BC Failure

[Crush]

bold added

bold added - assumption is air in the tank

He said "with an empty tank". If there is air in the tank, then it is reasonable to have a little air in the BC.

Neoprene also rebounds less with use and we have no idea how old or new his wetsuit is. Around here in extremely cold water, large steel doubles and wetsuits are not a recommended combination, and the redundancy of the SMB is a good call.

You are trying to wiggle your way out of a mistake. You posted:

And would your BC have been empty at the safety stop? If you require air in your BC at the safety stop, then you are overweighted. It certainly sounds from your description, that you were overweighted.

Which is an error - by your own admission, this you are posting general information for new divers. Do you not agree?

 

[Ayisha]

You are trying to wiggle your way out of a mistake. You posted:

Which is an error - by your own admission, this you are posting general information for new divers. Do you not agree?

No, this is not a mistake. I responded to his direct quote. The two quotes are together, exactly as you see above:

I was carrying the exact amount I needed to perform a safety stop at 15 feet, without floating up and being able to breath normally, with an empty tank.

And would your BC have been empty at the safety stop? If you require air in your BC at the safety stop, then you are overweighted. It certainly sounds from your description, that you were overweighted.

The missing part of DD's statement was that he did not state whether his BC would have had air in it when discussing his correct weighting for a safety stop. If you look at previous posts where I've discussed my weighting, I was taught that I am correctly weighted when I can do a safety stop with a nearly empty tank and no air in the BC. BTW, I test this while holding a stop at 10 feet and I strive for it. Then I am correctly weighted. The missing part of DD's statement is the BC, hence I began the sentence with AND. We cannot look at weighting without the whole picture.

 

[Crush]

I was taught that I am correctly weighted when I can do a safety stop with a nearly empty tank and no air in the BC.

I can name a few very experienced divers on SB who have posted that the prefer to be slightly negative at their safety stop at the end of a dive. They have also justified their positions, and those justifications seemed reasonable to me.

I can name a few very experienced divers on SB who have posted that the prefer to be slightly negative at the surface at the end of a dive. They have also justified their positions, and those justifications seemed reasonable to me.

I do not doubt that there are some that agree with your position with respect to neutral buoyancy at safety stops. I do not doubt that their (and your) justifications might seem reasonable to me.

So, if you post:

And would your BC have been empty at the safety stop? If you require air in your BC at the safety stop, then you are overweighted. It certainly sounds from your description, that you were overweighted.

Why should I not challenge your statement, which is universal and without caveats?

So, given the breadth of experience on SB, and the contradictory nature of the posts by very experienced divers, and your admission that your post was:

...a general comment for newer divers.

should we not be fair to new divers and tell them that there are many "correct" answers, and that some are more correct than others, depending upon the circumstances?

Personally, I do not believe that DumpsterDiver did anything wrong.

Personally, I would have been "out of there" as soon as my BC failed, but I seem to have a lower risk tolerance and a lower experience level and therefore a smaller comfort zone than he does.

I do not believe that DumpsterDiver is glorifying his actions or recommending them to new divers.

After all, given a course of action, depending upon who you are and your abilities, your mileage may vary (YMMV).

 

[Ayisha]

This was your quote of my post:

Everyone should be neutrally buoyant at the surface and should be able to swim up their rig, and if not, then have redundant lift.

Ayisha, you have the zeal of a new DIR diver.

He did have redundant lift - his DSMB.

This was my answer with your above quote in the post:

Nope, not DIR. Relatively new at 9+ years.

Yes, DD did have a DSMB, and he could also swim up his rig. That was a general comment for newer divers.

You then attempt to use the above quote regarding swimming up a rig with an entirely different quote on having an empty BC:

So, given the breadth of experience on SB, and the contradictory nature of the posts by very experienced divers, and your admission that your post was:

a general comment for newer divers.

should we not be fair to new divers and tell them that there are many "correct" answers, and that some are more correct than others, depending upon the circumstances?

