John Kean on the Thistlegorm, breathing direct from a cylinder in a way you wont often find described in the manuals. For emergencies only!

FRED DIBNAH, THE LEGENDARY LANCASHIRE STEEPLEJACK, once said: I never fell off a big chimney. You'd only fall off once, like.
As a teenager in the early 80s, I learnt a lot from listening to Freds TV philosophising, which included such gems as If you make one mistake, its half a day out with the undertaker.
He didn't mince his words. Years later, I wonder how my aquatic education might have proceeded had it been Fred Dibnah writing the manual instead of a more politically correct global giant. He might have replaced such statements as you have five available options in the unlikely event of you running out of air with if you sit under an elephants backside, it'll...
Beneath the flat cap and amiable persona was perhaps the greatest technical diver that never was. Fred's chosen passion was attaching himself to tall chimneys. Nonetheless, he made as much of the preparation and planning in going several hundred feet above sea level as those who went several hundred feet beneath it.
Our relationship with water is a unique and often personal one. Non-swimmers may reach their comfort zone waist-high in the sea, while babies without a sense of their own mortality will happily swim under water at a few weeks old.
Most adults can scrape a length under water in their local swimming pool but few can emulate a champion freediver and cover 100m on a single breath.
Scuba divers, of course, interact with water at many different levels of depth and experience, where the environment that is one mans comfort level could prove fatal to another.

THE ACTIONS OF OTHERS sometimes appear crazy, until under closer examination we realise that behind them are years of training, experience and commitment. The result is that their activities appear simple and easy, although anyone taking a short-cut by dipping their untrained toes in the water would receive a swift reminder to go back and fulfil the prerequisites.
For recreational divers, it is all too easy to judge others who conduct their activities outside traditional recognised parameters.
For me, the difference between one diver and another was never more apparent than a few years ago, when I saw a championship freediver drop to 143m on a single breath and return to the surface by pulling himself up a rope.
My job that day was in support diving at 50m, wearing a four-tank configuration and enough redundant dive equipment to kit out a small shop.
Carlos Coste passed me twice at the 50m point, the second time returning from his record depth after an elapsed time of more than four minutes.
He wore nothing but a shiny silver wetsuit and a plastic nose clip - I felt somewhat overdressed! Still, it was a reminder of what was possible, and it was obvious that he wasnt in the business of taking short cuts.
My own early training in scuba-diving took place in a swimming pool where, among other useful things, I was asked to breathe from a simulated free-flowing regulator by sipping air for 30 seconds.
The instructor looked at his watch as vast quantities of bubbles flew to the surface, and after half a minute asked me to stop. I then received a hearty OK signal, followed by a small clap to indicate that Id done this properly.
I wondered if hed still be clapping when my tank ran dry and my face turned pale with anoxia. It begged the question: Now what
It may be obvious to seasoned divers that they should reach for an alternative air source or make an ascent, but I have twice seen divers with real free-flowing regulators just sitting still sipping their escaping air - waiting for someone to come along and clap, perhaps, as they depart for the big reef in the sky
We are often advised to visualise a series of what-if scenarios not normally covered in courses, and discuss or imagine how we would deal with them under water.
This is a great idea, as it gives us a mental movie to re-enact should the incident occur in real life. However, nothing will trigger the reflexes better than in-water practice and repetition.

WHAT-IFS SHOULD BE FAIRLY REALISTIC and in keeping with training, experience and ability. An open-water diver would have far less exposure to problems than regular sub-100m trimix divers with at least eight courses and several years of experience behind them. Their respective what-ifs should reflect that.
My own what-if scenarios have changed over the years, perhaps beginning with the free-flowing regulator and what to do next example.
Later, after Rescue Diver and Instructor training, they encompassed
a wider range of scenarios unique to guiding and teaching in the Red Sea.
Now, as a Trimix Instructor and project-support diver, they have moved even further, involving the practice of dealing with multiple threats and failures simultaneously in challenging environments.
What-ifs help identify and prevent problems, but rarely is the required action necessary if youve briefed and prepared against the risk, having anticipated it in the first place.
This makes us good instructors, but also a little rusty in scenario rehearsal. So, just like the emergency services dress-rehearsing for a national calamity, it was high time to see what could be achieved in a similar vein under water - the technical disaster from hell!
Of course, for this scenario of multiple failures to happen in real life, your diving, teamwork and equipment-maintenance skills would have to resemble those of an underwater Mr Magoo.
If tech dive training is about the development of self, then what tricks and secrets do we have available if our expensive life-support gear fails on us spectacularly
Shooting to the surface isnt an option in any form of diving, but when youre in trouble at depth, youd be surprised by the many other options you might have available outside the manual.

