If you’re a new diver, you probably have a lot of questions about the sport of SCUBA diving. Even experienced divers have questions about the latest gear or how to advance their diving education! We’ve compiled a list of questions – and their answers – that people tend to ask about SCUBA diving for your convenience. Do you have a question that isn’t listed here? Fill out the form below (please make sure to include your email address). Our dedicated staff of professionals will answer it for you via email – and you may even see it appear on this page!
When’s My VIP Due? At the beginning of the month stamped on the sticker or the end?
The industry standard, and in some cases, federal regulations, state than an annual inspection is required. Annual means ONE year. Therefore the sticker becomes invalid 365 days after application. If you know the exact day of the month that the sticker was applied, then that is the due date. However, we generally DO NOT know which day of the month the sticker was applied. Therefore, to be in compliance, you must accept the first day of the month as the expiration date, as the last day of the month would be some number of days in excess of 365.
— Bill High, PSI Cylinders
How to Use Less Air: Strategies, Tips, and One Opinion
More air means more dive time and more dive time means more fun. That alone is reason enough to practice these tips for getting the most out of every tank. But there are other reasons as well: a bigger safety reserve for emergencies and the priceless feeling of never having to cut a dive short because your tank is running low.
Repair leaking O-rings and fittings anywhere on your regulator and BC. Don’t forget gauge console swivels since a small stream of bubbles from a high pressure leak and is actually more air than you would imagine.
Overhaul your regulator regularly because when it is operating at peak efficiency, you waste less energy trying to suck air through it.
Make sure your octopus doesn’t free flow. You may elect to have your licensed regulator technician “de-tune” it a bit. And, be sure to secure it so that the mouthpiece is facing downward.
Streamline yourself and your gear. More drag moving through the water means more energy expended. Leave behind anything you are not going to use on the dive. Of the rest, put what you can in BC pockets instead of letting it dangle on D-rings. If it has to dangle, clip it close to your body. Stow your snorkel in a pocket or strap it to your leg with your knife.
We are taught to “breathe normally” under water but that advice is more aimed at getting you to relax and simplify the lesson at conserving air. In fact, the most efficient underwater breathing pattern is not “normal” at all.
Breathe deeply. A deeper breath brings air to more of the tiny “air sacs” (alveoli) in your lungs where gas exchange actually takes place. It also adds more fresh air to the volume of “dead air” that remains in your lungs, throat, and mouth from the previous breath, so the mix is richer. Although each breath uses more air, you will take fewer breaths and the net effect will be less air used.
TIP: Concentrate on a complete exhalation. This reduces the amount of “dead air” you re-breathe and keeps your level of carbon dioxide (CO2) lower. Higher CO2 will trigger the next breath even though your blood oxygen level is still adequate. On the other hand, a deep exhalation extends the time before you feel the need for another breath.
Breathe more slowly. As air passes from tank to lungs, turbulence is created at each narrow opening and corner turned. Turbulence restricts air flow. The work of breathing is obvious in the breathing resistance you feel from even the best of regulators. Some turbulence is unavoidable, but the amount of it goes up dramatically when you try to breathe quickly — just as a faster-moving boat creates a bigger wake. To minimize resistance, move the air slowly — suck the air in slowly, push the air out slowly.
TIP: Breathe slower at depth. Turbulence increases with depth because the air is denser. Concentrating on a slow breathing rate will pay even bigger dividends on deeper dives.
Pause after inhaling. Give those alveoli more time to work by holding that breath for a few seconds before exhaling. To avoid any risk of embolism, hold your breath by holding your lung expansion with your diaphragm. Do not close you epiglottis but keep your chest expanded and your airway open. On the surface, your normal breathing pattern is inhale-exhale-pause. Under water, a more efficient pattern is inhale-pause-exhale-pause-inhale-pause-exhale-pause . . .
TIP: Try yoga. Seriously! Yoga exercises teach awareness and control of your breathing pattern. Divers who practice yoga generally report their air consumption rate goes down.
