Blog | John Clarke Online

How Will You Try to Kill Me?

Émile_Jean-Horace_Vernet_-_The_Angel_of_Death — Émile Jean-Horace Vernet-The Angel of Death

It’s been over three years since I posted a cautionary tale about oxygen sensors in rebreathers, and the calamities they can cause. Since then, the toll of divers lured to their death has been steadily mounting. In one week alone in April 2016, at almost the same geographical latitude in Northern Florida, there were two diving fatalities involving rebreathers. It is an alarming and continuing trend.

I know a highly experienced diver who starts each dive by looking at his diving equipment, his underwater life support system, and asking it that title question: How will you try to kill me today?

This deep cave diver, equally at home with open circuit scuba and electronic rebreathers, is not a bold cave diver. He is exceptionally cautious, because he is also the U.S. Navy’s diving accident investigator. He has promised me that his diving equipment will never end up in our accident equipment cage.

He and I have seen far too many of the diving follies where underwater life support systems fail their divers. But the crucible in which those fatal failures are often born are errors of commission or omission by the deceased.

Carelessness and an attitude of “it can’t happen to me” seem all too prevalent, even among the best trained divers. Divers are human, and humans make mistakes. Statistically, those accidents happen across all lines of experience: from novice divers, to experienced professional and governmental divers, and even military divers. They all make mistakes that can, and often do, prove fatal.

It is exceedingly rare that a life support system fails all by itself, since by design they are robust, and have either simple, fool-proof designs, or redundancy. In theory a single failure should not bring a diver to his end.

http://www.jj-ccr.com/the-jj-ccr/rebreather-lid.aspx — The “head”, triplicate oxygen sensors, oxygen solenoid and wiring leading to the rebreather CPU. Image from jj-ccr.com.

Are oxygen sensors trying to kill you? That depends on how old they are? Are they in date? Ignoring the expiration date on chocolate chip cookies probably won’t kill you, but ignoring the expiration date on oxygen sensors may well prove fatal. Complex systems like rebreathers depend upon critical subsystems that cannot be neglected without placing the diver at risk.

Oxygen sensors are usually found in triplicate, but if one or more are going bad during a dive, the diver and the rebreather can receive false warnings of oxygen content in the gas being breathed. We have seen a rebreather computer “black box” record two sensor failures, and it’s CPU logic deduced that the single working sensor was the one in error.

The controller’s programmed logic forced it to ignore the good sensor, and thus the controller continued to open the oxygen solenoid and add oxygen in an attempt to make the two dying sensors read an appropriately high O2. Eventually, the diver, ignoring or not understanding various alarms he was being given, went unconscious due to an oxygen-induced seizure. His oxygen level was too high, not too low.

Unlike fuel for a car or airplane, you can have too much oxygen.

Oxygen sensors do not fail high, but they do fail low, due to age. Rebreather manufacturers should add that fact into their decision logic tree before triggering inaccurate alarms. But ultimately, it’s the diver’s responsibility to examine his own oxygen sensor readings and figure out what is happening. The analytical capability of the human brain should far exceed the capability of the rebreather CPU, at least for the foreseeable future.

2016031295100655 — JAKSA high pressure 6-volt solenoid used in a Megalodon rebreather. NEDU photo.

Oxygen addition solenoids hold back the flow of oxygen from a rebreather oxygen bottle until a voltage pulse from the rebreather controller signals it to open momentarily. The oxygen flow path is normally kept closed by a spring inside the solenoid, holding a plunger down against its seat.

But solenoids can fail on occasion, which means they will not provide life giving oxygen to the diver. The diver must then either manually add oxygen using an addition valve, or switch to bailout gas appropriate for the depth.

Through either accident or design, divers have been known to invert their solenoid spring and plunger, thereby keeping the gas flow open. In that case, oxygen could not be controlled except by manually turning on and off the valve to the oxygen tank. Of course, knowing when oxygen is too low or too high would depend upon readings from the oxygen sensors.

Suffice it to say that such action would be extremely reckless. And if the oxygen sensors were old, and thus reading lower than the true oxygen partial pressure, the diver would be setting himself up for a fatal oxygen seizure. It has happened.

Assuming a solenoid has not been tampered with, alarms should warn the diver that either the solenoid has failed, or that the partial pressure of oxygen is dropping below tolerance limits.

But as the following figures reveal, if the diver does not react quickly enough to add oxygen manually, or switch to bail out gas, they might not make it to the surface.

The three figures below are screen captures from U.S. Navy software written by this author, that models various types of underwater breathing apparatus, rebreathers and scuba. In the setup of the model, an electronically controlled, constant PO2 rebreather is selected. In the next screen various rebreather parameters are selected, and in this case we model a very small oxygen bottle, simulating an oxygen solenoid failure during a dive. On another screen, a 60 feet sea water for 60 minutes dive is planned, with the swimming diver’s average oxygen consumption rate set at 1.5 standard liters per minute.

On the large screen shot below, we see a black line representing diver depth as a function of time (increasing from the dashed grey line marked 0, to 60 fsw), a gray band of diver mouth pressure, and an all-important blue line showing the partial pressure of inspired oxygen as it initially increases as the diver descends, then overshoots, and finally settles off at the predetermined control level of oxygen partial pressure (in this case 1.3 atmospheres). Broken lines on the very bottom of the graph show automated activation of diluent add valve, oxygen add solenoid, and over pressure relief valve. Long horizontal colored dashes show critical levels of oxygen partial pressure, normal oxygen level (cyan) and the limit of consciousness (red).

Screen shot 1 — Screen shot of UBASim results after an ill-fated 60 fsw dive.

