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  • December 29, 2018 11:31 AM | Anonymous

    If you’re like most divers, you’ve heard of — and perhaps adhere to — procedures that are considered “normal” within our sport. A few classic “always and nevers” include: always dive with a buddy; always do your deepest dive first; always wear a snorkel; never put your mask on your forehead; always end your dive with at least 500 psi remaining in the tank and — perhaps the number one scuba diving “never” of all time — never hold your breath.

    At first glance, these might seem like black-and-white concepts. Except, guess what? They’re not. At least not entirely.

    This might sound like I’m on the verge of committing scuba heresy, but please take a couple of deep breaths and keep reading, because in this article we’ll examine — and even challenge — several widely accepted “rules” of scuba.

    Rulemaking 101

    Human beings are social creatures. We essentially want to be accepted in society, to be viewed as normal. Without diving deep into sociological terminology, the concept of norms provides a key to understanding social influence in general and conformity in particular. Social norms are the accepted standards of behavior of social groups. Behavior that fulfills these norms is called conformity. Social norms often evolve into rules, which are defined as explicit or understood regulations or principles governing conduct within a particular activity. Rulemaking is one of the basic impulses humans have for organizing and simplifying actions.

    Norms — and the rules that often evolve from them — provide order in society. These are some of the reasons why most people, most of the time, conform to social norms and abide by certain rules.

    The thing about rules is that sometimes they are based more on folklore than fact. And sometimes rules change when new facts are revealed. Take Nitrox diving, for instance. When it was first introduced decades ago there was a big hubbub about it being a dangerous “voodoo” gas that could potentially kill divers. It was condemned by the major scuba diving magazine at the time and banned at popular dive destinations. Now we know differently and divers everywhere are safely using Nitrox.

    Those who challenge social norms and set out to bend or even break the rules sometimes find themselves at the center of controversy. They often get branded as troublemakers and might even find themselves at odds with the law. However, these people also tend to be significant change makers.

    Let’s examine some commonly accepted scuba rules regarding equipment and dive practices that might be worthy of bending. If nothing else, they’re worth pondering.

    Equipment-Related Rules

    Always wear a snorkel.

    The snorkel is a required accessory for scuba diving students and their instructors to wear during training dives. But once certification requirements are fulfilled there are instances when wearing a snorkel attached to the mask can prove problematic. For instance, it presents a potential entanglement hazard when scuba diving in overhead environments, such as wrecks or caverns. In addition, it can create drag when diving in a current.

    Still, a snorkel is a useful accessory when at the surface. In recent years several innovative scuba equipment manufacturers have developed flexible snorkels that roll up small enough to fit in your buoyancy compensator (BC) pocket and/or fold into their own “shell” carrier that clips to the BC. For this reason, I’d like to edit the “always wear a snorkel rule” to read, “always carry a snorkel.” When the dive is done and you’re ready for a surface swim, locate your snorkel, attach it to your mask and you’re good to go.

    Divers with masks on forehead

    Guilherme Garcia photo

    Never put your mask on your forehead.

    Okay, this one is a pet peeve of mine. I wrote about it in the May/June 2016 Final Check column, titled, “What It Looks Like When … Safety is Your Best Practice.” Somehow, somebody got a whole bunch of divers believing that placing the mask on the forehead is the international signal for “diver in distress.” Except, that’s just plain wrong.

    It is not uncommon for a panicky diver to jettison the mask and regulator. This action is a panic response, which is an indication, or a sign, that the diver is experiencing a problem. However, it is not a signal, as in “if you are having a problem, put your mask on your forehead to signal you are in distress.” If you surface from a dive and need help, signal, “I am in distress and need help” by waving one or both arms above your head. (It’s also a good idea to use an audible signaling device such as a Dive Alert™ or whistle.) There are plenty of instances when a completely happy, non-panicky diver might place the mask on his or her forehead without incident. That said, there are times when placing the mask on the forehead might not be a good idea, like when you’re in choppy seas. If your practice is to prop your mask on your forehead upon surfacing from a dive instead of leaving it in place, you run the risk of having the mask dislodged by a wave — and getting lost to the deep.

    No gloves allowed.

    Believe it or not, this is actually a hard-and-fast rule in many tropical dive destinations. In some locations, divers caught wearing gloves while scuba diving, face stiff penalties. (Fines may also apply to dive operators.) The idea behind this rule is that wearing gloves encourages divers to grab — and subsequently damage — delicate corals, whereas barehanded divers will think twice about doing so because they risk being cut by sharp coral or stung by stinging marine creatures.

    I wholeheartedly support the environmentally conscious intent behind this rule. However, I do not agree with the practice of strictly prohibiting divers from wearing gloves. Some divers have medical issues requiring them to protect their skin from exposure to sunlight, have clotting issues that turn a simple cut into a medical crisis or run risk of infection due to a cut. These folks shouldn’t need a note from their doctor in order to be allowed to wear gloves while diving.

    This month’s Final Check column, “What It Looks Like When … You Are Careful What You Touch,” addresses the potential danger of grabbing a marine-life encrusted mooring line during a safety stop. While no one associated with this magazine promotes the wanton destruction of marine life, we think the ban on dive gloves goes a bit too far. Instead, we’d like to see industry stakeholders continue to promote environmentally safe scuba diving practices that encourage divers to avoid touching corals, while still allowing them to wear gloves when needed. For instance, a diver can easily stash a pair of gloves in a BC pocket and retrieve them for use when grasping an encrusted mooring line during a safety stop.

    Always turn the tank valve back a quarter- or half-turn.

    Scuba divers entering water

    Before entering the water, make sure you tank valve is turned all the way on.
    Guilherme Garcia photo

    This one’s been around forever. And it’s wrong. Don’t do this. Instead, always turn the valve all the way on and leave it that way. Do not turn it back at all.

    Apparently, the reason this practice got started is because someone decided that divers might inadvertently “strip” the valve by attempting to turn it on after it was already on. Tank valves are pretty hardy. The chances that you’ll damage a valve are slim. However, if you partially close the valve and then descend to a deep depth, the partially closed valve could restrict the airflow from the valve, making it difficult for you to breathe while on a deep dive. To avoid having problems with restricted airflow at depth always turn the valve all the way on. You are more important than a tank valve. Never turn it back a quarter- or half-turn.

    Ruling How We Dive

    Never dive alone. Always dive with a buddy.

    When recreational scuba diving first started, the relatively crude nature of early dive gear made it necessary for divers to help each other out. The buddy system was born of common sense. It’s hard for many new divers to imagine going on a dive without a BC, submersible pressure gauge (SPG), alternate (or redundant) air source or a dive computer, but all these devices were absent from early dive training. They simply hadn’t been invented yet. Keeping this in mind it’s easy to imagine why having a buddy was considered mandatory. In fact, buddy breathing — sharing one tank and regulator between two divers — was a critically important skill taught in early scuba classes. Over several decades, equipment advances have enabled divers to become safer. And more self-sufficient. Thanks to the development of alternate air sources and redundant air delivery systems, and the fact that buddy breathing itself could be inherently dangerous, the buddy breathing skill has been purged from today’s scuba diving training courses.

    Where it was once considered risky and even foolhardy to solo dive, the practice is slowly gaining acceptance. Several major scuba-training agencies offer Solo Diver and/or Self-Sufficient Diver certification courses aimed at increasing diver independence and reducing an individual’s dependence on the buddy system.

    However, despite advances in equipment and training, the issue of solo scuba diving remains controversial. Some industry experts argue that buddy diving can carry with it greater potential risks than solo diving. Some recreational divers agree, complaining about being randomly paired with a buddy they’ve just met. Some dive operators prohibit solo diving, insisting that their customers be in buddy pairs or teams, often on guided dives. Still other dive operators allow solo diving for those qualified and equipped to do so.

    A word of advice for those who wish to solo dive on a charter: reach out to the dive operator in advance to discuss your solo diving preference. Be willing to provide proof of your solo diving experience. Recognize that the dive operator has the right to deny your request to dive solo and insist that you abide by their stated operational policies. If this is the case, you have the option to seek the services of a dive operator that welcomes solo divers.

    It’s also important to note that in certain areas, such as city, county, state or national parks, solo diving might be prohibited. It pays to read the fine print when planning a solo dive inside park waters.

    On a personal note, I’ve made my share of solo dives, usually on shallow sites not far from shore. I have enjoyed the freedom and solitude of solo diving without any problems. I think those who are willing to accept responsibility for their own safety as a solo diver should be respected rather than viewed as reckless.