Relax: Easier said than done. But when you are relaxed, you naturally breathe more slowly and deeply. On the other hand, rapid shallow breathing is your body’s natural response to anxiety. Anxiety occurs when physical and emotional stresses accumulate. In order to relax, you need to stop, identify what’s causing stress and deal with it.
Improve your aerobic conditioning. Better aerobic conditioning means you can do more work at a lower breathing rate. “Out of breath” is almost synonymous for “out of shape”. And it’s likely, though not proven, that a stronger cardiovascular system is more efficient at off-gassing nitrogen too.
Move slowly. This goes with breathing slowly. Water creates turbulence — friction — as it passes over your body. Turbulence goes up exponentially with speed, which means swimming twice as fast produces something like four times as much turbulence, which requires four times as much energy to overcome. Producing that energy uses four times as much air. All your movements, not just your swimming, should be slow and deliberate. Turn around slowly, reach to tighten your fin straps slowly. Do everything as if you were submerged in molasses.
Fin efficiently. Again, the goal is to minimize turbulence. Generally speaking, fairly short fin strokes, where the fins stay within the slipstream of your body, produce the most thrust with the least drag. Likewise, kick mostly from the hips, not the knees. “Propeller or split” fins generally call for a shorter, faster stroke than the more traditional paddle fins.
Don’t use your hands. Minimize the frontal area you push through the water by keeping your hands to your sides. An easy way to do this is to clasp your hands together. Try to achieve a posture as nearly horizontal as possible so your fins follow through the “hole” made in the water by your body. Don’t drag your tail (fins lower than your body).
TIP: While paddling with your hands wastes energy, pulling yourself across the bottom from rock to rock or along a rope saves energy. Likewise, when trying to maintain your position in surge or current, it saves energy to hold-on to a rock. Obviously, this is not acceptable with live coral as we are not to touch live coral.
Minimize your weight. Carrying extra weight required extra BC inflation to achieve neutral buoyancy. The air used to inflate the BC is probably insignificant but the extra drag caused by the larger, inflated BC is not. For the least effort in swimming, try to carry no more than the weight necessary to make you neutral at 15 feet with a nearly empty (buoyant) tank.
TIP: Take a class. Minimum weighting depends on precise buoyancy control. And that comes only with practice. But classes in weighting and buoyancy control are available and can greatly shorten your learning curve.
Stay warm. Wear enough exposure protection to stay warm. When you are chilled, your body burns energy (and uses air to do it) to generate heat. In a clam shell, fighting being cold wastes air.
TIP: Even 82° water is cool enough to chill you on repeated dives without exposure protection. You may not feel cold, but your body does lose heat and does use energy to replace it.
TIP: Wear a hood. Wearing a hood of any thickness allows you to use a thinner wetsuit because your head is a comparatively large source of heat loss.
Airing An Opinion (PUN)
Don’t you just hate that dreaded question: “How much air ya’ got left?” When another diver brags about having 200 psi more air than you at the end of the dive, chances are he’s really trying to say that he’s a better diver, more relaxed and in tune with the sea or something. He may be that — or he may simply be smaller — or have a different metabolism — or have followed a slightly shallower dive profile. Or he may be a she: most women use less air than most men. But because numbers are so easily compared, the amount of air you have left has become a convenient shorthand for how good a diver you are.
Convenient, but not very accurate. In fact, divers are not created equal and there is no ideal air consumption rate to which all divers should aspire. Sure, if you use 1,000 pounds more than your buddy in the same amount of time, you’ve got a problem which you should — and can — correct. But, a 200-300-pound difference is meaningless.
How to choose your regulator?
Not surprisingly divers tend to develop a special ‘feeling’ towards their regulators. A smooth, reliable air source can make you feel that breathing underwater is the most natural thing to do; conversely, a problem with your air source can transform your dive into a nightmare.
For the safety of all divers, international standards have defined strict performance parameters and all modern regulators are now conceived to guarantee you safe operation under all circumstances during recreative dives.
All divers know that a regulator is made of three parts: a first stage, a hose and a second stage.
