Monday, July 14, 2008

UST Sea-bed Mapping

Over two days, we were to map the sea-bed outside UST. Five buddy teams were to complete three dives per day, swimming along a grid of lines in the water. Every 10 meters, they were to record the depth, substrate, wildlife, etc. So far the theory, the practical aspects were significantly more messy.

First, I had difficulties in finding divers, especially well trained ones. I do have have great scuba friends, like Mark, Martin and Ken, but this is not sufficient to staff such a large endeavor.

Second, seemingly simple things, like placing a straight line of rope in the water, can become quite a challenge.

In the end, I spent better half of Saturday morning laying out one single line (the mother line) pointing due-north of the little platform next to UST's pier. We quickly gave up on the idea of laying out more lines, for divers to follow. Especially, since we noticed that a line, once on the ocean floor, is impossible to move, as it gets too easily caught on small rocks.
Hence, we devised a simple scheme, in which divers follow a compass course, parallel to UST's pier. Every buddy team has a rope of 10 meters, each holding onto one end. One diver sets the compass course, and as soon as he stretches the line, the second divers follows. When the divers thus meet again, the second diver takes notes of the sea floor, while the first immediately sets out for another 10m route.
Instead of taking notes by hand, divers would photograph their computer and the sea floor, thus recording the environmental conditions.

We managed to get about two dives per team on Saturday, and three on Sunday. Because we only had about three teams per day, we had to space divers further, and essentially ran dives in a distance of about 20 meters. Yet, the sea floor outside UST is relatively smooth, and we gained a decent understanding of the conditions.

I had borrowed a large jet-ski from my friend Notes, whom I must have asked on one of his particularly generous days. So while everybody else was diving, I spent the entire day on the jet-ski, dragging divers to their initial positions, and back to the pier. Moving at walking speed, I was significantly bored, and my heart bled, for I was not scuba diving. Baking in the wet-suit, I suffered a minor heat stroke on Saturday, and on Sunday wore shorts only. Despite the clouds and occasional shower, I then gained a significant sunburn.

Finally, on Sunday, Harvey took over the ski for half an hour, so I could get one single dive myself, buddying with Ajay. Starting from the most northern buoy, we witnessed various conditions, from silt, to rocks, to sand, to rocks, and back to sand. Several large crabs, two octopuses, a moray, and several large sand-eels. Unfortunately, no sight of the rays that some of the other divers had seen. Still, after a long day on the jet-ski, the dive was a big relief.

Now, its up to Ajay and me, to make sense of the photos taken and data gathered during the day.

Your correspondent, preparing to drag divers out

Mark, in between dives




Mark, Harvey, Bassey, and Bill

Octopus, by Ajay and me

Large stingray, buried in sand, by Harvey and Mark

Mooray, by Ajay and me

Sand Eel, by Ajay and me