Projects > Doux de Coly 04 (June)
Survey dive
Latest update: June 28, 2004
Was this before the dive or was it afterwards? :-) This is is Hervé's special surface deco technique. And the Dopler test proved it worked!
I found in Sandro Madeo another volunteer to push the survey a little further. His predecessors were Ralph and Nick. These stories are available in the Coly 2003 reports. The current end of the surveyed line was at 1465 meters from the entrance. The plan was to use a 150 min bottom time in order to push it as far as possible.
On Thursday we prepared all the equipment: one forty meter rope to hang the
bottles in the shaft, four oxygen bottles (two for open circuit bailout),
four trimix 50/25 bottles (also two for open circuit bailout), two trimix
35/35 bottles, four trimix 18/65 bottles, six magnum Gavin scooters, some
reels with knotted line, a heating tube, some food and drinks.
In the second part of the afternoon we went away to place all this, except one 50/25 bottle and one magnum scooter each that we would need for the travel to the shaft the next day. Ralph was kind enough to take two oxygen bottles for me. After the dive, Sandro found that he had a leak in his brand new drysuit. It came from the newly installed P-Valve. Lesson learnt: do the installation yourself.
On Friday we all met in front of the chalets for breakfast and a briefing. It was agreed that Sandro and I would be the first RB team to go in since we needed the visibility to operate an efficient survey. Then Thomas and Götz would follow an hour later. We planned on having the first support team check on us three hours after our departure: 30 minutes to leave the shaft area, then 150 minutes of bottom time. Then a check every two hours would be enough.
Ralph helps Hervé. But where is Sandro? Somehow he managed to avoid all the pictures.
Everything went smoothly, except that Sandro was diving with his backup drysuit that did not have the heating plug. I also had to leave one of my scooters at the bottom of the shaft since it suddenly decided to not make contact when I pressed the trigger. That was ok though, we could afford one scooter failure. So after 25 minutes we were riding the deep tunnel with 2-3 magnum scooters and two stages each.
We relaxed and enjoyed the ride to the old end of the survey line at 1465 meters from the entrance. The cave goes from landscape to portrait, back to landscape and from sandy dunes to rock plates. It's like several caves in one. Most of the time the tunnel is about 10 meter wide. It makes for an easy side by side scooter ride. For the first kilometer, we did not really have to worry about which line was which. There are four of them down there and a cleanup should be organised. But as we neared the end of the knotted line I had to watch carefully so that we would not miss our starting point.
We did find it right away but unfortunately the dive was not as productive as I hoped. We did a lot of bottom time for only 200 meters added to the survey. Sandro was laying the line and I was doing the survey at the same time. We were delayed by a scooter from Sandro that was slow and had to switch. Then came the reel jamming. With patience we resolved that one too. That's the nice thing about rebreathers. We have plenty of time. And then to wrap it all up, I knocked my manifold on the ceiling and triggered some rather forceful leak. There we were one mile back in the cave with a rapidly forming cloud of ceiling silt dislodged by my manifold's leak. Sandro was very fast on this one: he literally jumped on me and closed my isolation valves. He was extremely fast. Much faster than I could have been doing it myself. That proves again the efficiency of the buddy system. Then he explained what was leaking: just the manifold. That meant that I still had access to both my backgas tanks, both in open circuit and in rebreather mode. Not a huge issue then, but time to think about wrapping up the dive.
This was after a dive that lasted a bit more than 7 hours. Hervé switches off his heating tube that kept him nice and warm during the four hour deco.
The way back was uneventful, except that it was my turn to be very slow on the scooter. After a few minutes of trying to fix the problem on the fly I finally signalled Sandro and stopped. I unclipped the reels, stages and scooters and clipped everything back on. And of course the problem was gone. It took us 50 minutes of scootering to reach the shaft, so spending 2 minutes fixing something causing some serious slowing done is not only more efficient but also safer since too much drag could end up causing a scooter failure.
Decompression was uneventful and boring. We had 4 hours of it. Sandro was cold since his backup drysuit was also slightly leaking at the P-Valve, but he had very good underwear that enabled to make it through without shivering. We were visited several times by the support teams that brought us some hot tea and took away unnecessary gear from us.
We came out of the water after 7 hours and 15 minutes of immersion. Both Sandro and I thought that we were getting close to the limit that can be done safely without habitat. Nevertheless, we should do the same bottom time again in August and try to cover more ground.
Next on the list: get some diner, clean up the gear and start preparing the presentation.