into consideration the entire course traveled, because each position solution is a function of the previously recorded position. The added benefit of the aided INS is that, with an RLG at its core, it can provide very accurate heading and attitude referencing to correct for the attitude of the ROV and thus any onboard profiling sonars.
Survey Operation
SeaVision performed the survey of the accessible portions of the berths at Pier 1 from a small survey vessel. It used an Innerspace 455 200 kHz Digital Survey Echosounder and paired with Trimble DSM 132 Differential GPS. NMEA-0183 strings from the DGPS were captured through the Hypack survey acquisition software and converted to the North American Datum of 1983, Rhode Island State Plane feet. Tidal elevations were measured at a nearby NOAA tide station to provide corrections for
tide relative to Mean Lower Low Water (MLLW), and sound velocity corrections were applied by performing bar check calibrations with an Innerspace 443a Digital Sound Velocity Profiler. Survey profiles were collected with a track spacing of 25 feet, perpendicular to the pier face in each berth, and several checklines parallel to the face of the pier (thus parallel to the length of the aircraft carrier) were conducted on a spacing of 100 feet on each side of the pier. A docking garage, similar to the one shown with this SeaEye Falcon, was deployed adjacent to the pier to provide a known starting and ending reference point for the ROV prior to and after the ROV-based survey under the carriers. Divers from Halcrow/HPA assisted SeaVision by placing a docking garage at the offshore tip of the pier at an elevation of -31 feet MLLW. The diver positioned the skid and a plumb line from which a static DGPS position and
A docking garage, similar to the one shown with this Saab Seaeye Falcon, was deployed adjacent to the pier to provide a known starting and ending reference point for the ROV prior to and after the ROV-based survey under the carriers. 28 MTR January 2008
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