When Diving Goes Wrong by Brian Goddard
Monday, 21 January 2013 13:22

Diving is considered to be a group sport, after all it requires a group to organise an expedition and a buddy pair to carry out a dive. Of course there are those of an individualistic nature who prefer to dive alone and are content to join charter boats as one off contributors. I have always belonged to the school that believes diving is much safer and more fulfilling when undertaken as a group. Discussing the day’s events with friends in the bar on an evening is for me all part of the diving experience and camaraderie and brings added pleasure to diving.

A recent minor incident brought home to me the true isolation that diving, particularly in UK conditions creates.

June 2012 found me in Eyemouth undertaking five days gas diving with Marine Quest. Having dived the Boyne Castle and the Exmouth earlier in the week, on the Wednesday we were to dive the British submarine K4.

As the shot went in the echo sounder was recording 55 metres to the seabed. Keen not to miss the available slack window I was the first to jump and dropped down the line in no discernible current, my buddy close behind. Below 40 metres all ambient light had gone and I was on the seabed before my eyes regained focus. Turning on my torch the substantial hull of the wreck rose at my side, my light reflecting off the soft coral adhering to the rusty plates. It was immediately obvious this was much larger than the usual U boat wrecks I have dived; I set off back up the line to position the strobe above the wreck.

Immediate investigation did not reveal a suitable location to secure the shot, even down at the seabed. I located my distance line reel and clipped off to the shot line and finned up on to the casing of the wreck looking for a suitable place to tie off. As I reached the top of the wreck I started to feel out of breath; fortunately I found a pipework fitting where I was able to quickly secure the reel.

Allocated jobs done I settled down on the wreck and tried to regain control of my breathing. My initial thoughts were I had over exerted myself, too busy with assigned tasks to worry about correct buoyancy control. When this has happened in the past a short rest period to regain trim and relax has quickly restored breathing rhythm. Alarmingly on this occasion the feeling of being suffocated intensified and I realised all was not well.

I realised I would be unable to continue as my distress increased with every breath; but still believed this was due to over exertion (I am the first to admit I am getting on in years and not as fit as I used to be). I decided to bail out and started breathing air from my 7 litre side mount. I have this connected to my bail out valve mouthpiece, changeover was a quick twist of a lever; no complicated switching of mouthpieces to contend with; I was relieved it worked flawlessly. I was initially sucking hard on the mouthpiece the usual silence now broken by the heavy stream of bubbles passing my ears. After a few breaths I was relieved to feel better and my breathing started to slow.

During this relatively short period of time, probably only a minute in total, my buddy was close by but oblivious to the difficulties I was experiencing, despite the large volume of bubbles rushing towards the surface. The initial crisis had passed and I began to think about my options.

An immediate ascent was necessary if I carried on breathing open circuit air, I would have to get to

14 metres before I could access my rich nitrox mix. The folly of not having topped up my side mount prior to the dive was obvious to me now, despite the pressures of the moment. I would need to ascend quickly missing any deep stops, not ideal but possible. Although I had not had the time or ability to check only 100 bar of air remained in the cylinder, I had just consumed 50 bar. I decided to try going back onto closed circuit, my only option if I was going to continue the dive.

With hindsight I now realise this was a risky strategy that could have created further problems. It did not occur to me to carry out a DIL flush (replace the gas in the loop) to ensure the loop was fresh; at this stage of the dive I still believed the problem was due to over exertion. I took a few more breaths without moving and was happy that I continued to feel OK. I decided to continue the dive and set off down the starboard side of the wreck. My buddy was still by my side hovering over the wreck.

By the time I had finned past the bridge section and was approaching the bow I started to suffer with a pounding headache. I now realised I was suffering high CO2 in the loop. Minimising effort and conserving energy seemed to work reducing the headache to manageable proportions and I felt able to carry on with the dive. Had I needed to bail out again I would have needed my buddies bail out gas to regain the shot and get up the line.

The forward torpedo tubes came into view and gave me a focus of interest other than my headache.

I started to take interest in the wreck and on the way back from the bow was able to have a detailed look around the bridge and gun. Moving on the stern proved to be a disappointment, sloping gently down into the bottom, the rudders and props appeared buried. We returned along the top of the wreck to the shot and I recovered the strobe and untied the reel. I set off up the line with 34 minutes bottom time on the computer and around 60 minutes of deco to complete.

I was above 20 metres before the headache went altogether and I could relax into the deco and reflect on the dive. I was now convinced that I had been getting higher than normal levels of CO2 in the loop. Later inspection of the scrubber revealed a double half-moon crevice going deep into the stack. This would have caused channelling, allowing some CO2 to bypass the scrubber material. I was lucky that my body had been able to function with the elevated level of CO2 that existed. It was only the higher work load at the start of the dive that I had found unsustainable.

I have spent over 500 hours using a rebreather and have become very comfortable underwater. For all those hours I have carried bailout cylinders without needing to use them in anger. Unfortunately familiarity can lead to complacency; when I did need to bail out I had failed to ensure the cylinder was topped up for the start of the dive. A full cylinder would have provided a greater margin of safety had I opted to bail out to the surface. One thing is clear when you are underwater dealing with a problem, experience is no substitute for due diligence. Self- reliance is essential, a buddy has limited awareness and effectiveness in deep dark conditions and has to be regarded as a last resort.

Complacency is a constant danger we all must guard against whatever the level of diving undertaken. It is however a fact that we are human and imperfect, try as we may mistakes will tend to happen. I have packed the scrubber for my unit perfectly hundreds of times; on this occasion I got it wrong, the error still haunts me. Thankfully my training and back-up systems got me through.

Note to self “must do better”.

 

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