The oxygen solenoid fails 53.7 minutes into the dive, no longer adding oxygen. Therefore the diver’s inhaled oxygen level begins to drop. Rather than follow the emergency procedures, or perhaps being oblivious to the emergency, this simulated diver begins an ascent. As ambient pressure drops during the ascent, the drop in oxygen pressure increases.

In this particular example, 62.5 minutes after the dive began, and at a depth of 13.5 feet, the diver loses consciousness. With the loss of consciousness, the diver’s survival depends on many variables; whether he’s wearing a full face mask, whether he sinks or continues to ascend, or is rescued immediately by an attentive boat crew or buddy diver. It’s a crap shoot.

So basically, the rebreather tried to kill the diver, but he would only die if he ignored repeated warnings and neglected emergency procedures.

What about your rebreather’s carbon dioxide scrubber canister? Do you know what the canister duration will be in cold water at high work rates? Do you really know, or are you and the manufacturer guessing? What about the effect of depth, or helium or trimix gas mixes? Where is the data upon which you are betting your life, and how was it acquired?

Scrubber canister and sodalime. NEDU Photo

Sadly, few rebreathers have dependable and well calibrated carbon dioxide sensors; which is unfortunate because a depleted or “broken through” scrubber canister can kill you just as dead as a lack of oxygen. The only difference is a matter of speed; carbon dioxide will knock you out relatively slowly, compared to a lack of oxygen.

But if you think coming up from a dive with a headache is normal, then maybe you should rethink that. It could be that your rebreather is trying to kill you.

Samael_(Angel_of_Death)_Personification — Samael_(Angel_of_Death)

In the Claws of a Monster

By Huhu Uet (Own work) [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons — By Huhu Uet via Wikimedia Commons

Nature does not always provide good options. When faced with weather-related adversity, making the right decision can be as much a matter of luck as wisdom.

Homerville, Georgia is the home of some first-rate southern barbeque and home of one of the best genealogical libraries in the Southeast, the Huxford Geneological library. In June of 1975 I made an unintended stop at the Homerville Airport after flying my 1962 Cessna 150 from Thomasville, Georgia to Waycross, Georgia. My wife and Mother-In-Law were in Waycross, visiting, and on a Friday afternoon I took off in my 2-seater aircraft to meet my wife’s family 92 miles away.

As I approached Waycross a thunderstorm was directly on top of the field. The Waycross Fixed Base Operator confirmed they were being clobbered, so I made a 180 degree turn and flew 26 miles back to the Homerville airport that I had passed on the way in.

When I landed I found I was the only aircraft, and only human, on the field. But regrettably, there were no tie-downs, ropes or chains that I could use to secure the little Cessna while I found a phone to call my wife and tell her about the change in plans. The weather was good, and it should take only a few minutes to bother one of the nearby neighbors for a phone call. What could go wrong?

After I explained to my family where I was, I thanked the friendly lady who let me use her phone, and headed back to my aircraft. But as I approached the plane, the view at the other end of the runway was turning ugly. Another thunderstorm was headed straight for the field. And it was close, and mean-looking.

I climbed into the cockpit, started the engine, and sat there assessing what I was seeing out the windscreen. And thinking about options.

What I wanted to do was take-off and head for Waycross. I was not at all prepared to abandon my airplane and watch it be destroyed by the approaching storm. As I considered the fact that I would be taking off towards a thunderstorm, I thought of riding out the gusts on the ground, using the engine power and rudder to keep the plane pointed into the wind. But as I throttled the engine and rudder back and forth, reacting to the increasing gusts, I realized the 1000 pound plane would inevitably be picked up, with me in it, and dashed to the ground. It would not be a pretty sight, especially if it was lifted to a significant height by updrafts before being dropped.

The wind ahead of the thunderstorm rain shaft was picking up, gusting, and as I weighed the different options, the storm kept getting closer, closing my window of opportunity. As they say, the clock was ticking.

Finally, I decided I’d rather be airborne, in some semblance of control, than being airborne out of control. The storm was not yet on the field, but I knew I had scant seconds before the cloudy violence would make an escape impossible. I pressed hard on the brakes, dropped my flaps one notch, pushed the throttle full in, and when the engine was roaring as loudly as a 100 horse power engine can roar, I let go of the brakes and started my takeoff roll.

Thanks to the advantage of straight-down-the-runway storm winds, I lifted off very quickly. I stomped a rudder pedal and dipped a wing to turn as fast as I could away from the storm, passing over the roofs of nearby houses much closer than the residents were used to, I’m sure. But the plane was fully in control and headed quickly towards safety.

Although the storm winds were actually helping to push me away, I felt an occasional shudder from the back of the plane. I imagined the storm shaking me in its jowls, plucking at my wings with its sharp talons, as if angry that I had escaped its clutches.

I made it safely to Waycross, but my aircraft’s escape was short-lived.

If there were such a thing as a Storm Monster, I would think that it was malevolent, because exactly two weeks after that incident another thunderstorm hit the field in Waycross, where the plane was supposedly safely chained down. I was on the field as a vengeful storm snapped the steel chains holding down my plane’s tail, flipping the plane over on its back, crushing the tail. My little bird never had a chance.

I had risked my life in Homerville to avoid watching my beautiful bird be destroyed, only to see it destroyed in the same manner only a fortnight later.

We tell our children there are no monsters … but I’m not so sure.

Where Things Move Quickly and Darkly

I came across a great article from the New Yorker with an interesting title. In fact, my interest lasted all the way to the end.

Spooked: What do we learn about science from a controversy in physics?

Albert_Einstein_(Nobel) — “Albert Einstein (Nobel)” by Unknown – Official 1921 Nobel Prize in Physics photograph. Licensed under Public Domain via Wikimedia Commons

If you get the feeling that science is not as pure of thought and logic as it pretends to be, then you will find some comfort in Adam Gopnik’s approachable review of the deeply hidden controversy surrounding what Albert Einstein called “spooky action at a distance.” Spooky action is the weirdest of all science, and makes telepathy and clairvoyance seem almost banal by comparison.

