Practising a gas shutdown

AS AN INSTRUCTOR, I am often frustrated by divers who are not really prepared for the training they are about to undertake. Its not just me. Those who are unprepared also hold back the others on the course, forcing me to dedicate a disproportionate amount of my time to the unprepared and giving less to those who have made the effort.
The skills any diver is expected to bring along to a course naturally vary with the level of the training. For any given course, there are skills that a diver is expected to have already mastered, and skills that a diver would quite rightly expect to polish or learn from scratch on the course.
After all, if there were nothing new to learn, there would be little point in doing it.
On the theory part of any training, the answer is easy - read the manual from cover to cover before the classroom work begins, and perhaps even do some of the example exercises. That way, by the time the real training starts, a diver will know which bits present difficulties, and the instructor will be able to concentrate on those parts.
Thats preferable to having to talk through information that could just as easily be read from the manual.

1 Buoyancy control
On the practical side, the most commonly sub-standard skill is buoyancy control. Even divers who think they have good control are often negatively buoyant and finning to stay level. Provide the distraction of an exercise, and they soon sink.
It shows up readily on out-of-air drills. In basic training, OOA is practised on a flat seabed. The divers swim towards each other and kneel on the seabed to sort out octopuses and prepare for the ascent.
Thats OK in basic training, but many real dives are on a wall. Many real OOA incidents happen when an ascent has already started. In both cases, the last thing we want to happen is to begin the emergency drill by sinking and making the incident worse.
I like to make drills on advanced and technical training more realistic.
Having introduced an exercise on a flat seabed or a training platform, drills move on to a wall or midwater, with just a shotline for reference. This applies not only to OOA, but all drills.
Phrases that come up all the time in technical training are task loading and perceptual narrowing. While a diver may be able to focus on one task, perhaps even two, start adding more and soon the diver becomes overloaded.
One or more of the tasks becomes neglected as the divers brain looks for a way out, and perception focuses on something that can be achieved, often at the expense of failing to cope with more important issues.
Its what happens when practising the OOA drill on a wall. The divers are so busy worrying about the drill that barely adequate buoyancy becomes neglected and they sink.
The trick about mastering buoyancy control is to practise it in the pool in association with other drills.
What these drills are depends on the level of training. The important thing is to develop a feel for keeping neutrally buoyant while distracted.
Out of air and alternative air source is an obvious starting point. With a view to moving on to technical training, gas shutdown and stage-cylinder removal and refit are skills that benefit from some concentrated practice before a formal course begins.
All of these can be safely practised in a swimming pool, even for the first time, without an instructor. Just have a capable friend watching to help out if things get out of hand.

Out Of Air and Alternative Air Source are skills worth practising at all levels, from beginner to technical.
In its simplest form, begin the exercise separated by several metres, neutrally buoyant and hovering horizontal in the water, halfway between the surface and the bottom of the pool. In a typical 3m-deep pool, this will give 1.5m above and 1.5m below. Take enough time to ensure that genuine neutral buoyancy has been achieved before starting the actual OOA exercise.
I wont go into the details here, except to say that there are variations based on training agency, equipment configuration and the level of training.
What is more important at this stage is to make contact and donate/receive the AAS while keeping horizontal and without sinking to the bottom of the pool or breaking the surface.
While the objective of the exercise is obviously for both divers to end up on the surface and positively buoyant, we want this to be intentional rather than a result of losing control of buoyancy!
Initially, just practise with pool kit or wetsuits. As control improves, move on to doing it with gloves and in full kit with drysuits.
In the middle of this, work at increasing the separation between divers and doing it all without masks. Not because this will ever happen in real life, but because doing anything without
a mask will add to the task-loading and make divers develop a feel for buoyancy, rather than relying on visual references.

3 Gas shutdown
As soon as divers move on to a manifolded twin-set, gas shutdown is an essential survival skill. If you are diving with a manifolded twin-set and have not mastered this skill, the only safe option is to keep the manifold closed and dive as if the set were independent cylinders.
Shut-down drill is a key skill taught and practised on any entry-level technical course on which a twin-set is used, but that doesnt mean you cant get a headstart with a bit of practice in the pool. Most divers with twin-sets end up taking them diving before they take them on a technical course, so they may as well practise shut-down drills.
The sequence for shutting down varies between agencies, so that is a detail to leave to the official training course, or check with your instructor.
More important at this stage is simply to get used to reaching and operating the isolator tap and the individual cylinder taps.
Begin by resting on the bottom with just a light wetsuit and the twin-set, and reaching back to locate and operate the taps. The positioning of the twin-set on the backplate may have to be adjusted slightly to find the most comfortable location.
With the basic movement well rehearsed, the skill can be developed in the pool by continuing to practise while neutrally buoyant in midwater, with gloves on, in a drysuit, and even without a mask. It is worth moving on to the neutral-buoyancy part early in the development of the exercise.
The order in which the other components are developed is unimportant; whatever takes your fancy.
As with the OOA exercise, the mask- off bit is not something you would ever need to do for real. It is just a way of injecting a bit more stress.
If youre just thinking of buying a twin-set, rig up a set of independent twins and practise shutting them down one at a time.

4 Side-mount removal and refit
In most training schemes, removing and refitting a side-mount cylinder is a skill that comes in later than using a twin-set, but that is not necessarily the case. Some single-cylinder open-water divers prefer to carry a bail-out pony cylinder side-mounted rather than on their backs.
For some, removing and refitting a side-mount is an easy skill. For others it is more difficult.
The positioning of D-rings can be a compromise between comfort while diving and ease of removal and refit.
The awkward D-ring is often the hip or back one to which the lower clip on the side-mount attaches. It can be quite a challenge to fiddle a bolt-snap onto it while wearing gloves.
There are a few tricks on kit-rigging that can make this easier. For example, D-rings welded to a backing plate or backed with a plastic clip will stand out, rather than fold where they are difficult to find.
As with gas shutdown, get the basics sorted out by resting on the bottom of the pool while removing and refitting the side-mount. The exercise can be done top clip or lower clip first, and while you may find one method easier than the other, it is worth practising both because you never know when circumstances will conspire to force you to use the other method.
With the basic movement sorted out, the next step should be to get the feel for it with gloves on, then move into midwater before adding full kit and a drysuit (still in the pool, of course).
For a final challenge, see if you can do it all without a mask, just to complicate matters and add to the task-loading while trying to maintain neutral buoyancy.
While you have the side-mount in the pool, another trick to play with is trailoring a side-mount by attaching its top clip to the hip D-ring. This is a convenient way to get an empty and floaty aluminium cylinder out of the way when it has been finished with on a decompression stop.
It isnt particularly useful with just one side-mount, but can come in handy when more than one is carried on the same side.
If you are warming up for a more involved technical course using more than one side-mount, the pool is the place to get in some advance practice for that as well.

5 Kit removal and refit
While you have all your dive kit in the pool, another skill that may come in useful one day is to take your harness/ BC/wing/cylinders off your back and put it on again.
You are most likely to need this skill on real dives at the surface when diving from a small boat and needing to dekit in the water, or from a really small boat, where there is not enough room to kit up onboard and you have to throw the kit in and put it on in the water.
Removing full kit while under water is a skill that may be taught on advanced wreck penetration or cave courses. It is not something to make a habit of during normal diving, but is still worth practising. One day, when circumstances conspire to make it necessary, you will at least have an idea of what to do - but only as a last resort. In most cases the safe option is to return to the surface to sort out a problem.

doing any exercise with mask off serves to add to the stress levels
reaching back to operate the taps
Practising side-mount removal and refit.
You never know when the ability to remove all your kit and put it back on will come in useful.