Hello,
I am a keen tech diver as well as pilot, so have a couple of cents to chip in. I think GadgetGuru's post is excellent.
I fully agree that continued recurrency training is the only way to keep your skills sharp. After a year, your knowledge of a subject may still be fresh, but your physical skill and ability may well have eroded.
ABSOLUTELY IMPORTANT: I also would like to go further to stress the importance of breathing out as you ascend. ONLY IF USING A STASS or UNDERWATER BREATHING APARATUS.
In addition, I would like to suggest, that anyone using a 'Spare air' or pony-type bottle (for emergency egress or recreational diving) really consider the limitations of this system and get proper training, before adding them to your emergency equipment.
Test on it, and train with it or IT WILL KILL YOU! No point in having something, and then when you really need it, you find you can't turn it on or it runs out!
Some simple maths...It holds 85 litres at 200 bar so its is 0.42 litres in size. Assume a 10 m/min ascent rate (to allow for delay in egress and equipment / clothing drag)
Assuming our 40 lpm panic breath rate (and I've seen higher).
10m bail requres 80 l so OK (Just)
20m bail requires 120 l so you're dead
30m bail requires 160 l so you're very dead
Even assuming a 20l breath rate (and many people use more than this at rest)
10m bail requres 40 l so OK
20m bail requires 60 l so you're OK
30m bail requires 80 l so you're OK (just)
As you can see from this, it could be easy to run out very quickly unless you are pretty focused, fit and well practiced. It is definitely not a system to use to return to depth and attempt a rescue of others.
I personally have not been that keen on them because the capacity of these systems is usually too small for they type of diving I am doing. However for Helicopter emergency egress I fully support their use (with proper training). As they say 'owt is better than nowt'. Any little thing can help.
The most important thing is to 'STOP, ASSESS, ACT'.
cl12pv2s