In my opinion, parts of Gopnik’s none-too-technical article remind me of the quote by Dr. Jason Parker, the protagonist in the science fiction thriller, “Middle Waters“. In a supposed speech to the open-minded Emerald Path Society, Parker said, “There are regions between heaven and Earth where magic seems real and reality blurs with the surreal. It is a place where things move quickly and darkly, be they friend or foe. The hard part for me is knowing the difference between them.”

Gopnik expressed that thought more prosaically by the following: “”Magical” explanations, like spooky action, are constantly being revived and rebuffed, until, at last, they are reinterpreted and accepted. Instead of a neat line between science and magic, then, we see a jumpy, shifting boundary that keeps getting redrawn.”

Gopnik goes on to say, “Real-world demarcations between science and magic … are … made on the move and as much a trap as a teaching aid.”

To be honest, I did leave out Gopnik’s entertaining reference to Bugs Bunny and Yosemite Sam. Again, if you have ever been suspicious of the purity of science, the New Yorker article is well worth the read.

Unlike the concerns of Einstein, Neils Bohr and the rest of the cast of early 20th century physicists, the anxiety of Jason Parker, the fictional hero, is not cosmological; it’s personal. It’s every bit as personal as it is for each of us when we sometimes question our sanity.

Yes, real life can be like that sometimes, when things intrude into our ordered lives, as quickly as a Midwest tornado, but with less fanfare and warning. But every bit as destructive. And it is at those points, those juxtapositions with things radical, unexpected, that we end up questioning our grip on reality.

After all, what could be more unexpected and unreal seeming than the notion that cosmological matter we can’t see, dark matter, could send comets crashing into the Earth, as Gopnik mentioned, and the Harvard theoretical physicist Lisa Randall wrote about in her book Dark Matter and the Dinosaurs.

So, Jason Parker had every reason to be wary of things that move quickly and darkly. They can be a killer.

Sometimes, as in the case of Parker, those internal reflections do end up having a cosmological consequence. But even if they don’t, it’s a good idea to occasionally reexamine our lives for the things which may seem one day to be magical, and the next day to be very real.

In short, the magic should not be dismissed out of hand, because, after all, just like “spooky action at a distance” and “dark matter”, it may not be magic after all.

Remote Viewing – Stretching the Limits of Science in Fiction

puthoff_lg — Laser physicist Harold E. Puthoff.

I once met the Father of the U.S Remote Viewing program, unawares.

A decade ago, at the request of a Navy engineer who ended up being a character in my novel Middle Waters, I invited Dr. Harold E. Puthoff into the Navy Experimental Diving Unit to give a talk on advanced physics. He had attracted a small but highly educated and attentive crowd which, like me, had no idea that the speaker had once led the CIA in the development of its top secret Remote Viewing program.

Of late, Puthoff’s energies have been directed towards the theoretical “engineering of space time” to provide space propulsion, a warp drive if you will. Although strange by conventional physics standards, similar avant-garde notions are receiving traction in innovative space propulsion engines such as NASA’s EMdrive.

Puthoff is the Director of the Institute of Advanced Studies at Austin, in Texas, but before that, and more germane to this discussion, Puthoff was a laser physicist at the Stanford Research Institute. It was there that the CIA chose him to lead a newly created Remote Viewing program, designed to enable the U.S. to maintain some degree of competiveness with Russia’s cold war psychic spying program.

09-02-1220_26_07low — 6800 feet down in the Desoto Canyon

Psychic spying was purportedly the method used by the two superpowers to visualize things from a distance; not from a satellite, but from what some call the highly developed powers of the mind’s eye. If we believe what we read on the subject, Remote Viewing was eventually dropped from the US psychic arsenal not because it had no successes, but because it was not as reliable as signal intelligence (SIGINT), satellite imagery, and spies on the ground. But, it has been argued, it might be ideal in locations where you can’t put spies on the ground, such as the dark side of the moon, or the deep sea .

Serendipitously, as I started writing this blog post, Newsweek published a review of the Remote Viewing efforts of Puthoff and others in a November 2015 issue. The article seemed fairly inclusive, at least more so than other articles on Remote Viewing I’ve seen, but the Newsweek author was not particularly charitable towards Puthoff. Strangely, the strength and veracity of Puthoff’s science was reportedly criticized by two New Zealand psychologists who, as the Newsweek author quoted, had a “premonition” about Puthoff.

“Psychologists” and “premonitions” are not words commonly heard in the assessment of science conducted by laser physicists, especially those employed by the CIA. The CIA is not stupid, and neither are laser physicists from Stanford.

To the extent that I am able to judge a man by meeting him in person and hearing him talk about physics, I would have to agree with Puthoff’s decision to ignore his ill-trained detractors. Every scientist I know has had detractors, and as often as not those detractors have lesser credentials. Nevertheless, I have the good sense to not debate the efficacy of remote viewing. I don’t know enough about it to hold an informed opinion. However, there seems to be some evidence that it worked occasionally, and for a science fiction writer that is all that is needed.

Enrico%20Fermi%20chalkboard — Nuclear physicist Enrico Fermi.

As my curiosity became piqued by the discovery of the true identity of my guest speaker at NEDU, and as I learned what he had done for the U.S. during the Cold War, I thought of another great physicist, Enrico Fermi, one of the fathers of the atomic bomb. In the midst of a luncheon conversation with Edward Teller, Fermi once famously asked, “Where are they?” The “they” he was referring to, were extraterrestrial aliens.

What became known as Fermi’s Paradox went something like this: with all the billions of stars with planets in our galactic neighborhood, statistically there should be alien civilizations everywhere. But we don’t see them. Why not? “Where are they?”

