| | 278 |
| Study Name: | | Survey Type: |
| PDS-1998-1999 | | Bathymetry |
| Survey Name: |
| PDS-1998-1999 BASELINE Bathymetry | | Disposal Site: |
| | PDS (1995-pres) |
| | Start Date: | 9/14/1998 | End Date: | 11/2/1998 | Collector: | | SAIC |
| Process Description | Hydrographic surveying operations during this study were conducted using the SAIC HydroBat 2000 |
| | TM (HB-2000) Survey System. The HB-2000 is a powerful data acquisition and processing system |
| | which is used for in-shore, near-shore, and off-shore hydrography and seabed mapping. The |
| | system is a complete multibeam survey system with integrated sensors, software, computers and |
| | peripherals. The functional capabilities of the HB-2000 include real-time data acquisition and |
| | navigation, survey planning support, real-time helmsman and autopilot steering guidance, and post- |
| | processing of hydrographic data collected during operations. The HB-2000 consists of several major |
| | subsystems including: Integrated Navigation Subsystem (INS), System control display console, |
| | Multibeam display, Multibeam sonar subsystem, and Helmsman display console. Multibeam data are |
| | collected and processed in the Generic Sensor Format (GSF), which allows ping and beam flags to |
| Logical Consistency | The precise navigation and data integration required for all field operations was provided by use of |
| | SAIC's Portable Integrated Navigation and Survey System (PINSS). The PINSS navigation software |
| | was resident on a Toshiba personal computer (PC) capable of providing real-time navigation, as well |
| | as collect position, depth, and time data for later analysis. |
| Attribute Accuracy | Swath bathymetry data was collected using the Reson Model 8101 SeaBat Multibeam Echo Sounder |
| | System interfaced to a Reson SeaBat 6042 Multibeam Data Collection System. The 8101 operates at |
| | 240 kHz and is capable of measuring water depth to a resolution of 1.25 cm at a maximum depth of |
| | 400 m. The echo sounder produces 101 discrete beams each covering an angle of 1½° x 1½°. The |
| | resulting swath covers an angle of 150° x 1½° encompassing a swath width of approximately 7.4 |
| | times the water depth to a maximum 300 m slant range. The SeaBat 6042 Multibeam Data Collection |
| | System combines both hardware and software into a stand-alone system that provides real-time |
| Horizontal Accuracy | Vessel position was accomplished using differential Global Positioning System (DGPS) data. A |
| | Trimble® 7400 DSI GPS receiver, in conjunction with a Leica 41R differential beacon receiver, |
| | provided DGPS positioning data in the horizontal control of North American Datum of 1983 (NAD 83) |
| | to an accuracy of ±5 m. The Coast Guard differntial beacon broadcasting from Brunswick, ME |
| | (316kHz) was utilized for satellite corrections due to its geographic position relative to Portland |
| Vertical Accuracy | The Reson Model 8101 SeaBat Multibeam Echo Sounder System interfaced to a Reson SeaBat 6042 |
| | Multibeam Data Collection System operates at 240 kHz and is capable of measuring water depth to a |
| | resolution of 1.25 cm at a maximum depth of 400 m. Real-time attitude compensation was |
| | accomplished in the SeaBat 6042 system using ship¿s attitude data collected using a TSS Model |
| | 335B motion sensor. This instrument uses heading sensors and accelerometers to calculate roll, |
| | pitch, yaw, and relative heave. Heading data for both the motion sensor and INS was provided by a |
| | Sperry MK-32 gyrocompass. The accuracy of the TSS 335B sensor is 5 percent of 10 m or 5 cm for |
| | heave; ± 0.10° dynamic accuracy for roll and pitch, and ± 0.05° static accuracy for roll and pitch. |
| | Sound velocity profiles were calculated from conductivity, temperature, and depth data that were |
| | collected using a Model SBE 19-01 Sea-Cat CTD logger manufactured by Sea-Bird Systems. This |
| Depth Datum Name | Mean Lower Low Water |
| Depth Distance Units | m |