Day 8: We had high hopes of a second deep dive today, but we’ve discovered more problems with the ROV circuitry and/or software. Voltages in several places aren’t what they should be. While diagnosing and fixing those problems, we’re also trying to complete some unfinished features. For example, the ROV has a depth sensor, compass, and battery voltage sensor already built into the ROV hardware, but we have not yet finished writing the software to read and display the sensor values. Those “upgrade” attempts didn’t work very well, so we eventually gave up and focused on getting the essentials ready, to make sure we’re ready for a dive tomorrow. The rest of the group headed out to some far away islands to survey reefs there, while we worked on the ROV. By evening, we thought we were close to having everything working again, but then one of the cameras started acting silly about 10:00 pm. Hope began to fade. Three hours later (1:00 am), we still had not resolved the problem. This certainly did not bode well for a deep dive the next day, but we were completely exhausted and figured we might make matters worse by working on the ROV while half-conscious, so we went to sleep.
Day 9: This morning all the boats are out taking other members of the team to present preliminary results to villagers on other islands, but one is supposed to come back for us this afternoon to take us out for what will likely be our last chance for a deep dive. We work frantically to get the ROV prepared. By 1:30 pm, we think it’s ready. At least it seems to be working. Fingers crossed. That afternoon, the winds are good, so we take Ulithi ROV to the Asor dropoff with the goal of diving to our maximum rated depth of 150 meters (500 feet). All systems check out, so we begin our descent a little after 3pm. Eighty-five meters down we encounter a vertical wall full of huge pink and yellow sea fans. At 95 meters, we get 4 full minutes of good video of a large Silvertip Shark circling the ROV. At 4:00 pm, we reach 100 meters (330 feet), and all systems are still working fine. Whew!!! Lots of colorful sponges, sea fans, and whip corals. Then, at about 130 meters depth, James reports a problem. One of the thrusters seems to be acting funny. Not good. Gradually over the next several minutes we lose control of more thrusters. Before long, the ROV is immobile in the water, drifting somewhere over 400 feet below us. Then we lose the video lights. Then we loose camera control. We’re all thinking the same thing, but nobody wants to say it. Do we have a leak? Fortunately, we lost camera control while both cameras were still running, and we can see the live video images on the pilot’s TV monitors, so it can’t be a total disaster down there. Hoping the problem might be something simple on the surface, like a loose wire or a glitch in the topside control circuits, we try troubleshooting the topside circuit in a rocking boat. No luck. The ROV is still completely unresponsive, and yet both cameras are still rolling and transmitting live video to our TV monitors. Something is definitely wrong, and it doesn’t seem to be the topside. Gulp. Do we do the sensible, conservative thing and abort the dive to recover the cameras (and their SD cards on which the dive’s video is stored) while we still can, even though we’re just shy of our 150 m goal? Or do we risk it all, and hope the cameras will survive long enough to record video at our maximum depth and bring it back intact? Steve gambles that the cameras and camera housings are intact and makes the executive decision to let out more tether and lower the ROV to its full rated depth of 150 meters. We can’t control it, but if the camera housings hold, and if there’s enough light for the cameras to see down there, we’ll at least be able to record something of what’s down there. After a few minutes at 150 m, we begin reeling in the 150 meters of tether as quickly as we can. Everyone on the boat is nervous. We get the ROV on board, and the cameras are still running. The camera housing are dry. But there’s no way to turn off the cameras without opening the housings. We don’t want to do that in a rocking boat sloshing with seawater, so we cruise back to our “workshop” as quickly as we can. Long-story short, the cameras and SD cards survived. The electronics can had developed a tiny, slow leak, and some salt water had dripped on the circuit boards, shorting them out and eating way some of the wires.
Day 10: The power has failed on the island. No lights. No ROV battery charging. No air conditioning. We can’t even flush the toilets, because the water pumps don’t work. And, of course, the Ulithi ROV is dead, or nearly so. James is bummed and playing his Ukelele to console himself. The one remaining thing James really wanted to do while we were here was take the (working) ROV down to investigate the wreck of the USS Mississinewa, a US Navy refueling ship that was sunk in the lagoon by a Japanese manned torpedo (called a kaiten) during WWII. Plus, we’re supposed to check some pinnacles near the wreck to get fish population estimates. It’s our last day on Ulithi before we need to start packing everything, and there’s no time to repair the ROV, even if we had some power for the soldering iron. Never a group to give up easily, we develop a last-ditch plan. Using the tether and a 100 m transect tape in combination, we decide to turn the Ulithi ROV into a big underwater puppet. We may not have working thrusters or lights, but we do have working cameras, and with these two lines attached, we can raise, lower, and steer the ROV. At least in theory. In the afternoon, we hop in the boat with our disabled ROV and head out to the pinnacles and then to the site of the wreck. The pinnacles turn out to be too shallow to bother with the ROV. Snorkeling suffices to gather the fish observations. Then we move and after a bit of searching, we locate the stern of the wreck upside down in 130 feet of water. It’s a big ship (over 500 feet long), and its upturned belly is barely visible 70 feet below us. It’s impossible to anchor the boat directly over the wreck, so we use an Action Packer tote as a float and a carabiner as a pully to swim the battery box from the boat over to the wreck site and lower it right next to the wreck. While James holds the ROV near the wreck, Steve swims around with the tether tied to the front of the ROV to control the direction it’s pointing. It’s not elegant, particularly since neither James nor Steve can actually see the ROV that far down, but it works. Josh is watching the ROV video live on the TV and is able to guide James and Steve by voice commands. We experience a few delays, like the time the transect tape reel jams and the time the shark comes up out of the blue depths to eye James, but we get some reasonably good video of a sobering piece of WWII history.
Day 11: This morning we started cleaning and drying all the gear in preparation for packing. In the afternoon, we gave a final presentation to the village summarizing our findings during our 12 days on Ulithi. They seemed especially interested in the ROV’s underwater videos, which Josh had edited together into a presentation for them. All day, the villagers were busy preparing a huge farewell feast for us. That night there is much eating, singing, and socializing. Josh, James, and Steve, like many of the men in the village, wear their thus and the traditional headbands made of flowers and ferns. Quite the sight! Josh and Steve spent a good part of the evening chatting with the Chief of Falalop, learning about some of the opportunities and challenges they face, while James plays ukelele and guitar with the local kids. We will miss the wonderful people of Ulithi and this incredible place, but it will also be good to get home and see friends and family again. It’s really weird spending 12 days in a place that has absolutely no contact with the outside world. No TV, no radio, no phones, no newspapers, no internet. We wish we had gotten more ROV data, but we got enough to start a detailed analysis and — hopefully — to prepare for another, more productive visit in a year or two.
Day 12: Departure day. In the morning, we reluctantly make our way back across the island to the airport, which happens to double as the post office. Half the village is there to watch the plane land and take off. It’s the big event of the week. James is playing his Ukelele while some of the Ulithi kids sing along. A tiny white dot appears on the horizon. Soon we can hear the propellers, and a few minutes later, Amos is parking his plane. He walks into the building and switches from pilot to airport ticketing agent. Then he heads back out to the plane as the baggage handler and loads our gear. Next, he’s the flight attendant giving us our safety briefing. A few minutes later, we are airborne and headed for Yap, the first stop on a long journey home.