Well, sure, Bob... But I can also see Bob (Grateful Diver)'s point in the real value of teaching how to prevent having to make that decision.
...And I can also see serious value in Thal's "desperate measure" into a "routine procedure" thought.
I just don't see the need for a bouyant ascent when it comes to a scuba diver. Sure, it can be done, but wouldn't a CESA (ascending by swimming and becoming progressively bouyant, rather than instantly bouyant by dropping weights and/or inflating your BC) be a better solution? Add that a scuba diver would be N2 loaded (unlike an escaping submariner), and would likely receive another breath out of his rig every few tens of feet while ascending, and it simply too small a benefit for the risks associated.
Think about this:
For this type of emergency to occur, the following would have to have happened:
1. The diver would have to have totally ignored his/her gas supply and his/her gauges.
2. The diver has lost his/her buddy.
3. The diver has not heeded the warnings of a low tank like progressively flexible hoses, a "lightening" of his/her rig, and an increasing difficulty of drawing gas through the regulator.
4. The diver would have to have zero inherent understanding of time limits... In other words, be unaware that "they've been down here for a lot longer than ever before."
Okay, so... If all of the above is true, and we actually have a solo diver totally out of gas at depth, in addition, they'd have to:
1. Be too overweighted to swim up.
2. Have a simultaneous, complete wing or BC failure.
If one of the above is not happening to this diver, then the diver can simply swim up... That is, do a CESA. That way, the diver remains in control of themselves during the entire ascent, and gets another breath of gas from their tank or tanks every few tens of feet. It's even possible that, in doing a CESA, the diver does not exceed a recommended 30 fpm ascent rate... Or at least a 60 fpm ascent rate.
There is simply no reason to dump weight and shoot to the surface... That is, no reason to choose an emergency buoyant ascent over a CESA.
You have it backward. The Navy’s usage dates back before I saw my first manual published in 1959. The recreational industry has taken it on their own to redefine, some say bastardized, the terms.
...And I understand that. The concept of the recreational community doing that - "bastardzing" - seems consistent with what I see coming from the recreational community today.
...But if the whole world is defining a term one way, then it's a miscommunication to call it something else, even if you were the first one to use the term.
How can I put this gently… the Navy trains their divers better.
I hear that, and... Having studied for the USN at Duke University's Hyperbaric Facility... I can tell you that I completely understand where you're coming from. However, that opinion is a broad generalization and doesn't account for individual instructors or exactly what part of dive training that you're talking about.
For example, I can tell you that I saw the direct results of Jarrod Jablonski and DAN working together to create dive profiles that affected the USN dive tables. Jarrod, by military definition, is a "recreational" dive instructor. Yet they sought his expertise, and clearly learned a lot from him.
Another example is the citation that you provided from the USN Dive Manual. While emergency bouyant ascents might be appropriate for escaping submariners that are effectively freedivers... Or described by Bob as "bounce divers," N2 loaded scuba divers - that is, divers that have been breathing gasses at depth - have better, safer, faster, simpler options to the triple-catastrophe of being simultaneously lost from their buddy, without any other backup breathing gas, and out of gas on their primary source... Namely, swimming up and taking another breath... The CESA.
They don’t sugar-coat the realities of barotrauma with non-threatening rules like “never stop breathing”. Free ascents are taught and practiced. Navy, commercial, and other “old-school” trained divers virtually never embolize themselves. Exhaling on ascent is as reflexive as a cough.
I agree. But that doesn't explain why a loaded scuba diver would choose a bouyant ascent over a swimming, neutral one, especially after suffering a double or triple (depending on how you look at it) catastrophe. Bob's right... It shouldn't ever get to that point. And Thal's right... If it does, the diver needs to know how to handle it. "Bouyant" is uncontrolled, dangerous, likely going to cause some sort of barotrauma in the person that's never done it before, and probably slower overall (slower to initiate) than a "CESA," which is natural, comparatively safer, and consistent with all of their training.
Granted it isn’t obvious from 7-8.1 Emergency Free-Ascent Procedures alone that it isn’t necessary to dump your weight belt and inflate your BC unless you deem it appropriate.
I have yet to see an intelligent argument for when it is "appropriate" to dump your weight belt and inflate your BC at depth. The idea of an "escaping submariner" may be, in retrospect, but it's definitely not a good idea for a scuba diver. That is... There are safer, simpler options including the CESA... And as Bob (Grateful Diver) pointed out... Not getting to the point of needing to consider a CESA.
