Nitrogen Narcosis

The Rapture of the Deep

DCIM100GOPRODeep diving is something that I am passionate about – especially if it involves a shipwreck. It is a chance for me to push my skills, training and equipment and to explore some of the lesser dived or known sites. However this comes at a considerably higher risk which involves specialised training and equipment to manage safely. One of these risks is Nitrogen Narcosis – aka “the rapture of the deep”. Not a lot is known about the causes of nitrogen narcosis, but it is a narcotic effect brought on by the increased partial pressure of nitrogen in the breathing gas at depth. The threshold for nitrogen narcosis is different for each diver and can even vary dive-to-dive within a diver, depending on many factors. I usually enjoy getting a little “narc’d”. It can be quite euphoric and enjoyable if managed well. Nitrogen narcosis itself is not dangerous, unlike decompression illness, and there are no long lasting effects – no nasty hangovers. What can be dangerous though is the impaired actions of the diver experiencing euphoria. It’s essentially diving drunk. Nitrogen narcosis, like other narcotics can also present as paranoia and confusion which can lead to panic. Bad news in any depth of water. Thinking about these effects, I thought I’d share a story I wrote about a dive many years ago where I was overcome by narcosis paranoia in the hope that others can learn from my bad experience. This dive was a huge learning experience for me and still serves as a source of healthy anxiety before a deep dive. Nitrogen narcosis is not something that can be (nor should be) avoided, but it is certainly something to be aware of.

Before I get into the story, I should also make a quick note about solo diving. This practice is often frowned upon in diving circles and I do agree that diving with a buddy significantly reduces many risks associated with diving. However, I also believe that with proper training and additional equipment, many of these risks can be minimised and solo diving can be conducted reasonably safely. The training that I have done to enable me to dive outside the recreational limits had a special focus on redundant equipment and self reliance in emergency situations. I personally find solo diving to be quite relaxing and enjoyable, but only because I take the necessary precautions when I do it (which isn’t often).

When 3 things go wrong…

“If you turn right when you get to the anchor you’ll see the boiler. Then if you go left from there, you’ll get to the stern section” said my buddy.

“No worries. Too easy”. I think to my self.

There are some days when you really should just stay in bed. I was gearing up to dive a wreck off Sydney. It was one of those magic days on the water, with the sun newly risen and barely a whisper of a breeze to ruffle the smooth surface of the ocean. Unfortunately this magic had been marred by the realisation on the trip out that I’d left the undergarment for my dry suit laying on the back seat of my car. Idiot! This was to be the least of my troubles on this dive. As I was gearing up, to my horror I discovered that my fins were no where to be seen. They too were laying in the boot of the car along with my ankle weights. The ankle weights didn’t really concern me, but without my fins I was resigned to being the boat boy. Shit! how could I forget my fins! The undergarment and ankle weights were no big deal, I could get by without them, but my fins! You Idiot! I cursed my self again.

My buddy has said on many occasions “when you have 3 things go wrong on a dive, any 3 things at all, call it off”. Hmmmm, fins, ankle wights, undergarment…. I should have taken that advice.

The two others on board rolled over the side and descended onto the wreck 50 m below. I watched them disappear into the inky blue depths. 20 minutes later my buddy reappeared on the surface. He was diving in a wetsuit and was getting cold so had called his dive short. He climbed back on board raving about the excellent visibility and the fish life. He suggested I take his fins and go check out the wreck. It didn’t take much to talk me into it, although I could hear his words (spoken to me so many times) going through my head “when 3 things go wrong….”. But I couldn’t resist. I had gotten up early and made the trip out here and I was grateful to him for the offer of his fins, giving me the opportunity to explore this wreck that I’d heard so much about.

So I turned on the air for my two back mounted tanks, checked my gauges and climbed into my harness. As I was attaching my stage tank (a 3rd tank containing a Nitrox mix to reduce the ascent time) my buddy described the layout of the wreck to me.

“If you turn right when you get to the anchor you’ll see the boiler. Then if you go left from there, you’ll get to the stern section”.

I was so excited by this stage as this was my first time on this wreck and the conditions couldn’t have been better.

“What bottom time are you going to do?” He asked me.

“I’ll just do 10 minutes” I replied, feeling safe in the knowledge that I’d previously planned a 20 minute bottom time with breathing gas to spare.

I donned my buddies fins, went through my final checks, rolled over the side and kicked below the surface to the anchor line.

Breathe in breathe out…. slow, even breaths. Equalize. The particles suspended in the water whiz past me as I descend. I’m dropping fast. Breathe in, breathe out, equalize. Check instruments: depth – 12 m, dive time – 0:00, air – 223 bar. Every thing looks good. I feel great! I love this part. There is nothing around me. The only reference is the anchor line in front of me, disappearing into oblivion. I feel like I’m in free fall.

The visibility at this depth is only 5 m at best. My descent continues. 15 m… 22 m… 25 m… The visibility opens up. I can just make out the wreck below me sitting in 50 m of water. The gunk in the water above me partially blocks out the sunlight. I turn on my torch, more for comfort than anything else. I’m breathing a little harder now with the increased pressure so I adjust the resistance on my reg and add some more air to my dry suit to slow my descent. as I pass through 30 m depth I’m still dropping fast so I add some air to my BC to slow my descent.

