Sea Technology

JUN 2013

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

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(Top) HyBIS with OBS deployment module for GEOMAR. (Middle) HyBIS with OBS deployment module for NOC. (Bottom) Detail showing the hydraulic release mechanism for various tool modules. The ship used was the RRS James Clark Ross, which is operated by the British Antarctic Survey, a division of the Natural Environment Research Council (NERC). Both the lander and ship from which HyBIS operated belong to NERC. Limitations set by the vessel operator for this task included a restriction on deployment of more than one um- bilical cable to be deployed over the side of the ship at any one time. As a result, a solution was developed that would involve the HyBIS command module deploying a lander recovery module carrying a passively driven drum of 600-meter-long lifting with a 4,000-kilogram safe working load and 200,000-newton breaking strain. The lander recovery module was fabricated in 316 stainless-steel tubing forming an open chassis structure. It was ftted with a Hydro-Lek HLK-HD5 fve-function manipulator arm from the tool sledge module that carried a lifting hook, attached to the jaw of the arm via a T-bar, and spliced onto the lifting warp. This warp was then attached to the 4-tonne lander and the HyBIS instrument recovered to the ship while the lifting warp spooled off from the drum. The drum had both a friction clutch and a restriction on the spooling of the lifting warp to ensure the warp remained tightly wound on the drum. In the event of the lifting warp fouling causing the vessel to become anchored to the lander via the HyBIS vehicle, two options were retained: the capacity to cut the lifting warp with the manipulator arm cable cutter or to jettison the entire lander recovery module. HyBIS has had prior experience with recovering landers, but not as heavy as the 4-tonne one in the Arctic. In 2008, on its frst trials cruise, HyBIS recovered a benthic lander from 2,200 meters of water in a location off the coast of Tenerife, Spain. This lander was a long-term monitoring system with CTD and acoustic Doppler current proflers (ADCP) as part of its scientifc payload. It was designed with two independent acoustic releases and glass sphere buoyancy such that it should have jettisoned its anchor weights and returned to the surface on command. Unfortunately, at the end of its trial mission, the lander failed to release its anchors and became stuck on the seafoor. By acoustically ranging to its sonar transponders, its position on the seafoor was triangulated to within a few tens of meters. Deployed from a nondynamic-positioning ship, the HyBIS vehicle managed to sweep a path towards the lander's position and www.sea-technology.com CLEARLY SUPERIOR IMAGING The Leader in Underwater Technology Acoustic Releases | USBL | MRU Side Scan Sonar | Sub-bottom Proļ¬lers Bathymetry | AUV & ROV Sonars Combined & Customized Solutions Connect With Us At: For more information, visit EdgeTech.com info@edgetech.com USA 1.508.291.0057 June 2013 / st 31

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