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dock allows a variety of different tool modules to be inter- faced with the command module, including a 0.5-cubic- meter hydraulic grab, a five-function manipulator arm and retractable sample tray, a passive winch to recover up to 3- tonne bottom landers and a module for the visually guided delivery of ocean-bottom seismometers to the seafloor. Unlike a conventional ROV, HyBIS does not have any floatation; rather it is suspended directly from the ship by its umbilical cable, allowing it to recover or deploy heavy payloads with thrusters powerful enough to provide a radius of maneuverability between 2 and 5 percent of the water depth (e.g., 200 meters radius at 5,000 meters depth). De- ployment from a ship using a standard 18-millimeter diam- eter electro-optic oceanographic cable minimizes heave. During the MCSC survey, HyBIS was able to maintain a constant survey speed of 0.5 knots, even at 5,000 meters, for at least eight hours. As a result of its small footprint and relatively simple configuration, HyBIS requires two operators, making it both cost effective and readily accessible to the scientific com- munity. Operation involves a pilot (usually a scientist) and winch driver (usually a ship's crew member) sitting side-by- side in front of screens relaying video feeds from the cam- eras, as well as position, depth, heading and other onboard data. Other members of the scientific team operate the high- definition camera and act as navigators. The versatility of the HyBIS system was demonstrated during the MCSC expedition when it was fitted with a slurp gun for biological sampling, pumps and filters for sampling minerals in the hydrothermal plume, and watertight bottles for sampling hot vent fluids as they exited the seafloor. "A traditional ROV would need expensive floatation and require a large operating team. Instead, the HyBIS was developed, a smaller, lighter, modular and versatile system." The Ultradeep Beeb Vent Site During its first dive to about 5,000 meters depth, and following a three-hour search pattern, HyBIS located and imaged the vent site named Beeb, which is surrounded by basaltic pillow lavas and forms a steep mound that is almost vertical in places. Near the top of the mound, both diffuse and mineral-rich, high-temperature "black smoker" chim- neys were found. The AS6K AUV bathymetry maps show that the active chimneys are located on the western side of a sulfide deposit that is 100 meters wide and 30 meters high. Clusters of ac- tive chimneys are also located close to north-south aligned basement faults. An area of older sulfide mineralization was found to extend eastward for at least 500 meters more, mak- ing this one of the largest seafloor massive sulfide mounds known to date. HyBIS collected sulfide samples, including an intact 1.2- meter-long sulfide chimney. Analyses of the sulfides show they are copper-rich, with atacamite staining giving a char- www.sea-technology.com SEPTEMBER 2012 / st 17