In most scientists’ opinions, it would be absurdly arrogant for us to believe we are the only intelligent life form in the entire universe. And so ETs must be out there, somewhere. And if there, perhaps here, on our planet, at least occasionally. And that is all the premise you need for a realistic, contemporary science fiction thriller.

But then there is that pesky Fermi Paradox. Why don’t we see them?

Well, they could indeed be here, checking us out by remote viewing, all the while remaining safely hidden from sight. After all, as one highly intelligent Frog once said, humans are a “dangerous species” —fictionally speaking of course.

That “hidden alien” scenario may be improbable, but it’s plausible, if you first suspend a little disbelief. If we can gather intelligence while hiding, then certainly they can, assuming they are more advanced than humans. A technological and mental advantage seems likely if they are space travelers, which they almost have to be within the science fiction genre. Arguably, fictional ETs may have long ago engineered space-time, which could prove mighty convenient for tooling around the galactic neighborhood.

So, if in the development of a fictional story we assume that ETs can remote view, the next question would be, why? Is mankind really that dangerous?

Well, I don’t intend for this post to be a spoiler for Middle Waters, but I will say that the reasons revealed in the novel for why ETs might want to remote view, are not based on fear of humans, but are based on sound science. From that science, combined with a chance meeting with Hal Puthoff, the basic premise of a science fiction thriller was born.

So, to correct what some of my readers have thought, I did not invent the concept of “remote viewing”. It is not fictional; it is real, and was invented and used by far smarter people than myself, or even that clever protagonist, Jason Parker.

Eating Crow – Safe Water Temperatures for Scuba Regulators

Scientists and engineers love to argue, and unlike the case with politicians, compromise is not an option. Technologists speak for nature, for the truth of a universe which does not speak for itself. But when a technologist is wrong, they usually have to eat some crow, so to speak.

Stephen Hawkings, the famous cosmologist, freely admits his brilliant doctoral dissertation was wrong. Crow was eaten, and Hawkings moved on to a better, arguably more correct view of the universe.

Now, on a much less grand scale, this is my time for eating crow.

There has been quiet disagreement over the water temperature above which a scuba regulator is safe from free-flowing or icing up. Those untoward icing events either give the diver too much gas, or not enough. Neither event is good.

Based upon an apocryphal Canadian government study that I can’t seem to put my hands on anymore (government studies are rarely openly available), it has long been believed by the Canadians and Americans that in water temperatures of 38°F or above, regulator icing problems are unlikely. That temperature was selected because when testing older, low flow Canadian regulators, temperatures inside the regulator rarely dropped below 32°F when water temperature was 38°F.

As shown in an earlier blog post, in 42°F water and at high scuba bottle pressures (2500 psi) in instrumented second stage regulators (Sherwood Maximus) second stage internal temperature dropped below zero Celsius (32°F) during inspiration. During exhalation the temperature rose much higher, and the average measured temperature was above freezing. Nevertheless, that regulator free flowed at 40 minutes due to ice accumulation.

Presumably, a completely “safe” water temperature would have to be warmer than 42°F. But how much warmer?

My European colleagues have stated for a while that cold water regulator problems were possible at any temperature below 10°C, or 50°F. However, as far as I can tell that assertion was not based on experimental data. So as we began to search for the dividing line between safe and unsafe water temperatures in another brand of regulator, I assumed we’d find a safe temperature cooler than 50°F. For that analysis, we used a generic Brand X regulator.

To make a long story short, I was wrong.

To understand our analysis, you must first realize that scuba regulator freeze-up is a probabilistic event. It cannot be predicted with certainty. Risk factors for an icing event are diving depth, scuba bottle pressure, ventilation (flow) rate, regulator design, and time. In engineering terms, mass and heat transfer flow rates, time and chance determine the outcome of a dive in cold water.

At NEDU, a regulator is tested at maximum anticipated depth and ventilated at a high flow rate (62.5 L/min) for a total period of 30 min. If the regulator free flows or stops flowing, an event is recorded and the time of the event is noted. Admittedly, the NEDU test is extremely rigorous, but it’s been used to select safe regulators for U.S. military use for years.

Tests were conducted at 38, 42, 45 and 50°F.

Next, an ordinal ranking of the performance for each regulator configuration and temperature combination was possible using an NEDU-defined probability-of-failure test statistic (P_f). This test statistic combines the number of tests of a specific configuration and temperature conducted and the elapsed time before freezing events occurred. Ordinal ranks were calculated using equation 1, where n is the number of dives conducted, E is a binary event defined as 0 if there is no freezing event and 1 if a freezing event occurs, t is the elapsed time to the freezing event from the start of the test (minutes), and k is an empirically determined constant equal to 0.3 and determined to provide reasonable probabilities, i is the index of summation.

Conshelf XIV pic 2 — Click for a larger image.

Each data point in the graph to the left represents the average result from 5 regulators, with each test of 30-min or more duration. For conditions where no freezing events were observed at 30 min, additional dives were made for a 60-min duration.

As depicted, 40-regulator tests were completed, using 20 tests of the five primary second stages and 20 octopus or “secondary” second stages. Regression lines were computed for each data set. Interestingly, those lines proved to be parallel.

file0001735338997 — A second stage of a typical scuba regulator. The bite block is in the diver’s mouth.

The “octopus” second stage regulator (the part going in a scuba diver’s mouth) differed from the primary only by the spring tension holding the regulator’s poppet valve shut. More negative mouth pressure is required to pull the valve open to get air than in the primary regulator.

The test statistic does not provide the probability that a given test article or regulator configuration will experience a freezing event at a given temperature. However, it does provide the ability to rank the freezing event performance of regulator configurations at various temperatures.

