Learned Wrong...

[Deep South Divers]

Here's the real questions:

Have you ever done a buoyant emergency ascent? Have you ever trained to do one?

I have trained to do one, but never done one out of necessity. It was part of our AAUS training at the SC Aquarium in Charleston. In order to qualify as a diver capable of diving what they call the "Giant Ocean Tank," we had to demonstrate a bouyant emergency ascent... That is, drop weights and ascend to the surface bouyantly.

In fact, we were taught to do with with a fin kick to get the ascent started... Then a flair as you described to reduce the effects of accelerating toward the surface. For what it's worth, our BCs were completely empty and we were at a max depth of 44' in the GOT to perform the maneuver.

With regards to a CESA, yes, I have both trained to do one AND actually performed one in my one-and-only total OOA with no buddy at depth. Will never happen again, I can promise that! See previous post.

After this training, and with my experience, I can not understand why anyone would ever drop their weights at depth. Well, so long as they're not 128 lbs overweighted, of course...

 

[Deep South Divers]

You keep repeating the assertion that a quick kick or two and you will be positively buoyant. I think that part of the problem is that so many divers - especially new ones - are over weighted.

With 21 total dives, the last 17 in cold water with my current gear, I have been max weighted at 32lbs. I could not easily hold a 5m safety stop - kept wanting to go up. Over the course of the summer, I have dropped to 28 lbs, and on my last dive had to keep air in my BCD to maintain my SS, indicating I am ready to drop more weight. In the spring, I am going to start at 26. This is all related to my relaxation and breathing in the water, a shift of weight of 6lbs. A couple of kicks will now get me closer to buoyant than it did a year ago, but a year ago it would have been more work.

So for a not atypical over weighted recreational diver, is it not possible that just kicking up is not as simple as you are asserting? I guess my point is that as an advanced diver you may be oversimplifying, assuming a capability / skillset / gearset / experience level that may not actually exist for an average recreational diver of the weekend warrior sort.

This is a great point, gcarter, and I'm really glad that you brought that up.

Overweighting really doesn't have much to do with it.

Here's an example:

Let's say that we have two identical divers that require 20 lbs of lead to be properly weighted. However, one of the divers is brand new and is wearing 35 pounds of lead and is fairly dramatically overweighted... He has, after all, almost twice the amount of weight necessary.

Now let's put both divers near the bottom, at 100'.

Both divers have a bubble in their BC or wing that they need to make them neutral. The skilled diver has his nailed... Let's say it's the size of 1 cuft, and he's neutral. The less experienced diver has 2 cuft to make him neutral, but has to play with it a lot to get the bouyancy right. Sometimes it's 1.75 cuft and sometimes it's 2.25 cuft. He's also somewhat vertical in the water column, and having a tough time balancing his bubble, his lungs, and his fins to stay at one depth.

Now... Suddenly, both divers are totally out of breathing gas.

They both go vertical and kick up. The skilled diver is bouyant the moment that he goes vertical, and with his fin kick, can achieve ascent speeds of almost 300 feet per minute, instantly. However, if he stops to breathe at all, he'll realize that he has additional breathing gas as he ascends, and can probably safely keep an ascent rate of 60 fpm or even 30 fpm. In fact, he'll probably need to vent his wing - not inflate it or drop weights - to maintain control.

The less skilled diver is bouyant or nearly bouyant (depends on how sloppy his adjustment was) the moment he goes vertical, and with his fin kick, can achieve speeds of - well, it depends on how fast he can swim in his new fins, but suffice to say it's faster than 60 fpm and bouyant and while delivering another breath about every 30' or so.

In other words, being overweighted has no effect on whether or not you're more bouyant as you go up. In fact, the unskilled diver - with about 2 cuft of gas in his BC will experience the bubble increasing to about 3 cuft in size at 66 ft, 4.5 cuft in size at 33 feet, and almost 9 cuft in size at the surface... All without adding additional gas. (The skilled diver will go from 1 cuft to 1.4 cuft to 2 cuft to 4 cuft respectively.)