Low-vis training
With a mask off, it is less easy to determine depth, and without an immediate visual reference you may find yourself feeling vulnerable. Your ears will react to increasing or decreasing water pressure, and changes in sensation will provide an indication of your direction up or down.
Of course, you must react quickly and draw on other methods if available to avoid ear injury and loss of control.
Still, ears dont lie, and with practice in a controlled environment under instruction you will have an additional resource available.
I teach this during decompression and trimix courses at around 6m deep. Under supervision, students remove their masks during a simulated stop and practise holding position by using their ears, as well as any references they can make out. What used to be an anxious exercise for novice divers is now destigmatised, mastered and added to a portfolio of useful tricks.
An easier way to control position with a mask off is simply to observe the hazy objects around you. In the picture, I dont need to see the finer detail of Thistlegorms bow, only to know that its there. Without a mask, I can still make out the shape and avoid any sharp objects nearby.
Low-visibility simulation training is carried out in all technical diving courses, beginning with Advanced Nitrox. This also takes place in shallow water, usually with a sandy bottom.
Additionally, the student holds his or her own mask and carries a spare anyway. A useful scenario is a short, no-mask, out-of-air swim to a team-mate, whose attention you gain before taking his or her alternative air source.
Who says that if you have a gas problem it will always be in clear water
Another little trick is to trap small air bubbles in your eye cavities. People sometimes laugh at this suggestion, but I discovered this years ago during
mask-removal-and-replacement teaching with beginners.
Often, when the mask was removed, air would run across my face and occasionally leave bubbles around my eyes. By lowering my face horizontally to the seabed the bubbles stay in position. and by opening my eyes a little the tiny airspace allows you to read instruments. It takes practice and experimentation, but youll get it eventually.

Still neutral
In decompression and technical dive training, we practise kit removal and replacement, making sure that, with correct weighting, we will not float to the surface. We need additional weighting to offset the buoyancy characteristics of the tanks, which become lighter as we breathe them down during a dive.
For example, in the Red Sea a 10-litre aluminium stage tank with a regulator on it will become positively buoyant with about 35 bar of pressure inside.
There are several buoyancy considerations when conducting technical decompression dives, as you need to know how your suit and gear will behave when exposed to both deep and shallow water.
Being too light in the shallows will compromise deco-stops and could lead to injury, whereas being overly negative at depth will require excessive wing/BC inflation to avoid rapid descents.
In the example picture I am carrying 4kg of weight on my belt and breathing from a near-neutrally buoyant tank.

EVEN WITH LUNG-VOLUME changes during breathing and wetsuit expansion on ascent, there is little deviation of buoyancy control.
Bare-tank air-sipping isnt found in the manual, but Ive given this a go over the years out of curiosity.
You could deal with a free-flowing regulator by simply opening and closing the valve when you want to breathe - fluttering the handle. A complete blow-out and waterlogged regulator would not allow this.
By placing my mouth almost over the outlet and turning the valve slowly, I can sip the air. Practice allows a good rhythm and the right amount of air to maintain a decent breathing pattern.
Its not as efficient as a regulator, but by keeping movement to a minimum, carbon dioxide build-up can be reduced to allow breathing control.

How much gas
My measured breathing rate, tested frequently during tech training, is 15 litres per minute at the surface. At 15m deep it would be 2.5 times more, giving
a consumption of 38 litres for every minute spent at that depth.
There is little escaping gas during bare-tank breathing, although the drill does result in a slight increase of the breathing rate - due to excitement! Sixty litres per minute would be more realistic.
With a 12-litre tank at 200 bar, I have 2400 litres of gas with which to play around. In terms of minutes remaining on the bow of Thistlegorm, this translates to 40 - which I can check on my computer by using trapped air bubbles.
So how does it look now You wouldnt make a habit of this type of diving, but where others have died or been seriously injured, these extra options could save your life.
Further training in decompression and technical diving opens up more possibilities, and a greater range of solutions in dealing with underwater problems, scenarios and challenges.
Its not essential that every type of problem a diver could encounter is rehearsed in courses, but that a good selection is covered, not only to deal with the problems at hand but to widen our thinking and creativity.
This gives us a resource far more valuable than any piece of kit that we carry, including the gas on our back.
Despite using previously tested escapology methods, the extreme what-if scenario carried out over ss Thistlegorm was revolutionary, and possibly a first
in scuba diving.
For this reason, support divers and back-up equipment were used.

Low-visibility exercises under supervision.
While there is gas in the tank a diver can still breathe
With practice its possible to manoeuvre and hold air bubbles over the eyes to allow gauges to be read should a mask be lost.
Exercise to remove and replace all diving equipment while maintaining buoyancy control.