THURSDAY, 04.30.09

0703: Days 21 (Cont’d), 22 & 23 (April 27-29)
Quite a bit going on, so let’s go to the board. On April 27, we recovered three Deep Ocean Transponders (DOTs) in the C columns and the one stepchild DOT, still on the bottom over in the A boxes. We then transited to the E boxes and deployed five DOTs, surveyed three in and readied the equipment for launch. Mary Ann went in at 1946 and Ginger went in at 2239. Mary Ann went to depth and started working, but Ginger got down to about 500 meters and suffered yet another EdgeTech re-start (where the sonar stops communicating with the vehicle, the vehicle re-starts its mission, but the EdgeTech logging does not re-start). This is an ongoing and intermittent issue, and we are still working with EdgeTech and Hydroid to resolve.

We recovered Ginger at 2319, grabbed her files to send them to EdgeTech and Hydroid, and readied her for another launch. During her next launch while still on the surface, we saw the re-set condition happen again — except this time the vehicle and the logging DID start up the way it was supposed to. This just after an aborted mission where it did not perform as expected. We pulled it back out of the water to grab THAT log file to further help us explain this inexplicable condition, which we have been unable to replicate on the surface. She was then launched at 0114 on the morning of April 28.

We then headed south and dropped two more DOTs, surveying three in. Around 0840, we were back on station to track the vehicles. At 1801, we recovered Mary Ann with good data and at 2012, we got her back into the water. At 2200 that same evening, Ginger came back up. We found she again, inexplicably, had changed her range scale to 338 meters (don’t even ask, we have no idea). This one has us flummoxed. We’ve never even set the vehicles to this scale. The number is just so weird, where did it come from? We could find nothing wrong. We checked the vehicle log files and found that if we dug deep enough there was a way for us to “see” this on the surface before we launched the vehicle. When the vehicle magically switched ranges this changed the ‘wave form’. The wave form is basically the power level, frequency and amplitude that the sonar transducer is using, the wave form determines the range. We then created a new pre-launch check to confirm the wave form before launching. No understanding, but at least a way to prevent it. We suffered a productivity loss though; at 328 meters, the vehicle did not fully cover the grid, so we had to run it again. That’s a lost day on one of the girls. If we want to finish the C boxes before we leave (and we do), we cannot afford more of these.

We got Ginger back into the water at 0230 on April 29. We then did a net trawl at 1500 meters for one hour, deployed a DOT, surveyed three others in, and recovered Mary Ann at 1846. Her data was good, but no targets. She did have an issue with her drop weight (ascent weight) and so we replaced her ascent weight solenoid. At the same time, we found a very small set screw was not fully set. That took a couple hours. We put her back in at 2209 and then recovered Ginger at 2316, a pretty tight tolerance. We just got Ginger back in the water right around 2:30 a.m. this morning.

I had a little chat with all the teams today at the noon changeover, reminding them that we are in the final stretch and that any failures or operator errors are really going to stand out. I asked them all to be extra diligent and to keep paying attention to details. Many of us have been out here going on three months, and we’re a bit tired. I still think this mission has every chance at finding its target and — given that we have had 100 consecutive vehicle dives and covered close to 1,700 square miles — it’s already a hell of an accomplishment. Now we just need the lady to show up for the last dance.

Oh yeah, it’s also raining like cats and dogs out there. Glad I’m in something watertight. Cheers.