Buoyancy and trim Newsletter September 1997
What's in a Card?
Carbon dioxide and the diver Newsletter March 1998
Dangerous Diving Newsletter May 1998
What's up with that guy? Newsletter October 1998
Not Just Your Ordinary Dive Published May 1999 Extremz Magazine
They're Ba a a ck ! ! Rebreather article Newsletter July 2000
Solo Diving and the Recreational Diver .........Part 1 pdf format June 2001
Solo Diving and the Recreational Diver .........Part 2 pdf format June 2001
SOme of the articles are in the Adobe Acrobat format. If you do not have Adobe Reader you can download it for free at http://www.adobe.com/products/acrobat/readstep2.html
This month I would like to cover a subject with which most divers are not very familiar: the interrelationships between air consumption, buoyancy and trim.
Most divers are aware of buoyancy control, even if they are not very proficient at it. Buoyancy is that magic trick of staying in the water column at any depth without moving your hands or fins. Good buoyancy techniques take knowledge of the physics involved and time to put this knowledge into practice. The practice time is bottom time, and there is no substitution.
Most divers expend large amounts of energy trying to stay "neutral" without actually being neutral. If they stop kicking and flailing about, they sink or start to rise. The net result, of course, is that all that exercise consumes air and shortens bottom time. While proper weighting is very important, it is not the most important consideration. A technical diver generally dives with far too much weight due to the amount of gear he carries on a dive. Yet, most of them can outdive the average diver by a factor of two or more. Why is this?
Trim, the ability to stay horizontal in the water, is by far one of the most important considerations as far as air consumption is concerned. Except on drift dives, you must propel yourself through the water. To do this efficiently, you must present the lowest possible profile in the direction you are moving through the water. If you stop kicking and you find that your legs sink, making you vertical in the water, you need to work on trim. How do you accomplish this?
The easiest way is to contact us at Airheads for a one on one buoyancy and trim workshop. For a small fee you will get the personal attention of a technical instructor or dive master for two dives. He or she will dive with you and make suggestions on how you can improve your diving through changes in gear configuration, weighting techniques, etc. Then you will be able to put into practice some of the tricks of the trade that you will not find in any book.
The rewards will be evident to you immediately. By moving efficiently through the water you use less energy. Your bottom time will automatically increase, allowing you to join the ranks of the first in and the last out. Remember: you don't get seasick down under!!
IDEA Instructor # 2454
NAUI Instructor # 19500
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I get to the dive site and need to show a certification card to the owner. I pull out my dive binder and rummage through my cards. They all fall out in a heap.
I reach to pick them up, and my mind doesnt really register as I read the different certifications: Openwater, Fish I. D., O2, Master Diver, Nitrox ... I remember a joke I have often heard: The more cards you have, the more important you are. But thats not really the reason all these cards with my name on them are staring at me.
I recall how exciting it was when I was first certified nine years ago (a different life before diving). Our openwater certification dives were, to say the least, not something to write home about. However, we perservered, sure that diving had to be more than murky water and holding hands to maintain contact with your dive buddy.
Spurred on by our instructor and a good dive staff, we immediately signed up for the next class (currently called Advanced). Our first real dive experience was in Greece a few weeks later. That was what diving was all about!
On our return we decided to take still more classes. We had always been people who wanted to be as knowledgeable as possible about anything we do. When this knowledge translated into making us safer and more competent at a potentially dangerous sport, it seemed to us common sense to continue our education.
So it was that we received our Rescue, First Aid/CPR, and Master Diver certification in the spring of the following year. In the space of nine months time, we had taken five dive classes. We were at the dive shop more often than we were at home!
Since that time, Dale and I have taken many other classes. Some of them pertained to specific interests, such as our Fish I.D. certification. This class was not only interesting but has contributed a lot to our diving since that time. Theres something special about being able to give a name to the critters who are sharing their home with you!