Our testing reveals that in spite of my predictions to the contrary, for the Brand X regulator our best estimate of a “safe” water temperature, defined as Pf = 0, is roughly 53°F for the standard or “primary” second stage regulator and 49° F for the octopus or secondary regulator.

For all practical purposes, the European convention of 50°F (10°C) is close enough.

Eating crow is not so bad. Some think it tastes a little like chicken.

Equation 1 came from J.R. Clarke and M. Rainone, Evaluation of Sherwood Scuba Regulators for use in Cold Water, NEDU Technical Report 9-95, July 1995.

Diving a Rebreather in Frigid Water: Canister Concerns

As evidenced by Under the Pole diving expeditions, rebreathers are being used in some of the most isolated and frigid places in the world. Some of those dive missions are surprisingly deep (111 meters, 330 feet) and long, about 2 hours.

That gives me cause for pause.

I suspect most divers are aware of the 1/3 rule for gas consumption on an open circuit (scuba) cave dive. You should use no more than 1/3 of your air supply on the way in, leaving you with 1/3 for the trip out, and 1/3 of your gas supply available in reserve. Sadly, even that amount of reserve has not saved all cave divers.

Now that cave divers are using rebreathers, the rules, at least for some, have changed. Some savvy rebreather cave divers use the rule of doubles: Always have twice as much oxygen, twice as much diluent, and twice as much canister as you think you’ll need. That plus an open-circuit or semi-closed circuit bailout should keep you safe — in theory.

Gas supply is easy to measure throughout a dive; there is a pressure gauge for all gases. But what about canister duration? Most divers assume they will have more canister duration available than gas supply; which means they don’t need to worry about canister duration. That would be a good thing, if it were true. After all, how many manufacturers provide expected canister durations for various work rates and water temperatures? Maybe, none? Or certainly very few.

I would be very surprised if manufacturers could say with certainty that during a two hour dive in -2°C (28°F) water, at depths to 111 meters that the scrubber can provide double the duration needed. That would be four hours in -2°C water, at all potential diver work rates.

Some of you may say, “Under-the-ice-diving is not like cave diving, so the doubles rule is too conservative.” I invite you to think again. Under polar ice, is there ready access to the surface? Not unless you’re diving directly under the through-ice bore hole the entire time.

In the U.S. Navy experience, obtaining useful data on canister durations from manufacturers is difficult. Duration data as a function of temperature is practically nonexistent. Therefore I will share the following information gleamed from scrubber canister testing in extreme environments by the Navy. While this blogger cannot reveal canister durations for military rebreathers, the information on the coefficient of varation (COV) is not protected. (There is no way to figure out what a canister duration is based solely on the COV.)

The following 4-minute video gives a good introduction to the coefficient of variation.

https://youtu.be/XXngxFm_d5c://

All rebreather divers should know that canister performance declines in an accelerating manner as water temperature drops between 50°F and 28°F. But what your rebreather manufacturer may not know is that the innate variability of canister durations also increases as water temperature drops. The Navy has found that trend in all types of rebreathers.

So, while canister durations drop considerably in cold water, you’re also less certain about what your canister’s endurance is going to be, because of the increase in duration variability. When canister duration drops and variability increases, a diver’s margin of safety becomes a gamble. Personally, I don’t like to gamble under water.

Coefficient of variation (COV, mean duration divided by the standard deviation) of a typical rebreather. Each data point is the mean of five canisters (n=5).

In the U.S. Navy, published canister durations take into account mean canister performance, and variability. That is accomplished through the use of 95% prediction intervals. The greater the variability in canister duration, the lower the published duration.

This method of determining safe canister durations has been in use by the U.S. Navy since 1999. However, I do not know if manufacturers use similar statistically-based methods for publishing canister durations. If they or you do not take duration variability into account as you dive cold, you may be in for a shock. Due to the nature of statistics, you may have 9 deep, cold dives with no CO2 problems, but find yourself in bad shape on the 10th dive.

If you did have a CO2 problem, it wouldn’t necessarily be anyone’s fault: it could just be a result of canister variability in action.

So, diver beware. Give yourself plenty of leeway in planning rebreather dives in frigid waters. After all, you do not want to become a statistic, caused ironically by statistics.

If you have an interest in understanding the derivation of the prediction interval equation and its application, two videos of lectures by Dr. Simcha Pollack from St. John’s University may be helpful. Part I is found here, and Part 2 is found here.

Thanks to Gene Hobbs and the Rubicon Foundation, NEDU’s original report on the use of prediction limits to establish published canister durations is found here.

Burn My New State Flag – I Don’t Care

I’ve decided to invent a new series of non-controversial flags for all 50 states of the United States of America.

I began with a plain white flag. Not much to be controversial about there. (By the way, I was not the first to think of that.)

Then I proposed adding to each state flag the two letter state identifier used for our postal system. We’ve been using those for decades, so again, no controversy.

For instance, the Florida flag would be white with FL in the middle of it. If the state is really proud of itself, it could be a big, bold FL. If they’re a little embarrassed by, oh I don’t know, crime rates, hate crimes, voter apathy, or whatever, they could use smaller letters, and maybe not bolded. The voters could decide.

But voters would not get a choice on the overall design. Two white letters on a pure white background – that is the state flag formula.

Of course I tried this idea out on a focus group made up of mixed gender identity, mixed ethnic, educational level, and mixed financial levels. I even took care to keep the test group evenly divided among political parties.

And that’s when the trouble began.

Unfortunately there were many, many complaints, but I’ll only mention some of the more interesting ones; all based oddly enough on the Periodic Table of the Elements.

