Sea Technology

JUL 2013

The industry's recognized authority for design, engineering and application of equipment and services in the global ocean community

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scan sonar, acoustic imaging, environmental characterization optics (ECO) sensors, a sub-bottom profler and a still-camera system. While the ABYSS is on board the support vessel or surfaced, engineers can interface with it using the same Vehicle Interface Program (VIP) used by all Hydroid REMUS AUVs. This highly refned software runs on a ruggedized, waterproof laptop, allowing it to be operated safely in poor weather conditions. In addition to mission planning, the VIP software helps users export data, maintain the vehicle and perform quality-control checks. When collecting data on seafoor volcanoes, the ABYSS is equipped with the following sensors: an EdgeTech (West Wareham, Massachusetts) 2200M 120/410-kilohertz side scan sonar, a Sea-Bird Electronics Inc. (Bellevue, Washington) SBE 49 FastCAT CTD and a Teledyne RESON (Slangerup, Denmark) SeaBat 7125 multibeam (200/400 kilohertz). Additionally, the multibeam echosounder can be exchanged for an EdgeTech 2200-M subbottom profler (4 to 24 kilohertz) or a 4-megapixel monochrome Allied Vision Technologies (Burnaby, Canada) Pike camera on a mission-to-mission basis. These instruments are signifcantly more effective when mounted on an AUV compared to boat-mounted systems—in addition to the vehicle's ability to maintain a constant altitude during a mission, AUV-mounted instruments also operate in a signifcantly lower-noise environment than their surface-ship analogs, and provide higher-quality data that is not subject to interference by surface phenomena such as wake and swell, wave-induced chop and bubble entrainment near the air-sea interface. For navigation, the ABYSS relies primarily on a Kearfott Corp. (Little Falls, New Jersey) T24 Inertial Navigation System (INS) in conjunction with Teledyne RD Instruments's (Poway, California) 300-kilohertz acoustic Doppler current profler/Doppler velocity log. After the sensor-aided INS on board the AUV dead reckons itself using a position provided by an external GPS, the INS independently determines its angular velocity and acceleration in three-dimensional space. To counter errors made over time by the INS and to provide additional accuracy, the ABYSS is optionally supported during its programmed mission by a Hydroid long baseline (LBL) positioning system, which allows the vehicle to periodically fx its exact position and depth. Additionally, the ABYSS is outftted with a Paroscientifc Inc. (Redmond, Washington) 8B7000 pressure sensor, which provides depth readings, and an IMAGENEX (Port Coquitlam, Canada) forward-looking 852 Echo Sounder for detecting and avoiding obstacles while submerged. In the event that an emergency forces a mission to be terminated prematurely, the ABYSS has several emergency systems that ensure its safe return to the support vessel. For example, if the vehicle's battery power reaches a critically low level, the AUV immediately surfaces and transmits SMS messages via satellite with its status and location to the ship crew. Additionally, the AUV team can deliver emergency instructions to the ABYSS using acoustic communication, allowing them to quickly abort a mission if necessary. Sea & Sun Technology Launching the Vehicle One of GEOMAR's key criteria in the AUV tender process was a system for launch and recovery that did not require the deployment of an assist boat from the support vessel. The REMUS 6000 launch and recovery system (LARS) used with the ABYSS achieves that goal, allowing safe and quick launch of the AUV in a variety of weather conditions. The ABYSS LARS can launch the AUV off either the side or stern of any large or medium-sized research vessel and can be set up for shipboard operations in a couple of hours. When launching the ABYSS, the AUV is placed on a cradle and attached with a lift/tow line. The LARS then uses its built-in A-frame, which tilts the vehicle until it is suspended a safe distance outboards. The vehicle is then lowered into the water, and its tow line is released. Additionally, the unit's docking head stabilizes the vehicle, reducing swing and allowing the vehicle to be launched in sea states up to 5. Once the programmed mission is complete and the ABYSS has surfaced, it provides the crew with its GPS coordinates using Wi-Fi or Iridium. After the support vessel approaches the vehicle's location, the ABYSS can be manually driven via Wi-Fi until it is close enough to be recovered. The ABYSS then deploys a recovery line www.sea-technology.com July 2013 / st 31

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