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    Successful deep water trials for Subsea 7's underwater vehicle

    Vessel & ROV News // September 1, 2003
    ASV Geosub, the Autonomous Underwater Vehicle (AUV) developed by subsea engineering contractor Subsea 7, has successfully completed comprehensive sea trials in Orkney's Scapa Flow and off of the West Coast of Scotland. The demanding tests mean that Geosub is now ready for commercial use.

    The first phase of the trials in the sheltered waters of the Scapa Flow was conducted from the survey vessel, Jean Charcot at the end of July. During this phase which lasted 10 days, the 7m, 2,300kg vehicle executed surface and shallow water missions toassess the reliability of its sub-systems and survey and positioning sensors in a water depth of up to 60m.

    The second phase of the trials took place off Raasay in water depths of up to 150m where Geosub undertook deeper water test dives.

    Murray Dick, Subsea 7's global remote technology group manager commented: "During the trials, Geosub consistently performed every task that was asked of it.

    The trials team worked tirelessly to ensure the vehicle was put through the most stringent of tests. We are delighted to have reached the stage of taking Geosub to the commercial market and in doing so, bringing a new dimension of the latest underwater technology to Subsea 7's customers."

    ASV Geosub was developed, following a licensed technology transfer, with Southampton Oceanography Centre, to address the need for high resolution geophysical surveys with extremely accurate positioning in ever deeper waters. The initial focus for the vehicle will be site surveys, pipeline and cable route surveys. The vehicle is fitted with multibeam echo sounder, sidescan sonar and sub bottom profiler systems as standard.

    ASV Geosub is powered by batteries and has a classic torpedo shape. When programmed with a mission the vehicle is launched from the support vessel and sent a mission start command via a VHF radio link. On the surface the vehicle follows a figure of eightpattern until the onboard Inertial Navigation System (INS) is calibrated.

    When this is completed the vehicle dives to a pre programmed altitude and commences the survey. Navigating around a pre programmed trajectory on the seabed the vehicle gathers and logs data from the survey sensors. During the dive the surface vessel canif required communicate with the vehicle using an Acoustic modem. When the vehicle has finished the mission it will surface and be recovered by the vessel.

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