    No matter where you stand on the issue of solo diving, I think we all can agree that every diver should train and equip for self-sufficiency and be able to handle potential problems that might arise during a dive.

    Always do your deepest dive first.

    This rule was considered law for many years, and it is still widely practiced today despite the development of sophisticated dive computer algorithms and new research into decompression sickness. Dive Training’s Senior Editor Alex Brylske revisited this topic earlier this year in an article titled, “Deepest Dive First? The History and Science Behind How We Plan Our Dives,” which ran in the January/February 2017 issue. Here is an excerpt from Brylske’s article:

    “The issue of reverse profiles is sometimes confusing because the term actually can have two meanings. First, a reverse profile can refer to a series of repetitive dives where the deepest is not the first in the series. On the other hand, it can also describe a single multilevel dive that doesn’t follow the ‘stair-stepping’ procured described earlier; and the diver finds him or herself in the deeper phase of a dive after completing a shallower segment. Both procedures violate the deep-first rule.

    It may surprise you to learn that the deep-first rule is a relative newcomer to the diving liturgy, traceable only back to the 1970s. The story is also an interesting lesson in the history of scuba diving.

    A popular assumption is that the recreational scuba diving community simply adopted the deepest-first rule from the US Navy. Such an assumption seems entirely reasonable given that the USN Tables were the first standard for recreational scuba diving. The problem is, it’s not true. The US Navy does not now, nor did it ever, have any prohibition against reverse profile diving. In fact, one of the example dive table problems an older version of the US Navy Diving Manual involved a reverse profile. Likewise, there is no such prohibition in commercial scuba diving. So where did the rule come from?

    The first suggestion to make the deepest dive first appears to have been offered in a relatively obscure reference — and only as a suggestion — by a researcher named Dennis Walder in 1968. His rationale was that by making the deeper dive first, one might crush “silent bubbles” — assumed progenitors of decompression illness — making the development of bends less likely on that and subsequent repetitive dives. But this was based primarily on theory and informed speculation, not empirical evidence. Moreover, no reference to any deep-first guideline appeared in any recreational diving literature until 1972, when the following statement was published in PADI’s Basic Scuba Course Manual (a curriculum segment of the then-current PADI Instructor Manual): ‘One very important rule — WE ALWAYS MAKE OUR DEEPEST DIVE FIRST when using the dive tables.’ No rationale was provided, though examples were often included during training showing the aforementioned advantage of avoiding decompression stops.

    By the 1980s ‘deep dive first’ was growing beyond a recommendation.

    By the 1990s, the mantra of-deep first was firmly ensconced in diver training materials as well as in the psyche of divers; and no prudent diver even considered violating the warning. But by this time dive computers had become standard equipment, and whether by accident or intention, divers were making — and getting away with — repetitive and multilevel reverse profile dives.”

    Brylske sums it up by saying, “In all probability, the deep-first rule might never have been challenged had it not been for the widespread use of dive computers. Although the rules say otherwise, no dive computer in existence explodes, calls the police or ceases to function if the user engages in a reverse profile dive.”

    Always end the dive with at least 500 psi remaining in your tank.

    This statement is uttered during practically every pre-dive briefing in locations all over the world. The rationale behind it is solid; divers should plan their dives well and monitor their gauges carefully to avoid running low on — or out of — air. And responsible dive guides should remind divers to monitor their air supply to avoid an out-of-air emergency.

    However, in some instances, well-meaning but overzealous divemasters might take it a bit too far. I’ve heard divemasters jokingly “threaten” divers with penalties, like, “You’ll owe me a 6-pack,” if they surface with less than the mandated 500-psi.

    If a diver is nearing the end of a dive and needs to consume air below the 500-psi mark in order to complete a safety stop, the diver should feel comfortable doing so without fear of reprisal by the dive crew, because there’s simply no place for shaming in scuba diving.

    Never, ever make contact with the bottom.

    Diver sitting in sand

    In some instances, making contact with the bottom is considered an acceptable practice.
    Guilherme Garcia photo

    If you haven’t wanted to burn me at the stake by now, here goes. Over the years we have occasionally published photos of divers kneeling on the bottom. This usually results in a flurry of reader letters calling Dive Training out for promoting bad diving practices. Most recently, in the July/August issue, we ran cover photos that feature two divers standing/kneeling on a sandy bottom while on a shark dive at the famous “Tiger Beach” dive site off Grand Bahama Island. I am one of the divers pictured in the photo. I’m not sure where or when the “never touch the bottom” rule got started, but I can assure you there are several instances in which kneeling in the sand is an accepted practice. Tiger Beach is a perfect example. The site is shallow (less than 30 feet [10 m]), there’s usually a moderate current running — and the water is filled with sharks. For these reasons, attempting to stay neutrally buoyant, kicking hard against a current while hovering a few feet off the seafloor and keeping an eye on the sharks would be impractical — and potentially dangerous. Here, kneeling in the sand is the best practice. Dive operators in other parts of the Bahamas, Fiji, Tahiti, the Maldives and other popular dive destinations follow this practice.

    Those who teach underwater photography know it is better to position beginning photographers in a sandy patch adjacent to a reef than to have them crashing into the coral while just starting out with a camera. Yes, the sand biome contains marine life, but in most instances it is not as delicate as fragile corals. A diver who carefully settles on a sandy area will have minimum impact on the environment.

    In parts of the world where strong currents are common, dive operators instruct divers in the use of “current hooks” as a means of having minimum impact on the environment. A current hook, as its name implies, is a large hook attached to a short length of line with a clip at the other end. The clip attaches to a D-ring on a diver’s BC. Divers learn to hook into an area of coral rubble in order to stay put in a strong current. By using the hook, they avoid grabbing the bottom with their hands.

    Here’s one more real-world “contact” scenario: If a diver accidentally ventures too close to the reef, rather than kicking to attempt to move farther away, using a one-finger touch of a dead or algae-covered section of reef to carefully push up and away from the reef is likely to prevent the diver from damaging living coral.

    The “look but don’t touch” mantra is ideal, but there are instances when it’s not always practical. What I’m suggesting here is careful and conscientious contact with the bottom (and with dead sections of coral) when conditions warrant it.

    Always breathe continuously. Never hold your breath.

    As I mentioned earlier, this is arguably the “number one rule” of scuba because breath holding while scuba diving can lead to serious injury, even death. However, there’s a however here.

    I bring it up in honor of a diver I met years ago. We’ll call her Janet. I guided Janet on her first recreational dives after she got certified. She bought a weeklong dive package and her first day of diving with the dive center where I worked went flawlessly. The conditions were perfect and Janet appeared comfortable in the water. I took a few underwater photos of her, smiling and signaling “OK.” She said she had a great time.

    The following morning, she was waiting at the dive shop very early when I showed up for work. She told me she wanted to cancel her dives. When I asked why, Janet explained that she’d been awake most of the night because she was worried that she might have accidentally held her breath at some point during the dive the previous day. She said, “My instructor drilled it into our heads, ‘If you hold your breath, you will die,’ and I’m just afraid. I can’t remember if I held my breath or not, but I don’t want to die.” I explained in great detail why divers should breathe continuously and avoid holding their breath. When I was finished, Janet decided not to give up on scuba diving after all. She sat out the morning dives in favor of some sleep, but was back out on the boat later that afternoon.

    So, here’s my little secret about breath holding while scuba diving. I often do it when taking underwater photos. I admit this not to encourage any diver to adopt the practice of holding their breath while on scuba, but rather to add some clarity to the breath-holding issue. If you’re like me and you sometimes briefly hold your breath while stationary, it is unlikely you will risk a lung-expansion injury. The key here is the word “stationary,” as in remaining in place and not ascending. If you hold your breath while ascending, you do indeed put yourself at risk of a potentially serious and possibly fatal lung-expansion injury. This is why scuba instructors drill it into students’ heads to “breathe continuously and never hold your breath.” But if you’re like Janet and you might have briefly forgotten to breathe continuously just for a second, say, when posing for a photo underwater, chances are, you’ll be okay. Still, do as your instructor insists. Breathe continuously and avoid holding your breath.

    Diver over coral

    MaFelipe photo

    A Question for You

    If you’ve read this article all the way to the end, thank you. I hope you found it thought provoking. However, the take-home message I wish to leave you with isn’t about following rules. It’s about asking questions. Asking why we divers do or don’t do certain things is important. It’s how we learn and understand and it’s also how we grow. Not everything is black and white. I want to encourage you to ask the questions and find the answers and then question the answers if they don’t sound right. This is ultimately how we advance our sport, making it safer and more enjoyable for all. 