The first stage of a regulator attaches to the tank and reduces the pressure of the air in the tank to ambient pressure plus a preset intermediate pressure. The inner mechanism of the first stage may be based on a piston or a diaphragm. The two technologies, despite all passionate dicussions between divers, are more or less equivalent. Perhaps the piston may present an advantage in cold waters, althogh in these cases it is always better to mount an anti-freeze kit on the first stage.
First stages are usually made of chrome plated brass; some producers have also introduced hi-tech metals like titanium that have higher corrosion and abrasion resistence but with higher costs. All first stages on the market are ‘balanced’. This means that they are disgned to maintain the intermediate pressure constant independently from depth and tank internal pressure. The hose connects the first stage to the second. The best ones have a larger internal diameter to allow a higher high flows. They also have special coatings and protections to increase their robustness.
The second stage is the piece of the regulator that has evolved most in the last years. Initially built with metal, now many producers prefer polymers that are both extremely rugged and lightweight. The aim of the second stage is to minimize breathing efforts and guarantee a smooth air flow in all conditions. To achieve this, second stages often offer external adjustments that can be made by the diver while diving to vary the performance of the regulator. The venturi assist is a two position adjustment that creates a venturi effect to optimize breathing performance and help prevent free flows at the surface. Another type of adjustment is the adjustable air flow knob or dial. This adjustment alters the flow rate to compensate for depth changes.
An important characteristic of a good regulator is a simple internal mechanism with few moving parts. This helps reduce internal wear, leading to more consistent performance between service intervals and lower maintenance costs. Finally, an advise to guarantee a long life and a consistent performance to your regulator: always clean it in fresh water after dive and have it serviced at least once a year by a specialised service centre.
Technological perfection coupled with perfect materials, titanium coating for absolute resistance, maximum performance even in extreme temperatures.
MR 22 Abyss is the top-performing regulator, the technical product embodying the latest underwater breathing innovations. Designed to meet the severe U.S. Navy specifications, it has proven it can substantially exceed them.
MR 22 First Stage
MR 22 diaphragm first stage featuring the DFC (Dinamic Flow Control) system and a replaceable HP seat connector. The high pressure poppet was designed for a “2 year or 200 dives” service interval; double the high pressure seat life standard!
Compact body, in a modern and smart style, it is made of hot-forged nickel-plated and chromed brass. It is fitted with a preferential intermediate pressure port for connection to the main second stage, plus 3 other LP ports and 2 HP ports. The latter are inclined at a 45º angle to allow a more rational layout of hoses.
Abyss second stage, with its V.A.D. system, is made of nickel- and chrome-plated brass.
This material offers a number of benefits:
- absolute ruggedness
- thinner walls, hence compact dimensions obtained without using smaller diameter diaphragms; this results in reduced water drag.
- anti-freeze function, which is enhanced by the “radiator action” of the metal.
Its streamlined shape optimizes the traditional profile that is now made efficient by the functional contour on the cover which were developed to make water inflow and outflow easier while breathing and swimming. The cover is made of technopolymer, a lightweight and impact-resistant material. The large manual purge button is placed in a central, perfectly ergonomic position. The mouthpiece is of soft hypoallergenic silicone: limiting jaw fatigue and offering a secure fit even after very long dives.
MR22 offers the unique Mares patented V.A.D. (Vortex Assisted Design) system.
This system allows smooth breathing at all depths and is unique.
Its operating principle is very simple. The air coming from the hose passes through the second stage valve and is conveyed directly to the mouthpiece through the by-pass tube. Within the mouthpiece, the air flow undergoes a “vortex” effect.
Whenever this swirl occurs, the core of the vortex creates a low pressure area. This low pressure helps keep the second stage diaphragm down while inhaling, thus increasing the regulator sensitivity.
The Minds and Bodies of Children -- are they really suited to scuba?
Make no mistake. More children at increasingly younger ages are going scuba diving.
Many diving parents want their children to experience the colors, creatures, calm and curiosity of the underwater world. And, the dive industry wants to expand the market. By marketing diving to families and certifying children, the entire industry — the training agencies, the manufacturers, dive stores, and dive travel — benefits economically.