Instrument check: depth – 48m, dive time – 0:02, air – 204 bar. As I arrive at the bottom, I try to unclip my reel from my harness. My fingers are clumsy, I must be narc’d but I still feel fine. I get my reel free and manage to tie onto the anchor line. I take a couple of seconds to catch my breath and gather my senses. Breathe in… breathe out… Wow! I am narc’d! I can’t concentrate…. better check my gauges: 0:05 dive time. What happened to those 3 minutes! This is fantastic! The vis is at least 30 m! 3 huge trevally cruise past me glinting bronze in my torch light. I watch them disappear into the distance. I’m surrounded by wreckage covered with tiny pink, purple and white bryozoans. Orange and yellow sponges fight for space with iridescent algaes. A school of pomfret, glowing golden in my torch light, cascade over parts of the wreck. I’m loving it!

Ok, what was I doing?…. Turn right from the anchor…. Right or left? No it was definitely right…. Which way is that? Ok concentrate now… this is my right hand… turn that way. I see the edge of the debris field and sand…. Where is the boiler? I keep turning. There’s the anchor…. Ok, I’ve turned right around. maybe it was left…. Ok turn left…. Wreckage… Sand… Anchor. I’ve turned around again…. where is that boiler? it was definately “turn right from the anchor”…. Ok, calm down, breathe. Should I bail out? I’m really really narc’d and I feel like I’m really pushing my abilities. No I’m ok, I’m well trained, I’m using familiar equipment (apart from the fins), my skills are up to scratch and I have heaps of air… I can handle this situation. Stop, breathe, think and act. Breathe in….breathe out. Think: “turn right from the anchor…” Act. Ok…. turn right. Ok I see a shadow out on the sand…. Is that the boiler? All the way out there? Ok… Start swimming…. It’s hard work…. Bugger that. I’m not swimming out there. Turn around… Which way?… Oh yeah, that’s right, it won’t matter.

I turn around and reel my way back to the anchor. I’m so narc’d. I can’t think. Calm down…. Breathe…. Check instruments: dive time 0:08 minutes. damn! I’ve wasted most of my bottom time. Air – 182 bar. I can’t think straight.

I close my eyes to try to gather my thoughts. Breathe in… Breathe out… Ok…. I’m on the edge of the debris field. I’ll just follow the sand line for a little bit. Which way? There’s a slight current… I’ll just drift along with that…. No wait!… I tell my students not to do that in the open water course… But I only have 2 minutes left. I’ll just drift a little way, then turn around. It’ll be fine.

I move along the wreck with the current. There are some beautiful little gorgonian fans, and some little pink bryozoans. Three juvenile blue wrass scull along beside me…. This isn’t so bad… A little leather jacket moves out of my way. Wow! this is a beautiful wreck! There are scattered deck plates and beams all around me. I wish I could have found that boiler or the stern section. Ah well next time… Oh shit! what’s my bottom time? 0:10! Shit! Turn around. I swim into the current. It’s not strong, but I have to work harder. I can feel my breathing rate increase with the extra effort. I reel in my line as I swim back to the anchor.

Back at the anchor. Instrument check: dive time – 0:11 minutes, air – 156 bar. My computer tells me that I require a 4 minute stop at 6 m with a total ascent time of 13 minutes. It’s ok, I have plenty of air and a 40% nitrox mix in my stage tank. Ok… relax… I try to detatch my line from the anchor chain, but my fingers just won’t work the way I tell them to. Finally the line comes free (I was so close to cutting it). I secure the reel to my harness and begin my ascent. Dive time – 0:14. Shit! I stayed way too long. I’m ok, I’ve got plenty of air left. I make my way up the anchor line. not too fast….dump air….breathe in breathe out. Up I go… at 25 m (the safe operating depth for a 40% nitrox mix) I reach for the reg on my stage tank but unbeknownst to me, the hose is caught on the buckle. I pull at the reg, but it wont come free. I’m still going up… dump air…. breathe…. I’m thinking more clearly now. Ok stop… Breathe… Think: “why won’t the reg come free?…. It’s caught on something”… Act: follow the hose with my hand. Ok, it’s caught under the buckle here. Ok, there it goes. I pull the reg free and start to breathe my nitrox mix. Instrument check: Dive time – 0:18 minutes, gas – 200 bar, 10 minute stop now required at 6 m. I make the gas switch on my computer. it re-calculates my ascent profile taking into account the new gas mixture I’m now breathing. Dive computers are such wonderful things! 1 minute of decompression now required at 6 m, total ascent time, 7 minutes. I slowly make my way to my 6 m stop and wait for 1 minute. Up to 3 m for just 5 minutes (oh how I love nitrox).

Hanging on the anchor line at 3 m I have time to contemplate the dive. I was out of my depth (excuse the pun). It all started out wrong. I feel lucky to be back near the surface. Things could have really gone wrong down there. Well, actually, maybe I’m not lucky, per se. When I knew I was getting into trouble, my training kicked in: Stop, breathe, think and act. And I was able to gather my self sufficiently to be able to get back safely. Nevertheless, I’ve learnt some valuable lessons from this dive. I should have bailed out when I felt the narcosis become overwhelming. Always start the dive swimming into the current. Practice practice practice with your equipment so that muscle memory can relieve some of the task loading on your brain at depth. And especially “When 3 things go wrong…”

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