Cutting the cost of LBL installationProjects and Operations // August 15, 2003
The HiPAP system on the vessel was upgraded to full LBL and a remote computer installed for the survey crew to interface the subsea transceiver on the ROV for LBL and the HiPAP 500 system. This meant that the topside equipment was already installed on the vessel cutting the need for additional equipment.
The next phase was to review existing procedures on calibrating LBL acoustic arrays. The traditional "Box-in" and baselines is time consuming in both vessel time and manpower for processing the data. A geographic calibration method was decided on which utilises the collection of DGPS, Heading, LBL ranges and the high accuracy acoustic angles the HiPAP could detect.
The result of this method was that calibration of the LBL array (water depth 1030m) was cut to two hours from the traditional six to eight hour. The absolute accuracy of ROV position was determined to be well under 0.5m. Kongsberg Maritime supported thejob through their Operation Support department and provided training for Thales Geosolutions.