With an eye toward promoting the sport, in 1999 the Recreational Scuba Training Council, a standard – setting body whose membership is composed of training agencies, eliminated its recommended age of 15 for junior certification. No longer fettered by minimum age limits, several major training agencies lowered the age for extended dive experiences and conditional certifications. For example, today PADI’s “Seal Team” and “Scuba Rangers” offer scuba experiences to children as young as age 8, and junior open water certification at age 10.
Despite the undeniable appeal of introducing youngsters to the underwater world and making scuba a family activity, several psychological and physiological reasons demand consideration in opening scuba to 8-year-olds.
To understand the psychological and physiological concerns requires recognizing the age variation at which children make the cognitive, behavioral and physical transition from one developmental stage to the next. In fact, this well-known variability itself forms a basis for questioning the policy of lowering ages.
Among cognitive concerns is the child’s ability to acquire and manipulate information. According to Jean Piaget’s widely influential system, three developmental periods are germane to child scuba divers.
The first, the Pre-Operational stage, begins about age 2 and extends to about age 7. In the later years, a child has an intuitive though rudimentary grasp of some logical concepts. A child’s perceptions still dominate his judgment. He will tend to focus attention on one aspect of an object while ignoring others. He is unable to understand the principles underlying proper behavior, relying on the do’s and don’ts imposed by authority.
While it is uncommon, some children 8 and older are delayed in the Pre-Operational stage and the dive agencies have no explicit criteria for screening them out. But, a late-developing child could forget to continue to exhale while making an emergency ascent or may not place anothers’ safety on par with his own. It is up to the instructor (who could himself be a teenager of 18) to recognize cognitive immaturity and refuse to teach the child.
During the next, or Concrete Operational stage (covering approximately age 7-11 years), logical thought develops. But it remains dependent upon concrete referents. While the child is developing the ability to appreciate concepts such as length, mass and volume, and to arrange objects in a logical sequence, it remains linked to objects present — not objects in the abstract. One can assume that the child at age 11 is much more capable than the child at age 8 in this stage.
The new policy for PADI, SSI and others clearly allows children in the Concrete Operational stage (7-11 years) to enroll in scuba programs. The risks are not inconsequential. For example, a child in this period may be able to understand basic scuba theories such as Boyle’s law and solve a few problems. However, he will be unable to hypothesize from such principles and extend them to a wider application — such as appreciating that an empty tank may allow for a few more breaths as one ascends. More worrisome, when faced with a scuba emergency, such as a BC inflator mechanism stuck in the open position, they will unlikely be able to generate multiple solutions to the situation. And, they would unlikely be able to select the best alternative: attempting to vent the BC continuously rather than disconnecting the inflator hose.
In the final stage of Formal Operations (covering approximately age 11-15 years), thought gradually becomes less tied to concrete reality and becomes more abstract. The ability to generate abstract propositions and multiple hypotheses and assess their possible outcomes becomes evident. This development allows individuals to think about what might be, rather than just what is. The levels of cognitive ability evident when a child completes this stage are those most appropriate to safe scuba.
Children are notorious for being exuberant, impulsive and feeling invincible. These are normal childhood traits that typically aren’t mastered until the mid to late teens, or even later. This has obvious implications for the appreciation and avoidance of risk — and the ability to act as a responsible dive buddy.
Patent foramen ovale (PFO): During fetal development, blood flows through a small opening between the right and left upper chambers of the heart. The lungs are inoperative and the mother oxygenates blood. At birth, however, this opening is supposed to close, shunting blood to the now-functioning lungs. While this “hole in the heart” usually seals by the third month of life, it does not always. Estimates of incomplete closures in older children and younger teens run higher than 50 percent in certain groups. Whatever the exact figures, the research suggests an increased incidence of PFO as age decreases below 20.
Without complete closure, blood can flow from the right to the left side of the heart without passing through the lungs. Increases in right chamber pressure that occur with common equalization techniques like the Valsalva maneuver — squeezing your nose, closing your mouth, and blowing — can move blood through the hole and bypass the lungs. When this happens, nitrogen bubbles that can form in the bloodstream may pass directly into the arteries and not be filtered by the lungs. This of course can lead to an embolism or DCS.