    Courtesy of Dive Training Magazine. 


  • October 01, 2018 7:08 PM | Anonymous

    Hello all,

         With the recent closures of area beaches from possible Red Tide and the issues of Green Algae, we need to take consideration as to possible health issues when diving.  Here is a 2011 article from Alert Diver Magazine on health considerations when diving. 

    Microbial Hazards

    By Michael Miller, Ph.D., and Petar Denoble

    A threat to scuba divers?

    The hazard of human infection for those exposed to the sea has been known for a long time, but the public is becoming more aware of it as new evidence of the oceans' rapidly deteriorating health emerges. Even the most pristine seawaters are inhabited by large numbers of microbes.

    Most of them are harmless to humans, but some, like the vibrio species, can make people sick or even kill them. Increased pollution, warming and acidification of the oceans, all of which cause the death and extinction of fish and coral species, also promote the growth of indigenous microbes and increase the concentrations of terrestrial pathogens. Pollution and microbial hazards are greatest in coastal waters; unfortunately, this is where most recreational activities occur.

    Routes of infection

    Indigenous and introduced microbes may cause illness in humans either by infection or indirectly by intoxication. The sheer volume of seawater and its constant movement usually dilute foreign microbes below concentrations necessary for human infection. But there are many conditions when critical concentrations may be reached or when the threshold for infection in an individual is lowered. The greatest risk for human health comes from consumption of seafood.

    Human potential for contracting diseases from pathogens in the marine environment depends on exposure time, the virulence of the pathogens and the susceptibility of the individual. Microbes generally infect humans through ingestion, inhalation or mucous-membrane exposure (naturally occurring or in wounds). Microbes can infect through injured skin, the ears and the mucosa of the mouth, eyes and nose. Infections may also result from swallowing water. Nonfatal drowning in marine environments brings seawater into the lungs and can result in pneumonia. Some hazards like aerosolized bacteria, generated in coastal environments by wave activity, can transmit algal toxins to humans and cause viruses to become airborne. This type of hazard is less likely to cause illness in divers than swimmers, thanks to masks and regulators.

    Risk of direct infection by microbes from seawater is very small. However, the risk increases significantly in warm, brackish waters, in waters proximate to sewage and run-off inlets, at places of animal access and at populated beaches Divers may acquire dive-specific infectious diseases from exposure to the marine environment or as a result of close contact with other people and their dive equipment. If equipment is not properly cleaned, dried and stored after use, colonies can grow and microbes can reach sufficient numbers to infect users. Paradoxically, efforts to protect equipment from the corrosive effect of sea salt may also result in unwanted risks to divers' health.

    Communal culprits

    Communal rinse tanks have been shown to concentrate bacteria, so rinse
    gear that comes in contact with skin — and especially mucous membranes
    — under running water when possible.

    Most dive operations offer some kind of communal fresh-water tank for the postdive rinsing of equipment. Generally there are tanks for rinsing wetsuits, masks, boots, regulators and buoyancy compensation devices (BCDs) along with separate tanks for photo equipment. Despite the best of intentions, such a system may demonstrate more care for camera equipment than for human health. The volume of dive gear passing through rinse tanks in a day may significantly exceed the volume of water in it. Because of the inequity, rinse tanks become the means for collecting and concentrating microbes from all users, creating the potential for spreading infections among them.

    In 2007, a research team under Michael Miller of West Virginia University embarked on a study to sample water from communal rinse tanks and check it for the presence of bacteria. The first test was conducted at a popular Caribbean dive destination. For four days, the team collected daily water samples from communal rinse tanks after they were first filled in the morning and again several times throughout the day. They divided small amounts of the water samples onto agar plates and subsequently observed bacterial growth of different morphologies and swimming patterns. They did not attempt to identify the bacteria during this phase of the study and, therefore, did not determine if any were harmful to humans. This preliminary research simply confirmed the possibility of significant bacterial presence in rinse tanks.

    Several months later, a similar study was undertaken at a dive facility on another Caribbean island. The operation's two boats each had two rinse tanks: one for wetsuits and BCDs and another for masks and regulators. The operator fully cooperated with the study; for five days the wetsuit tanks were drained each morning, and one of them was cleaned with bleach before they were refilled. The team took water samples from both tanks at that point and again at multiple times throughout the day.

    Notably, this facility also allowed the sampling of water from the pipes used to fill the tanks, an opportunity not previously afforded the team. Tests showed the water used to fill the tanks was free of bacteria, nor were bacteria detected in either tank immediately after they were filled in the morning. However, by the afternoon all three tanks contained a lot of bacteria of many different types. Precleaning with bleach did not impact bacterial contamination. The two mask rinse tanks on the boats were also sampled, and both of these contained very high levels of various, unidentified types of bacteria. The time pattern of the findings indicated the bacteria were rinsed off of the diving equipment, but it remained unknown whether they originated from the sea or from divers as well as if they were pathogenic.

    Finding the answer

    Public health officials measure levels of certain species of bacteria to evaluate the risks to humans in many popular recreation areas.

    In June 2008, the team performed a third study with the aim of identifying bacteria in rinse tanks along with their source. The study was done at yet another Caribbean dive resort. Water samples were collected from the hose used to fill a communal rinse tank, the rinse tank itself, buckets on the boats in which masks were rinsed and stored, several dive sites in the ocean at various depths and, finally, ocean water near shore at the dive facility. Again, the water used to fill the rinse tanks was found to be safe. But this time the bacteria that developed throughout the day were identified, confirming that some likely originated from the ocean and others from the divers themselves.

    None of the identified bacteria would be considered overt human pathogens, but some are considered opportunistic pathogens: They could infect individuals with compromised immune systems or may infect open wounds. Bacteria identified in the communal rinse tanks are generally associated with unsanitary conditions. Where these bacteria are present, other pathogenic bacteria may occasionally occur. The scope of the study did not include checking for viruses usually found along with bacteria that may cause serious diseases.

    In the eye of the infected

    In March 2006, a group of 27 health-care providers attended a conference at a dive resort in the South Pacific. On the second day of diving, two divers reported eye problems, and over the next few days 13 divers (roughly half of the group) were diagnosed with conjunctivitis, an inflammation of the eye. It is characterized by the sensation of a foreign body in the eye, redness of the mucosa and possible discharge. Conjunctivitis of viral or bacterial origin spreads easily from person to person through close contact. There was an outbreak of conjunctivitis among the local population, but the divers did not have much contact with them.

    Two physicians from the group investigated the spread of the conjunctivitis among the divers. They concluded the conjunctivitis originated from a divemaster who had an eye infection prior to the diver outbreak. The divemaster placed his mask in a communal container of diving masks, which apparently became the means by which conjunctivitis was spread among the divers. Only divers who used this tank were infected. Those who did not use the tank were not infected despite close contact with those who were.

    To prevent further spread of infection, divers used bleach and detergent for mask cleaning. Affected divers received antibiotic drops and ointments and were healed in the next several days. One diver manifested symptoms after returning home. This case study demonstrated that disease can be spread among divers using communal rinse and storage containers. Conjunctivitis is a disease with short delay from infection to symptom manifestation, which made it possible to identify the source of infection. Other infections may have been transmitted by the same means, but due to longer periods of incubation as well as occurrences after the divers returned home, the link to communal tank was missed.

    Based on the lack of reports, the risk of infection by means of communal rinse tanks appears negligible, however, it's possible divers incorrectly attribute such infections to other sources. Miller's findings and the report of the conjunctivitis outbreak indicate communal rinse tanks may serve as avenues of infection transmission between divers. When it comes to rinsing dive equipment in direct contact with divers' skin and mucous membranes, such as masks and regulators, instead of using communal rinse tanks, divers are advised to clean gear using disinfectants under running water.

    Other areas of consideration

    Besides rinse tanks, there are at least three additional areas in which infections may spread among divers: the common, the rare but dangerous and the feared but unlikely. The most common infections reported in diving are otitis externa (swimmer's ear) and skin infections (impetigo and others). Fortunately, these can be easily prevented, diagnosed and successfully treated.

    On the other hand, diving or swimming with an open wound may result in a rare, but often fatal, infection with Vibrio vulnificus, an opportunistic pathogen commonly found in warm coastal waters. The Centers for Disease Control and Prevention receive approximately 150 reports each year of people infected with V. vulnificus, most by eating oysters and a few through open wounds.

