NOAA Charting - Mississippi and Alabama Gulf of Mexico

We provided hydrographic surveying for approximately 225 Square Nautical Miles (SNM) of sea floor in and near the Safety Fairways along the Mississippi and Alabama Coasts. An additional area nearer shore was added later, bringing the total to 337 SNM.

For this project, we mobilized the 175' R/V Davidson with a Reson 8101 multibeam and an EdgeTech 4200 high speed sidescan system. The survey required 200% sidescan coverage with concurrent multibeam data collection. All significant contacts were surveyed using multibeam sonar. Most of the survey was performed from the Davidson between the end of May and the middle of August.

The shallower areas, inaccessible to the Davidson, were surveyed simultaneously with the M/V Bella Marie, our 39' catamaran. The Bella Marie surveyed with a multibeam Reson 8124 and an EdgeTech 4200 sidescan. Also used was our 25' jet boat, the M/V Royal Fish. The Royal Fish surveyed as a "day" boat from shore and worked with a Reson 8124 and an EdgeTech DF1000. Both the Bella Marie and the Royal Fish worked in areas as shallow as 4 meters. The shallow areas were surveyed to the same specifications as the deeper areas.

For these two surveys we:

• Acquired shallow water multibeam sounding data;
• Acquired sidescan sonar data;
• Determined positions and least depths on hazards to navigation;
• Installed and operated water level (tide) stations;
• Acquired related supporting data including, water level correctors, velocity of sound in the water column, vessel motion correctors, bottom sediment samples, DGPS checks and more;
• Processed the data including tidal tabulation, computation of tidal datums, tidal zoning determination, applying water levels, vessel motion and velocity of sound correctors to determine the true depths, correlating sonar targets, and compiling reports and digital data; and
• Performed quality control during data acquisition and processing.

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