Day 5: June 13
The day started tranquilly. We left the hotel at 6:30 AM and headed for Mhoon Landing where we’d take the runner
boat south to the Strong to begin the day’s next survey leg. We were concerned days before about the tow depth of the Chirp in the water. We were uncertain how it was riding through the water as it is towed under the murky
swirls of browns where the river’s demands are hidden from observation. The streamer was in the same boat (excuse the pun). Last year the streamer was likely not riding high in the water and got caught on
a “planter” (a tree stuck in the mud hidden under the water), wrapping itself around
the roots and ultimately lost forever.
To gain insight into the depth at which these instruments of research ride beneath
the water, we installed pressure transducers that are often used to measure ground-water
levels in wells onto the devices. The transducers would record the water depth every 10 seconds throughout the day. But before we get to the exciting results, let’s talk about my first sentence of
this day. Now anyone who begins the blog by saying the day “started” tranquilly has a story
to tell, right?
As many in the Mid-South know, we had a little sprinkle today. Okay, it was a torrential downpour. We had a drenching rain that, like a waterfall, fell straight down and horizontal
rain that pummeled us. The Strong clocked winds at 75 mph. Another vessel on the river recorded 78 mph winds. I thought at one point the Harvey Pete’s shed roof (side barge from where we deploy
the streamer and energy source) was going to be ripped off. I was looking for falling green leaves. If a tornado crosses the river, it will carry with it green leaves from its destruction
of the forest along the river’s banks. It would be the visual siren to get inside fast. We held fast in the river, trying to catch glimpses of Dolly who seemed to be having
fun dancing among the swells. She’d swing left, she’d swing right, she’d disappear. Please let’s not loose the streamer!
After an hour the rain subsided and the winds subdued. We reinitiated our downriver drift toward Helena.
At the end of the day, the transducer data was pulled. The Chirp averaged ~3-4 ft below the surface except during the storm where it rose
closer to the surface to within 1 ft. The streamer depths were quite interesting. On average it was suspended 9 ft below the surface. We’d like for it to be between 3 and 6 ft. In some instances it went as deep as 20 ft. Not good. We’d have to address that somehow. During the storm it rose to the top within 1 ft of the water surface. That was most likely due to us holding our place in the river with the Strong thus
causing Dolly to be pulled more strongly downriver due to it receiving the full current
of the river. Normally we drift with the river’s current with only a slight push by the Strong
up river to lessen our speed to only an equivalent 2 mph over land.