    Some divers fear sinusitis and cystitis (bladder infection). Indeed, swimmer's sinusitis has disrupted the careers of many aspiring athletes. However, it is most often caused not by microbial infections but by chemical irritation from chlorine used to disinfect pool water. It does not occur in ocean swimming. Indeed, some people with chronic sinusitis maintain that swimming in the sea and flooding their sinuses with salt water helps, a notion seemingly supported by an increasing number of ear, nose and throat physicians who advise patients to use saline sinus rinses to relieve nasal and sinus congestion. However, it's important to remember that the intentional or inadvertent introduction of seawater into the sinuses could cause infection if the introduced water is loaded with a sufficient number of pathogenic bacteria or viruses. It is difficult to come by any such cases in conventional medicine literature.

    The effect of swimming on cystitis in women is a popular topic of discussion in the media. The prevalence of cystitis is very high, and in many cases it is recurrent. Each occurrence often is the result of infection by a new causative microbe. Chemical irritation from chlorinated water or the prolonged wearing of a wet swimsuit may enhance the recurrence of cystitis, regardless of the bacterial contamination of fresh or salt water. When it comes to cystitis, it may be a predisposition rather than a specific causation that affects its occurrence.

    Putting it in perspective

    While it seems there are many microbial hazards in the sea, the true risk of serious infection to divers seems negligible. Most infections that may be occurring among beachgoers, swimmers and divers probably manifest as diarrhea, but that is so common among travelers it is rarely linked to seawater. The two most common infections in divers are ear and skin infections.

    To mitigate risks of infection while diving, regularly clean and disinfect equipment, avoid polluted waters, never dive with open wounds (including tooth extractions) or sores, never rinse your mouth or sinus cavities with seawater, keep your ears dry, avoid prolonged wearing of wet clothing and shower after diving. Divers with an acute infection such as a common cold, conjunctivitis, skin infection or gastroenteritis are not fit to dive and must take precautions not to infect others.

    Beach Bacteria

    Waterborne disease outbreaks (WBDO) have been reported in people bathing in pools and rivers but not among seaside beachgoers. However, due to presence of the diarrhea-causing microbes on seaside beaches, epidemiologists assume that cases of gastroenteritis resulting from exposure to marine pathogens must be common, too. The summertime increase in occurences of gastroenteritis in coastal states indicates a possible role of beaches in disease transmission.

    In 2009 and 2010, scientists discovered methicilin-resistant staphylococcus aureus (MRSA) in the sand of many beaches on both the West and East coasts. MRSA causes intrahospital infections with a high mortality rate due to its resistance to many antibiotics. MRSA also occurs outside of hospitals, but the source of infection is not known. Seasonal increases in MRSA infections coinciding with times of increased beach use may indicate beaches are a possible means of MRSA transmission.

    Clean and Sanitize Your Dive Gear

    By Daryl F. Stanga, HM1/SCW/DV, U.S. Navy

    Although the risk is considered to be very small, second stages and mouthpieces could transmit disease. Divers are encouraged to disinfect equipment properly.

    Commercial products designed for cleaning dive gear are widely available. Make sure to choose a cleaning agent that does not contain hydrocarbons. If in doubt about a product's usability on dive gear, consult the equipment manufacturer for recommendations.

    To clean scuba regulators, use a scrub brush to remove any gross contamination such as mud, dirt, sand, seaweed or saliva from the regulator. Rinse thoroughly with fresh water, then spray a liberal coat of the chosen cleaning agent on and into the mouthpiece and second stage until all surfaces are wet.

    Let stand for 10 minutes. If the solution appears to be drying, apply more to keep the regulator wet for the full 10 minutes. After 10 minutes, rinse with clean, fresh water or under running potable water.

    If several regulators need to be sanitized at the same time, or if you prefer immersion to clean the equipment, regulators may be immersed in the disinfectant solution for 10 minutes and then rinsed in fresh water.

    Use the same procedure to sanitize snorkels and the oral inflation tubes of BCDs. To clean the BCD thoroughly, pour several ounces of the solution into the bladder and agitate for 10 minutes. Then empty the bladder and rinse with fresh water.

    Before reassembling, allow the BCD to air dry.

    Public Health Policy

    From a public health perspective, monitoring popular recreational areas for various indicators is one of the major steps taken in risk reduction. There were more than 24,000 beach closures and advisories in 2010, the second-highest number on record. The majority of these were due to the presence of bacteria. Scientists and public-health officials rely on several factors to determine whether risk of infection is elevated in a particular area.

    1. Unsurprisingly, the presence of sewage is correlated with elevated infection rates. Gastroenteritis and respiratory illness in particular increase with the degree of site pollution. Pollution with sewage is generally assessed by monitoring the presence of enterococci bacteria.
    2. High swimmer density is a second factor shown to increase infection risk. Elevated numbers of minor ear and skin infections from human-shed bacteria are observed where swimmer density is high. Skin granulomas from Mycobacterium marinum have also been observed. Staphylococcus aureus levels have been proposed as indicators of exposure.
    3. Eutrophication, the increased abundance of algae, phytoplankton and other marine plants, may be linked to higher rates of infection by pathogens native to the marine environment. Runoff from agriculture and golf courses is a major cause of eutrophication. Blooms of plankton and algae can promote growth of associated populations of marine pathogens by increasing nutrients in the water and providing microenvironments that favor growth. The prevalence of Vibrio species has been proposed as an indicator for measuring eutrophication.
    4. Elevated seawater temperature is associated with increased incidence of shellfish poisoning and cholera. Remote sensing of sea surface temperature is being explored, but its predictive value needs further study.


    Miller MR, Motaleb M (2007). "Scuba divers rinse tanks harbor many microorganisms." Microbe 2(12): 577.

    Olsson DJ, Grant WD, et al. (2008). "Conjunctivitis outbreak among divers." Undersea Hyperb Med 35(3): 169-74.

    Thompson JR, Marcelino LA, Polz MF (2005). "Diversity, sources and detection of human bacterial pathogens in the marine environment" from Oceans and Health: Pathogens in the Marine Environment, Belkin S and Colwell RR (eds.).

    Washburn BK, Levin AE, et al. "Identification of bacteria in scuba divers' rinse tanks." Undersea Hyperb Med 37(4): 233-40.

    Want to learn more?

    Read White Pox

    © Alert Diver — Fall 2011

  • September 04, 2018 4:19 PM | Anonymous
    We are fairly spoiled here in South Florida with dive boats set up for easy diving. But as we have seen on some of our travels, sometimes we need to do water entries outside of the normal one we do.

    The Easy In: Tips for Performing the Giant Stride Entry (GSE)Always evaluate the entry area before gearing up.  This is especially important if diving from a boat. Check for any visible hazards.  Entry areas vary from boat to boat. Some are as much as six feet above the surface of the water making it necessary to perform a high-platform version of the GSE.  You may need assistance from a crewmember, especially if there are no handrails or bars to grasp for balance.  A water-level swim platform extending from the stern of a boat is the easiest type of entry area.  If you are diving from a stable platform such as a pool deck or dock, check the water level to confirm it is deep enough for a safe entry.  If you don’t know the depth, do not enter the water to avoid an injury.giant stride

    Step One — Approaching the Entry Area

    If diving from a boat, you will be given a pre-dive briefing to learn boat procedures and specifics about each dive location.  Following the briefing, finish donning your gear and perform a buddy check with your dive partner. Make sure your gear is in place and working properly.  Also check the tank to assure the air is turned on.  Depending on boat policies and crew instructions, you will either carry or wear your fins to the entry area.  When carrying fins, proceed to the entry and don the fins prior to the GSE.  If you are asked to wear your fins, slip them on and carefully shuffle heels first or step sideways to the entry point.

    After donning the fins, place your mask securely on your face and the regulator in your mouth.  Partially inflate your buoyancy compensator (BC). Move to the outer edge of the platform, place the balls of your feet on the outer edge and extend the fin blades over the water.  Whether entering the water from a rocking boat platform or a stationary pool deck, position your feet so the fin tips are not below the surface as you begin your giant stride. Once you are properly positioned and ready to make your entry, take one last look into the water close to the entry point to confirm there are no obstructions (such as another diver) in the vicinity.  Watch for diver’s bubbles beneath the surface.  If you see any bubbles, delay your entry until the area is clear.

    Step Two — Securing Your Gear

    Once you have ascertained that the entry area is clear, secure your gear by placing the palm of your hand over the second-stage regulator and spread your fingers across the front of the mask.  Gently but firmly hold the regulator and mask against your face to prevent them from becoming dislodged on entry. If you are wearing a conventional weight belt, use your free hand to hold the buckle in place.  This will prevent the buckle from opening on entry, possibly allowing the loss of the weight belt.