This proves that a diver - even without dropping a weight belt - will become progressively more bouyant as he ascends... All while getting additional breathing gas on the way up. Likely, if he doesn't vent his BC, it will vent itself. There is no need to add gas, and in an emergency, I wouldn't recommend stopping to do so. Dropping the weight belt is not only unnecessary, but provides the diver with a control problem that wouldn't be there otherwise.

It doesn't really matter if the diver is overweighted or not... I mean, within reason. 15 lbs isn't a problem, especially if you've compensated with a larger bubble in your BC. 128 lbs... Well, apparently that was too much.

 

[Belmont]

I had a client-rep try that concept on for size for a 600' sat… of course it was a “client pays for gas” contract.

Seriously, were any parameters attached or was this in all cases? Sure there can be better choices depending on the profile just as there are worse. Now Propane and Nitrous Oxide would be bad.

MERC would certainly leave you with bad breath.:yuck:

 

[MXGratefulDiver]

There’s that word “should” again. I’m more inclined to put my chips on “when” while betting my life... or even ego. Can you imagine how much crap you guys will pile-on if I’m the next body recovery! :shocked2:

LOL ... that same thought has occurred to me many times.

No ... I wouldn't pile-on any crap ... we're all the product of our training, experience, and the mindset that came with them. That's what makes these conversations interesting ...

... Bob (Grateful Diver)

 

[DCBC]

Here's the real questions:

Have you ever done a buoyant emergency ascent? Have you ever trained to do one? Do you know what one feels like? From what depth(s)?

Have you ever done a CESA? Have you ever trained to do one? Do you know what one feels like? From what depth(s)?

When I was 16, I was diving with a "K Valve" and ran out of air. My SPG was indicating 900 psi. Although I had a buddy, I was inexperienced (diving for 4 years). Breathing was difficult, I exhaled and was OOA. I inhaled about a half-a-breath then no-joy. I was at about 65 FFW. Without thinking, I dropped my belt and started for the surface (I didn't even look for my buddy). I was positively buoyant (1/4" WS) but inflated my CO2 cylinder (like that would bring me to the surface) I tried to exhale slowly and recall the unusual feeling of having no air in my lungs and then magically having the feeling of air available. It was a learning experience and come to think of it, I never did find the weight-belt. Healthways did replace the SPG at no charge, but I never trusted a SPG again...

I would like to add that although I may have had air available in my tank upon ascent, my mental focus was to do a free ascent and get to the surface. I just didn't consider breathing off my regulator. Some may look at this and laugh, but when the *hit hits the fan and it's over in less than a minute, the mind doesn't always work in a rational way.

As far as a CESA is concerned, I have done a doff and don with SCUBA in 100 FSW and yes it was part of the Navy diver training program in the 70's. I currently teach a controlled rate emergency ascent to basic students from 60 FSW and routinely do a FA to my decompression/safety stop.

 

[DaleC]

Here's the real questions:

Have you ever done a buoyant emergency ascent? Have you ever trained to do one? Do you know what one feels like? From what depth(s)?

Have you ever done a CESA? Have you ever trained to do one? Do you know what one feels like? From what depth(s)?

I appreciate this question as all the theory in the world will go out the window when stressed under water.

I have done a dive before with someone who couldn't even find their releases for the weight pockets. What would they do in an emergency (besides panic and die)? If they had to practice some simple techniques till they became proficient (in order to pass the course) they may have a fighting chance but apparently that was not required for them.

I also believe the value in practicing these techniques in real conditions is that one then knows the options are a real workable possibility (I know I can do this). Knowing that, many divers would then be more relaxed in an emergency and be able to work through their issues - probably not needing to resort to either an EBA or a CESA. People with no experience working through sub optimal conditions often have a problem solving pathway of A>B>Z. With training and practice it can become A>B>C>.

I would prefer an EBA to a CESA for the control it offers but I also keep a CESA in the back of my mind. If I were to go OOA in the traditional sense I would have some warning (increasing breathing resistance) and could react premeditatively, but if I were to go OOA on an exhalation with no warning it would be a whole different ball game. I have done a lot of static and dynamic apnea training and know that under stress, vigorous physical activity (finning) will cause a much much faster breathing reflex than being able to relax into the ascent.

