2017-10-19Pacific Hydrographic BranchDan JacobsTeam Lead, Navigation Response Team 4The purpose of this survey is to respond to requests for hydrographic surveys to reopen the channels in Gulfport, MS, to to the effects of Hurricane Nate. The survey limits and methods (i.e., sensors used) will be determined by the Team Lead in consult with the NRB Chief and NOAA Navigation Manager. Data will be collected in the most efficient manner to provide USCG information that is critical to make real-time decisions on channel and/or port closures and openings. The data from this survey are not intended to meet NOAA charting specifications and are not intended to be applied to the nautical chart with the exception of hazards to navigation (i.e. DToNs), subject to branch review.A .pdf file was created for USACE that showed survey depths within Gulfport's harbor and the ship channel leading out to Ship Island.All survey systems and methods utilized during this survey were as described in pdf document named "NRT4_DAPR_2017_Signed" accompanying this memo.Soundings were reduced to Mean Lower Low Water (MLLW) using observed tides from gage 8741533 and TCARI grid J925NRT42017.tc provided by CO-OPs from a 2017 survey of the area.All data was reviewed for DTON and none were found.Several soundings in the main channel exhibited depths shoaler than 29 feet. It was recommended to USACE that the crew of R/V Irvington investigate the following day to verify or disprove the 29 foot depths as they had been scheduled to survey the bar channel.
This survey does not meet charting specifications and is not adequate to supersede prior data.Wind and a choppy sea state caused a high frequency of noisy data during the course of this survey. Compounding these unfavorable atmospheric conditions, the real time SVP sensory came out of the sea often resulting in sound speed data broadcast gaps to Kongsberg's processing unit. This, in turn created sonar signal 'blow outs." Once these numerous errors were deleted in post processing, the remaining multibeam data appeared representative of the bottom and allowed for the creation of preliminary sounding plots.S-J925-NRT4-17D00241MississippiGulfportMississippi Sound10000Kongsberg EM2040C Multibeam SonarEdgetech 4125 Sidescan SonarNorth American Datum of 1983 (NAD83)Mean Lower Low WaterTCARIUTM Zone 16NNavigation Response Team 42017-10-092017-10-10Dan Jacobs2017-11-08