    When wearing a weight-integrated BC, use one hand to secure your mask. The other hand can be used to hold gauges close to your body or used to secure the mask strap.  The choices you make are determined by your gear configuration and personal preference. Your scuba instructor can help you decide what works best for you.

    giant stride

    Step Three — Giant Stride in Action

    Now that you have completed Steps 1 and 2, it is time to complete the entry. After a quick look to confirm the area below is clear, place hands in their proper positions, look straight ahead and take a giant step outward from the entry platform. To execute a successful giant stride, it is especially important to look and stride toward the horizon. By doing so, your body will remain vertical, creating the desired entry into the water.

    Either leg may be used to stride outward from the platform.  Raise the leg high, keeping the fin tip pointing upward to avoid dragging it in the water, which can cause an awkward “face plant” entry.  The foot remaining on the platform will pivot on the edge as you are carried away from the boat by the momentum of the giant stride. As you take this giant step away from the boat, enough space will be left for the scuba tank to clear the entry platform.

    In rocky seas, proper timing is critical to making a safe GSE.  Time the giant stride entry for when the boat pauses at the peak of the platform’s upward movement just prior to the boat’s descent.  The split-second timing will prevent you from being thrown off balance by the upward motion of the boat. Instead, you and the boat will both move in a downward motion at the same time.

    Step Four — Ready to Dive

    When executing a giant stride correctly, you will enter the water in a vertical position.  If striding from a low platform, you can minimize the entry depth by bringing your legs together immediately after contacting the water.  This motion will reduce your downward momentum by creating an upward thrust. When making a GSE from a higher platform, this is not appropriate.  Instead, immediately after making your giant stride, bring your legs together in a straight line with your torso and make a sleek entry. You will go a little deeper into the water but due to the partial inflation of the BC, you will surface quickly and safely.

    After every entry, regardless of where, when or how high, always remember to immediately turn to the boat or shore personnel and give an OK signal by placing your fingertips on the top of your head. If you need assistance, wave your hand(s) back and forth above your head.

    giant stride

    “Have a Seat, Please”: The Controlled Seated Entry

    The controlled seated entry (CSE) is pretty much as its name implies — it’s a controlled entry done from a seated position.  The CSE is typically performed from a platform no higher than 12 to 18 inches (30 to 46 cm) above the surface of the water.  Platforms include small boats, swim platforms, pool decks, a dock or the gunwale of an inflatable.  The CSE can typically be done in place of the giant stride or backroll entry and allows a slow, gentle entry instead of a big splash.

    It is appropriate to use the seated entry when obstacles may be below the surface or when attempting to enter water with a current.  Using this type of entry in a current, allows you to hold onto the platform or current line until your group is ready to descend together.  By descending together, you are less likely to be separated from your group.

    The seated entry is also helpful if you prefer to slip into your scuba unit after entering the water.  This technique is very useful for divers with back problems or other issues because the weight of the gear is not placing strain on your back.  At the end of the dive, you can remove the scuba unit before exiting the water.  Just be sure that your buddy or a crewmember is available to assist with securing the scuba unit after removal.

    Controlled seated entry - scuba diving

    STEP 1

    The first step begins by seating yourself on the edge of the entry platform or, in our case, the pool deck. Don your fins and scuba unit.  Your buddy or divemaster may need to assist you when donning the scuba unit.  After the unit is in place, confirm that the gear is secured properly.  Hoses and gauges need to be clipped and stowed to avoid the possibility of getting caught on the platform.  Now partially inflate the buoyancy compensator (BC), don your mask and place the regulator or snorkel in your mouth.  As you begin the entry, you are seated so that your bottom is near the edge of the platform, your legs are bent at the knees and your lower legs and feet are in the water.

    Controlled seated entry - scuba diving

    STEP 2

    For the CSE to be successful, proper placement of the hands is critical.  To begin this step, place the heel of your right hand on the edge of the pool deck, fingers facing the deck and the wrist near your thigh.  This hand position may feel awkward at first, but hand placement — with the heel of the hand on the edge of the platform and the fingers pointing away from the water — is important as you initiate Step 3.

    For this exercise, the model shown here is entering to the right, but the CSE is performed the same way whether you pivot to the right or the left. You will maneuver your body in the direction of your hands.

    Controlled seated entry - scuba diving

    STEP 3

    The next three steps are broken down for the purpose of explanation but, when you perform the entry, will be executed in one continuous pivoting motion.  You begin seated on the pool deck facing the water and finish floating in the water facing the deck. During the entire process, you will remain in control of the entry.

    With gear in place and right hand positioned as in Photo 2, move your left arm across your torso while twisting to the right, pivoting on the right hand, transferring your weight onto your arms.  The right arm will remain straight (vertical to the pool deck), allowing you to stay close to the edge of the pool.

    Controlled seated entry - scuba diving

    STEP 4

    This step begins as you place your left hand on the pool deck.  The left arm will remain vertical to the pool deck with fingers pointing toward the deck. The hands will be shoulder-width apart.  You will be leaning slightly forward, facing away from the water.  At this point you have the option of stopping the entry process if needed or continuing on to Step 5.

    Controlled seated entry - scuba diving

    STEP 5

    The final step provides a transition from pool deck to water.  Done correctly, there will be little or no splash upon entry.  With both hands and arms in the position shown in Step 4, slowly lower yourself into the water. Your partially inflated BC will provide the buoyancy needed as you lower into the water. At this point you may wish to add more air to your BC to float comfortably at the surface while you wait for your buddy to enter.

    After reviewing the steps for the controlled seated entry, it is easy to understand why many divers prefer this method of entering the water.  The prime benefit is that you are in control at all times and feeling in control helps calm pre-dive anxiety or jitters. You also have the option of halting the entry if needed, which cannot be done once you’ve initiated the giant stride or back roll. Both of these methods can create a jarring entry if not done correctly.  We suggest you take time to practice the CSE so you can move with confidence from Step 1 to Step 5.  This will enable you to start your dive with a gentle, easy entry.

    The Modified Controlled Seated Entry

    The controlled seated entry described in this column might need to be modified for those with certain mobility issues.  If you have particular physical concerns, discuss them with your instructor.  Together the two of you can likely come up with a modified seated entry technique that will get you in the water safely and easily.

    Enjoy and thanks Dive Training Magazine for the help. 

    Tom Stenger

    Image result for indiana jones choose wisely

  • August 03, 2018 1:54 PM | Anonymous

    Improving Your Dive Performance and Comfort Isn’t a Massive Stretch

    By Kristen Fassolas posted on SDI/TDI/ERDI Blog site 

    Stretching isn’t just for those who don tight leggings and own a yoga mat. Good flexibility can help improve your scuba diving experience and performance.

    • Do you sometimes struggle to put on your wetsuit or your BC or harness?
    • Do you find it hard to reach down to put on your fins?
    • Is it difficult to bend down with your gear on to reach for something you have dropped?
    • Are entries and exits into or out of the boat or water difficult?
    • Would you like to be able to reach your own tank valve if required?
    • Is just turning around to look at your buddy difficult?
    • Do you suffer from lower back pain?

    If the answer to any of these is yes, you should work on improving your flexibility. Having a healthy range of motion can help with all of the above. This even includes lower back pain. It can also improve your daily life and help to prevent injuries. Taking the time to stretch even helps clear the mind.

    Stretching is most effective when your muscles are warmed up. Before you stretch, complete your usual exercise routine. If you simply want to have a stretching session, do a light warm up first. This can consist of a few minutes of gentle jogging on the spot, some arm circles and some hip circles. This will get the blood flowing.

    To ensure progress, aim to complete the following stretches every day or at least every other day. If done frequently, they will also help to avoid cramps from tight muscles and ease tension in your body.

    Once in position, hold the stretch for 20 to 30 seconds. No stretch should be painful. If it is, adjust the intensity when you need to. Never pull or push through pain. Inhale and exhale deeply while holding the stretch, relaxing further with each exhale. Perform each stretch twice.

    Chest and shoulder stretch 

    Stand in the middle of a doorway with one foot in front of the other. Bend your elbows in a 90-degree angle. Place your forearms on each side of the doorway. Shift your weight onto your front leg, leaning forward, until you feel a stretch in your chest and shoulder muscles.

