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I won't say that this was a particularly close call. From the outside, it was quite undramatic. However, it definitely was something I learned from.
The other day my club arranged a night dive at a site where a certain species of deep water fish often is seen at rec depths at this time of the year. Conditions were not too bad, except the weather wasn't particularly good. THere was no wind, but we had a bit of rain. We've had a bit of snow, rain and wind lately, and both the ground around the site and the bottom at the site is fine clay, so the shallows were totally silted up. To add to the viz situation, we were at low tide. The viz was less than 1m (3ft).
We were pretty certain that the viz would improve further out and deeper down, so we decided to do the dive. Since we had dived the site before, we were certain that we had a hard bottom at reasonable, i.e. OW limit, depth where we chose to descend. Descending through the fog wasn't particularly stressful, but it was a bit weird that the only sensations we had was the increasing suit squeeze, the pressure in our ears, the glow of each others' lights and the silt particles traveling upwards relative to us. Almost psychedelic. The bottom came a bit abruptly at 15m (50ft), so although we didn't slam into it we weren't able to avoid some silting from our fins. After checking the compass and the bottom slope, we slowly started finning outwards, looking for the species we had come to see. As expected, viz improved noticeably, and soon we had some 5-8m. Not particularly good for this time of the year, but not too bad either. And more than good enough for a night dive. At about 20m (65ft) we spotted one of the fish we had come to see, and while we followed it slowly I started shooting. I got some decent shots, including one with my buddy in the background, but as I started to hug the bottom to get a better angle, I of course silted out the place royally. Even though I didn't use one single flutter kick, but only frog kicking. Still no reason for alarm, since we were moving away from the cloud.
We had agreed on a max depth of 25m (80ft), with a 30m/100ft contingency in case we spotted something cool below us while were close to the planned max. We're both fairly regular divers, I have somewhat more than a hundred logged dives, my buddy has just a little less than a hundred. Because of our regular diving we know from experience that we're both somewhat susceptible to narcosis and take this into consideration when we plan our dives. So the 25m planned / 30m contingency is a very normal depth plan.
My first mistake that precipitated the situation was when I thought that we'd followed the fish for long enough and that we should leave it alone to go looking for another. Our predetermined course would take us straight through the silt cloud I'd created, but I didn't see a problem with that. I was pretty certain that the cloud was of limited size, so in my opinion we could just go through it. We were at ~22m (72ft), so we were still above our agreed max depth. My buddy didn't quite see it the same way I did. When I grabbed his arm to stay in contact and just started off through the silt cloud, he became apprehensive. His breathing rate started to go up, and he was getting closer to hyperventilation. This was something I didn't notice. Strike two. The bottom sloped a little more than I was aware of, so when I saw a clearing in the silt and let go of his arm, we were at 26m. Slightly deeper than planned max, but well within contingency limits. Strike three. Since I was leading and had my camera in one hand and my buddy's arm in the other, I wasn't aware we had exceeded max depth slightly, but since his only task had been to follow my course he had monitored our depth closely. His apprehension got a bit out of control, and he started to freak out. His breathing rate might well have contributed by causing CO2 retention, but anyway he self-diagnosed a dark nark. At about 26m, I was probably starting to become slightly tipsy myself, and I was task loaded enough, so I didn't quite get his signals (index finger rotating at temple, flat hand diagonally upwards, i.e. "I'm narked, let's ascend somewhat"). Whether I was dense or his signals weren't clear enough is something we'll never know. He of course got frustrated at me not "getting it", so he wrote "dark nark" on his slate instead of ascending and forcing me to follow him. Strike four, because in his state, his buoyancy control wasn't as good as it should be and he could feel himself sinking a little (perhaps about 1m) while writing. At this point he was really freaking out, but he had enough self-control to keep from bolting. Finally I got it, we started finning upslope, and back at 22m (72ft) he was fine again. The rest of the dive was nice but uneventful, and we never got to see a second one of the fish we were looking for.
After the dive we had our usual post-dive chat, recounting our experiences and comparing our different perceptions of the situation. This cleared up the misunderstandings we'd had underwater, and I was pretty shocked to hear how close he had been to full-blown irrational panic. We both agreed that there was no environmental danger in that situation. We had a hard bottom shallower than our contingency depth and even shallower than our MOD, our nitrogen loading was very low (we had had some 10-15 minutes' bottom time, and we were both on EAN32), and there was no current whatsoever. OTOH, if my buddy hadn't been able to contain his growing anxiety and act rationally, it could have gotten ugly. Panic and bolting to the surface from >25m carries, IMO, an unacceptable risk for an embolism.
Lessons learned, for both of us:
The other day my club arranged a night dive at a site where a certain species of deep water fish often is seen at rec depths at this time of the year. Conditions were not too bad, except the weather wasn't particularly good. THere was no wind, but we had a bit of rain. We've had a bit of snow, rain and wind lately, and both the ground around the site and the bottom at the site is fine clay, so the shallows were totally silted up. To add to the viz situation, we were at low tide. The viz was less than 1m (3ft).