Possible retardation of bone growth: Long bones, like the humerus and femur, mature from growth plates, the active ends of bones where increases in length occur. The last of the growth plates generally do not cease activity until the late teens or early twenties. As these growth plates depend upon nearby blood vessels for oxygen and nutrition, physicians have long been concerned that nitrogen bubbles in the bloodstream may result in damage to these critical tissues. In addition, the development of bone and connective tissue involves molecular oxygen, raising the possible adverse effects of the elevation of oxygen partial pressures occurring during diving.
Heat regulation: Due to a relatively large skin mass to body mass ratio, children do not regulate body heat as well as adults. Until the mid-teens or so, youth are far more vulnerable to hypothermia. And, alarmingly, a child may be hypothermic yet have no complaints, and still feel warm to the touch.
Eustachian tube development: In younger children, the Eustachian tube is narrower and more horizontal than later in development. While this is unlikely to be problematic in children over age 12, it has implications for equalizing, including potentially damaging reverse squeeze, for children closer to age 8. Furthermore, young divers with immature Eustachian tubes may be subject to more frequent middle ear infections. Since a diver must be able to clear his ears safely and comfortably, a person with a middle ear infection should not dive. So, a child must recognize it, tell someone, and not dive.
The Response of the Dive Training Community
The positions of several agencies are based on conclusions expressed by John Kinsella, Director, Training and Quality Management of PADI America, in his article entitled “Kids and Diving” (The PADI Undersea Journal — First Quarter, 2001). After reviewing the evidence for potential medical concerns expressed by DAN, he concluded: “There is insufficient information available to make any evidence-based medical judgment for or against children in scuba diving.”
SSI allows children as young as age 8 to have a shallow water scuba experience in their “Scuba Rangers” program. Children 10 to 12 may receive a junior open water certification with certain limitations. Once they turn 12, they may upgrade to a regular open water diver. Those 12 and older are eligible to become a Nitrox specialty diver.
When we asked Dennis M. Pulley, SSI Director of Training, about their program, he told us that “SSI is aware of medical and psychological concerns in divers as young as 12.” However, he cited the RSTC position that medical experts are unable to provide any documentation or proof why an individual must be at least 12 years of age to begin scuba training. Pulley also remarked that, “Psychologically, one could argue that many young males between the ages of 16 and 30 could have the same attitude of being invincible.”
It is true that many theoretical medical and behavioral concerns have not been subjected to controlled studies on humans. And may never. The ethical issues are obvious. For those issues that may be studied, it will be a long and painstaking process, as evidenced by how difficult gathering useful data on DCS has been.
It seems, then, to drop the training age with no longitudinal, hard data about the effect on children is questionable at best. Historically, the response of training agencies to incomplete knowledge has been to err on the side of safety. Think about how the agencies have treated dive tables for all gases, how they fought against Nitrox because it was unsafe and unstudied, how conservative they have been on dive-to-fly estimations, depth limits, and clearance to dive for medical disorders that may pose a risk to scuba divers. Yet the leadership in this conservative industry has taken a “relaxed” attitude regarding the diving safety of children.
However, while there may be no formal studies of the effect of diving on children, PADI and European-based CMAS have long offered swimming pool scuba to children as young as age 4, and restricted open water certification for those to age 8. To date, the results cause no alarm. Even allowing for the extent to which good PR may influence disclosure of adverse events, if children were sustaining harm in significant numbers, liability issues would presumably force this information into the open.
To their credit, PADI and SSI have taken sensible steps to address medical and developmental concerns. For example, the Seal Team, Bubblemaker and Scuba Rangers programs are restricted to a pool or pool-like environment. Both agencies require that certified divers ages 10-11 be accompanied by a certified parent, legal guardian, or professional dive leader, and limit maximum depth to 40 feet. We should note, however, that while these depth limits do control the partial pressures of nitrogen and oxygen, an embolism can occur in as little as four feet of water. PADI has taken special educational efforts to alert instructors to the safety issues. And while current instructors haven’t been trained to certify children but still can, future instructors will find extensive material incorporated into upcoming revised Instructor Development Courses.