Another issue is what happens on the surface. There are accident reports wherein divers have surfaced in distress only to sink down again to be recovered at depth. While a CESA may not have ultimately saved them is of course debatable, but the fact that they did not attempt to drop their belts could be the result of never having practiced doing so in a real world setting.

Anyways, good discussion.

 

[Darnold9999]

As I understand it the problems at depth that kill you typically are not one off. Most divers can resolve the single failure and a CESA will likely resolve a single failure. What do you do when your dry suit floods, and you run out of gas - probably trying to resolve the suit failure at depth. Or any other combination where your source of boyancy fails so your are suddenly negative and you run out of gas.

Properly weighted likely CESA is still possible but you will require significantly more than a fin kick or two to get positive. I think in that situation I would be ditching weight rather than fighting the loss of boyancy - I know that dropping weight will work. Might not know until too late that kicking up will not work.

Personally when diving cold I keep weights in three separate compartments - a belt that is not easily ditchable as I would really rather not be 10 lbs positive for any reason (specifically a buckle failure which I have seen happen more times than I am comfortable with) - and two 5 lb pouches attached to my BC that are easily ditchable, but not prone to accidental failure.

I want the option of being positive by dropping weight available, but also want to keep the control of only being slightly positive rather than uncontrollably positive.

 

[Thalassamania]

Dale's got some real gold here:

I appreciate this question as all the theory in the world will go out the window when stressed under water.

I have done a dive before with someone who couldn't even find their releases for the weight pockets. What would they do in an emergency (besides panic and die)? If they had to practice some simple techniques till they became proficient (in order to pass the course) they may have a fighting chance but apparently that was not required for them.

I also believe the value in practicing these techniques in real conditions is that one then knows the options are a real workable possibility (I know I can do this). Knowing that, many divers would then be more relaxed in an emergency and be able to work through their issues - probably not needing to resort to either an EBA or a CESA. People with no experience working through sub optimal conditions often have a problem solving pathway of A>B>Z. With training and practice it can become A>B>C>.

I would prefer an EBA to a CESA for the control it offers but I also keep a CESA in the back of my mind. If I were to go OOA in the traditional sense I would have some warning (increasing breathing resistance) and could react premeditatively, but if I were to go OOA on an exhalation with no warning it would be a whole different ball game. I have done a lot of static and dynamic apnea training and know that under stress, vigorous physical activity (finning) will cause a much much faster breathing reflex than being able to relax into the ascent.

Another issue is what happens on the surface. There are accident reports wherein divers have surfaced in distress only to sink down again to be recovered at depth. While a CESA may not have ultimately saved them is of course debatable, but the fact that they did not attempt to drop their belts could be the result of never having practiced doing so in a real world setting.

Anyways, good discussion.

As I understand it the problems at depth that kill you typically are not one off. Most divers can resolve the single failure and a CESA will likely resolve a single failure. What do you do when your dry suit floods, and you run out of gas - probably trying to resolve the suit failure at depth. Or any other combination where your source of boyancy fails so your are suddenly negative and you run out of gas.

Properly weighted likely CESA is still possible but you will require significantly more than a fin kick or two to get positive. I think in that situation I would be ditching weight rather than fighting the loss of boyancy - I know that dropping weight will work. Might not know until too late that kicking up will not work.

Personally when diving cold I keep weights in three separate compartments - a belt that is not easily ditchable as I would really rather not be 10 lbs positive for any reason (specifically a buckle failure which I have seen happen more times than I am comfortable with) - and two 5 lb pouches attached to my BC that are easily ditchable, but not prone to accidental failure.

I want the option of being positive by dropping weight available, but also want to keep the control of only being slightly positive rather than uncontrollably positive.

