TONY CHANEY
Contributor
Not necessarily (with a drysuit and an empty tank):
http://www.scubaboard.com/forums/ac...ing-found-floating-kurnell-nsw-australia.html
I was not there but she was found on the surface.
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Not necessarily (with a drysuit and an empty tank):
http://www.scubaboard.com/forums/ac...ing-found-floating-kurnell-nsw-australia.html
Even with a buddy there to donate the long hose primary reg, you just don't let your own free-flowing gas expire away uselessly with all its noise and bubbles --have your buddy shut down your cylinder valve and then ascend normally together sharing gas to your safety stop and surface. Worst case --if you lose your buddy to begin with-- Loosen that waist belt on your BP/W Lynne and reach back & pull that tank valve up to the back of your head. Feather/modulate the tank valve while doing a CESA to your safety stop & surface.
RickyB, not to detract from this thread but there was a poster a few years back who posted several of these scenario based threads that I think you might be interested in reading. Might have been AWAP, but the search is only showing me posts back to 2012 now, so I can't find the specific links. I'll keep digging and see what I can find.
One thing that was definitely covered in my OW class was that alveoli can be ruptured by as little as 2 psi, so having air forced into my lungs is only very slightly more appealing than not getting any air at all. I like to think that my tongue is a highly skilled and dexterous tool, but I'm not sure I want to rely on it for such an important task without some redundancy, so keeping the reg in my mouth *and* having a good seal around it don't strike me as an ideal strategy. I'm inclined to think it's only a good choice when it's the only 2nd stage available.
Er..... yes it can. In the exceedingly unlikely event that the HP seat inside the 1st stage becomes dislodged the 1st stage can deliver about 1100 litres of air per minute to your 2nd stage. Basically, it's just blowing tank pressure straight into the 2nd stage.
I've only seen something like this happen once and only read about it online a few times in the time I've been active, but the pressure will literally blow the 2nd stage right out of your mouth.
Well in that instance [a completely empty tank] ---hopefully you're at the surface already in good shape AND can orally inflate your BCD/Wing. But it gets even more confounding if you have a drysuit that's "shrink wrapped" tight upon surfacing. . .
Can you be in good enough condition on surfacing to ditch your weights, orally inflate you BCD/Wing but with no positive tank pressure remaining to effectively inflate your Drysuit --maintaining positive buoyancy-- all after just performing a near out-of-air CESA??
1) A clear unobstructed surface here in SoCal is not always directly available --ever dive in a thick canopy Kelp Forest, DaleC? Just another potential confounding & compounding factor in this free-flowing scenario thread which is another reason for kelp divers to never ever surface with an empty tank.IMO... Wrong.
The safety inherent in OW diving is that the surface is always directly accessible. Planning your dive that way is the most important skill you can possess, not feathering a valve, which has no place in OW diving. If you are following safe diving practices you will have enough reserves to ascend breathing off a free flowing reg. You should also either have a buddy or redundancy if the dive is more complex. Suggesting that basic divers waste time at depth attempting to feather a valve takes away the foundation of safety that the whole system is based on. Why have people trying to preserve a depleting resource at depth? What do you gain? What do you risk?
Also, the linked accident has nothing to do with the topic at hand. Kev, why are you making stuff up? Ascending with a freeflow is not a CESA. It's an ascent. You wouldn't arrive on the surface with a DS shrink wrapped unless you were venting it all the way up. And, even if you did, a tug at the neck seal would increase the negative pressure inside to manageable levels. Can't maintain buoyancy on the surface.. drop your weightbelt; or is that a skill neglected because of focus on feathering valves. All of these things have pretty simple OW responses that don't involve delaying surfacing to preserve gas. Linking an incident in which your DM had a catasrophic failure and you continued the dive anyways doesn't impress me with safe diving decision making. It would appear your priorities for OW are OOW.
FWIW, here's a video of a freeflow. At :25 I am breathing off the FF reg as I prepare to swap out for my B/U reg.
1) A clear unobstructed surface here in SoCal is not always directly available --ever dive in a thick canopy Kelp Forest?
2) If a novice diver at basic OW depth 18m/60' --with no buddy in sight--
has the option & ability and can successfully make the effort to conserve as much free-flowing gas by the valve modulation/feathering breathing technique, what he gains is time --time for the Buddy to find him
and gas share. If not, then perform a "modified" Controlled Emergency Swimming Ascent (CESA) while taking breaths as needed by the valve modulation technique as described above. If possible & skilled enough to hold depth, do a safety stop. At the very least, the main objective is to safely reach the surface without suffering an AGE and with some tank pressure left to adequately inflate your BCD and Drysuit.
You don't want an "out-of-the-frying-pan-into-the fire" SoCal worst case scenario of surfacing with an empty tank; getting tangled in kelp; inability to orally inflate the BCD because you're out-of-breath having just performed a conventional CESA; shrink-wrapped drysuit hampering mobility; and working hard treading water to maintain positive buoyancy in a typical prevailing 2' to 4' afternoon swell & wind chop --you had better at least be able to drop your weights!
A simple motivating analogy (reply to "Why have people trying to preserve a depleting resource . . .? What do you gain? What do you risk?"):
That makes it "not an Open Water dive" and OW divers have no business being there.
