I would be interested in mapping this term more accurately, i.e.
1) what subcategories does tech diving have or which keyphrases describe it?
overhead environment (ice, mine, cave, uw structures), mandatory staged decompression (any gas), helium mixtures, bottom stages, rebreather manual operations, ... any other? Restricted access to surface, gas planning and non-baseline equipment are common to these. Or planning and error recovery really. Is technical a synonym to resilient?
2) What are the grey areas? Surface tended ice dives, recreational trimix (wt*?), dive by touch, extreme currents, any other? No limits freediving is technical, for sure?
I think you've actually just mentioned a few aspects, but p
erhaps a brief look at how recreational technical diving evolved and came into it’s current form (at least in the U.S.) may assist us in mapping out the term more accurately.
I believe the actual term "technical diving" was first used by Michael Menduno in his diving magazine
AquaCorps around 1990. At the time, he was beginning to write and give lectures about divers and diving techniques that were being utilized to dive beyond what were becoming the fairly standardized recreational guidelines of NDL Sport diving agencies. More specifically, the techniques that were being utilized in Cave and Wreck diving (overhead) and deeper dives with longer bottom times.
As has been mentioned, one of the primary determining factors has been the lack of the
direct free ascent to the surface as in NDL diving and as such, the use of staged decompression techniques and equipment redundancy were/are utilized. In addition, experminretation with other gas mixtures to either allow for increased depth or accelerated decompression were also being pioneered in recreational "technical diving". This made it necessary for the diver to calculate not only required decompression times, but also how much gas volume was needed and the appropriate gas mixtures to be used at given depths. This added pre-planning and the requirement to adhere to a stricter diving schedule by following exact runtimes also contributed to the "technical" nature of this approach to diving... in actual diving practice and in the mindset to this approach.
It is worth mentioning that as the sport has evolved, so has the definition of tech diving... where it has either grown to encompass other types of diving with a "technical" nature (rebreathers, ice diving etc..) or shifted. Conversely, certain aspcts that were unique to technical diving 25 years ago - for example the use of Nitrox, have now become an accepted norm in the more mainstream sport diving community and depending on whom you talk to, may no longer be considered technical diving within that context.... and not without significant contreversay. Back in the early 90's indeed some mainstream agencies and publishers tried to get the use of Nitrox banned.
So times have changed and evolved and we're already starting to see the signs of Trimix moving a little more into the mainstream with the intdroduction of recreational Trimix courses and it's use at much shallower depths. I'm sure we will continue to see more changes and a redrawing of the already fuzzy demarcation lines that differentiate technical diving to NDL sport diving. Additionally, the same relevant questions will continue to be asked:
At what point does a mandatory decompression stop constitute a "technical dive" ? and when will self-contained equipment redundancy (with or wihtout a buddy) be required? over 5 minutes of deco? 10 minutes? etc..
Will diving in a Cavern with a more extended penetration but still within the light zone at some point still be sport for some agencies or does it turn into technical for others? How does this affect our equipment considerations and gas calculations?
Has solo diving, once considered a heresy among certifying agencies, now for all intents and purposes evolved into an acceptable middle ground…. or even a mainstream sport diving activity? A visit to SDI/TDI's website would seem to indicate that it is now considered at least by this agency an acceptable non-techcnical form of sport diving.
Will the inevitable more mainstream use of Trimix, even at shallower depths or within NDL limits (similar to the evolution of Nitrox use) still constitute technical diving? As Nitrox once did and still does under certain uses (i.e. accelerated deco)
One could start with a list of certain prerequisites that either include all or a combination thereof:
- A dive where direct access to the surface is no longer an option due to a decompression obligation where the exact calculation of gas volume is required prior to the dive with equipment redundancy considerations being mandatory.
- An extended range dive either vertically or horizontally in which direct access to the surface is no longer an option and again as a result of these criteria, equipment redundancy is mandatory rather than optional
- The more “advanced" use of mixed gases such Trimix to extended the depth and bottom time (multiple stages) and/or Nitrox 40% or more for the specific use of accelerated decompression.
- The use of a CCR with Trimix and bailout cylinders to undertake extended range dives and significantly increase bottom times well beyond practical Open circuit use (i.e. 5 cylinders or more).
I'm sure there are several additional characteristics that have already been mentioned that could constitute a technical dive and maybe just as many grey areas... but I believe for the time being, as far as tech agencies and the tech diving community at large is concerned, we can certainly find common terminology and characteristics that can serve as points of reference and help to shed a little more clarity on the subject.