Properly weighted, a few kicks should get you moving up; and if you are in a wetsuit or have air in your BC, it should start a positive feedback loop that will cause you to accelerate toward the surface. But ... if your wearing a drysuit and the shoulder valve is set right and your BC is empty, this will not be the case, you will have to actively swim all the way up. In fact, the way in which your valves is set, and if it is set for horizontal or vertical attitude, or if you even have a shoulder valve vs. an arm or wrist valve, will determine what is going to happen and what additional steps you'll have to take.

I try, when it comes to emergency procedures, to take as many decisions out of the process as possible, I'd rather not have to stop and say to myself, "What gear am I wearing today?" Oh ... that's right if drysuit and wings, I do thus and so, but if wetsuit and BC I do this other thing, and if I'm diving vintage ... well I have to do something different. I'd rather have one plan that fits them all: drop the lead and try to enjoy the ride.

 

[Akimbo]

I think you misread the scenario and forgot what they are in response to. Your statement was:

…I have yet to see an intelligent argument for when it is "appropriate" to dump your weight belt and inflate your BC at depth.....

Just like the last post, the simple answer is Because you believe you will die if you don’t.
Of course your statement should read “dump your weight belt and/or inflate your BC at depth” which are options to the free ascent procedure we are discussing. This list describes scenarios when you would find yourself in that unfortunate circumstance.

This paragraph sets the stage for the following four scenarios. Please consider the red portions and your responses:

….Fair enough. How about you are approaching your planned minimum cylinder pressure to leave bottom. For whatever reason you get separated from you buddy — visibility is bad, the surge is up, he’s a macro photographer focusing on a critter, or she found a better looking guy. It doesn’t really matter. Then:
(each bulleted item is an “or” not an “and” to the scenarios)

• You experience a total loss of air. Perhaps an HP O-ring or blow-out plug fails, an LP hose lets loose, or flow just stops because your rental cylinder has clogged your regulator inlet filer or valve dip tube. The important part is there is nothing left to breath by the time you figure it out. You can’t inflate your BC and you fear the additional drag of all that inoperable gear will reduce your chances of survival.

...

Your reply:

…CESA. I don’t know a faster way to the surface.…

That defies the laws of physics and your own judgment (highlighted above). The comparison is between the hydrodynamic resistance of a diver wearing a cylinder and BC to the same diver without. It is also the difference in energy required to surface between a swimming neutral to negatively buoyant diver and a non-swimming positively buoyant diver.

….

• You swim into a wad of monofilament and can’t get lose. You remove your cylinder, still breathing from it, to get unhooked. Three is a hopeless knot of stainless wire entwined with the mono and you sense inhalation resistance on your high-performance balanced regulator. That means about three more labored breaths before you pass out.

...

Your reply:

……So I’m entangled, without a buddy, and totally out of gas? Well, if I can’t free the rig, then I guess I’m leaving it there… No choice. Total abandonment of gear is neither a standard CESA OR EBA… And since almost all of my weight is in my bp/wing, I’d likely be bouyant anyway. This scenario would end with me swimming like hell to the surface, probably bouyant… I guess both a CESA and an EBA. ...

That is a buoyant emergency free ascent… executed in an uncontrolled manner and on the verge of panic. Congratulations, you found an intelligent argument. Hope you remembered to exhale!

However, if you practiced free ascents you wouldn’t waste energy “swimming like hell” since you are buoyant. The dominant emotion would be pissed-off at having to salvage your gear rather panic exemplified by your mad-dash for the surface. Of course your panic is understandable given your belief that the practice is deadly — understandable, but incorrect.

….

• You start to vent your BC when the corrugated hose pulls off in your hands. You start to sink during your night dive and the option is drop your 3 Lb negative $8,000 dollar camera or your 20 Lb $50 weight belt. You try to swim against the current and negative buoyancy and notice the needle approaching 300 PSI as the debate continues.[/U] You are tired, concerned, and not sure what to do if anything else goes south. Your computer shows green in the deco box.

...

Your reply:

… Well, I can’t see that happening, since I don’t pull on my corregated hose, and it’s double-bolted with two screwed clamps… But I get your point… Let’s say that the wing was catastrophically completely holed and totally inoperative, right at the end of my dive.
Depending on my depth, I’d be negative by less than ten pounds, I’d simply swim the rig up… Probably not even classifying as a CESA. ...