Other classes simply added to our knowledge of diving and have made us the safest divers we can be. I shiver to think of all the things we would have had to learn the hard way if we had not had all this education. I am also not ashamed to admit that I have picked the brains of more experienced divers often during my years as a diver. Why not learn from others with experience? I have not yet met a veteran diver who was unwilling to help a more novice diver learn a new skill and in so doing gain some self-confidence.
So the next time you see a diver with a whole pile of certification cards, dont be disparaging of him. Hes not just trying to show the world hes important by flashing a bunch of cards around. He is a diver who is honestly committed to learning the most he can about a sport that he obviously loves.
NSS-CDS Full Cave Diver, Master Diver, etc. etc.......
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CARBON DIOXIDE AND ITS EFFECTS ON DIVING
Have you ever developed a headache while diving? Have you ever felt you could not get enough air to breathe? Do you plan on making dives deeper than 60 fsw, or would you like to take a course in Nitrox? Have you ever been narced? These are just some of the reasons you should be aware of CO2 and its effects on you.
Carbon dioxide (CO2) is colorless and tasteless in low concentrations. It is an oxidative byproduct of metabolism. Basically, our bodies create energy by burning fuel with oxygen, and carbon dioxide is a byproduct of that process. Acute exposures to higher concentrations of CO2 can produce effects ranging from almost imperceptible increases in ventilatory rates to loss of consciousness and death. An increased level of CO2 in our system, (measured as an increase in the pressure of the dissolved gas in our blood stream or PCO2), is known as HYPERCAPNIA. Some of the symptoms of hypercapnia are restlessness, dizziness, weakness, confusion, throbbing frontal or bitemporal headache, nausea, or a feeling of breathlessness or suffocation.
Not everyone has the same tolerance to a higher PCO2, and we can even train ourselves to tolerate higher levels. Divers who can tolerate a higher PCO2 are known as CO2 retainers and are at a greater risk for the problems listed below than non-retainers. A retainer is less sensitive to the ventilatory (breathing) urge than a non retainer. Retainers could find themselves in a situation in which their bodies cannot adequately eliminate the extra CO2 generated during moderate exercise!
There are several factors that contribute to higher levels of PCO2 in the diving population in general. Some of these are:
1) Snorkels and regulators add dead space to the breathing circuit. Normal dead space consists of mouth / nasal passages, pharynx, trachea, and larger bronchi, (the area of the breathing circuit not directly involved in gas exchange). By adding more dead space we increase the amount of recirculated air.
2) All regulators offer some resistance to breathing, which increases the effort required to breathe.
3) When the diver's head is higher than the lungs and diaphragm, there is a hydrostatic pressure differential established which increases the effort needed to breathe.
4) As depth increases, the density of the gas increases. The increased density makes it much more difficult to move the air in and out of our lungs. In fact at just 100 fsw our MVV, Maximum ventilatory volume, is down 50%. MVV is the maximum volume of air we can breathe by voluntary effort. Our dead space is increased significantly at depth.
5) Wetsuits, BC's and other gear restrict the movement of our chests making it more difficult to breathe.
6) Some divers "train" themselves to tolerate a higher PCO2 in order to stretch their air and stay down longer.
A higher level of CO2 in the blood stream is a contributory factor in many different dive maladies of which the following are a few:
Nitrogen narcosis - On making a swimming descent and not breathing properly you will raise you PCO2. This can bring on nitrogen narcosis at much shallower depth and its effects will be worse than if you took your time and breathed properly.
Decompression sickness, (bends) - a higher PCO2 has been implicated as a risk factor for DCS. It appears that the CO2 molecules will readily bind with nitrogen bubbles often increasing their size to critical values.
CNS O2 toxicity - Using nitrox, hypercapnic divers are at a greater risk of developing a CNS O2 toxicity hit. It has been shown that the body is much less tolerant of oxygen with an elevated carbon dioxide level. Remember that a central nervous system oxygen hit which results in a seizure is usually fatal to a submerged diver and the symptoms are not reliable indicators of an impending seizure.
Depth blackout - diving deep on air can be hazardous to your health - On deep air dives over the recommended 130 fsw limit for divers a CO2 retainer can put himself / herself at risk for CO2 blackout. Any time consciousness is lost under water death usually follows.
