Thanks to Robert N. Rossier Dive Training Magazine
https://dtmag.com/thelibrary/the-good-stuff-is-deep-dispelling-common-scuba-myths/
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I remember from years past a particularly eager young diver who was seemingly obsessed with the desire to dive deeper. After all, he had heard that the “really good stuff” was in deep water, and that’s where he wanted to go. The misinformation he had received, combined with his desire to be seen by others as a dashing, daring conqueror of “the deep” conspired to make him a particularly “at risk” individual. Fortunately, through the efforts of a good instructor and more enlightened peers, he learned to be more cautious, and to appreciate the magical, mystical elements of the ocean realm that lay in safer depths.
The diving world is filled with misinformation, misconceptions, misunderstandings and plain-old myths. It’s surprising that even well-educated divers and instructors can unwittingly subscribe to these untruths, and pass them on to others. After all, we were all students, and most of us took as gospel every word uttered from the lips of our instructors. What we may not have realized is that they, too, were victims of myth, misinformation, and misconceptions.
Sometimes, especially when the information seems to make perfect sense, it’s easy to “go along” with what you’ve heard, and pass the bad data on to friends and students. In some cases, the information might be true, but the rationale is unsound. Sometimes the “myth” is partially true, or has an element of fact around which rumor and speculation have been wound. As we wade through the material required at any level of training, we must strive to separate the truth from the fiction, debunk the myths and replace them with accurate, up-to-date, verifiable information. And we need to encourage our dive buddies to do the same.
That said, let’s take a look at some of the more common myths, and the truth surrounding those issues. Among those misconceptions are untruths and myths regarding everything from general diving safety to physiology, physics and marine life.
Myth No.1: Diving is dangerous.
Of course it is. If it wasn’t dangerous, nobody would need training, now would they? What’s important to understand is that while diving presents a multitude of potential hazards, it is a diver’s knowledge, training, judgment and decision making that limits or controls that risk.
In fact, diving has an arguably good safety record. According to Divers Alert Network (DAN) Senior Research Director Petar Denoble, Ph.D., the injury rate for scuba diving is in the range of one per 2,000 participants, or an injury rate of 50 per 100,000. The Insurance Information Institute publishes injury rates substantially higher for many popular sports (2002 data), including basketball (21,300 injuries per 100,000) and golf (140 per 100,000). Diving may have an element of danger, but no more so than many other activities that are generally considered safe.
Myth No.2: Modern scuba gear is virtually foolproof.
There’s no question that modern scuba gear is well-engineered, well-designed, and highly reliable. That said, we still need to account for a fair number of diving accidents that occur each year that appear to be related, at least to a degree, to equipment malfunctions.
Data on equipment problems in diving is notoriously lacking in the industry, but an Australian report on the Diving Incident Monitoring Study (DIMS) prepared a few years back for the SPUMS (South Pacific Undersea Medical Society) sheds some light on the subject. According to the DIMS data, 457 of the 1,000 reported incidents (roughly half) involved equipment, and more than 25 percent of these resulted in harm to the diver. Similarly, DAN data reveals that roughly half of the 89 fatal dive accidents in 2002 involved equipment problems.
While such data might at first blush seem to implicate dive equipment, that perspective shifts when we dig a little deeper. In fact, the studies show that many of the equipment-related diving accidents and deaths are not “true” equipment problems. Example: Of the 52 regulator-related incidents reported in the DIMS data, only 20 were considered actual regulator malfunctions. Running out of air, panic, and other causes contributed to the remaining incidents and accidents. Similarly, while weight belts were implicated in 33 incidents out of 457 reported equipment-related incidents and accidents (7 percent), and were involved in 12 percent of the reported injuries, few of those were actually due to faulty weight belts. Many times the problems resulted from failure to drop the belt in an emergency, tangling of the belt due to improper use or placement, and other training-related issues.
The fact of the matter remains that while our equipment may be highly reliable, it isn’t infallible. Gear is generally good, but it’s no better than the person who maintains and uses it. A diver who isn’t well-trained and prepared, or who uses poorly maintained equipment, may end up suffering the consequences. On the other hand, a diver with the proper training, knowledge, and decision-making skills who takes proper care of his equipment is less likely to suffer a problem.