No direct access to the surface, losing gas, and no buddy, means that the OW diver is now kicking Darwin squarely in the balls, yelling "come get me you loser!"
The buddy is both unaware of the emergency and lost. This is not the time to be screwing with valves, waiting for the buddy. This is the time to be "going up".
The BC can be easily inflated orally. It's an OW skill. The drysuit will have the proper amount of air in it (or more if the diver hasn't been venting on the way up). Drysuit inflation on the surface is nice for feeling all fluffy and comfy but is absolutely not necessary.
OW training isn't sufficient for the solo overhead dive you described. A well-trained OW diver would have surfaced within a couple of minutes of losing his buddy. In fact, a well trained OW diver would have said "I'm not trained for anyplace where "up" might not work, so I'll wait on the boat."
Open Water divers that are quickly losing gas do not need to "preserve a depleting resource." They need to be on the surface.
flots.
Flotsam has it right. Basic OW by definition is a dive in which the surface is always directly available. If it isn't, because of Kelp, boat traffic, excessive current, near or exceeding NDL's etc... it no longer is a basic dive and begins becoming an advanced dive. Then you need to consider alternative air sources, more cohesive teams (though that ought to be the norm regardless) or other strategies for dealing with failures.
At the OW level, the best and safest strategy is to abort the dive and seek the surface in a direct and calm manner. Wasting time seeking the bottom, feathering valves or attempting to continue a dive after someones air source has been compromised, is a perfect way to turn what should be a non-event into a stressed bolt CESA or OOA (which then leads to risk of drowning, AGE, arriving on the surface with no air for suit inflation etc...). You have two proven, dependable excellent strategies to use: Switch to your buddies octo and surface. Surface.
In an emergent situation, much drama can be avoided if the participants know to a.) avoid the situation or b.) leave the situation early. OW divers should not try to "stick around and run with the bulls".
In OW, the analogy of severe bleeding doesn't quite add up. Your air is not some vital substance you need to preserve to live and you do not need to remain "on the scene" of the accident. There is a huge blood/air bank called the surface that you can access. Aborting a dive because of a freeflow should be no more dangerous than a normal OW dive (though it may create a good post dive story to tell). Every OW dive contains these components. Swim down, swim around , swim up. The freeflow just means you swim up a little sooner than expected.
If you have a pre-dive Rock Bottom gas plan and you know how much pressure your tank has during all phases of the dive --you lose or become separated from your Buddy for an instant-- then why would you let vital breathing gas bubble away because of an unfixable free-flow on an emergency surface ascent? Especially if you have the ability to reach and manipulate your tank valve on & off to take breaths while not panicking, maintaining buoyancy at depth, spending a moment on the chance that your buddy will find you again? And if not, then how about a nominal ascent with a safety stop while still modulating your tank valve as needed for breaths? --What a novel, viable and more common sense option & approach as compared to current agency procedure as proferred by those above."Feathering" is not a basic technique for a very good reason. Last thing I want a basic recreational diver to be doing if they're forced to make an emergency ascent is to be shutting off their air supply ... imagine how that works out if for any reason your hand comes off the valve at the wrong time.
We don't teach it in OW for a very good reason ... it's a great way to induce a worse situation than you're already in.
Feathering is a technique that works well, and should be learned, at a more advanced level ... after the diver has sufficient training and experience to be able to handle the basics without conscious effort. Prior to reaching that level, you just shouldn't be diving in an overhead environment ... particularly without a dive buddy.
... Bob (Grateful Diver)
Jerome Bruner (1983: In Search of Mind) described creativity as "figuring out how to use what you already know in order to go beyond what you currently think."
Wisdom improving adaptability:To be wise is not to know particular facts but to know without excessive confidence or excessive cautiousness. Wisdom is thus not a belief, a value, a set of facts, a corpus of knowledge or information in some specialized area, or a set of special abilities or skills. Wisdom is an attitude taken by persons toward the beliefs, values, knowledge, information, abilities, and skills that are held, a tendency to doubt that these are necessarily true or valid and to doubt that they are an exhaustive set of those things that could be known.
The overconfident shun curiosity because they feel they know most of what there
is to know. The overcautious shun curiosity for fear it will only deepen their uncertainties. Both the cautious and the confident are closed-minded, which means neither makes good judgments. It is this sense in which wisdom, which avoids extremes, improves adaptability.
Karl E. Weick (1993), The Collapse of Sensemaking in Organizations: The Mann Gulch Disaster
If you have a pre-dive Rock Bottom gas plan and you know how much you pressure your tank has during all phases of the dive --you lose your Buddy for an instant-- then why would you let vital breathing gas bubble away because of an unfixable free-flow on an emergency surface ascent? Especially if you have the ability to reach and manipulate your tank valve on & off to take breaths while not panicking, maintaining buoyancy at depth, spending a moment on the chance that your buddy will find you again? And if not, then how about a nominal ascent with a safety stop while still modulating your tank valve as needed for breaths? --What a novel, viable and more common sense option & approach as compared to current agency procedure as proferred by those above.
Wisdom improving adaptability:
http://www.scubaboard.com/forums/ba...ponse-free-flowing-regulator.html#post7100372