A well trained diver aware of the subtlety of hypercapnia can anticipate and avoid some of the more severe manifestations brought on by higher PCO2's. Come join us in one of our advanced training programs here at AIRHEADS to learn more about this subject as well as many others. Remember your open water certification is your license to learn. Safe and enjoyable diving from all of us.Top of Page
Since the summer of 1990 I have been a scuba diver, and I love the sport. As you can imagine, during the past eight years I have heard many conversations regarding diving. Often these conversations revolve around what people consider "dangerous divers". Because this definition varies from person to person, I usually try to avoid lengthy discussions on the subject because they always seem to turn into arguments. However, a recent comment made by one of the dive professionals in our area regarding "unsafe divers" made me stop and reflect.
Just what is dangerous diving? Ask a newly-certified openwater diver what it is, and he or she may tell you that it is dangerous to dive below 60 feet. Ask a more experienced diver, and he or she is liable to respond, "Wreck diving" or "Cave diving" or something of the sort. The only thing that most divers are in agreement on is that solo diving in its literal sense is inherently dangerous.
I can relate to all of these fears because I've thought many of these things myself during my years as a diver. As you progress through different levels of training, though, you find that what you consider to be risky changes. For instance, diving below 60 feet at first sounded scary. However, after taking the Advanced Diving course, I made dives below this depth. While some of the rules change at these depths, it is still a safe area to dive -- WITH THE PROPER TRAINING. Obtaining more knowledge before I made these deeper dives gave me more confidence. Consequently, I was able to dive safely.
Because I want to be a safe and self-reliant diver, I dive as often as possible. Experience is one of the best ways to improve your abilities and self-confidence. I also continue to read and take classes to further my education.
It's a never-ending cycle. Dive -- gain some experience -- take more training -- become a safer, more confident diver. Dive more -- gain more experience ... You get the idea.
Contrary to what seems to be the popular belief, no one at Airheads Scuba condones solo diving. Going to a dive site alone and getting in the water is not challenging: it's stupid. On the other hand, we do try to teach our students to be as self-sufficient as possible. It is not always practical or possible for our buddies to extricate us from every problem. Learning to rely on yourself and your own equipment is the best means to assure that you make consistently safe dives.
I cannot count the number of times I have seen divers panic because they have lost sight of their dive buddy. This kind of overdependency on another person does not make you a safer diver; worse, it contributes to negligence among many divers. Because they have a buddy to help them, they are often less diligent in their gear maintenance, equipment preparation, and dive planning. This can be very dangerous.
Continuing education gives both you and your dive buddy more confidence in your abilities and allows both of you to be better, more reliable partners -- even if bad visibility causes you to lose sight of each other momentarily. Good divers will not panic in this situation but will instead search for each other for a pre-determined interval and then follow their pre-established dive plan should they not be able to locate each other.
Having recently gone through instruction in Cavern and Basic Cave diving, my idea of dangerous has changed again. I can honestly say that this type of diving is much safer than I had believed, and I have a lot of respect for these guys. Not only do they wear enough redundant equipment to eliminate the risk of danger from equipment failure, they are also drilled in numerous emergency scenarios to assure that both they and their dive buddy will be able to make a safe return to the surface. If anything, the use of redundant equipment and the safety rules cave divers follow (air usage, etc.) make this type of diving safer than openwater diving. (This is quite a statement coming from someone who used to say I couldn't be dragged kicking and screaming into an underwater cave!)
We understand that advanced diving such as deep diving, wreck diving, and cave diving is not for everyone. That's perfectly acceptable. This is a big world with lots of water and all sorts of possible diving from which to choose. You have to decide what's right for you. ALL WE ADVISE IS THAT YOU HAVE THE RIGHT EQUIPMENT AND OBTAIN THE PROPER TRAINING FOR THE TYPE OF DIVING YOU INTEND TO DO. If you do this, you won't be doing any "dangerous diving".
The next time you hear someone say, "Those guys are dangerous!", consider this: Most openwater divers have one regulator first stage, one tank, and usually no lights. Many of them have had no training beyond basic openwater class. Who do you want for a dive buddy?
