A Chamber Dive to 165ft "Depth"

We met last week in the physics building on upper campus of UCT. The objective: to simulate a very deep dive (to a depth of 50 meters, or 165 feet "underwater") in the Research Dive Unit's decompression chamber. This would also simulate the effects of nitrogen narcosis, or what they call the "martini effect" or "laughing gas effect" when deep diving. More on that later. My regular diving buddies were also in attendance, ready to do a dive of a different sort this time. One where you didn't have to drive to Simonstown or spend large amounts of time filling cylinders and getting kitted up.

Now, this type of chamber is usually meant to treat people with decompression sickness, or "the bends". If someone surfaces too quickly, the compressed nitrogen in their cells can expand too quickly and cause big problems. A person is then placed back in the chamber to re-pressurize them.

It's safe... climb in.

I was a little worried before we got in. The old man, Paul, made sure we didn't bring anything into the chamber. The extreme pressure is such that even a fault in a diamond ring could cause it to implode or break at depth. I couldn't bring my camera with me, and to be safe took everything out of my pockets. He also said that the depths and time, although conservative, have caused problems for some people. The majority of the dives go fine, but the problems come from people that "aren't normal" and don't say they aren't. Like people that have had surgeries, don't like small spaces, or whatever else. But what an intimate and scary question... "Am I normal?" Will I die in this little pressurized tube? I tried not think about it. He also warned that you'll need to equalize your ears very frequently, because the pressure changes fast. The warning was simple: "equalize your ears before things get very bad, so that your ear drums don't burst." We were also provided with a rubber mallet to hit against inside of the chamber if there was a problem, and he spoke vaguely about firefighting equipment in case there was a fire. I was thinking about other things at that moment.

Getting ready to load in.

The inside of the chamber, through one of the little windows.

The space wasn't that large, as your can see in the photo. It was also pretty dark until small lights were turned on. Six of us climbed in, shuffling around, pressed against one another, as they shut and sealed the huge steel hatch door. They first lower you slowly to the first 10 meters, by pumping air inside the tank to pressurize it. This first stage goes more slowly, since most problems that people experience will happen during this time. Indeed, one in our group had a problem equalizing the pressure on her ears (similar to what you do when going through the mountains), and it was starting to get painful. So we surfaced, let her out, and went back down.

You can see me equalizing as we descend.

Typically when you dive, you equalize your ears every 20 seconds or so, as you descend to greater depths. We were pumped down to the full 50m/165ft over the course of only two minutes, so you need to equalize once per second or more. It is difficult to also breath air when going this quickly, because if you stop to take a deep breath you can feel the pressure building up on your ears. So I just kept blowing out of my ears and taking quick deep breaths every once and a while.

But, we made it to the bottom. This is where nitrogen narcosis comes in, or "being narced". It is where the nitrogen that builds up in your cells and your blood steam reaches your brain and releases endorphins. It makes divers feel drunk underwater, and can make them do silly things like swim off alone or think they can breathe without their regulators. It is controllable, though, since going up makes it go away and there is no hangover or after-effects. We immediately felt so drunk at the bottom that the slightest humorous thing had everyone in the chamber laughing uncontrollably. And at a depth of 165 feet, the air is so pressurized that everyone sounds like they are speaking through pure helium... voices are actually that high. Which is simply hilarious! Needless to say, we laughed a lot, and any anxiety that I had before was long gone.

Narced.

At the very bottom, the pressure is six times what it is at the surface. This also means that you breath 6 times the amount of air to fill your lungs to capacity. We stayed at 165 ft for about 10 minutes, and then ascended very slowly over the next half hour or so. To test the air compression concept, we blew up two condoms at the very bottom, and watched them grow larger and larger as we rose to the surface. By the time we got to the surface, the condoms weren't six times their original size, but a lot larger.

Safety stops were observed at 10 meters and 3 meters, I believe, to be sure we didn't ascend too quickly. Even though it is sort of cramped in there, you're supposed to make sure you don't cross your legs or anything, to aid in blood circulation. It gets sort of cold as you go up, also. I'm not sure why but mist began to form as the pressure decreased, and it got chilly. Luckily, I brought my winter hat and my UW Homecoming sweatband.

Emerging from the deep, like a gila monster!

We were told that decompression illness could still develop over the next few hours, and it would be prudent not to drink very much or take hot showers. Tempered by water, though, we went to the UCT graduate bar and had celebratory beers!