beam mean values shows an even scattering around a zero mean, except for an increasing trend in the outer beams on the starboard side. The reason for this is not known, however, the largest deviation is less than three centimeters. Additionally, a difference surface was created between the mainscheme-only surface, and the crossline-only surface. The Caris surface statistics tool was used, and showed the difference surface had a mean value of 0.0, and a standard deviation of .11 meters. Overall, the crossline analysis indicates good data quality, and vertical sounding uncertainty falling well within IHO order 1a requirements. Some of the crossline/mainscheme junctions show a vertical offset upto around 15 cm. Analysis of the data suggests that these are tide artifacts. Offsets of similiar magnitude can be seen between adjacent mainscheme lines that were collected on different days. It is possible that there are local dynamic tidal effects caused by the presense of Long Sand Shoal that are not adequately modeled in the TCARI grid. Local wind setup not measured by the controlling tide gauges is another possible cause.Crosslinesfile:///M:/OPRB370NRT512/Surveys/H12508/Compilation/Report/Components/Figure4%20-%20Crosslines.pngBeam-by-beam Standard Deviationfile:///M:/OPRB370NRT512/Surveys/H12508/Compilation/Report/Components/Figure5%20-%20BeambyBeam%20StDev.pngBeam-by-beam Mean Differencefile:///M:/OPRB370NRT512/Surveys/H12508/Compilation/Report/Components/Figure6%20-%20BeambyBeam%20Mean%20Diff.pngSurface statistics of Mainscheme/Crossline Difference Surface.file:///M:/OPRB370NRT512/Surveys/H12508/Compilation/Report/Components/Figure7%20-%20Main%20Cross%20Diff.pngCrosslines totaled 8.8% of the mainscheme lines, which meets the 8% requirement for set line spacing multibeam. The crosslines obtained have excellent geographic distribution and compared favorably to the mainscheme lines with differences falling within vertical error budgets. NOAA does not use IHO uncertainty standards. Where the field references IHO standards, the statement should be amended to read "TVU falls within NOAA's "Complete Coverage" vertical uncertainty budgets as assigned for this survey."An IHO layer was created for the CUBE surfaces to highlight nodes where the IHO TVU was exceeded. For all surfaces, less than 1% of nodes failed to meet IHO Order 1a TVU requirements.BAGs from the most recent adjacent surveys were downloaded from NGDC. Difference surfaces were created, and statistics were computed using the Caris "Compute Statistics" tool. The results of each comparison are discussed below.H11361100002004NOAA Ship THOMAS JEFFERSONSWData agreement was best for H11361, although it was the oldest survey junction analyzed. The mean difference was less than 1 cm, with a standard deviation of 20 cm. The good agreement is likely due the area being deeper, and less dynamic. The other two junctions are in dynamic areas with significant sand wave formations, which makes a meaningful comparison difficult.H11361file:///M:/OPRB370NRT512/Surveys/H12508/Compilation/Report/Components/Figure8%20-%20H11361%20Junction.pngH12012100002009NOAA Ship THOMAS JEFFERSONSThe mean difference between H12508 and H12012 in the area of overlap is .1 meters. The standard deviation is .6 meters. There are extensive sandwaves in this area, making a meaningful comparison difficult. Significant sandwave movement was observed within the time span of data acquisition for H12508. H12012file:///M:/OPRB370NRT512/Surveys/H12508/Compilation/Report/Components/Figure9%20-%20H12012%20Junction.pngH12013100002009NOAA Ship THOMAS JEFFERSONEThe mean difference between H12508 and H12013 in the area of overlap is .2 meters. The standard deviation is .8 meters. There are extensive sandwaves in this area, making a meaningful comparison difficult. Significant sandwave movement was observed within the time span of data acquisition for H12508. H12013file:///M:/OPRB370NRT512/Surveys/H12508/Compilation/Report/Components/Figure10%20-%20H12013%20Junction.