We were pretty certain that the viz would improve further out and deeper down, so we decided to do the dive. Since we had dived the site before, we were certain that we had a hard bottom at reasonable, i.e. OW limit, depth where we chose to descend. Descending through the fog wasn't particularly stressful, but it was a bit weird that the only sensations we had was the increasing suit squeeze, the pressure in our ears, the glow of each others' lights and the silt particles traveling upwards relative to us. Almost psychedelic. The bottom came a bit abruptly at 15m (50ft), so although we didn't slam into it we weren't able to avoid some silting from our fins. After checking the compass and the bottom slope, we slowly started finning outwards, looking for the species we had come to see. As expected, viz improved noticeably, and soon we had some 5-8m. Not particularly good for this time of the year, but not too bad either. And more than good enough for a night dive. At about 20m (65ft) we spotted one of the fish we had come to see, and while we followed it slowly I started shooting. I got some decent shots, including one with my buddy in the background, but as I started to hug the bottom to get a better angle, I of course silted out the place royally. Even though I didn't use one single flutter kick, but only frog kicking. Still no reason for alarm, since we were moving away from the cloud.
We had agreed on a max depth of 25m (80ft), with a 30m/100ft contingency in case we spotted something cool below us while were close to the planned max. We're both fairly regular divers, I have somewhat more than a hundred logged dives, my buddy has just a little less than a hundred. Because of our regular diving we know from experience that we're both somewhat susceptible to narcosis and take this into consideration when we plan our dives. So the 25m planned / 30m contingency is a very normal depth plan.
My first mistake that precipitated the situation was when I thought that we'd followed the fish for long enough and that we should leave it alone to go looking for another. Our predetermined course would take us straight through the silt cloud I'd created, but I didn't see a problem with that. I was pretty certain that the cloud was of limited size, so in my opinion we could just go through it. We were at ~22m (72ft), so we were still above our agreed max depth. My buddy didn't quite see it the same way I did. When I grabbed his arm to stay in contact and just started off through the silt cloud, he became apprehensive. His breathing rate started to go up, and he was getting closer to hyperventilation. This was something I didn't notice. Strike two. The bottom sloped a little more than I was aware of, so when I saw a clearing in the silt and let go of his arm, we were at 26m. Slightly deeper than planned max, but well within contingency limits. Strike three. Since I was leading and had my camera in one hand and my buddy's arm in the other, I wasn't aware we had exceeded max depth slightly, but since his only task had been to follow my course he had monitored our depth closely. His apprehension got a bit out of control, and he started to freak out. His breathing rate might well have contributed by causing CO2 retention, but anyway he self-diagnosed a dark nark. At about 26m, I was probably starting to become slightly tipsy myself, and I was task loaded enough, so I didn't quite get his signals (index finger rotating at temple, flat hand diagonally upwards, i.e. "I'm narked, let's ascend somewhat"). Whether I was dense or his signals weren't clear enough is something we'll never know. He of course got frustrated at me not "getting it", so he wrote "dark nark" on his slate instead of ascending and forcing me to follow him. Strike four, because in his state, his buoyancy control wasn't as good as it should be and he could feel himself sinking a little (perhaps about 1m) while writing. At this point he was really freaking out, but he had enough self-control to keep from bolting. Finally I got it, we started finning upslope, and back at 22m (72ft) he was fine again. The rest of the dive was nice but uneventful, and we never got to see a second one of the fish we were looking for.
After the dive we had our usual post-dive chat, recounting our experiences and comparing our different perceptions of the situation. This cleared up the misunderstandings we'd had underwater, and I was pretty shocked to hear how close he had been to full-blown irrational panic. We both agreed that there was no environmental danger in that situation. We had a hard bottom shallower than our contingency depth and even shallower than our MOD, our nitrogen loading was very low (we had had some 10-15 minutes' bottom time, and we were both on EAN32), and there was no current whatsoever. OTOH, if my buddy hadn't been able to contain his growing anxiety and act rationally, it could have gotten ugly. Panic and bolting to the surface from >25m carries, IMO, an unacceptable risk for an embolism.
Lessons learned, for both of us:
- Your buddy may be more stressed than they appear, so keep that in mind when you experience conditions that are out of the normal. Monitor your buddy closely.
- If you're holding on to your buddy's arm to stay in contact in near-zero viz, don't just let go the second you think you see an improvement. Make sure you both agree on ending physical contact.
- If you're getting stressed and notice your breathing rate going up, communicate this to your buddy ASAP instead of trying to "tough it out".
- If you're not comfortable with the situation, take command and get both of you out of that situation before trying to communicate what's wrong.
- And finally, don't hesitate to thumb the dive if things just don't feel right. The ocean will be there tomorrow, the day after, next year. It'll be there even when we're busy pushing up the daisies.
