Technical Diving - Training
There are a broad range of organisations that offer tech diving training and each will differ to an extent in what they teach and how they do it so don't take what I say as gospel fact, but more of a guideline in whats expected. I'm not about to go into the intricacies of how to tech dive but I will give you a good idea of what the deal is and what's expected.
To even consider yourself tech diver material you should have at least 100+ dives, a chunk of experience in deep diving and by 'deep' I mean 30 meters and over and have dived on EAN/Nitrox.
Training to be a Technical Diver should not be taken lightly, it is not an attendance course nor is it a pay-and-purchase certification, it requires total dedication from the aspiring wannabe-tech diver. Before you ask yes, failures and referrals are commonplace. It isn't for everyone nor is it meant to be, you have to be of a different mentality and mindset or at least prepare to adjust to one.
Keeping your cool while all about you is going pear-shaped is crucial to any recreational diver. Now introduce that on a technical dive at 50M+ with a heavy narcosis loading in zero vis. with a full panoply of tech gear to manipulate and a complex run-time to follow! You begin to understand that its no joking matter embarking on tech diving course! Sounds like I'm putting you off a little? You bet! Tech Diving's not for the casual diver who see it as a trophy badge, you don't have to be undertake a tech diving course to become good at what you do on the recreational dive circuit. A perfect example of this is the late Jacques Cousteau who is considered the master/father of recreational diving.
The first thing you'll need to come to terms with is the shear weight and difference in equipment configuration (see below). A manifolded 'twin set', steel plate harness with a stage/deco cylinder clipped each side, all the regulators and ancillaries plus all the usual equipment for a dive can see you carrying over 60 kilos / 130pounds! A staggering weight by anyone's standards. Strength helps, as does technique and underwater you'll look like the man from atlantis, but that's all part of tech diving!
Its not just about the practical aspects though, the theory side of technical diving is a mathematicians paradise or a school kids nightmare! The equations and formulas to work out gas consumption rates, gas requirements, Surface Air Consumption can build-up to be more tricky and cunning than a sack of weasels! Add to this merry lot decompression schedules, back-up schedules, run-times and bundle them all together into a workable dive-plan, and you will begin to understand why its called Technical Diving.
Skills underwater that require total mastery are numerous, among the most critical is buoyancy. Not least because all the drills taught from gas shut down to stage and retrieval of cylinders culminate in a test whilst in mid-water neutrally buoyant, not easy. The error margin for holding neutral buoyancy varies but either side of half a meter (1.5 feet) is a typical benchmark that is set. The reason for this, you might wonder, is because if a tech diver is decompressing on a very high mix of oxygen (reduces deco. time and is highly effective) and looses his buoyancy and descends below his set depth the result (at the worst) could be a CNS convulsion and death. Conversely he could ascend too shallow and risk Decompression Sickness. The gas-switching drill to breathe off another gas cylinder for extending the no-stop decompression or actual decompression is another zone of extreme self responsibility. To put it plainly at set depths certain blends of gas are consumed from the relevant cylinder. Should you switch to the 100% oxygen (deco gas) at the wrong depth of say 30M when you should of switched to milder blend of Nitrox you will convulse, spit out your regulator and die. A very extreme example of how to ruin your day but something that is emphasised in training to ensure that you don't do it!
In Tech diving every diver is trained to be capable of completing his or her dive solo should the situation warrant it. This brings me to the lift bag and reel; very important, tricky to get used to and some would say a tech divers most important friend! Its the actual deployment that is critical, as in some situations you may have no way of decompressing on a shot line and a jammed reel or under-inflated lift bag is going could mean 'blue-water' or mid-water decompression; not the ideal way to spend an extended amount of time on an hour long decompression schedule! Another crucial responsibility to take aboard are the gas shut-down drills in the event of a regulator/manifold free flow.