Nonetheless, not all agencies have been willing to embrace scuba experiences for kids. Neither NAUI nor the YMCA — both nonprofit organizations in contrast with PADI and SSI — offer scuba programs for children less than 12 years of age. Frank Toal, of the NAUI training office, told Undercurrent that the agency found the medical and developmental concerns sufficiently compelling to preclude consideration of scuba for those less than age 12. Additionally, NAUI’s junior scuba certification, for ages 12-14, imposes a 60-foot maximum depth limit and requires supervision by a certified diver age 18 or older.
Such reservations are not limited to these two training agencies and many experts have been outspoken in their opposition (see sidebar). World-recognized dive medicine expert Dr. Ernest Campbell has expressed misgivings about allowing his children to be certified at a young age, and said that he probably would have waited until their midteens if he had it to do again.
So, what’s a parent to do?
Admittedly the issues are complex. Yet it is clear, children face greater risks than adults. Parents or guardians must be thorough and responsible when considering whether to enroll in a PADI or SSI program.
Any child being considered for a compressed air at depth experience or scuba certification should receive a pediatric examination with the expressed purpose of clearance for diving. The child’s psychological maturity for diving should be evaluated through open and honest discussions between the child, parent or guardian, and a knowledgeable instructor. If any party has substantial reservations, wait until these resolve. Under no circumstances should an unwilling child be coerced into scuba. If all signs are go, make sure the youngster has gear he or she can manage, wears adequate thermal protection, and is enrolled in a class of similar aged children. Finally, for those children receiving certifications with restrictions, ensure that all conditions are scrupulously observed. Attend the classes with your child and if you have any doubts about the child, the instructor, or the class, work them out or consider other classes later.
Buoyancy Compensator User’s Guide
Buoyancy compensators are constructed from rugged materials with unique features adaptable to advanced underwater environments. The general design philosophy allows for complete system integration of a number of components achieving high lift capacities, low drag, and increased safety through redundancy.
Independent Harnesses & Bladders/Wings:
With a selection of different harnesses, different air cells and accessories, a diver can configure his or her system for the specific environment they are operating in. This equipment is intended for use by individuals with the training and experience to dive these environments safely.
General Precautions & Warning:
- Before using a buoyancy compensator BC, you must receive instruction and certification in SCUBA diving and buoyancy control from a recognized agency. Use of SCUBA equipment by uncertified or untrained persons is dangerous and can result in injury or death.
- Prior to each dive, perform a complete pre-dive inspection according to the procedure taught by your Instructor, to ensure that all components are functioning correctly and no signs of damage or leaks are present. If you find that your BC is not functioning correctly or is damaged, remove it from service until a qualified technician can repair it.
- Become familiar with your new BC in a controlled environment first, such as a swimming pool, in order to weight yourself properly and to become comfortable with using its many features and adjustments.
- Your BC is NOT a lift bag, and should not be used to bring heavy objects to the surface. Doing so may cause permanent damage to the BC, and could also result in injury or death due to embolism or decompression sickness.
- In an emergency such as an out of air situation or uncontrolled descent, it is important to remove and jettison
If something goes wrong with my equipment during a dive trip, what should I do?
Unfortunately, equipment malfunctions do happen, and if you’re unprepared, a malfunction could mean the end of your diving day or even your whole trip. Luckily, there are a few simple items that you can bring on every dive trip to ensure your diving day doesn’t have to end with a broken zip tie or similar malfunction. Together, these items make up a “Save-A-Dive Kit”.
What should I include in my save a dive kit?
We’ve compiled a list of the most useful items to include in a Save-A-Dive Kit. These items can be placed in a plastic box (like a first-aid kit, or one that is water tight) and can be easily taken with you to any dive site.