Take my state of Florida or example. FL stands for Florida of course, but the “F” in it represents the element Fluorine, a chemical which I believe has strengthened my teeth since childhood. But some believe it is a toxic chemical dumped into our water supply by all levels of government, (county, city, state and federal) to poison Americans. [Google it. I will not provide a link to those websites.] I’m highly skeptical of that notion, but I wouldn’t want to offend them by forcing them to look at “Fl”uorine on their flag.

And then there’s Florida’s neighboring state, Alabama. AL can stand for Alabama, but it also is the symbol for aluminum. Aluminum is cheap and not very strong. Some Alabamians don’t like that word association, even though it’s been on their U.S. mail since 1963.

AR for Arkansas also means Argon, a narcotic gas. Some didn’t want to be associated with stoners.

GA for Georgia is also gallium. Gallium melts at approximately body temperature, which was too troublesome of an association for those who are still pained by Sherman’s March to the Sea through Georgia. A melting-in-the heat mineral connotes weakness, which Georgians certainly don’t want their flag suggesting.

The most memorable scene in "Gone With the Wind" was the recreation of Confederate Gen. John B. Hood's destruction of his own munitions train. The scene was filmed on a studio lot in Los Angeles in December 1938. — A frame from “Gone With the Wind” published at http://www.post-gazette.com/local/city/2014/08/31/The-burning-of-Atlanta-seared-into-America-s-memory/stories/201408310090

CA for California, also stands for calcium, a component of lime, which is basically crushed limestone. Water and carbon dioxide react to form acidic water that dissolves limestone. With an atmospheric carbon dioxide rise and global warming, some apparently fear that acid rain will dissolve their state, leaving nothing but caverns leading straight to geological fault lines. Even though I don’t think there’s an awful lot of limestone in California (certainly not like Florida), some just don’t concern themselves with the facts. Apparently, for them this fear is too horrendous to contemplate, so CA is out as far as a state flag goes.

MT stands for Montana, or Meitnerium. I must admit I wouldn’t have thought of that one, but apparently some apologist did. I was quite surprised to find out that Meitnerium was created by Germans after a week of bombardment of bismuth with iron. The notion of Germans bombarding anything with iron for a week was simply too painful for those who had survived the Nazi bombardment of Russia and Poland. Apparently some take the analogy very seriously. The MT flag had to go.

Louisiana, or LA, is also Lanthanum, which in Greek means “escapes notice”. It is soft enough to be cut with a knife. It was reported that students from the LSU Chemistry Department strongly objected to being compared to a soft, highly reactive, and hardly noticed element. I guess I can see their point.

PA or “Protactinium” sounded like an interesting element synonymous with Pennsylvania. That is until someone pointed out the following from the Los Alamos Periodic Table of the Elements. “Because of its scarcity, high radioactivity and high toxicity, there are currently no practical uses for protactinium other than that of basic scientific research, and for this purpose, protactinium is generally extracted from spent nuclear fuel.” OK, I get it. There is basically nothing in that sentence that would be a point of pride for Pennsylvanians.

Why does this have to be so hard?

Not far away geographically or chemically from PA is MD, or Mendelevium. That element is named after Dmitri Mendeleev, a Russian Chemist who apparently invented the (or maybe “a”) Periodic Table. He is certainly a noteworthy man to help us remember the state of Maryland (MD), but ever since Vladimir Putin went on the offense in Eastern Europe, no state wants to be associated with anything Russian. I can understand that.

Then there is Indiana, or Indium. Now who could find anything to complain about either Indiana or Indium? Well, lo and behold, someone read that Indium gives out a high-pitched “cry” when bent, somewhat like a little girl I suppose. That discovery immediately condemned it as being sexist, mocking our youngest young ladies.

Really? This is getting ridiculous.

There were a few flags that were not deemed objectionable by anyone. For example, MN stands for Minnesota, or Manganese, as in deep-sea manganese nodules. No one objected to MN, so Minnesota, I guess your flag stands. The same went for SC, South Carolina, or Scandium; no objection. Then there was CO for Colorado, or Cobalt, and MO for Missouri or Molybdenum.

Ironically, people have been writing these state initials on their stationary for years and no one objected. However place the same initials on a state flag and someone gets offended; which is a fact that puzzles me. You see no one salutes a state flag. No one pledges allegiance to it. It has no power, no meaning. If you don’t like my flag, make up your own!

To be fair and all-inclusive, I thought about alternative flag designs that might appease everyone. Suppose we just number the states in the order in which they entered the union (ratified the Constitution). The first four would be Delaware, Pennsylvania, New Jersey and Georgia. But of course some highly competitive New Yorkers might be miffed that Georgia, a Southern State, entered the Union before New York did. And we can’t have any New Yorkers miffed.

So then I considered a random number generator. Your state might be State 87.42 and the adjoining state might be 91.82. That was a fine idea until I considered that the same problematic scientists who fussed over their concerns with a Periodic Table of the States would question how truly random was the random number generator.

It exhausts me to think of the possibilities.

So, if I was King for a Day I would simply say this is how it will be: All states will have white flags with two letter state identifiers. If someone doesn’t like it, then burn it, deface it, walk on it; I don’t care. It has no meaning except to let people know what state they’re in. And if that’s a problem, if people really don’t know what state they’re in, then using my powers as King for a Day I’d give everyone a free GPS.

Now, does that make everyone happy?

A Novel – A Song Just Waiting to Bust Out

One of the most memorable quotes I’ve heard from a child came from his experience listening to classical music. I don’t remember who said it (Google comes up empty-handed), but I’ve never forgotten it.

“A symphony is music with a song waiting to bust out any minute.”

Those words were the child’s response to listening to a symphonic piece. The little listener kept expecting to hear a song, but no sooner did the musicians seem to be closing in on a melody, than the music changed and darted off down another musical path. I suspect that was a little frustrating to the kid; but at least it kept him listening, expectantly.

Being a musician, I can fully appreciate the correctness of his innocent comment.

