75 ft out of air, What do YOU do?

[Braunbehrens]

Iguana Don once bubbled...
There is another choice,
Not taught in mainstream scuba classes. you can breathe (inhale), not rebreathe the 2-3 breaths of air in your BC as you ascend. This method is taught in the DIR classes, but not in any other.

Depends on which book you read.

Don

I wasn't taught to breathe from my BC in my GUE classes. I would be hesitant to do so because I've heard that it can cause lung infections.

However, I do know that it is possible to use your BC inflator as a regulator by pressing both buttons at once. I have not tried this either.

I would consider breathing (or even rebreathing) the air from my BC if I was somehow trapped under water. It's probably less unpleasant to pass out this way than to drown ... so in any case it might be the way to go if that situation presented itself.

The best solution is to pay attention and dive with competent buddies. Then you won't need any of these "solutions".

BTW, did the original poster ever reply as to what his Boss had suggested was the appropriate action to take?

 

[The Iceni]

MHK once bubbled...
In short for the combination of loosing a unified team AND running out of air that diver has turned his brain off for that dive.

Are current certification standards that low?

That being said, I'm not sure why if you are ascedning you would need to replace air in your BC.. Moreover, if the choice is between drowning and ditching a weightbelt upon ascent my money is ditching teh weight. Accordingly, absent the weight I can't figure out a reason that a diver would need to replace air in his BC or sink, as you suggest.

Hi MHK,

Let us assume my understanding of Boyle's law is correct.

Can I suggest

1) It is imperative that the diver remains in control (or takes steps to regain control).

2) A rapid buoyant ascent is not controlled so anyone ditching a weight belt at depth loses all control over his ascent (and could hit the bottom of the dive boat like a Trident missile)

Lets look at this idea of taking a few breaths from a BC a bit more closely?

The diver is ascending from depth so the volume of air in his BC increases as the pressure reduces so it would indeed seem sensible to use this to take a breath - rather than directly dumping it in order to regain near-neutral buoyancy and control. In this situation the panicky diver is likely to take a deeper than normal breath - say 3 litres and may even be tempted to take two breaths - 6 litres.

In taking two breaths he will have rapidly lost 6 kgs of buoyancy and may not be able to replace this from his cylinders so I suggest he is likely to sink. (If there is enough gas to replace that dumped surely it makes sense simply to breath from it?)

This manoueuvre constitutes considerable additional task loading in any case.

The point I was making, and I think it was well made, is that gas will become available from the cylinders as you ascend to allow for a few breaths at least.

So, in my opinion if you do cock-up and find yourself in an OOA situation with no buddy there is no need whatsoever to panic since you can ascend safely without taking a breath (as long as you breathe out) but you can get a few breaths from your cylinder in any case. There is no need to carry a spare air device or to breath from the BC

In my opinion those that consider spare air devices are useful do not understand the physics or physiology or the high pressure environment and are deluding themselves (and others).

Which brings us on to the genuine overhead environment, which is a different matter entirely. In this situation the buddy is the most important item of kit after adequate gas planning (twinset/pony) and situational awareness.

I hope that makes sense.

 

[leadweight]

There often seems to be a mindset around here that every dive is in a "genuine overhead enviornment" and an inability to distinguish that from easy & shallow recreational dives.

 

[The Iceni]

leadweight once bubbled...
There often seems to be a mindset around here that every dive is in a "genuine overhead enviornment" .

Hi leadweight,

I tend to agree, which is why a well trained diver should never allow himself to run out of breathing medium. All dives are decompression dives and therefore require an obligatory (safety) stop.

Thus we really should not be discussing what to do when out of air at 75 ft with no buddy, or the benefits or otherwise of a miniscule air reserve but it seems some still consider this to be a possible scenario. Is this a symptom/sign of bad training?

 

[Scubaroo]

Braunbehrens once bubbled...
BTW, did the original poster ever reply as to what his Boss had suggested was the appropriate action to take?

J.P. did not post his answer, and in fact hasn't posted in over 2 years.

Seeing the names Mario S Caner, Warhammer and Iguana Don in a thread was a blast from the past.

Hopefully it's not because he bought a spare air

 

[Genesis]

is to carry a 19cf pony on any dive where I cannot count on a team member being within reach at all times.

