BY: Jonathan Bernot
Many times we as divers get stuck in a certain way of doing things. This may be a certain way we plan dives, a certain piece of equipment we refuse to part with, or a certain mentality on training and dive progression. In many cases this is natural and often times does no real harm. Every now and then however I see something that just cannot be justified anymore. As someone who was once attracted to deep air for its simplicity, and let’s be honest, its cost or lack thereof, I have found myself looking back and realizing how far we have come. I had a Trimix fill station in place at my small dive shop by the time I took a Trimix course. I did my Trimix course on wrecks that I had previously dove multiple times on air. In some ways that experience made me appreciate what helium does for us, having been able to experience the same dive both clear headed and not I began to realize the difference. Teaching my first tech course with my student on air and myself on helium I really appreciated being clear headed. I can’t imagine teaching that course on air. Even after having dove helium based mixes for a number of years though it wasn’t until a certain exploration dive that I really had the message driven home.
I had explored a tunnel at the bottom of a pit just far enough to realize the tunnel went and that it would require a sidemount configuration. The passage was shallow leading to the pit and the tunnel at the bottom appeared to go forward at a depth of 130 ffw/ 40 mfw. I made the decision to go back with one of my regular dive partners (wife) on open circuit 20 liter sidemount cylinders and finish exploring and survey the passage. It was low and silty with minor flow but quite pretty. Getting to the point where it was obvious the tunnel was essentially ending I turned the dive and began to survey. It was here I found the error of my gas choices. While I felt fine going in laying line on a non-helium based mixture, when I turned the open circuit bubbles caused bacteria growth and silt to rain down limiting visibility to inches. This once clear new tunnel was now quite an unpleasant place to be. I then realized I had several protrusions to negotiate on exit in the low passage and wished I had placed more silt stakes and ties than I had. I knew I would be alright…probably…but found the level of overt narcosis go through the roof. It wasn’t even that deep…compared to dives I had done on air previously, but when it came to a low visibility, unexpected scenario, helium would have been REALLY nice.
I respect the fact some areas have limited access to helium based fills. I also respect the fact it is prohibitively expensive in some areas. If you can’t do the dive safely, and this includes attaining the proper mixes, then you don’t do the dive. However, I am truly amazed how mainstream deep air remains even in North Florida cave country. An area that probably has the most readily available and most inexpensive trimix fills in the world. I do not think I will ever change the mind of the 40 year cave diver who is dead set on keeping things simple and diving air, however I find it reprehensible for new divers to be instructed and mentored in that diving deep on narcotic mixtures is acceptable. Most of us accept the fact that an END of 100 ffw/30 mfw is the maximum suggested for overhead diving. I consider this to be the maximum accepted for rebreather diving as well since a rebreather, like a stressful situation in the overhead required clear thoughts and reaction times to be at their best. As the owner of a facility where I see a wide shotgun style scattering of training philosophies and experience levels let us look at two of the most problematic scenarios.
MOD 220 FFW
I see MOD 220 way too often, especially on CCR divers bailout cylinders with Air in them. Divers, remember there are two things that create an MOD. One is oxygen content but the other is helium content.
DEEP AIR COURSES TAUGHT IN THE OVERHEAD
The maximum END in the overhead should be kept to 100 FFW. This keeps the diver sharp and at their best if something does occur. Agencies like IANTD have recognized the need for a diver to be able to complete their entry level technical courses without being forced to experience the deep air dives prior to going into what has traditionally been thought of as “Trimix” diver depths. Advanced Recreational Trimix courses for instance allow the diver to dive TRUE normoxic oxygen content while adding enough helium to keep the diver sharp and at their best. As a result I have not taught an “Air” decompression course in years.
We have the technology, we know the benefits of helium, and we also know that narcosis is a real thing that impacts all of us. A recent Florida Highway message was this: “buzzed driving is drunk driving”. Well I propose that ‘Buzzed diving is drunk diving’.
Most would look down on someone who slams two beers and jumps in the water to do a cave dive. Why do we see a 150 foot cave dive on air differently? We have the ability to be clear headed and we owe it to ourselves to be so. We as instructors also owe it to our students to promote such. The days of deep air need to die the way of stuffing the long hose. There is a better proven way. It does not matter what I or you, or anyone else may have done in the past out of convenience, lack of resources, or misguided interest. We build our sport on the experiences of those before us and hope that the next generation does not have to learn the hard way, lessons that we have already learned and survived. Let’s move forward!