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.None ExistThere were no other factors that affected corrections to soundings.SVP casts were typically taken every two hours in the deepest area being surveyed at the time.All equipment and survey methods were used as detailed in the DAPR.The static offsets from the RP to the transducer in the DAPR don't match the HVF. The X and Y offset values are reversed from what is shown in the HVF (both in SVP 1 and TPU Offsets) and the Z value is listed as negative in the DAPR, but positive for all entries in the HVF. The dynamic draft table reported in the DAPR is from 2012 and does not match any of the latest speed or draft values in the HVF which are from 2013 DN 176. Also, the values reported in the DAPR don't match any of the other entries in the HVF which date back to 2008. The data quality does not appear to be affected by these inconsistencies, which appear to be simple documentation errors.Gaps in along-track MBES Coverage.After MBES acquisition was complete, it was noticed there several small along-track holidays existed in the MBES data. After some analysis, it was determined that the gaps were caused by the SIS acquisition software automatically breaking, and beginning a new file mid-line. It appears that the file size was limited to 30 minutes of acquisition. When this was exceeded, SIS would end the file and create a new file. During the transition, a few seconds of data were lost, resulting in a holiday. This limit seemed to be related to acquisition time, rather than file size. All of these holidays fall within continuous 200% SSS coverage, and after review, the hydrograher is confident no significant features were missed.Problems were encountered with the logging and application of TrueHeave files. Due to frequent crashing of the acquisition computer, and consequently the TrueHeave file logging being cut short, it was not possible to apply TrueHeave to several MBES lines. Realtime heave was used for these lines instead. The files affected are listed below: 0038_20130730_202515_S3002.all 0095_20130805_161722_S3002.all 0099_20130805_182659_S3002.all 0099_20130805_175953_S3002.all 0218_20130819_200537_S3002.all 0286_20130903_153248_S3002.allAll sounding systems were calibrated as detailed in the DAPR.Raw Backscatter was logged as part of the Kongsberg .all file. The backcatter was converted, and a mosaic was created as a QC check, but no additional processing was performed.NOAA Profile V_5_3H12508_1mCUBE1NOAA_1mMBES TracklineSBES Set Line SpacingH12508_1m_FinalCUBE1020NOAA_1mMBES TracklineSBES Set Line SpacingH12508_2mCUBE2NOAA_2mMBES TracklineSBES Set Line SpacingH12508_2m_FinalCUBE21840NOAA_2mMBES TracklineSBES Set Line SpacingH12508_50cmCUBE0.5NOAA_0.5mMBES TracklineSBES Set Line SpacingH12508_SSS_Mosaic_100SSS Mosaic1N/A100% SSSH12508_SSS_Mosaic_200SSS Mosaic1N/A200% SSSPer HSSD 5.2.2.3, only a four meter grid is required, however, the sounding density easily supports Complete Coverage gridding requirements. Therefore, one and two meter surfaces are being submitted. A 50 cm grid, H12508_50cm, is also being submitted, but is not intended to fulfill any submission requirement.The 50cm grid was required for the AWOIS investigation as stated in the Project Instructions.No HorCon or VerCon operations were required for this survey.Mean Lower Low WaterTCARINew London8461490New Haven8465705B370NRT52013.tcFinal2014-06-302014-07-17The Tide Note is attached.North American Datum of 1983 (NAD83)Universal Transverse Mercator(UTM) - Zone 18Moriches, NY 293 kHzThe Moriches, NY beacon was manually selected in the Trimble DSM212, it was not changed during the project.The chart comparisons were performed using multiple methods. For each charted contour, the base surface generated by the survey was filtered to only show areas shallower than that contour. Doing so highlights areas where contours have shifted significantly, and isolated shoals. Shoal biased selected sounding layers were also created, and carefully compared to charted soundings to identify areas with depths that would be unexpected by the mariner based on charted depths.1237421622000012007-092014-01-282014-02-01The only survey data lying within the bounds of chart 12374 are the western portions of the Long Sand Shoal Dton investigation. Long Sand Shoal had shifted, resulting in significant disagreement with charted soundings. There were depths of less than 25 ft, 150 meters seaward of the charted 30 ft contour. There are discrepancies of similar magnitude with the 18 ft contour. At the time of this chart comparison, however, the data from the Dton investigation had been applied to the chart, so the discrepancies do not exist in the most recent chart version.1237521612000012010-102014-01-282014-02-08Long Sand Shoal is one of the most