Dateline: Nikumaroro, 15 July 2012
They are learning a lot about the reef slope. It’s a lot more demanding than we knew or even imagined. Immediately offshore the reef edge in the primary search area the reef slope drops away in an essentially vertical cliff hundreds of feet tall. Coral outcroppings on the steep slope tend to snare the ROV tether, forcing the pilot to back-track to free the snare. Further out and deeper, the slope moderates somewhat. Except for some Norwich City debris, no man-made objects were seen in two 60-foot search swaths from 21 meters (70 feet) down to 365 meters (1,200 feet). There are, however, many flat coral surfaces with right angle corners resulting in numerous false alarms.
At 03:45Z (17:45 KOK 7/14) the ROV was launched for a second mission. Immediately after deployment, and while the ROV was still close to the ship, the generator powering the entire ROV system failed, causing a blackout of all propulsion, video, and positioning telemetry.
There was great concern that the ROV tether might run afoul of the ship’s propellers before power could be restored, but the ship maneuvered clear of the tether and the ROV was soon recovered safely aboard. The second mission was cancelled and the generator problem was addressed.
At 05:30Z (19:30Z 7/14 KOK) the AUV was launched for an all-night side-scan mission to cover the southern half of the primary search area at depths similar to last night and will then try to cover some of the shallower, more hazardous, portions of the northern half.
At 07:30Z (21:30 7/14 KOK): at last report the AUV was running well.
At 10:30 7/15 (KOK time; conversion to follow as an update), the ROV was back in the water with the generator working reliably. There was some delay because the AUV ran successful missions all night, collecting much more data, which is now being proceesed and plotted. Now that there are targets plotted by the AUV, they need to ground-truthed with the ROV.
They did look at three targets, which all turned out to be coral blocks. There is a learning curve here as the technicians become familiar with the environment, understanding what is normal/usual/natural and what doesn’t fit and may in fact be man-made.
One big question has been, “Where is the aft end of the Norwich City?” To answer that question, they started looking with the ROV at about the 1600 foot depth, working in towards the shipwreck. At about 1050 feet they found old fashioned bottles. At 1000 feet they found a ship’s propeller, a huge (8 feet across), four-bladed, apparently iron or steel, prop with squared-off blades. At 980 feet they found the main body of the wreckage, a huge towering hunk of bent and twisted steel and iron. They took plenty of time to look at it and make sure there wasn’t any silvery sheet metal lurking around it, and took multiple fixes to be sure it’s identified in space very accurately.
No man-made debris has been found but there is still a lot of ground to cover. The weather is holding good, the sea is calm, which makes working the technology much easier.
Everyone was hoping for a quick find, but of course it is the slow solid approach that works.
On the primary monitor in the Phoenix lab, the one that keeps track of the fish, there is a hand-printed sign: “Worst Environment Imaginable.”