Kevin Raskoff stands by as Joe Caba flies the ROV from the control room. Joe was "flying" the ROV when a "knot" occurred in the line at 2000m. Click image for larger view.
A Family's Fancy Flying
July 2, 2005
Jeremy Potter
Expedition Coordinator
NOAA Office of Ocean Exploration
Untying a knot in your shoelaces is hard enough. Imagine trying to untie a knot underwater. . . . Now make the rope 2000m long, attach one end to a 420 ft ship stuck in the ice, add currents, and limit yourself to what you can see through a camera. Oh, did I mention that you have to do it by ‘flying’ a 2800 lb machine attached to the opposite end of the rope while 50 people look over your shoulder.
Well, that's exactly what Joe Caba, the ROV crew chief did earlier today.
At 0956, the crew deployed the ROV for the second benthic dive of the cruise. The scientists spent two hours patiently waiting as the ROV descended the 2650m from the Arctic Ocean's frozen surface. The crew and scientists were stunned when the ROV experienced an interruption in the telemetry control system, used to communicate with the ROV from the surface, just minutes before reaching the frigid seafloor. After a bit of tinkering, the crew determined that the telemetry problems seemed to coincide with use of the winch. Every time the winch onboard the ship was used to raise or lower the ROV, it would experience the same interruption . The scientist's feared the dive was cancelled before it even really started. As soon as the ROV crew found a way to maintain control while using the winch, the ROV started the slow ascent back to the surface.
At approximately 2000m, Joe Caba, the ROV pilot, noticed a strange twist in the tether connecting the ROV and the clump weight. Since any unusual bends or twists can interfere with fiber optic communications, he surmised that the kinks in the tether may be the cause of the telemetry interruptions . Given all of the technological advances and the expertise applied to designing, building, operating, and maintaining these innovative systems, it's almost comical to think that we can be stopped by a 'little knot.' It certainly was not funny for the science party or ROV crew at the time. A bend or twist in the cable can have serious implications for the ROV. It is quite possible that additional tension on the line could permanently damage the fragile fibers contained inside.
While the science party stared intently at the monitors, Joe's brother Jerry went to the 'high bay' and grabbed a short piece of rope. While Joe examined the orientation of the tether and ROV, Jerry sat next to him and used the rope in his hand to recreate, and then untwist, the knot on the tether 2000m below. After some brief discussion, Joe slowly and adeptly twisted and turned the ROV around the tether. Every few minutes Joe would pause and examine his progress while Jerry matched the rope in his hand to what they saw on the monitor. Approximately 30 tense minutes later, the neutral tether was untangled and telemetry was functioning properly. Cancellation of the dive was rescinded and the ROV continued its descent to the bottom.The rest of the benthic dive was definitely exciting. But the highlight of the day belonged to Jerry and Joe, the Caba brothers.
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