Of course you pull on your hose even when you don’t have a pull-dump. It’s called lifting it to vent. In any case, we agree the BC is toast.

Ten pounds, and probably -13 Lbs, is a fair amount of weight when holding that $8,000 SLR and checking your computer to see how fast you are sinking… at night. I think it is fair to assume your SAC rate will be elevated. Your balanced first stage is going to reach 135 PSI OBP (Over Bottom Pressure), which is ~180 PSIG at 100', so you can only use 120 PSI of the 300 PSI left. Don’t forget that you’re already tired and concerned…. Hope you make it!

Can I have that camera after they pry it out of your cold dead hands? I don’t need any more weight belts.

If you can swim up ten pounds negative so easily, which I fully accept, it is even easier to feather your ascent when 10 Lbs positive — resulting from dropping a 20 Lb belt.

….

• The bottom is somewhere past 600' on a wall dive. You feel funny and uneasy. Suddenly you get a splitting headache and lose all vision. Your weight belt is 16 Lbs and your BC has 40 Lbs of lift. You can’t sense if you are losing or gaining depth. You have no idea how much longer you will be conscious.

...

Your reply:

… Um… Turn to my buddy and signal “not okay, vertigo?” Maybe attempt to reorient myself against the wall? Thumb the dive and ascend in a controlled manner? Signal “OOA” and receive a donation, in case the issue is the gas in my tanks? I don’t see what a “blow and go” would achieve in this scenario, and there are a lot of safer options to deal with a depth problem at depth, rather than compound it with a bouyant, immediate and uncontrolled ascent. ...

What buddy — the one that left you for a better looking guy? Vertigo? You’re blind, don’t know which way is up, and have a justifiable concern that you will black out at any second. Your chance of bumping into the wall is less than 1:6 — if you are capable of swimming straight. How do you plan to make an ascent in a controlled manner? Good thing you didn’t have your camera on this dive!

BTW, this level of disorientation often causes projectile vomiting. Just thought I'd mention it.

 

[Akimbo]

… What I experienced when I had a real-world OOA emergency with no buddy around (the one and only time I will ever have to do it in real life), was tilting my head back and swimming like hell while going, "Ahhhhhhhh!" all the way to the surface. Okay, let me correct that... What I said was actually "Oh****oh****oh****o****!" I think I said a lot more choice words, too.

Well, by 50' or 60' or so, I was out of lungs. I had, by that point, completely vented my lungs and was swimming like hell for the surface in utter and eerie silence. The world began to turn black, and I began to wonder who would find the body and what my family would say about me and how I had died….

This is starting to explain your mental block on the subject. Obviously that’s not how it’s done.

… Well, by that point the bubble in my wing had expanded considerably, and I was quite bouyant, no dropping of weight necessary. But what really freaked me out was how much of a dumbass I felt like when I instinctively breathed in and got... Another breath. Wait, maybe I'm not really OOA...

I finished the rest of my dive ascending at 30 fpm, and even stopped at 10' for a minute or two.

Now that I know that an OOA isn't really if you're ascending, I would safely tell you that within PADI's recreational dive limits (which includes both time and NDL), a CESA can be performed from all depths. In fact, you'll actually have time to vent your wing to prevent too-fast of an ascent.….

All that is true and well understood by those who are properly trained in the full spectrum of free ascent options. You did not experience an out of air emergency; it was a low air condition that you perceived to be an emergency and over-reacted to.

However, there are real OOA conditions — as in total failure of breathing gas systems. If that were the case in this example, you would have to re-write everything past:

… The world began to turn black, and I began to wonder who would find the body and what my family would say about me and how I had died….

It would be so much easier if you had been trained and practiced how to prevent this.

…Dropping weights? Why?? That would only exaserbate the problem.

Why would you drop weight when you are already positively buoyant? Nobody is even suggesting dropping weight and/or inflating a BC UNLESS IT IS APPROPRIATE.