prominent features on chart 12375. During the course of the survey the shoal was found to have shifted significantly, especially in the western portions. The entire shoal was developed out to the 30 ft contour, and submitted as a DTON. The most current version of chart 12375 has had the DTON survey data applied, but only in the western portion of Long Sand Shoal. West of 72-22-23.03W, the contours and soundings are based on the new survey data, and so agree almost perfectly. East of 72-22-23.03W where the discrepancies were not as large, however, the chart does not appear to have been updated. Here the survey data shows that the contours have shifted seaward up to 60 meters in some places. On the western portion of the survey area, between Long Sand Shoal and the Hen and Chickens, there are several uncharted rocky shoals with depths significantly shoaler than the charted depths. Two of the most navigationally significant shoals were submitted as DTONs, and have already been applied to the chart, but there are several others that deserve attention. They are discussed in the Shoals and Hazardous Features section.A very small area in the southern portion of the survey also falls on Chart 12372_11, Scale 1:40,000. Three additional shoals and one submerged rock were submitted as DTONs during the SAR. US5CN16M2000082013-10-032013-10-03falseComparing US5CN16M to raster chart 12374, it was noticed that there are some discrepancies in the placement of depth contours around the western end of Long Sand Shoal. Although, the contours and depths appear to have been updated to include the submitted DTON, there are some small deviations from the raster.US5CN30M20000112014-01-272014-01-27falseUS5CN30M was compared to the raster chart 12375. Aside from some very slight differences in contour position, no discrepancies were found.A very small area in the southern portion of the survey also falls on ENC US5CN20M, Scale 1:40,000. A single AWOIS item, # 6818, was assigned inside the survey area - The wreck of the James Sheridan. The wreck was fully developed with MBES. The charted position of the wreck is accurate. The least depth measured by the current survey was slightly deeper than the charted depth of the wreck, so it is recommend to retain the wreck as it is presently charted.The wreck position was updated to the surveyed position; however the charted least depth was retained.No Maritime Boundary Points were assigned for this survey.A Position Approximate wreck is charted at 41-13-54.244N, 72-20-53.625W. The area surrounding the charted position of the wreck was developed with MBES. No signs of the wreck were visible in the MBES data. It is recommended for deletion.Within the survey area, one wreck, two submerged rocks, and one obstruction were recommended for charting. There is an uncharted wreck at 41-15-43.377N, 72-20-41.016W near the entrance to Saybrook Outer Bar Channel. Possibly a sunken barge. The two submerged rocks were submitted as Dtons. One pile-like obstruction was recommended for charting at 41-13-45.219N, 72-22-37.481W. Note: This survey area contains numerous uncharted rocks and rocky shoals that meet the HSSD criteria for significant features. The Pacific Hydrographic Branch was consulted, and at their direction no natural features, including significant rocks and rocky shoals, were included in the Final Features File. Every significant feature was carefully reviewed to ensure that it was adequately developed, and that its least depth was accurately represented in the BASE surface. However, only features appearing to be man made obstructions, or those which were determined to be Dtons, were recommended for charting, and included in the Final Features File.2H12508_Dton_12013-08-26H12508_Dton_22014-01-14Danger to Navigation Reports are included in Appendix II of this report.Three additional shoals and one submerged rock were submitted as DTONs during office review. The DTON Report is attached. On the western portion of the survey area, between Long Sand Shoal and the Hen and Chickens, there are several uncharted rocky shoals with depths significantly shoaler than the charted depths. Two of the most navigationally significant shoals were submitted as Dtons, and have already been applied to the chart, but there are several others that deserve attention: At 41-14-18.49N, 72-24-37.49W, there is an uncharted rocky shoal with a least depth of 27 ft under a