    Triceps stretch 

    Raise one arm up into the air. Then place the palm of your hand on your neck or back as low as possible. While doing so, keep your elbow pointing towards the ceiling. Use your other arm to gently pull your elbow back to increase the stretch. Repeat with the other arm.

    Glute (buttock) stretch 

    Lie on your back and bring your knees up to your chest. Cross your right leg over your left thigh. Grasp the back of your left thigh with both hands. Pull your left leg toward your chest. Repeat with your opposite leg.

    Quad (front thigh) stretch 

    Lie on your right side. Grab the top of your left foot and gently pull your heel towards your left buttock. Keep your knees touching. This will stretch the front of your thigh. Repeat on the other side.

    Hamstring (back of thigh) stretch

    Lie on your back and raise your right leg. Keep your left leg bent with your foot on the floor. Pull your right leg towards you, holding your thigh or calf and keeping the leg straight. Repeat with your opposite leg.

    Calf stretch 

    Put your right leg forward, keeping it bent, and lean forwards slightly. Keep your left leg straight and try to lower your left heel to the ground. Repeat with your opposite leg.

    Make stretching a new habit. Remember, good flexibility translates into a greater freedom of movement. It helps prevent injury and improves your performance and comfort both above and below the surface. 

  • July 09, 2018 11:03 PM | Anonymous
    Divers training had a good article a few years ago on Nitrox issues and since most of us dive Nitrox, it is important to know some risks. 

    The article is quite long, so I cut to the key sections. Here is the link for the full version.

    To Breathe or Not to Breathe: Exploring the nitrox controversy

    By Alex Brylske

    The issue of recreational nitrox diving has been at the forefront of the diving community for the past several months. There are no shortages of opinions about the topic but there seems to be very little objective information about the subject. This article is a milestone in that it addresses both the pros and cons of the activity in an objective and straightforward manner.

    When we originally planned a nitrox article for Dive Training, we envisioned it as a two-part series, much like the trilogy published about the dive tables. However, we felt a two-part series increased the chances of confusion, and opted for a single, comprehensive report. We hope you will enjoy the results.


    Recently an increasing number of recreational divers have begun purposely altering the air they breathe. Instead of using special gas mixtures to attain certain advantages while diving. These exotic mixtures go by such names as heliox, trimix, and nitrox. By far, the most common alternate breathing mixture is nitrox.

    Some of you maybe already know about nitrox diving. Others perhaps have heard about it, but know very little. Even if you’ve never heard of nitrox diving, you certainly soon will. Industry estimates are that from 1985 to 1991, recreational divers engaged in 30,000-50,000 nitrox dives. And the numbers are growing. As altering the diver’s breathing mixture involves serious practical and legal questions, nitrox diving is becoming a hotly debated topic. In this article we’ll examine the issues involved I this new and controversial form of recreational diving. Hopefully, we can put the subject into perspective.


    Why, you might ask, would divers want to alter the air they breathe? After all, humans have been breathing what Mother Nature has seen fit to provide us with for millions of years. Theoretically, the answer is simple. For land-based animals who breathe at normal atmospheric pressure, good ol’ regular air does the job of sustaining life quite well. But, when we venture either to altitude or underwater, there are certain disadvantages to regular air. At altitude we’re all aware that the reduced atmospheric pressure robs us of precious oxygen. This is why pilots must breathe oxygen when flying at high altitudes and why the cabins of jet aircraft are pressurized.

    When we venture underwater, air continues to have certain limitations. But these limitations have less to do with the oxygen component of air than the nitrogen. It all centers around a topic we have explored extensively in past issues of Dive Training –decompression. The length of time a diver may remain at depth, or the amount of decompression he must undergo if exceeding the no-decompression limits, depends upon the amount of nitrogen absorbed. If a diver breathes air, he breathes a gas mixture containing 79 percent nitrogen. In an EAN mixture, oxygen is used to replace some of the nitrogen. So, instead of breathing a mixture containing 79 percent nitrogen, an enriched air mixture might contain only 68 percent to 64 percent nitrogen. Therefore, as the diver is breathing a gas containing less nitrogen, he absorbs less nitrogen in his body. This means both an extension of the decompression limits and –if required—reduced decompression time. Reduced decompression time is the primary—though not the only—benefit of using EAN.


    As in most human endeavors, there is an up side and a down side to the EAN issue. Let’s examine the advantages before looking at the problems. As stated previously, the greatest advantage of using EAN is the extension of no-decompression limits for three of the most popular air dive tables, along with the limits for NOAA Nitrox I and II. As you’ll see, EAN can often more than double the no-decompression limits of the air tables.

    Additionally, using EAN can shorten the required surface interval between repetitive dives. Or the diver can make a longer repetitive dive with the same surface interval as a comparable air dive. Either option is possible, again because the diver absorbs less nitrogen than on a comparable air dive.

    While the extension of no-decompression time can be a real benefit, it is not—in the opinion of this writer—the primary advantage of using EAN. The real advantage of enriched air is that it can provide recreational divers with an additional safety margin when used with regular air dive tables or computers. Air tables and computers assume the diver will breath air containing 79 percent or 64 percent nitrogen. This means the diver actually absorbs far less nitrogen than the air tables or computer calculates. Thus, the diver’s actual nitrogen absorption will be far below what the tables or computer shows.

    Using EAN in this way can be an ideal method of automatically building In the conservatism so many authorities advise when using tables and computers. It might also be a way of overcoming the risks from such unquantifiable factors such as age, obesity, cold, fatigue, and dehydration. In addition, susing EAN with air tables could help decrease the decompression sickness (DCS) rish among dive professionals—instructors and divemasters—who dive continually as part of their duties. Some diver resorts, who maintain EAN filling stations, have already implemented the policy of having their dive guides use EAN for an added measure of safety.

    While using EAN with air decompression schedules offers great promise, it’s not a panacea for DCS. We still know far too little about the disorder to make any solid claims about the certainty of avoiding the bends.

    Other advantages of EAN have been reported, but haven’t yet been fully scientifically documented. The first involves nitrogen narcosis. The theory is this: The breathing mixture contains less nitrogen than normoxic air, and nitrogen is responsible for narcosis. Thus, as the diver breathes less nitrogen, he is less susceptible to nitrogen narcosis than when breathing air at the same depth. Many EAN divers have confirmed this hypothesis, while others have seen no noticeable difference between air and EAN.

    Another benefit experienced by many EAN divers is what can be called the “feel goods.” Quite often divers who use EAN report noticeable lack of post dive fatigue. In many cases, excessive post dive fatigue is attributable to what is termed “sub-clinical” DCS. The theory is that the higher percentage of oxygen in EAN reduces or eliminates these symptoms. The “feel goods” might also result from better oxygenation of the tissues by the enriched air-breathing environment.

    A final benefit of EAN, oddly enough, is assumed to occur if a diver is stricken by decompression injury. Because the breathing gas contains a higher-than-normal level of oxygen, it’s theorized that tissues affected by these disorders will survive longer than if the diver was breathing air. Evidence also suggests that breathing EAN can help significantly reduce asymptomatic or silent bubbles after a dive.


    EAN is not a magical answer to the physiological problems facing divers. For instance, EAN divers are still subject to the same effects of Boyle’s law – squeezes and lung overexpansion. And while the reduced percentage of nitrogen will increase no-decompression time, EAN divers are not immune to DCS. In addition, EAN creates a few unique problems of its own.

    We have known since the late 18th century that humans cannot tolerate breathing pure oxygen at high pressure with eventually falling victim to a disorder called central nervous system (CNS) oxygen poisoning. The symptoms of this disorder include: tunnel vision, ringing in the ears, nausea, facial twitching, irritability, and dizziness. But the most serious effect of CNS oxygen poisoning is the onset of epileptic-type convulsions. Normally, convulsions are not a life-threatening event—if they occur on land. A diver who convulses underwater, however, could drown. Thus, divers must avoid any circumstance where convulsions might arise. (This is why people with seizure disorder are usually disqualified as candidates for diving.)

    A complicating factor is that individuals vary greatly in their susceptibility to CNS oxygen poisoning. Even the same individual can vary in his own susceptibility from day to day. Based on years of experience and tens of thousands of dives, both the U.S. Navy and NOAA long ago determined specific oxygen tolerance limits. The modern EAN diving community has followed suit and also adopted these limits. Recently, though, some authorities have recommended a reduction in these limits for recreational divers.