Classical music is technical; in fact, highly so. Orchestration is a wonderment to those of us who aren’t both talented and trained in the art. The printed lines for a solo instrument, like the clarinet I play, are defined by strict mathematical relationships between frequencies of sound. If the math is not precise, then the sound will not be precise and melodic. That is to say, the sound will not be music, but rather noise.

I consider myself a technical person. As a scientist, I understand the technical rigor and precision which is required for composing and orchestration, but also for scientific and engineering calculations and publications. Indeed, I’ve spent decades writing technical papers, many with a fair amount of mathematical basis. I kept the creative, the musical side, bottled up, because it’s not publishable. Technical publications are, well, technical. They are neither pretty nor tuneful.

But as I mingle vicariously with other technical writers, I find that some of them also have a pent-up desire for creative writing. With a somewhat guilty feeling, they have actually penned very good, non-technical prose. And even a few poems.

Now that I, a scientist, have released my first novel, Middle Waters, hugely imaginative compared to my day-to-day paid technical writing, I feel I have birthed a bastard child.

Oh, but how I love that child.

Now let the song begin…

Authorized for Cold Water Service: What Divers Should Know About Extreme Cold

The following is reprinted from my article published in ECO Magazine, March 2015. It was published in its current format as an ECO Editorial Focus by TSC Media. Thank-you Mr. Greg Leatherman for making it available for reprinting.

It is the highpoint of your career as an environmentally minded marine biologist. The National Science Foundation has provided a generous grant for your photographic mission to the waters 100 ft below the Ross Ice Shelf, Antarctica. Now you’re on an important mission, searching for biological markers of climate change.

Under Antarctic Ice, photo by Dr. Martin Sayer.

Above you lies nothing but a seemingly endless ceiling of impenetrable ice, 10 ft thick. Having spent the last several minutes concentrating on your photography, you look up and notice you’ve strayed further from safety than you’d wanted. The strobe light marking the hole drilled in the ice where you’ll exit the freezing water is a long swim away. And, unfortunately, your fellow scientist “buddy” diver has slipped off somewhere behind you, intent on her own research needs.

You’re diving SCUBA with two independent SCUBA regulators, but in the frigid cold of the literally icy waters, you know that ice could be accumulating within the regulator in your mouth. At the same time, a small tornado of sub-zero air expands chaotically within the high-pressure regulator attached to the single SCUBA bottle on your back—and that icy torrent is increasingly sucking the safety margins right out of your regulator. You are powerless to realize this danger or to do anything about it.

At any moment, your regulator could suddenly and unexpectedly free flow, tumultuously dumping the precious and highly limited supply of gas contained in the aluminum pressure cylinder on your back. You’re equipped and trained in the emergency procedure of shutting off the offending regulator and switching to your backup regulator, but this could also fail. It’s happened before.

As you try to determine your buddy’s position, you’re feeling very lonely. You realize the high point of your career could rapidly become the low point of your career—and an end to your very being.

The preceding is not merely a writer’s dramatization. It is real, and the situation could prove deadly—as it has in far less interesting and auspicious locations. Regulator free flow and limited gas supplies famously claimed three professional divers’ lives in one location within a span of one month.

There is a risk to diving in extreme environments. However, the U.S. Navy has found that the risk is poorly understood, even by themselves—the professionals. If you check the Internet SCUBA boards, you constantly come across divers asking for opinions about cold-watersafe regulators. Undoubtedly, recent fatalities have made amateur divers a little nervous—and for good reason.

Internet bulletin boards are not the place to get accurate information about life support safety in frigid water. Unfortunately, the Navy found that manufacturers are also an unreliable source. Of course, the manufacturers want to be fully informed and to protect their customers, but the fact remains that manufacturers test to a European cold-water standard, EN 250. By passing those tests, manufacturers receive a “CE” stamp that is pressed into the hard metal of the regulator. That stamp means the regulator has received European approval for coldwater service.

As a number of manufacturers have expensively learned, passing the EN 250 testing standard is not the same as passing the more rigorous U.S. Navy standard, which was recently revised, making it even more rigorous by using higher gas supply pressures and testing in fresh as well as salt water. Freshwater diving in the Navy is rare—but depending on the brand and model of regulator in use, it can prove lethal.

The unadorned truth is that the large majority of manufacturers do not know how to make a consistently good Performing cold-water regulator. Perhaps the reason is because the type of equipment required to test to the U.S. Navy standard is very expensive and has, not to date, been legislated. Simply, it is not a requirement.

Some manufacturers are their own worst enemy; they cannot resist tinkering with even their most successful and rugged products. This writer is speculating here, but the constant manufacturing changes appear to be driven by either market pressures (bringing out something “new” to the trade show floor) or due to manufacturing economy (i.e., cost savings). The situation is so bad that even regulators that once passed U.S. Navy scrutiny are in some cases being changed almost as soon as they reach the “Authorized for Military Use” list. The military is struggling to keep up with the constant flux in the market place, which puts the civilian diver in a very difficult position. How can they—or you—know what gear to take on an environmentally extreme dive?

My advice to my family, almost all of whom are divers, is to watch what the Navy is putting on their authorized for cold-water service list. The regulators that show up on that list (and they are small in number) have passed the most rigorous testing in the world.

Through hundreds of hours of testing, in the most extreme conditions possible, the Navy has learned what all SCUBA divers should know:

• Even the coldest water (28°F; -2°C) is warm compared to the temperature of expanding air coming from a first stage regulator to the diver. There is a law of physics that says when compressed air contained in a SCUBA bottle is expanded by reducing it to a lower pressure, air temperature drops considerably. It’s the thermal consequence of adiabatic (rapid) expansion.