I can make a free ascent on the 19cf bottle from 130' and get there, particularly if I start at 100-110, by doing a nice controlled exhale from 130!

From anything less than 100' I can do a full 3 minute safety stop as well, and STILL not run out of gas.

Also, I can hand the entire thing off, since I sling it like a stage - so now I can give the bottle to another diver who needs it, and clip it to HIS BC if necessary.

Now there are those who say "dive a unified team and there are no problems like this."

To that I say "if you admit and allow for EQUIPMENT to fail, then you must also admit and allow for HUMANS to fail. If you do THAT, then you would be wise to control for BOTH scenarios, and that requires some source of independant gas."

 

[JeffG]

Genesis once bubbled...
<snip>
To that I say "if you admit and allow for EQUIPMENT to fail, then you must also admit and allow for HUMANS to fail. If you do THAT, then you would be wise to control for BOTH scenarios, and that requires some source of independant gas."

And on that note, we should all carry a Spare Air with 100% O2 to do our safety stops (Oh hell, lets call them deco stops...we all know that all dives are deco dives)

Using the Spare Air with 100% O2, you can use the Oxygen window to the max benefit (See GI3's article on the oxygen window). And if we label our spare air with the MOD, and clip it to our left hand DRing we are also fully DIR too.

 

[leadweight]

I consider it to be really bad form to run out of breathing gas, short of an equipment failure or an entrapment situation. Like, you are at depth and enjoying yourself so much that you used it all up. That is pretty bad. Unplanned deco? Dumb, but at least you can surface and go to a chamber if something happens.

It is almost like driving a car with your eyes closed.

From my perspective as a recreational diver it is a matter of having the right response to potential equipment failures without resorting to a pony bottle.

For those in true overhead enviornments it is a different ball game with responses based on true redundant gear and no quick bail out route.

 

[The Iceni]

Hi Guys,

I have just returned from a very interesting week with the Royal Navy, some of which was spent at their diving and submarine training establishment in Gosport, Hampshire (formerly HMS Dolphin).

One of the demonsrtations at the submarine escape training tank (SETT) brought home to me the physics of a swimming ascent and I think it useful to describe for Scubaboarders, at least two of the many demonstrations we were shown.

The SETT instructor descended to 30 metres in the bell, took a breath of air at ambient pressure, exited the bell in swimming trunks alone, and then performed a perfectly controlled buoyant ascent at no more than 5 metres per minute, breathing out gently all the way, without moving a muscle!

It took him well over five minutes to ascend, and he controlled his rate of ascent perfectly through adjusting his buoyancy by means of exhaling sufficient air to keep his lung volume constant against the ever reducing ambient pressure in the water column. He made no swimming actions at all. When he reached the surface, he was not even short of breath and was entirely composed.

I was initially puzzled by this party trick, attributing it to his unique level of fitness, but of course he did not actually experience any degree of hypoxia because the Pa O2 at depth was close to 4 x 0.21 = 0.84 bar and the ascent simply reduced this back to the more normal level of 0.21 bar (less his metabolic needs);- Unlike the situation with free divers, his lungs continued to oxygenate his blood.

There would have been a certain amount of CO2 retention during his ascent but clearly he was able to counter the reflex urge to breath

1) by reducing CO2 build up by his low activity levels and

2) because of his fitness and training.

So if you do run out of gas at depth, there really does seem to be no need to panic (- as long as you remain buoyant).


Ths brings me on to another demonstation. On this occassion the SETT instructor took a deep breath on the surface and demonstated he could float unaided. He then repeated the exercise and pushed himself down to the 9 metre mark, where he remained neutrally buoyant for about 30 seconds - the lung compression had removed all effective buoyancy.

He then pushed himself down beyond the neutral position and sank, at an ever increasing rate, until he reached the bottom and entered the bell.

The point of the exercise?

Jumping off a high bridge is a effective way of committing suicide because if you hit the water fast enough it will take you below the neutral point and you will not float to the surface.

 

[Big-t-2538]

Dr Paul Thomas once bubbled...

The SETT instructor descended to 30 metres in the bell, took a breath of air at ambient pressure, exited the bell in swimming trunks alone, and then performed a perfectly controlled buoyant ascent at no more than 5 metres per second, breathing out gently all the way, without moving a muscle!....It took him well over five minutes to ascend.....

Do you mean 5 seconds per meter????