    The current recommended oxygen tolerance limits for diving are determined by calculating the partial pressures of oxygen breathed under pressure. These tolerance limits are established in order to prevent divers from encountering CNS oxygen poisoning at depth. You’ll remember that, according to Dalton’s law, each gas within a gas mixture exerts a pressure proportionate to the surrounding pressure. This explains why as a diver descends, the partial pressure of oxygen he is breathing increases. If the diver continues his descent, oxygen toxicity, due to increasing partial pressures, will occur. The depth at which CNS oxygen poisoning occurs is directly related to the amount of oxygen in the diver’s breathing gas. The more oxygen in the mix, the shallower the depth for the oxygen tolerance limit.

    When using normal air, the oxygen toxicity limit has no impact on divers who restrict their diving to 130 feet or less. This is because the partial pressure of oxygen in normal air does not reach toxic partial pressures until depths of more than 210 feet. However, EAN mixtures, because of their increased oxygen content, reach this limit at much shallower depths. The chance of CNS oxygen poisoning, therefore, becomes a very real concern even at recreational diving depths. For example, the Maximum Operating Depths (MODS) for NOAA Nitrox I and NOAA Nitrox II are 130 and 110 feet respectively. Exceeding these depths exposes divers to the same risk of oxygen poisoning as breathing air beyond 210 feet!

    Oxygen tolerance is the reason for one of the most important rules when using enriched air: “The diver must closely adhere to depth limits.” As you’re aware, the maximum depth for recreational diving is 130 feet. This is because of the possibility of severe nitrogen narcosis beyond that depth.

    However, it’s the onset of CNS oxygen poisoning that determines the depth limit for EAN, not the effect f nitrogen. Unlike nitrogen narcosis, CNS oxygen poisoning does not always come about gradually. While the diver might experience minor symptoms before convulsions occur, convulsions often begin with no prior symptoms!

    Dr. Lee Sommers, diving safety coordinator at the University of Michigan, sums up the matter quite well. He states in an article in the recent issue of NAUI (National Association of Underwater Instructors) journal Sources, “I suggest that, unlike nitrogen narcosis, which appears to manifest itself progressively from mild to severe impairment, oxygen toxicity can be a much greater threat to the diver. The simple fact that the onset of oxygen-induced convulsions with no preceding symptoms is possible adds another unpredictable dimension to (enriched air) diving. Oxygen may prove to be far less forging than nitrogen!”

    The conclusion is both harsh and simple: While a diver breathing air might get away with exceeding the recreational diving limit f 130 feet, it’s unlikely he’ll live to tell about it if he exceeds the depth limits using EAN.


    Some in the recreational diving industry vehemently opposed the proliferation of EAN diving. The reality is, however, that this is like trying to push water uphill. The question is no longer should recreational divers use nitrox; the fact is that they are using it. ANDI and IAND have, to date certified almost 300 instructors and more than 4,000 divers. Furthermore, authorities expect this number to double within the next year! These figures, of course, don’t account for those using EAN who have not been formally trained to do so. How many divers this involves is difficult to determine.

    Rather than trying to resist the inevitable, it’s more useful to ask the question: Are the advantages of EAN worthwhile given the problems it presents? Frankly, this depends on the type of diving one does and how EAN is used.

    For divers of less than 60 feet, there really is no particular advantage to using EAN over air—if increasing your no-decompression time is what you’re after. Although EAN will theoretically extend the no-decompression limits greatly, this has little practical effect. Unless a diver wears double tanks, he’d run out of air long before he reached the EAN no-decompression limits.

    For dives below 130 feet, EAN provides no advantage to recreational divers. In fact, because of the increased partial pressure of oxygen, NOAA Nitrox I cannot be used safely below 130 feet. And NOAA Nitrox II can’t be used safely below 110 feet.

    The advantage of using EAN to extend no-decompression time, as Table 1 shows, occurs on dives in the 60- to 130-foot range. EAN probably gives a significant enough advantage to consider its use in this depth range if you’re properly trained and closely adhere to EAN diving procedures. (See the “EAN Do’s and Don’ts “sidebar.)

    Still, the primary benefit of using EAN is that it can probably enhance diving safety considerably when used in conjunction with air tables or computers. For this reason alone, enriched air deserves a close and thoughtful examination by all divers.

    DO’s and DON’Ts of EAN DIVING

    Be trained and certified for EAN diving: Never dive with enriched air if you haven’t completed a sanctioned course. The dangers of enriched air are both subtle and insidious. Also, certified EAN divers should never encourage friends who are not EAN-certified to use enriched air without proper training
    Secure EAN from a reputable source, and never dive using a “home brew”: All divers must be certain of the quality of their breathing air. For EAN diving this means not only avoiding contaminates, but also verifying the mixture’s oxygen content. Ask whomever is providing your fill to give you a tour of the compressor/storage system, and ask them to explain the operating procedures and safeguards in place. Above all, never try to mix your own EAN.

    Always personally analyze your gas before use: Only an analysis can confirm the actual percentage of oxygen in an EAN mixture. Never use a cylinder containing enriched air unless you analyze it first. And be sure to use at least two in-line analyzers. Multiple analyzers validate the results of one another.
    Never exceed the Maximum Operating Dept (MOD) for the mixture you are using: The maximum depth for using EAN is not approximate or flexible. Remember, convulsions from CNS oxygen poisoning can come without warning. Know the Maximum Operation Depth for the mixture you’re using and don’t dive beyond that limit.
    Use only dedicated oxygen clean and compatible cylinders: Use of non-dedicated cylinders results in a high risk of explosion, and could subject an unknowing diver to oxygen poisoning. Follow the proper labeling procedures.

  • June 01, 2018 8:20 PM | Anonymous

    Hello Club Members,

         June 1 has arrived and this means hurricane season. As we leave for our summer dive trips, Yah Caymans, we leave our homes vulnerable. Although the likelihood of early hurricanes are rare, one can never predict mother nature. 

         With this in mind we need to prepare our homes and cars before we leave for our trips. This means we need to keep in mind when the peak storm season is and be ready to come home from a trip a few days before a storm and find the stores empty. This should not be the time to prepare and you should have done it early.  As we continue our travels, it is important to start stocking up on goods early and have them set before you leave for your vacations. 

         For me this is an important must do. Since I work for the City of Ft Lauderdale, I am typically called in early to assist the city to prepare for the storm. This means that while everyone is fighting for gas at the pumps, I am already at work keeping the peace. So I must have my preparations done  very early. I always ensure that I have my stock in order early, which I have already done and am ready to return from a trip and goto work the next morning. 

         There are dozens of links to help you prepare and I have attached the links for Broward and Palm Beach EOC. If you get stuck on a trip have a plan in place with some friends of family to secure your home. Although be gentle on them because they are doing you a big favor. 

    With all the negatives out of the way , time to enjoy a great dive season. Stay away hurricane.

    Tom Stenger



  • April 29, 2018 7:02 PM | Anonymous

    Hello Club,

         Unless you invest in the fancy full face mask and U/W comms system, you are probably using hand signals? But, just like different languages, hand signals may get a bit confusing and the last thing you need is to send out mixed signals.

         So lets review some of the basic signals right from the Open Water Dive Manual. 

    Image result for padi hand signals

    Here are some for Marine Life. 

    Image result for scuba hand signals for marine life

          As we begin the summer dive season be sure to refresh on you signals and before every dive brief your buddy on any special signals you may use. That way when you give them some weird signal, they don't look at you like a confused minion. 

    Image result for scuba hand signals for marine life

    Tom Stenger

    Image result for scuba minion

  • April 02, 2018 7:01 PM | Anonymous

         As we prepare for our busy local and overseas dive season, it is always a good ideal to refresh our basic dive skills. The basic skill you learned in your Open Water Class are important every time you dive, even if you don't have to use them. 

         I can't tell you how many times my mask has flooded or my tank came loose as I bankrolled off of a friend's boat. Although considered a unusual issue, it was easily handles with little issue because of the confidence I had in my basic skills.

         So what should I focus on and how can I practice. When ever I get new gear or items back from service, I love to jump into my community pool and test it out. I also use this time to practice some basic skills like mask flooding , regulator recovery, and locating my alternate air source. 

         What if you don't have a pool? Well, next time you are on a club dive at the end of the dive practice your skills. Just remember to brief your dive buddy first, so they know.

    Here are some tips to start the season: 

    1. Do you ABC’s

    Take your time to go through your kit, and make sure all is in order, and that you’re being extra thorough in assembling the elements.

    Haste makes waste. So take your time.

    2. Practice your basic water skills

    Go through the basic dive skills.

    Do a hover (if you struggle, start with the fin pivot), remove and replace regulator, remove and replace mask.