Wrong again. Nice attempt at twisting wording. The general comment began with the word "Everyone" and was clearly separated from the paragraph above that directly responded to DD's post. It is quite clear what is directly asked of DD, and which he failed to answer.

Some people prefer to be slightly negative in high boat traffic areas in order to dive down quickly if necessary. I sometimes dive in high boat traffic areas and even shipping channels. They are treated as overhead environments and we plan to surface very carefully under our boat or with a float. I find it no problem to descend quickly while being neutrally buoyant. Given the number of accidents due to overweighting and people drowning at the surface due to being overweighed and not releasing weights, I think it is prudent for newer divers to work on being neutrally buoyant. In addition, of course, there are the considerations of gas consumption, trim, and environmental protection, which can all be adversely affected by overweighting.

However, the question of whether his BC would be expected to be empty was directed at DD clearly because I suspect that it was not empty or anywhere near empty. I asked him and he refused to answer, even though he gave every other relevant part of the equation.

 

[TSandM]

I have very few dives where nothing goes wrong. To call a dive is something rather minor goes wrong would be to call a majority of dives.

I find this interesting. I'm inching up on 1000 dives, and I would say at least 950 of them were dives where nothing went wrong at all. I think that's the virtue of a good dive plan, a thorough equipment check before getting in the water, good underwater communication, and good dive skills. Of course, there are those times when water conditions change, or the very rare unexpected equipment issue . . . but overall, dives where anything goes wrong AT ALL are noteworthy in my log book.

 

[John C. Ratliff]

Aysha,

I think it was pretty evident that with the type of failure he had, DD had an empty BC. I think he refused to answer because he had made it pretty clear that the BC would not hold air.

To all,

I'm looking at your quote from B.F. Skinner, that "Education is what survives when what has been learned has been forgotten." I think this is a bit of a contradiction, in that if something is actually learned, it is almost never forgotten. But what can happen, and has happened to me, is that in a situation which is perceived as an emergency, attention is focused. Sometimes that focus is inappropriate to the circumstances. NAUI, in its instructor manual, had a section titled Exertion and Breathing (The Panic Syndrome). I seem to remember it also as the "panic-exhaustion syndrome." Here is what that manual stated:

When one works very hard, the normal reaction is to breathe at a faster and deeper rate. But if the person is apprehensive the breathing may become very fast and shallow. Rapid, shallow breathing does not properly flush the lungs of the increased CO2 load, nor does it bring all the available oxygen down into the lungs.

The best way to recover from heavy exertion is to relax as much as possible and breathe deeply and slowly. Fight the urge to pant or take shallow short breaths. This is particularly important when breathing through divivg equipment, such as a snorkel or scuba regulator.

If you are on the surface and get out of breath, turn over on your back, kick slowly as you inflate your BC. If underwater with scuba gear, relax, slow down, drop any heavy oxjects you are carrying, take longer, slower, deeper breaths and maintain your position while you recover...

In some of my past training, it was pointed out that people who are in the Panic Syndrome focus their attention on one thing. If they are drowning, someone may try to literally climb out of the water until they are too tired to maintain themselves, and sink. However, if they started out the dive about neutrally buoyant without anything in the BC, then attaining positive buoyancy is a simple thing--dropping weights or inflating something. If a float is available, it can be used (indeed, that's what we did before BCs--use inner tubes on the surface).

Let me show you two photos taken of me in an underwater physiology experiment in 1971:

Here, I'm descending to a depth of 73 feet in a fresh water lake (Clear Lake, in the Oregon Cascade Mountains east of Eugene, Oregon). Note that I'm carrying my weights in my hand.

In this photo, I'm getting ready for the work physiology research by switching regulators so that my respirations, O2 consumption, and exhalations can be sampled. I was to swim along a horizontal line for a set number of minutes to determine the effect of cold and depth on work (we did this at 3 feet and 37 feet too, simulating 1, 2 and 3 atmospheres of pressure). But note that I am not wearing any weights--none at all. And I'm neutral in the water.

