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Starting the IDC Prep Course, And the Map Project

The Divemaster training is wrapping up now. The last two items remaining to be done are to turn in the map for our mapping project, and demonstrate a certain mastery of the various skills required to become a SCUBA diver. This is something called a “Skill Circuit” and consists of about 20 skills, though during the actual circuit, its possible that some skills might just be combined. During a practice session today, I did quite well in general, but we’ll see how things go in the future.

The mapping project is a bit dissappointing for me. The goal was to map out the engine room of the Kood, a landing transport ship sunk as an artificial reef not too long ago. The engine is not in the engine room any more, but Andy, Dan, Nathan and I were instructed to map out the area around and inside the engine room.  I’m not that satisfied with the way things have gone though.

Our first mapping dive, Dan and Nathan were paired up, as were Andy and I.  Andy and I had our wreck specialties, which would allow us to go inside the wreck. However, Dan didn’t stay with Nathan, who came to us and said that he had lost Dan. Unlike in shallower dives, where it is easy to ascend to the surface and wait for your buddy, at 30 meters, ascending would basically end the dive completely. So Andy and I helped look for Dan, but ran out of time and air to do anything. So we all surfaced together.

Then not a lot happened. We didn’t go to the wreck, and I had to complete additional certifications like Search and Recovery, so our next attempt was with Meg, if I recall correctly. We went down to the wreck with a tape measure, and tried to make some measurements. However, we ran into some problems. 1st, I found that I was so neutrally boyant, I didn’t sink, and  thus, it became very difficult to move around inside the wreck without stirring up silt. I can dive with no weight actually, and normally, on a wreck dive, I dive with just a little weight, and thus, I don’t need to add air to my BCD when at 30 meters. But I discovered that its just a bit better to have some extra weight when inside the wreck. Another problem is that the engine room is around 10 meters wide and long, so you can’t see your buddy, or even their dive light really. Signalling is done by tugs on the tape measure, and this was another problem. When you needed to see how much was played out, you might just see “60” (centimeters). However, in order to see which meter marking you were at, (say, 10 meters, 60 CM) you’d have to play out additional line to get to the next meter mark. Annoying. A final problem is that the batteries on my Ikelite torch were running low, and this caused the LED lights to flicker like a disco strobe. It was very difficult to see with this effect. And then I dropped my dive slates. It was time to come up, so I grabbed one of the slates, left the rest since I couldn’t get to them, switched to my smaller backup light to find my way out of the wreck and surfaced.

At 30 meters, many divers will find that they have more than enough air. The factor that limits the dive time is how much nitrogen the body absorbs. At the surface, the body has a certain amount of nitrogen in it. Under pressure, additional nitrogen is forced into body tissues, and if you stay down too long at depth, you’ll end up with so much nitrogen, you can not ascend directly to the surface. If you try it, the nitrogen will form bubbles, much like coke that is opened after being shaken. These bubbles may kill you. Divers with special training and equipment can stay down longer, but they make stops on the way up for varying amounts of time to allow the nitrogen to exit the body safely. However, such “decompression stops” are beyond the scope of normal recreational diving, and in fact, are only used by normal divers in an absolute emergency.

I did have one tool up my sleeve that could extend the time in the wreck. Normal air has about 79% nitrogen, and 21% oxygen. I am qualified to use EAN Nitrox which is an air mixture containing more oxygen than normal air.  For my desired dive, I wished to use EAN 32, which would allow me to stay on the wreck for around 20-25 minutes rather than the usual 10-15 minutes.

The only problem was, I basically could only go down with Andy. I needed someone who had the wreck specialty (probably about half the interns) the Nitrox specialty (basically just a couple who had both) AND had nitrox tanks that they could use (basically, only Andy had all three requirments.) Nitrox tanks cost $10 to dive with them, and only certain interns had free tanks to use. Nobody else wanted to pay for the tanks. The final two hurdles were whether or not we were even going to the wreck, and would Andy be on the boat.

Additionally, would AQ bother to give us the tanks when we requested them: AQ has a nice attitude of “we’ve got your money, so we can’t be bothered to serve you.”

Somehowe the stars all alligned and I had the nitrox tanks, but the water was too rough to safely dive the wreck. I had even gone so far as to set my dive computer to handle the special mixture. It was a couple of days later before I could dive the wreck with the Nitrox.

Andy and I descended. I of course wished to drop to the the bottom as quickly as possible, but Andy had some trouble with his ears. We entered the engine room and went to work measuring out things. Our idea was to use our noise makers to signal each other, but it appeared that they couldn’t be heard. Nitrogen at depths around 30 meters and greater has a narcotic effect, but the thing is, this effect, similar to having a drink or two, doesn’t affect all divers the same way and might affect the same diver differently from day to day. It seemed to me that Andy  was “narc’d” on this dive though. He was slow to respond to signals, and gave odd signals in response rather than the more common signals. Instead of swimming in a straight line directly to the opposite wall, he went off at an angle, through obstructions, and into the corner, rendering one measurement useless.

To be fair though, he might have been confused by his computer which was new. This one had a wireless transmitter on the tank which allowed Andy to see exactly how much air was in his tank by looking at his computer. Normally, we must look at a seperate guage to see this. Andy ran out of air much faster than he anticipated and he thought it might be a computer problem. This was a dissappointment for me. I figured on this dive, we’d run out of air and nitrogen time about the same moment, but in this case, Andy ran out of air so quickly we might as well have been on regular air. All the waiting and special gas mixtures were for naught.

At this point the plan to carefully draw out a measured engine room was abandoned. Instead, we just went down there and just sorta eyeballed it and used arm spans. This is reasonably accurate but no longer would be be drawing every guage and pipe in the room.

Tomorrow the map will be turned in, and hopefully, we’ll all be signed off.


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