Myth No.3: The air in my cylinder is safe to breathe.
Air is all around us, and we all know that breathing it is generally more healthy than not. We also know that the compressed air provided by a reputable dive center is usually up to par in terms of meeting the air quality requirements specified by the industry. But we live in an imperfect world, and the incidence of air contamination is perhaps higher than some would like to admit. Informal data from some of the larger independent air testing laboratories suggest that as many as 3 percent to 5 percent of all air stations tested will fail to meet the CGA Grade E standard for diver’s breathing air. As we travel to more remote destinations, the lack of good filtration equipment combined with other factors might add up to a greater likelihood of getting a “bad” air fill.
Here again, knowledge, protocol and common sense can often help us sort out the good from the bad and the ugly. To be safe, we should buy our air from professional air stations that adhere to accepted maintenance protocols, and subject their air to periodic testing by an independent testing facility. Such results should be posted in a conspicuous location. In addition, especially if we’re using nitrox or some other breathing gas, it’s important to verify the oxygen content with a calibrated oxygen monitor.
Myth No.4: If I use a dive computer, I won’t get decompression sickness.
This is probably one of the most common misconceptions among divers today, but be careful how you address it. According to the latest data from DAN, between 70 percent and 75 percent of the divers injured in 2002 were using computers as their means of dive planning. “We have not indicated that dive computers should be blamed for DCS,” Denoble says. “Decompression sickness is dependent on depth-time profile in a probabilistic way: The deeper and longer you dive and faster you come up, the more likely that you will get bent. The ‘Safety Curve’ [no-decompression limits] was meant to indicate low-risk dives, but there is no guarantee that there will be no DCS within the ‘Safety Curve.’ As a matter of fact, many cases of DCS occur after so-called no-decompression dives.” This means that a very small percentage of divers will still get DCS, even if they have a properly operating dive computer, and use it correctly.
On the other hand, we must also understand that dive computers are exactly that — computers — and as such they can readily succumb to the “garbage in equals garbage out” syndrome. While a properly functioning and correctly used dive computer is perhaps a diver’s best friend, they are not infallible, either.
Among the many ways to put that “garbage” into our computers is to make some fairly simple mistakes, like switching computers in the middle of a dive trip (the new computer assumes you haven’t been diving yet); breathing a gas other than that for which the computer is set (air instead of nitrox, or the wrong blend of nitrox); or following inappropriate dive profiles, including “saw tooth” profiles or rapid ascents. Remember that individual physiology, use of alcohol, and challenging environmental conditions can alter the blood flow, gas diffusion, and overall absorption/desorption of nitrogen to the extent that the model used by the computer is invalid for the particular diver on the particular dive. In fact, Dr. Richard Vann of DAN says that the issue of dive computer safety has been the subject of a Project Dive Exploration study, and “the major conclusion is that the dive conditions can have significant effects on risk.”
Myth No.5: Scuba cylinders are indestructible.
Just look at these things. Thick steel and aluminum walls, heavy, and built for high pressure; no wonder they call them “tanks.” While a scuba cylinder may appear to be virtually indestructible, the simple truth is that they are engineered components, and sufficient mistreatment, neglect, or physical damage can render them unsafe. According to sources at Professional Scuba Inspectors (PSI) in Woodinville, Washington, cuts, dings, gouges, dents, corrosion pitting, and bulges must be compared with specific damage limits for each cylinder type. Damage or other conditions that fail to meet the allowable limits cause the cylinder to be condemned. Despite their outward appearance, cylinders aren’t indestructible, and deserve to be properly used, maintained and handled. It’s important to remember, too, that even though the cylinder itself is durable, most damage to the cylinder involves the valve, through which air flows into the first-stage regulator.
Myth No.6: The guide/instructor/buddy will take care of me.