This is why I did not think DD was in any trouble at all in his situation. He simply had lost the BCs capability of achieving neutral buoyancy. But he was kneeling on a wreck at the time, and could stay there with no further problems. He could push off it to initiate a swim to the surface, and he elected to use a second buoyancy device to help him out. There was no Panic Syndrome, and no complicating factors where he was (although there was some chop on the surface).

In the next paragraphs, NAUI explains a hypothetical accident caused by this Panic Syndrome:

A tired, over-weighted diver fighting to stay on the surface may face disaster. Referred to as "The Panic Syndrome" the scenario develops as follows: The diver has failed to inflate the buoyancy system upon surfacing. The diver is too heavy, yet still does not drop the weight belt. The snorkel is out of the mouth and the more the diver struggles to stay up, themore CO2 the body creates. Increasing fatigue and awareness of danger leads to panic. Panic causes shallow, rapid breathing which is inefficient. Breathing inefficiency further starves the body of oxygen while the diver struggles harder and harder to stay above the surface. Unless this chain is broken, the diver may drown.

By improving breathing efficiency, gaining additional buoyancy with the BC or by dropping the weight belt, the chain of events may be broken. Such surface accidents are definitely preventable. All divers should be properly trained in how to rest and relax inthe water. They should also be able to recognize when they are getting into difficulty and know what steps to take to break the chain of events leading to The Panic Syndrome.
NAUI The Pro Manual, II-39, 1977

One more piece of information which can contribute to The Panic Syndrome--the diver's regulator. I collect old, vintage diving regulators. I tear them apart, dive them, and improve them. A diver needs to know that his regulator is working as well as it can work. (S)He also needs no know whether it is a good-performing regulator. I recently got a 1950s version of the Dacor Dial-A-Breath regulator to tear apart. I had owned their later R-4 regulator, and was not impressed with it. The earlier version performed in the pool pretty well, as well as their later version. But this was a pool test. When I looked up the US Navy tests, I found that this regulator did not pass because of high exhaust effort, and poor performance at depth under high work load. The Navy recommended to Dacor that they look at the interstage pressure, opening size, etc. before re-submitting this type of regulator. I now have the US Navy Tests on the Dacor R-4, and the Dacor C3NB, and none of these two-hose regulators passed the U.S. Navy Experimental Dive Team tests. Dacor did not vastly improve these regulators over the years (their Pacer regulators did pass these tests though).

I dove a similarly poor-performing regulator in the same lake mentioned above, and it was bad enough I had to swim underwater on my back to get the air I needed out of it (US Divers Aqualung, their original unit, which also was tuned badly).

I remember investigating a fatal accident many years ago which involved what should have been a high-performing regulator. When I tested that regulator, the suction effort was over 10 inches of water pressure (measured on my home-made manometer). This regulator should have been measuring less than 1.5 inches of water pressure suction effort. This was a primary contributing factor to this fatality--the poor maintenance of the regulator, but not the only one (overweighted, very poor fitness for diving, ran out of air too). All these factors came together to cause this fatality.

But I saw none of this in DD's incident.

TS&M,

I have a spot in my dive log that is titled "Special Problems and Proposed Solutions." I have very few dives where there is no entry here. These are the little things that go wrong, and by tracking them, I can see trends. For instance, years ago I kept putting into this area that I was getting cold. I'd say it in many different ways, but when I went back and looked over a period of time, I found that I really needed a dry suit. Another instance, I stated that my "Avanti fins worked very well in the current, but are still very difficult to get off. They are also hard to hold out of water w/ their elongated foot pocket." This was in March of 1986. In April of 1986, I made the following observation in this section, "The Avanti fins are very difficult to get off. I had to take my gloves off to get them off." Water temperature was 46 degrees F. I ended up cutting away much of the elongated foot pocket. But if I had not started tracking this, I would not have figured out that these fins had that as a design problem.