NAUI Master Diver
NSS-CDS Basic Cave DiverTop of Page
WHAT'S UP WITH THAT GUY ?
Have you ever been to a dive site and seen someone who makes everything look so easy that you're jealous? Have you every wondered why that guy uses one tank of air all day when you can't make yours last thirty minutes? If this sounds familiar, you've probably seen someone who's had dive training beyond just openwater class.
There are many reasons to get training after your openwater class. Some of these concern safety while others relate to things such as self-confidence, access to different types of diving, and obtaining a leadership role in diving.
The dives you did for openwater certification were the minimum requirements necessary for you to be able to dive. Technically, your openwater certification only allows you to dive to a maximum depth of 60 feet in the environment in which you were trained. Think about that for a minute. If you only made dives in the local quarry, you have not been trained for ocean diving. Further, any dives over 60 feet are beyond the scope of your training. In essence, you openwater certification is like completing elementary school. You have learned the basics, but there is much more to learn to refine your skills and knowledge.
What if you want to dives at different sites and at deeper depths? Before you make that dive to 120 feet, ask yourself:
Do I have the knowledge and equipment to make this dive safely? Do I fully comprehend what is required for this dive?
If you cannot answer with an unequivocal "yes", you should consider getting more training. Just because good ol' Bob never had training past openwater and he has survived deep dives is not a reason to follow in his footsteps. Bob may have been extremely lucky.
Did you know that without advanced certification some of the dive sites are actually off limits? Check with someone who has tried to dive the Bibb in the Florida Keys. This restriction is placed on divers because the boat captains and dive resorts know that deep dives require extra training an experience.
Each level of training which you undergo makes you more self-confident. By rehearsing various "what if?" scenarios in classes, you learn how to handle problems which can occur while diving. In learning how to cope with these situations you become a safer, more self-sufficient diver. Also, by learning how to better plan your dives, you lesson the risk of problems occurring because you are probably prepared for the dive you are making.
Another benefit of further training is that you become a better dive buddy. Not only are you less reliant on your partner, but you are also more attentive to any potential problems your dive buddy may encounter. Then, as a team, you can resolve them before they become serious.
Many divers make only a few dives per year, thereby leaving themselves open to unnecessary risk due to less familiarity with their gear, reduced physical fitness for diving, and more stress trying to re-learn their diving skills. The majority of dive accidents is attributed to panic, a sign of inexperience or lack of training for the conditions in which they found themselves. By participating in further training you decrease your risk of injury or death by honing your skills, increasing your diving fitness, and lessening stress because you are more comfortable in the water.
You do not have to gain knowledge by trial and error. Learning from your mistakes instead of drawing on the knowledge available to you from your instructors is both time-consuming and potentially risky. It is much better to make 100 dives which are enjoyable and rewarding because you are mentally prepared and trained for them than it is to make the same 100 dives stressfully without any training, learning from your mistakes what not to do.
Another reason to take classes is simply to increase your diving pleasure by giving you more information about specific areas of interest to you. Dive photography and fish identification are just two examples .
Master Diver, Full Cave DiverTop of Page
NOT JUST YOUR ORDINARY DIVE
It looked like it was going to be a nice day. It was only about 8:00 in the morning, and there were no clouds in the sky. The temperature was in the low 80's already. Maybe it would be in the 90's soon. I'd have to keep that thought in mind during gear setup. You never want to get overheated before a long dive.
Today's dive would not be particularly demanding by cave diving standards. It would be deep, however, with the majority of the dive being around 120 feet. This meant we would have to do a moderate amount of decompression at the end of the dive. (Decompression means not being able to surface immediately following the dive but instead having to remain at a shallow depth for a predetermined amount of time.) This allows the nitrogen absorbed in our bodies to be released safely without causing decompression sickness (more commonly referred to as the bends).
While carrying my deco gas and stage bottle to the water, I couldn't help but wonder about the 28 people who were known to have died in this particular cave over the years. Was I as crazy as others believed I was for participating in this sport?