    If you’re really ambitious, you can also remove and replace BCD and weight belt at the surface.

    And if your buoyancy is top notch, take it up a level and try inverted hovers, trim, etc.

    If you have the opportunity, also practice a few water entry strategies, such as giant stride.

    2. Practice your basic water skills

    Go through the basic dive skills.

    Do a hover (if you struggle, start with the fin pivot), remove and replace regulator, remove and replace mask.

    If you’re really ambitious, you can also remove and replace BCD and weight belt at the surface.

    And if your buoyancy is top notch, take it up a level and try inverted hovers, trim, etc.

    If you have the opportunity, also practice a few water entry strategies, such as giant stride.

    3. Practice emergency skills

    Next, move to the more advanced skills, and consider repeating these from time to time, in-season.

    These include deploying an SMB, out-of-air scenario, and re-surfacing of an unconscious or injured diver.

    If you dive with doubles, also practice your basic shut-down drills.

    4. Work your communication skills

    Agree with your buddy that at some point during the dive, you both need to communicate something on the dive, preferably rather complex, to the other. Make it scenario based, and make sure you have a sign to communicate that this is in fact just a scenario.

    Bring two writing slates or wetnote books. You or your buddy then communicates a message to the other, who then writes down what he or she believes is communicated. Then you switch. Afterwards, you've compare notes and see how efficiently you've communicated the messages.

    3. Practice emergency skills

    Next, move to the more advanced skills, and consider repeating these from time to time, in-season.

    These include deploying an SMB, out-of-air scenario, and re-surfacing of an unconscious or injured diver.

    If you dive with doubles, also practice your basic shut-down drills.

    4. Work your communication skills

    Agree with your buddy that at some point during the dive, you both need to communicate something on the dive, preferably rather complex, to the other. Make it scenario based, and make sure you have a sign to communicate that this is in fact just a scenario.

    Bring two writing slates or wetnote books. You or your buddy then communicates a message to the other, who then writes down what he or she believes is communicated. Then you switch. Afterwards, you've compare notes and see how efficiently you've communicated the messages.



    3. Practice emergency skills

    Next, move to the more advanced skills, and consider repeating these from time to time, in-season.

    These include deploying an SMB, out-of-air scenario, and re-surfacing of an unconscious or injured diver.

    If you dive with doubles, also practice your basic shut-down drills.

    4. Work your communication skills

    Agree with your buddy that at some point during the dive, you both need to communicate something on the dive, preferably rather complex, to the other. Make it scenario based, and make sure you have a sign to communicate that this is in fact just a scenario.

    Bring two writing slates or wetnote books. You or your buddy then communicates a message to the other, who then writes down what he or she believes is communicated. Then you switch. Afterwards, you've compare notes and see how efficiently you've communicated the messages.

    2. Practice your basic water skills

    Go through the basic dive skills.

    Do a hover (if you struggle, start with the fin pivot), remove and replace regulator, remove and replace mask.

    If you’re really ambitious, you can also remove and replace BCD and weight belt at the surface.

    And if your buoyancy is top notch, take it up a level and try inverted hovers, trim, etc.

    If you have the opportunity, also practice a few water entry strategies, such as giant stride.

    1. Do you ABC’s

    Take your time to go through your kit, and make sure all is in order, and that you’re being extra thorough in assembling the elements.

    Haste makes waste. So take your time.

    1. Do you ABC’s

    Take your time to go through your kit, and make sure all is in order, and that you’re being extra thorough in assembling the elements.

    Haste makes waste. So take your time.

    Scuba skills include kit checks<img class="size-full wp-image-7249" src="//" alt="Scuba skills include kit checks" width="800" height="533" />

    A diver taking time going through her kit - Credit: PhotoSky 4t com

    2. Practice your basic water skills

    Go through the basic dive skills.

    Do a hover (if you struggle, start with the fin pivot), remove and replace regulator, remove and replace mask.

    If you’re really ambitious, you can also remove and replace BCD and weight belt at the surface.

    And if your buoyancy is top notch, take it up a level and try inverted hovers, trim, etc.

    If you have the opportunity, also practice a few water entry strategies, such as giant stride.

    Buoyancy scuba skills practice<img class="wp-image-7252 size-full" src="//" alt="Buoyancy scuba skills practice" width="800" height="531" />

    A scuba diver practicing buoyancy in a pool - Credit: Royster

    3. Practice emergency skills

    Next, move to the more advanced skills, and consider repeating these from time to time, in-season.

    These include deploying an SMB, out-of-air scenario, and re-surfacing of an unconscious or injured diver.

    If you dive with doubles, also practice your basic shut-down drills.

    4. Work your communication skills

    Agree with your buddy that at some point during the dive, you both need to communicate something on the dive, preferably rather complex, to the other. Make it scenario based, and make sure you have a sign to communicate that this is in fact just a scenario.

    Bring two writing slates or wetnote books. You or your buddy then communicates a message to the other, who then writes down what he or she believes is communicated. Then you switch. Afterwards, you've compare notes and see how efficiently you've communicated the messages.

    Scuba skills underwater communication <img class="size-full wp-image-7256" src="//" alt="Scuba skills underwater communication " width="680" height="510" />

    Underwater communication using a slate - Credit: Globalreset

    All of these skills are of course necessary for all scuba divers.. So a beginning of season run-through is valuable, and elements of it should be repeated during the season, preferably on easy dives at well-known sites.

  • March 05, 2018 6:34 PM | Anonymous

         One of the most important piece of Safety Gear we can have is one we often don't even know how important it is to use.

         Surface Marker Buoys (SMB's) are an important piece of safety gear to have on every dive. All scuba agencies now require it to be carried in classes and many dive boats require it as well.

         But how much do you know about it and how much consideration did you put into buying yours? Surface Marker Buoys have been around for many decades and have been a part of every Technical Divers tool box. But, it's more then one other piece of gear to carry.

         Although one never hopes to lose the person carrying the flag, in reality sometimes it happens. As you learned in your Open Water Class, the rule is to search for one minute and then surface. But, what if the line snaps on the flag and it continues to drift away with the charter boat following it?

         This is where a SMB can be helpful to make you visible. Divers in the water are hard to see by boats. Since only your head is visible and waves can obscure visibility, a SMB can give you some height over the water.

         When picking a SMB to carry you need to consider the brighter the better and size does sometimes matter. In rough seas or bright days, a dive flag can be hard to see and can be lost in the waves. 

    Image result for dive flag in water

    But deploying a SMB to supplement the flag on the surface now creates a bigger object to see and you can wave it. 

    An SMB signal is handier than a DSMB

    Several divers deploying a few SMB's make a bigger target. How easy do you think it would be to see these several divers with their deployed SMB's? 

    Image result for dive smb

         In ending, SMB's can be used to make a dive boat captains job that much easier in rough seas and can be valuable when you lose the flag or the person holding it. I prefer a bright yellow because it sticks out but red and even pink are pretty bright too. I also prefer one that can be filled manually or by inserting a regulator to fill. This SMB can be inflated solidly and can be raised over the head without going limp. But like all other dive gear you need to look at the cost you are willing to pay, how you will attach it to keep it out of the way, and how big you are willing to carry.

    Safe Diving

    Thomas Stenger 

  • February 04, 2018 2:07 PM | Anonymous

    Hello Everyone,

    I have had a few people ask me about putting on a CPR/ First Aid class for the club. As you may know I am a current Dive Instructor as well as CPR/ First Aid Trainer.

    I wanted to get a feel for who may be interested. It was suggested that this could be done as a social event and that would be a great ideal.

    I could either host it at a site down on Ft Lauderdale Beach for a minimal cost (paid to the building) at the USCG Auxiliary building followed by dinner down there on Ft Lauderdale Beach. It can also be hosted by a club member, if someone would like to host it at their home (my condo is too small)?  Keep in mind that if we have a big turnout space may be tight. I teach at the USCG Auxiliary site and it can easily hold 50 people.

    Although this would be a full certification class, you will not be issued a card. If you would like a card their is a fees, I have to pay to the certifying agency and if you would like to pay that I will issue you the card. The card is not necessary, but many need it to meet certain work requirements (IE: OSHA Standards, Daycare Workers, Boat Captains, Active Divemasters, ETC. )

    The class would take about 4-5 hours (depending on how everyone is getting it) and would be scheduled on a Sun late Morning till the afternoon.

    This is a great skill to have for your everyday life. If you are interested please email me and let me know it you want the card as well.

    Thomas Stenger

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