SeaRat

PS--If you want copies of those tests, follow the link and go to the bottom right side of the page to download the actual tests. If you want other tests, type "regulator" into the Rubicon search engine.

 

[DevonDiver]

Truly excellent post John. That should be re-posted in its own right and kept as a sticky.

I see lots of divers make assumptions about how they would (hypothetically) respond to an underwater emergency. They often fail to understand that physiological factors have a crucial effect, which can mean that the reality is far removed from what they anticipate.

 

[Crush]

However, the question of whether his BC would be expected to be empty was directed at DD clearly because I suspect that it was not empty or anywhere near empty. I asked him and he refused to answer, even though he gave every other relevant part of the equation.

(Emphasis added.)

Why do you think this?

I suspect that it was not empty or anywhere near empty.

(Emphasis added.)

Consider these my parting shots:

1. I have already detracted from the OP too much, even by SB standards;
2. I have no reason to assume that the OP was anything but truthful. You, it seems, may think otherwise; and
3. If I were to summarize: new divers, don't try this at home.

 

[doctormike]

One of the things that is often stressed regarding the downward spiral or incident pit is that it rarely starts with a "major" failure. Instead, it's exactly the minor failures which by themselves seem insignificant or ignorable that lead to complications if something else goes wrong (either independently or as a result of the first failure). It's not having a busted BC that completes the spiral, it's just the first step down.

Yup, and this is the point that I was trying to make... I think that a new diver might take away from this thread that since there was a logical way to complete the dive given this equipment failure (albeit by a skilled and experienced diver), that calling off the dive would be wrong, that it would be an admission of poor diving skills.

Judging from the pushback that I got here, I can certainly see a new diver looking at this thread, and finding themselves in a similar situation feeling a lot of pressure just to work it through and figure out how to complete the dive safely. Which might be fine, or it might not if something else went wrong (cramping, etc..). I'm not saying that we should never try to fix things underwater, or never try to work out backup plans - to the contrary, new divers like the rest of us should be encouraged to think things through, hopefully before an emergency happens. But they should also not feel that calling off a dive when a piece of equipment fails is a mark of weakness.

FWIW, I don't think that my instinct to call the dive in these circumstances is quite as off-base as it has been depicted here - I ran this scenario by a friend at a dive club meeting last night who is an instructor on multiple rebreathers and he felt that it was reasonable to call the dive as well.

Please understand that his opinion or my opinion does not mean that the OP or any of the other divers here are wrong, arrogant or foolhardy, but it does mean that there are reasonable and different opinions about how to handle this situation, and I didn't want the thread to be archived here without the other point of view.

dumpsterDiver, doctormike states (below your post quoted above) that you would not have been overweighted if your BC had not failed and recognizes that wetsuits do compress. Given that, I personally would have used the term "negatively buoyant" rather than "overweighted." However, like you, I get frustrated when warm water divers (doctormike may well dive cold water, don't know) claim that you should always be able to swim your rig to the surface, and that if you are carrying more than 10# in lead you are probably overweighted.

OK, I agree that overweighted has intent implications that negatively buoyant does not, but I think that we have already identified that terminology issue.

I do think that you should be able to swim your rig to the surface in case of failure of your primary and secondary flotation devices (wing and dry suit). I agree with the GUE guideline: "The diver should be able to drop unnecessary weight and swim up without a functioning BC. As with all diving, the key component to proper buoyancy is diving with a properly balanced rig."

I didn't say anything about an arbitrary amount of lead implying overweighting (hard hat divers carry a lot more then 10 lbs and are correctly weighted).

Sorry to frustrate you. I'm not a tech diver but I dive regularly off the NYC area dive boats in cold water.

 

[doctormike]

If I were to summarize: new divers, don't try this at home.

A perfect summary!