My thoughts turned to the rigorous training I had undergone to achieve certification in cave diving. I had done hundreds of dives before I felt competent enough to consider taking classes in this riskier type of diving. While reading the course material prior to enrolling in class, I remember wondering why any sane person would want to engage in such a hazardous activity. Then several times during the practical section of the class these doubts were further amplified.
My partner and I had practiced for months diving in double tanks and using the skills we knew would be required for class. We thought we were more than ready for anything the instructor might throw at us. Wrong!! No amount of practice in open water can adequately prepare a person psychologically for the actual cave environment.
Nothing is more humbling than an underwater cave. Knowing that improper kicking or erratic movements can cause silting which will totally destroy your visibility, you are in a constant state of anxiety until you master proper buoyancy control. And if you don't perform the skills adequately, the instructor will drill you over and over and over .... until you get it right or you decide that cave diving is not your forte! Even during training it is possible to reach penetrations of over 2,000 feet. In the back of your mind you are always contemplating how you will get back out if you have an equipment failure. This is why during the class redundancy and rescue techniques are hammered into you. You and your partner(s) must be able to handle any emergency which occurs, or someone will not come out of the cave alive. This is a very sobering thought and one which not all divers are able to handle. Cave diving is not for everyone.
During class we learned that there have been about 400 fatalities in caves in Florida in the last thirty years. Of these 400, however, only about 30 were actually properly trained in the methods of safe cave diving. Unfortunately, these statistics do not hinder many divers. I cannot count the number of times I have run across openwater divers (in openwater dive gear, of course) either exiting a cave I am preparing to dive or actually inside a cave after our team enters. A well-known expert in cave diving has stated that cave diving presents a deceptively easy way to die. How true that is without proper training!
The number one rule for cave diving is proper training. Without it even the most experienced openwater diver (or instructor) is asking for problems (potentially life-threatening ones). The second rule is that you must maintain a continuous guideline to the surface. You must be able to get out of the cave in zero visibility. The third rule is to properly manage your air supply to allow for emergency scenarios. The fourth rule of cave diving is to not exceed the depth for which you have received training. The last major rule is to carry adequate lighting (a minimum of three lights per diver). The trained cave divers who have died while diving have all broken one of these cardinal rules.
So why was I standing here about to enter this alien world again? Why does man have a desire to go to the moon? Why do people hang glide? Why parachute out of a plane that is working perfectly? There are as many reasons for these sports as there are participants.
For me cave diving offers rewards which exceed the risks involved. Some of these rewards include the solitude inside the caves, the absolute beauty of what nature can create, the glimpse into the past in areas which contain fossils, the chance to test your own abilities. Other benefits of cave diving are constantly calm seas, no overcrowded dive boats, normally good visibility, and divers of relatively the same experience level. In a real jam you can feel confident in receiving help from any other cave diver you encounter.
Back to my upcoming dive. We're all geared up. We have entered the water and performed our pre-dive safety checks. Laying out our primary line, we start into the cave. Once again, we find that an openwater diver has been there before us. The visibility is almost zero at the entrance. Pushing through this annoying area, we find ourselves in the beginning of the system. For the first 300 or so feet it resembles a subway tunnel. The visibility remains low, and I wonder again why openwater divers are even allowed access to this area.
Reaching the gate which bars access deeper into the cave, we re-check our gauges and air supply. Even now the dive can be cancelled for any reason by any team member. I notice as I fumble with the lock that nitrogen narcosis is indeed a factor with which we must contend at this depth. We pass through the gate and make our final tie-off to the permanent line in the cave. We exchange OK signals and continue the dive. Finally the visibility has increased to the point where we can see as far as our lights will penetrate.
As we pass under the first low restriction, we find ourselves in a room which appears to be at least 40 feet across and about 5 feet in height from floor to ceiling. Due to the clarity of the water, it takes on a blue-green glow as the red, orange and yellow wavelengths of our lights are absorbed by the water. The floor has changed from loose sand to a clay/sand mix and appears as though it is very fragile and could easily be damaged. We continue the dive.