- Dry Box
- Fin Strap(s)
- Mask Strap
- Snorkel Keeper
- O-rings (especially 003, 012, 013, 014, 112, 113, 114)
- O-ring Brass Pick
- Silicone Grease
- O2 Clean Lubricant (Crysta-Lube)
- Neoprene Patch
- Aquaseal or Goop Glue
- L.P. Port Plug
- H.P. Port Plug
- Quick Clip 1.5″ / 2″
- Wrenches (thin) 9/16, 5/8, 11/16, 1/2
- Allen Keys (2)port plugs, (3)spincerts
- Screwdrivers and jeweler’s set
- Pliers / Wire cutters
- Air blower
- XS Scuba Multi-tool (8 tools in 1)
- Zip ties (10+)
- Zip tie cutting tool (nail clippers may work)
- Webbing Retainer
- Rescue Tape TM
- Computer Batteries and Gasket
- Owner’s manuals
- Lens Cleaning fluid & lint free cloth
- Rubbing Alcohol
- Wet/Dry Sandpaper
- Pencil Eraser
- Torch Batteries
- Screws, Nuts, Wingnuts
- Electrical Adapter
- Duct Tape or Electrical tape
- Cotton Swabs
- Small Brush / Toothbrush
How Fit Do You Need To Be For Scuba Diving? - By Monika Kay
How Fit Do You Need To Be For Scuba Diving? – By Monika Kay
One of the great things about scuba diving is that it offers a fantastic opportunity to interact with the natural environment while engaging in quality family time! It is an activity that is suitable for people of all ages and athletic abilities which makes it a great family activity. However, even although the effect of weightlessness that being under water creates, scuba diving does require some degree of strength and stamina. With that in mind, let’s take a look at some of the health and fitness requirements that you should consider if you would like to take up scuba diving.
Are You Fit Enough?
One of the most important things to realise about scuba diving is that the conditions can be unpredictable. That means that from time to time you may need to perform a strenuous task with little notice if any unexpected situation arises. You may also need to swim against the current or for an extended period of time in order to reach your dive site or return to the surface. All of this means that you will need to have a reasonable standard of fitness and mobility in order to cope with the demands that scuba diving will put on your body. This is why you must disclose any illness or injuries when you are learning.
Conditions That Restrict Your Ability to Dive
There are a number of medical conditions and/or illnesses which can mean that you will be unable to participate in scuba diving temporarily. These include colds, flu, joint/muscle injuries and also pregnancy. In the case of colds and flu, these illnesses can result in swelling and blockages in the sinuses and airways which could make it difficult for your body to equalize with the water pressure during a dive. Similarly, joint and muscle injuries can not only restrict your range of motion in the water, but also can cause an increased risk of decompression illness, so it is best to wait until such injuries are fully healed before participating.
In terms of pregnancy, the main issue is that there is no data regarding the effects that scuba diving could have on an unborn child, therefore this kind of sport is not recommended during pregnancy and a responsible dive tour company will not allow pregnant women to participate.
Enjoying Your Experience
With all of the above, you may be a little put off of trying scuba diving! However, as long as you are in good health and moderately fit you can enjoy this activity. Even if you do have a long term health condition, it does not necessarily mean that you cannot participate, it may be the case that you simply need consent from your physician. It is also best to make your instructor or dive leader aware of any conditions that you have so that they can be prepared. Even if you have restricted mobility you could still participate in scuba diving by joining shallower dives and those accessed from shore.
Assembling Double Cylinders
1. Disassemble the manifold into its three primary components (outboard K-valves and center isolator or cross bar). Lubricate all exposed threads and o-rings with the appropriate grease (O2-compatible for components that will, at any time, be exposed to gas mixtures with FO2s of greater than 40%). Make certain the isolator lock nuts are tight against the center of the isolator of cross bar body.
2. Install one outboard K-valve into each cylinder.
3. Place the cylinders on table or flat surface upon which you will be working, parallel to one another.
4. Carefully orient the center isolator or cross bar so that its threads correctly match those of the outboard K-valves (this is important; serious manifold damage may result otherwise). The notched lock nut (indicating threads that turn opposite the normal direction) goes on the side of the manifold which will be on the diver’s left when facing the valves.