charted 32 ft sounding. At 41-14-19.71N, 72-24-15.30W, there is an uncharted rocky shoal with a least depth of 28 ft under a charted 36 ft sounding. At 41-14-41.61N, 72-24-16.59W, there is an uncharted rocky shoal with a least depth of 30 ft under a charted 38 ft sounding. Between the Hen and Chickens and Halftide Rock, there are several uncharted rocky shoals: At 41-15-31.08N, 72-24-22.44W, there is an uncharted rocky shoal with a least depth of 22 ft near a charted 37 ft sounding. At 41-15-29.71N, 72-24-31.83W, there is an uncharted rocky shoal with a least depth of 26 ft seaward of the 30 ft contour. The closest charted sounding is 33 ft. At 41-15-26.06N, 72-24-41.27W, there is an uncharted rocky shoal with a least depth of 29 ft, seaward of the 30 ft contour, and near a charted 34 ft sounding. At 41-15-19.97N, 72-24-18.72W, there is an uncharted rocky shoal with a least depth of 15 ft 120 meters seaward of the 18 ft curve. On the north side of Halftide Rock the contours do not accurately depict the shoal. Rocky shoaling with a least depth of 8 ft extends 50 meters seaward of the 18 ft curve. Between Cornfield Pt Shoal and red buoy "2", there is a charted shoal, with least depth of 29 ft. The surveyed least depth on this shoal is 18 ft. At 41-15-21.87N 72-22-40.90W, there is an uncharted rocky shoal with a least depth of 24 ft seaward of the 30 ft contour. Southeast of Old Kelsey Pt, there is an uncharted submerged rock with a least depth of 11 ft near a charted 15 ft sounding. 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.Twenty-one bottom samples were acquired during the survey. The samples were taken with a clamshell style bottom sampler. The bottom type samples were classified, photographed, and then discarded back into the water. The positions of the samples were captured with Hypack targets.Two assigned shoreline features exist within the survey limits, Hen and Chickens Rock, and Halftide Rock. MBES was acquired around the exposed rocks as close as was considered safe. No Detached Positions were taken. The positions of both rocks are accurately charted.Shoreline Featuresfile:///M:/OPRB370NRT512/Surveys/H12508/Compilation/Report/Components/Figure11%20-%20Shoreline%20Features.pngThere were three assigned features in the survey limits. The AWOIS item discussed in Section D.1.3 is the third.Prior survey comparisons exist for this survey, but were not investigated.All Atons in the survey area appeard to be on station, and serving their intended purpose.No overhead features exist for this survey.No submarine features exist for this survey.A ferry route exists between Saybrook Point in Old Saybrook, and Plum Island, but was not investigated.No platforms exist for this survey.Sand waves are a prominent feature in this survey area. Five meter high sandwaves exist in the southwest portion of the survey area, south of Long Sand Shoal. Smaller sandwaves exist north of the shoal. It is interesting to note that the direction of sandwave propogation appears to change in different parts of the survey area. On the western portion of the survey area, north of Long Sand Shoal, the sand waves appear to be developing from a west-to-east current, and just south of Long Sand Shoal, the direction seems to reverse, the sandwaves appearing to be created by an east-to-west current. The sandwaves in the eastern portion of the survey area, north of Long Sand Shoal, have a symetrical shape, and do not suggest a prevailing current direction. In some areas, the sandwaves appear to be propogating quickly. Movement of up to 10 meters can be seen by comparing survey lines acquired on different days. Moderate tide artifacts were observed on some survey days. It is likely that Long Sand Shoal creates a tidal and current dynamic in the area that is not accounted for in the TCARI grid.No present or planned construction or dredging exist within the survey limits.Recommendation for priortiy processingAlthough the most dangerous and navigationally significant features have been submitted as Dtons, many more uncharted shoals and chart discrepancies exist within the survey area. The hydrographer recommends that this survey be given priortiy in the processing queue, to hasten the new survey data reaching the chart.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.LTJG Andrew ClosChief of Party2014-11-24Data Acquisition and Processing Report2014-11-24Coast Pilot Report2014-11-24