It’s amazing to many of us how easily supposed well-trained divers can turn into “sea sheep,” simply following the herd without asking simple questions like, “where are we going, and how long will we stay?” All too often, divers regard dive guides as unerring, and will simply follow along. And while most of the time professional dive guides will be sufficiently conservative as to avoid decompression obligations, there are exceptions. According to the latest DAN data, 7 percent of the 348 divers injured in 2002 were relying on someone else rather than the tables or their own dive computer. What were they thinking? The take-home lesson for our students is that each of us is responsible for our own safety, and that means doing our own planning.
Other diving myths revolve around physiology and the physics of diving. Here again, we find some common myths and misconceptions that should be cleared up.
Myth No.7: If I feel warm, I am warm.
Unfortunately, our ability to sense heat loss from our own bodies is not as keen as we might expect. According to the “NOAA Diving Manual,” hypothermia can even be a problem when diving in warm waters. According to this source, “A phenomenon called ‘warm water hypothermia’ can occur even in the tropics, especially during long dives and repetitive dives made without adequate rewarming between dives. In warm-water hypothermia, long, slow cooling can take place in water temperatures as warm as 91 degrees Fahrenheit (33 degrees Celsius)… The physiological mechanisms of warm-water hypothermia have been demonstrated in various medical studies, but they still are not clearly understood. The victim in this situation may not shiver, because the drop in core temperature may not be rapid enough to activate the body’s thermoregulator defense mechanism…”
The implications here are clear: We must recognize the importance of wearing proper thermal protection, and understand that this equipment may be just as important in warm water as it is in cold.
Myth No.8: You can’t exceed the no-decompression limits on a single tank.
This is an old myth, stemming from the days when 72-cubic-foot (and smaller) steel cylinders were the standard of the industry, and virtually no one used a dive computer. While it may have seemed a good guideline, it wasn’t true back then, and it isn’t true today, especially when cylinders are larger, and divers go to greater depths wearing better thermal protection and consuming less air per minute.
Myth No.9: Divers should only drink water when diving.
Dehydration is one of the silent enemies of diving. It affects our circulatory system, and thus can alter the physics of gas transfer in the body, predisposing us to decompression sickness. While it’s true that divers should strive to maintain a high level of hydration, there’s a misconception that many of the so-called “sports drinks” are inappropriate for diving. According to Dr. Jolie Bookspan, author of “Diving Physiology in Plain English,” that simply isn’t the case. “Commercial electrolyte and carbohydrate sport drinks are not harmful to divers,” writes Bookspan. “Exercise studies are clear that sport drinks promote rehydration by helping you absorb and retain water. They stimulate your thirst mechanism to keep you drinking, and replace needed water.” According to the “NOAA Diving Manual,” divers should drink warm liquids between dives, and avoid alcohol and caffeine.
A final category of myths revolves around marine life. In fact, there’s a whole world of myths and legends regarding the nature and habits of undersea creatures, and not all the myths are as apparent as the tales of the Loch Ness monster. Here it’s best to turn to the experts, ferret out the truth, and separate it from the fiction.
Myth No.10: Sharks are a major threat to divers.
I think we can blame this one on Hollywood and the popular media. There are more than 400 species of sharks, and most of them will shy away from divers. There are of course exceptions, but proper precautions can drastically limit the risk of attack by the potential “evil-doers.” While sharks can be dangerous in certain circumstances, we’re much more likely to be injured by some other means.
Consider these facts: According to statistics from the International Shark Files project at the Florida Museum of Natural History, and the New York City Health Department, a person is roughly 600 times more likely to be bitten by a dog in New York City than by a shark when in the water. At least in the years 1981, and 1984-87, New York City documented reports of at least 8,000 cases in which a dog bit a human. The highest number of documented shark attacks nationwide in any one of those years was 14, in 1984. The number of lightning strikes offers additional perspective. Nearly as many people have been killed by lightning strikes in Florida than have been attacked by sharks, and only eight of those people have died as a result of shark attacks in Florida.
Some of the good stuff in diving really is deep, but the myths of diving can run even deeper. Legends are fun and myths are magical, but in the context of safe diving, there’s no substitute for cold, hard facts. If we strive to verify the “facts” we hear or have learned, turning to reliable sources for verification, we can help reduce the promulgation of diving myths.