5. Slowly turn the isolator or cross bar in the direction that will cause it to thread itself into both K-valves simultaneously. This is very important: If one side does not engage you must back the isolator or cross bar all the way out and begin again. Be patient. This may take more than one try.
6. When the isolator or cross bar threads engage properly, turning this center unit will draw the tops of the cylinders together. To keep the cylinders parallel to one another as this happens, stop periodically to gently tap the bottom of the cylinders together. You can tell when to do so because the isolator or cross bar will become difficult to turn when the cylinders are no longer in proper alignment. (This also helps explain why it is important you avoid using wrenches for this step and turn the isolator or cross bar only by hand; any resistance you feel will tell you something is wrong.)
7. Repeat step 6 as often as necessary until you reach a point where no more than 1/8-inch/3mm of threads shows on each side of the center section.
8. Make certain the isolator knob is positioned at the desired angle. (Again, if necessary, it is permissible to have as much as 1/8-inch/3mm worth of thread showing on each side of the isolator section; this may be necessary to ensure adequate clearance between tanks for the bolts.)
9. Turn the center unit lock nuts so that they rest snugly against the outboard K-valves. Lock them in place with the 22mm wrench. Do so gently; these components are brass and easily damaged by unnecessary force.
Now you are ready to install the tank bands and bolts.
10. Remote all the nuts and washers from the all-thread shafts (headless bolts) — except the aircraft nut (the nut with the nylon insert).
11. On the end of each shaft, opposite the aircraft nut, install a wing nut (turned upside down) followed by a regular nut. Lock these nuts against one another. This will enable you to hold the shaft without damaging any threads.
12. Place a 1/2-inch box-end wrench (or a 1/2-inch deep socket wrench) on the aircraft nut and another 1/2-inch wrench on the regular nut. Turn the aircraft nut until it is positioned so that approximately 1/8-inch inch of shaft protrudes from its top. Unlock the regular nut from the wing nut and take them both off the shaft.
13. Pull the cylinders to the edge of the table. Let the cylinders extend beyond the edge so that the portion where the upper band will go will be exposed. make sure the valve orifices face upward.
14. Place the top band right at, or just below, the shoulder of each cylinder (the shoulder is where the side of the cylinder begins to turn toward the valve).
15. Place a flat washer on the end of the shaft with the aircraft nut. Push the shaft up through the band’s bolt hole from below. On the other end of the shaft, place a flat washer, followed by the lock washer and regular nut. Put one 1/2-inch wrench on the aircraft nut; the other on the regular nut. tighten the regular nut until the band is moderately snug.
16. Turn the cylinders around so their bottom ends will be exposed. Position the bottom band so that the bolts will be spaced 11 inches apart, when measure center to center. (A back plate makes a good measuring device.) Repeat step 16 to install the bolt in the lower band.
17. Examine the entire assembly. Th bolts should not extend past the outside edges of the bands. If the cylinders are parallel to one another or reasonably close, and able to lie flat, finish tightening the nuts. this lat step should cause the cylinders to be parallel to one another if they were slightly splayed.
Commonly used Abreviations in Technical Diving
DIN – Deutsches Institu Fur Normung, German Industrial Standard, Used to describe the threaded captured O-Ring design of valves and 1st stage regulators that work at higher pressures
DPV – Drive Propulsion Vehicle, scooter
EAD – Equivalent Air Depth, If diving Nitrox, the adjusted calculated depth that accounts for the reduction in Nitrogen replaced by O2 in breathing gas, reducing the Nitrogen intake
EAN – Enriched Air Nitrox
EANx – Enriched Air Nitrox
END – Equivalent Narcotic Depth, Equivalent N2 Depth, adjusted calculated depth that account for the reduction in Nitrogen that’s replaced by Helium thereby reducing the narcosis level
EPIRB – Emergency Positioning Indicator Radio Beacon, compact automatic radio beacon
FFW – Feet of Fresh Water, depth measurement
Fg – Fraction of Gas
FN2 – Fraction of Nitrogen
FO2 – Fraction of Oxygen
FSW – Fee of Sea Water, depth measurement
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