I know this is a cave diving story, but I'm putting it in Basic Scuba because the lesson involved is relevant to all diving.
Several days ago, I was diving a cave in Florida. The plan for the dive was to follow the main line of the cave, which runs along a shallow corridor, and then follow that line down through a fissure to a deeper section of cave (approximately 100 feet). This line runs around a loop, and ascends through another fissure, to return to T into the mainline at the first fissure. (So it's a closed loop -- if you keep swimming, you end up where you started.)
Part of the plan was to put in a jump for a brief foray down a side tunnel. In cave diving, when you leave the main line to go onto a side line, you tie a spool into the mainline and run it to the side line, so that you have a continuous line to your exit. You also mark the exit side of the intersection you created, so that when you come back out, you know which way to turn to go home. I am not only compulsive about this marking, but I insist that EVERY member of the team mark the intersection, not just the leader, so that everybody on the team knows that we turned there, and has to think about which way we turn to go home.
On this dive, we got to the jump, and the leader put in the spool (as is normal practice). I watched him do it, and then we all swam into the side tunnel. Not only did I not mark the intersection, I didn't pay any attention to whether anybody else did, either. My husband, who was behind me, thought it odd that I didn't place a marker, but he didn't put one down either, because it didn't MATTER which way we turned when we came back. Either would take us home, and going forward was actually shorter than going back (and we knew that, from the distance markers, and I had dived the cave before, as had the leader).
At any rate, when my husband commented on this after the dive, I was horrified. I have had situational awareness problems in the past, but I have never, ever failed to mark an intersection -- I've never even had to remind myself, or be reminded by anyone else. This is just not something I forget.
When I last dove in Florida, I had problems with perceptual narrowing in the deeper section of cave, but I thought a lot of it was exertion and CO2, as well as sleep deprivation, stress, and poor morale. I felt confident that on this trip, well rested and comfortable, and in low flow, the problem wouldn't recur.
But it did. And my point for telling this story is that I didn't feel drunk, I didn't feel woozy or anxious or anything at all that would tell me that my brain wasn't working the way it should be. The only evidence is that I made a mistake I simply haven't ever made before, and it was an important mistake.
The (expensive) lesson I learned is that I will no longer dive deep Florida caves without helium in my breathing gas. I am too stupid to be safe at 100 feet without it. And the lesson for the rest of you is that you don't necessarily need to feel any different at all to be stupid at depth. You can manage your buoyancy and your equipment and your navigation, but still miss things that are important. Don't underestimate the effects of nitrogen!
Several days ago, I was diving a cave in Florida. The plan for the dive was to follow the main line of the cave, which runs along a shallow corridor, and then follow that line down through a fissure to a deeper section of cave (approximately 100 feet). This line runs around a loop, and ascends through another fissure, to return to T into the mainline at the first fissure. (So it's a closed loop -- if you keep swimming, you end up where you started.)
Part of the plan was to put in a jump for a brief foray down a side tunnel. In cave diving, when you leave the main line to go onto a side line, you tie a spool into the mainline and run it to the side line, so that you have a continuous line to your exit. You also mark the exit side of the intersection you created, so that when you come back out, you know which way to turn to go home. I am not only compulsive about this marking, but I insist that EVERY member of the team mark the intersection, not just the leader, so that everybody on the team knows that we turned there, and has to think about which way we turn to go home.
On this dive, we got to the jump, and the leader put in the spool (as is normal practice). I watched him do it, and then we all swam into the side tunnel. Not only did I not mark the intersection, I didn't pay any attention to whether anybody else did, either. My husband, who was behind me, thought it odd that I didn't place a marker, but he didn't put one down either, because it didn't MATTER which way we turned when we came back. Either would take us home, and going forward was actually shorter than going back (and we knew that, from the distance markers, and I had dived the cave before, as had the leader).
At any rate, when my husband commented on this after the dive, I was horrified. I have had situational awareness problems in the past, but I have never, ever failed to mark an intersection -- I've never even had to remind myself, or be reminded by anyone else. This is just not something I forget.
When I last dove in Florida, I had problems with perceptual narrowing in the deeper section of cave, but I thought a lot of it was exertion and CO2, as well as sleep deprivation, stress, and poor morale. I felt confident that on this trip, well rested and comfortable, and in low flow, the problem wouldn't recur.
But it did. And my point for telling this story is that I didn't feel drunk, I didn't feel woozy or anxious or anything at all that would tell me that my brain wasn't working the way it should be. The only evidence is that I made a mistake I simply haven't ever made before, and it was an important mistake.
The (expensive) lesson I learned is that I will no longer dive deep Florida caves without helium in my breathing gas. I am too stupid to be safe at 100 feet without it. And the lesson for the rest of you is that you don't necessarily need to feel any different at all to be stupid at depth. You can manage your buoyancy and your equipment and your navigation, but still miss things that are important. Don't underestimate the effects of nitrogen!