PADI and competing training companies are in a very different business. They must model recommendations to customers with very limited technical knowledge and skills. That appears to have perpetuated misconceptions even in their instructors.
You know, I agree with you, and I, too, feel that there are a lot of shortcomings in the recreational diving community's teachings. Still, I don't see what that's got to do with choosing an emergency bouyant ascent over a CESA, Lord forbid a diver ever get themselves into that situation.
I’m having trouble processing any comparison between PADI’s current guidelines and the collective work of the
US Navy Experimental Diving Unit, Diving School, and fleet diving operations since the first manual was published in 1905. I should probably shut up now.
Lol... Well, I didn't compare PADI specifically to USN, but I did say the "recreational community," which I suppose implies PADI. See my comment above about Jarrod, of GUE (and PADI and NACD and several others), and DAN working together at the Duke Hyperbaric Facility for the USN. In other words, there is much more "trading of ideas" than initially meets the eye, and not necessarily in one direction.
What healthy and positive option is there that meets the Navy’s guideline for free ascent? Please read them again. It is pretty clear that it is for last-ditch emergencies when all other alternatives have failed or are not available in time. Therefore the only options are to asphyxiate and die, hope for divine intervention, or surface.
See, I don't see this. Assuming that the obvious - Bob (Grateful Diver)'s recommendations are ignored and the situation really does present itself that the diver must ascend to the surface or drown - I don't see why a buoyant ascent would have an advantage over a CESA. That is, I see no advantage to dropping your weights and/or inflating your BC prior to ascending (inflating... with what? I thought we were OOA).
For all practical purposes barotrauma is not even a concern because it is a given that divers are skilled and practiced at preventing it.
No amount of skill or practice is going to prevent an air embolism or anneurism from expanding bubbles in the bloodstream or difficult-to-vent body cavities. That's the difference between a scuba diver who has been breathing compressed gasses at depth and an escaping submariner who is "freediving" or "bounce diving," depending on how you see it. That's why an escapting submariner can do a bouyant ascent at 600 fpm, while a scuba diver must (and can, since he gets another breath every few tens of feet) ascend much slower.
At that point the possibility of DCS is absolutely a very serious possibility, but not a certainty. However it is much more treatable, slower acting, and much less certain than forgoing breathing on the bottom.
Agreed. And you know what? I'd rather step out in front of a car instead of a bus. Or jump from a 2-story building than a 10-story building. But there are better options if the elevator doesn't work... Like the stairs. And if they're blocked, you could still wait for the helicopter or attempt to scale the building or wait for them to put that giant people-catcher down there... Or maybe wait out the emergency in hopes that it will be stopped before you have to jump, or maybe even a ladder truck will save your day. But for God's sakes, don't jump... Even if it works for those people who have parachutes.
Dropping weight at depth - and/or inflating your BC at depth - is akin to jumping. Why do that, when a CESA is available? At least you can control that...
Please don’t list all the reasons why this isn’t supposed to happen. Unfortunately it happens far too frequently to divers that are well within no-D limits (thus a marginal DCS risk). Way too many recreational divers are found dead on the bottom rather than potential DCS patients swimming toward the boat.
When? Where? Do you have statistics? How do you define "far too frequently," and who was "found dead on the bottom?" How would a bouyant emergency ascent have prevented the fatality better than a CESA? Do you know people who have been in the situation where they had to decide to CESA or bouyant ascend or drown? What was their choice, and what was the outcome?
And Bob DBF... What's to say that you're choosing to be bent at the surface or drowned on the bottom, anyway? If a diver, neutral in the water column, kicks up as a last resort - without dumping weight or adding gas to his/her BC - then guess what? They're bouyant. No additional work needed. That is, they'll be bent at the surface whether they like it or not, whether they dropped weights or not, if they kicked up as a last resort.
This idea of doing an emergency buoyant ascent - regardless of whose "standard" it is or when it was first published - is a more dangerous option than a CESA, if only because it is uncontrolled. It may have been the standard practice for a submariner, who is not N2 loaded... But in any situation where a diver is breathing compressed gasses - that is, open circuit or closed circuit scuba or surface-supplied... There are better, safer options than an emergency bouyant ascent.
If you disagree, that's your right... But until you can point out a reason why it's better to do an emergency buoyant ascent over a CESA (this isn't a comparison of EBA vs. drowning) as a last resort, we're not gonna agree.