• Gas expansion does not have to be adiabatic. Isothermal (no temperature change) expansion is a process where the expansion is slow enough and heat entry into the gas from an outside source is fast enough that the expanded gas temperature does not drop.

• The best regulators are designed to take advantage of the heat available in ice water. The most critical place for that to happen is in the first stage where the greatest pressure drop occurs (from say 3,000 psi or higher to 135 psi above ambient water pressure (i.e., depth). They do that by maximizing heat transfer into the internals of the regulator.

• First stage regulators fail in two ways. The most common is that the first stage (which controls the largest pressure drop) begins to lose control of the pressure being supplied to the second stage regulator, the part that goes into a diver’s mouth. As that pressure climbs, the second stage eventually can’t hold it back any longer and a free flow ensues.

• The second failure mode is rare, but extremely problematic. Gas flow may stop suddenly and completely, so that backup regulator had better be handy.

• Second stage regulators are the most likely SCUBA components to fail in cold water due to internal ice accumulation.

• Free flows may start with a trickle, slowly accelerating to a torrent, or the regulator may instantly and unexpectedly erupt like a geyser of air. Once the uncontrolled, and often unstoppable free flow starts, it is self-perpetuating and can dump an entire cylinder of air within a few minutes through the second stage regulator.

• A warm-water regulator free flow is typically breathable; getting the air you need to ascend or to correct the problem is not difficult. In a cold-water-induced free flow, the geyser may be so cold as to make you feel like you’re breathing liquid nitrogen and so forceful as to be a safety concern. Staying relaxed under those conditions is difficult, but necessary.

• Water in non-polar regions can easily range between and 34°F to 38°F; at those temperatures, gas entering the second stage regulator can be at sub-freezing temperatures. European standard organizations classify ~10°C (50°F) as the cold/non-cold boundary. The Navy has found in the modern, high-flow regulators tested to date that 42°F is the water temperature where second stage inlet temperature is unlikely to dip below freezing.

• The small heat exchangers most manufacturers place just upstream of the second stage is ineffective In extreme conditions. They quickly ice over, insulating that portion of the regulator from the relative warmth of the surrounding water.

• Regulator “bells and whistles” are an unknown and can be problematic. Second stage regulators with multiple adjustments can do unpredictable things to heat transfer as the diver manipulates his controls. The last thing a cold-water diver should want is to make it easier to get more gas. High gas flows mean higher temperature drops and greater risk of free flow.

• Only manufacturer-certified technicians should touch your regulator if you’re going into risky waters. The technician at your local dive shop may or may not have current and valid technician training on your particular life support system. Don’t bet your life on it— ask to see the paperwork.

• Follow Navy and Smithsonian* guidance on handling and rinsing procedures for regulators in frigid waters. A single breath taken above the surface could freeze a regulator before you get your first breath underwater.

U. S. Navy reports on tested regulators are restricted. However, the list of those regulators passing all phases of Navy testing is available online. If your regulator, in the exact model as tested, is not on that list, do yourself a favor and don’t dive in frigid waters.

The original Editorial Focus article is found in the digital version of the March ECO magazine here, on pages 20-25.

I Remember Nothing After the First Bounce

http://sandiegoairandspace.tumblr.com/post/63597123684/from-an-album-belonging-to-barnstormer-daredevil — From an album belonging to barnstormer Sergeant Carter G. Buton. Photo from latter half of the 1920s. Image found at San Diego Air & Space Museum Blog.

“It was a gorgeous day to jump from a perfectly good airplane. I, Mickey McGurn, was good at it, and I got paid well to do it.

But one day I got careless.

It was 1927, and parachute jumping was a new thing on the barnstorming circuit. It made people catch their breath when I jumped out of airplanes. They just knew they were going to see me fall straight to my death.

I would gather the parachute in my arms, without packing it, bundle it into the cockpit, and go aloft for a jump.

One day a number of my barnstorming friends protested at the way I handled the parachute. But I told them to mind their own business.

“Forget it,” I said. “I built this thing myself and I know what it’ll do.”

Well, I might have been wrong about that, because one day the ‘chute didn’t work. It opened only about a quarter of the way and I fell to the ground with a terrific speed. Those folks who were waiting to see me die almost got more than they bargained for.

Folks told me I bounced at least 10 feet into the air, but I don’t remember anything after I hit the ground.

The doctors said I broke pretty much every bone in my body, but obviously I lived, sort of.

I’m now hobbling around on crutches. I’m deaf, nearly blind, and can’t taste my food, or enjoy any of the things I used to.

My bones have healed, sort of, but not the way they were when I was a cocky young fool who felt invincible.

I guess I should have listened to my friends. They realized I was courting disaster, but I was too proud, or arrogant, or just plain stupid to notice it.

But they were right.

I suppose that no matter what you do, whether it’s racing cars, jumping out of airplanes, or walking on the bottom of the ocean, your friends are usually better at telling when you’re getting careless than you are.

I guess it’s similar to the way a friend can usually tell when you’re drunk before you can.

The above is a fictional version of an actual accounting by one aviation daredevil named Mickey McGurn, given to a newspaper reporter for the Syracuse American. The short piece appeared in the Sunday edition under a section called the “World of Aviation”. The publication date was February 26, 1928. The writer was Gordon K. Hood, a feature writer who penned several aviation-themed chapters for the paper, a collection of mini-stories such as this one, collectively called “Sprouting Wings”. Mr. Hood was himself quite an accomplished early aviation pioneer, as recounted in a 1939 edition of the Syracuse Journal.

I have taken the time to paraphrase this story due to its applicability to many potentially hazardous endeavors. Safety risks are not always noticeable to those at greatest risk.

The actual article is found below. It, and a full page copy of the 1928 newspaper page, was provided to the present author by Mr. Douglas Barnard, presently from Waldorf, Maryland.