Sunday, July 16, 2006

Laying cable and dropping the "elevator"

O'Reilly here, your deep sea guide. You're probably wondering "What's with the hard-hat?" Well, I actually wanted to be the Indian Chief, or maybe even the Policeman, but I guess the Construction Worker will hafta do. Heh - just kidding. I don't even like the Village People.

Remember to click on the photos for a larger image.

Above is a schematic picture of the system we are attempting to deploy; note that the vertical and horizontal scales have been drastically reduced in order to fit the entire picture on one page; the cables involved are actually several miles in length! I've been using this damn cartoon for several years now during presentations - now it is time to actually deploy the real thing.

Tiburon descends through Western Flyer's moon pool, and two hours later reaches the sea floor at a depth of 3,200 meters; no sunlight reaches these midnight depths, but Tiburon locates the base of the mooring on sonar, and closes in. Then Tiburon’s powerful floodlights and HDTV camera reveal the mooring’s base, sitting quietly on the ocean floor at the edge of Shepard’s Meander. Contrary to our worst fears, the mooring base and cable look beautiful. Even the rat-tail fish hovering above the float looks reasonably attractive. The mooring anchor consists of eight train wheels. The vertical “riser” cable extends more than 2 miles from the top of the yellow float to the sunshine far above. The loop of orange cable on the front of the float provides a plug into the riser cable. Tiburon's next task is to plug the seafloor cable into this connector, which she does without a hitch. Tiburon now slowly heads toward the science site, 2.7 kilometers to the north, paying out cable as she goes. However after traveling a few hundred meters, we detected a break in “optical continuity” – the optical fibers in the cable had broken! Tiburon retraced her path and found a nasty kink in the cable – much like a cheapo garden hose exhibits when you pull too hard on it. Tiburon pilots had to cut the cable and return to the surface. Fortunately we had brought a spare cable with us, and dove the next day to try again. This second attempt was, er, quite exciting. Almost immediately the cable snarled horribly after coming off the reel – but the pilots used incredible ingenuity and dexterity to untangle things, using the vehicle’s robot arm! Six hours later, Tiburon reached the science site, dropped off the spool on the bottom in preparation for the next day’s climactic operation, and came back to the surface.

Mark performs final checkout of the seafloor science station - akaBenthic Instrument Node” or BIN” - on the aft deck of Western Flyer. Science instruments are attached to the titanium sphere, which contains the computer, power system, and other electronics. The yellow cables wrapped around the base will be plugged into the seafloor cable by Tiburon, forming a real-time network that extends from the deep ocean to the sea surface, into low Earth orbit via Globalstar satellite and back to Moss Landing – providing the “data highway” for MBARI’s ocean observatory.

The team prepares the BIN for deployment on “the elevator”. The elevator transports payloads too heavy to be carried by Tiburon; the elevator and it’s payload will be dropped over the side of the ship and free-fall to the seafloor science site. After rendezvous with the elevator, Tiburon will pick up the BIN, and untie steel weights attached to the bottom of the elevator; the suddenly-buoyant elevator then “rockets” to the surface for recovery by Western Flyer.

The elevator and its payload are swung out over the stern of Western Flyer, and lowered into the ocean - the elevator is released and free-falls two miles to the ocean floor.

NEXT - plugging it in and throwing the switch!


Anonymous hippobean said...

nice pict O'Reilly! The white hat suits you very well.

11:50 AM  
Blogger tomoreilly said...

Thanks for the compliment on my hat. I'm getting a tattoo next week.

9:19 PM  

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