The character of the cave has completely changed at this point. Instead of a simple tube, we enter a series of small rooms with low ceilings where the techniques we learned in class are put to the test. Looking back, I am pleased to note that we have not stirred up any silt to detract from our return trip. Futher back in the system we come across a catfish which seems to have lost his way. Maybe he will follow us back out on our return trip.
Suddenly the small rooms open up into a vertical crack. The floor to ceiling height is perhaps 10 feet now, but we can reach both walls if we extend our hands. I never cease to be amazed at how quickly and drastically caves can change in just a few hundred feet. While caves in Florida do not have stalactites and stalagmites, they do have interesting patterns carved by water flow over millenia. Reaching the end of the vertical crack, we look down and see another low restriction. Although this looks interesting, we will have to pass on it for today. I have reached my air turnaround point.
I signal my partner that it is time to go, and he confirms that he understands my message. Turning, we reluctantly leave the area. There is a slight current to assist us on our exit so we don't have to work as hard as we did upon entering. We pick up our stage and deco bottles, exit through the gate, and carefully lock it behind us. During our decompression stop, I reflect on the dive. Wow! It was great! Rejuvenated and exhilarated, I am fully reminded why I take the risks involved to engage in cave diving.
Note: Sadly, we learn later that someone died in the cave that same day. As usual, it was an openwater diver with no cave training.
Full Cave Diver
Co-owner, Airheads Scuba
If you think cave diving may appeal to you, contact Airheads Scuba at (502) 957-1226 in Brooks, Kentucky. There are many qualified people who can assist you in equipment selection and training for this and other serious forms of diving.Top of Page
THEYRE B A A ACK ! !
Yes thats correct. Rebreathers are back and this time it appears to stay. I say they are back because rebreathers have actually been around since 1878. There are patents for them stretching back a hundred years. Open circuit SCUBA on the other hand, has only been around since the late forties.
In the early years, rebreathers ran into a lot of problems due to the general lack of understanding of dive physiology as regards oxygen and depth. Except for very few special applications they faded from view until around WWII, when the italian and british militaries used them. By then the rules of the game were better understood.
With the advent of open circuit SCUBA developed by Gagnan and Cousteau, rebreathers were sidelined due in large part to their complexity. As compared to rebreathers, open circuit scuba was very inexpensive to produce, simple to understand, and in general, could be operated to greater depths.
Photographers continued to use the old double hose regulators with the introduction of the single hose regulators because the bubbles from the double hose systems were not in their faces. Slowly, in the search of nirvana, they discovered the world of the rebreather. This was great. With the use of nitrox and the absence of bubbles, they could now stay down longer and get even closer to their subjects. Certainly there were some drawbacks, but the advantages outweighed these.
Certain technical dive operations needed the efficient gas use of the rebreather as the dive objectives could not be met with open circuit. (A matter of being able to transport the amount of gas needed.) From this point the need for a commercial unit was born.
In 1994 Dräger and Uwatec introduced the Atlantis I semi-closed circuit rebreather. Finally a commercially produced, economical alternative was available. In short order several other companies followed suit.
What is all the hype about? Well as a rebreather instructor and diver, I have been able to explore these units. I personally have found the SCR (semi-close circuit rebreather) to be operator friendly, and contrary to the stories I heard, easy to maintain. Breathing warm, moist nitrox lets me stay down longer than with open circuit SCUBA. Since diving the SCR, I have never had even a little cotton mouth. I have been able to extend my bottom time due to both the use of nitrox and the warm gas cutting down on the thermal losses making a more comfortable dive.
The quiet operation of the SCR can not be explained. It has to be experienced. When I do open circuit now it sounds like a freight train passing in the night. No wonder the fish scatter when divers are around.
The efficient use of breathing gas allows me to dive all day on less gas than I use on a single open circuit dive. Unlike open circuit, gas consumption is independent of the divers breathing rate and depth!
Given all that freedom it would be easy for an undisciplined diver to stay down too long and incur a decompression obligation or exceed his maximum operating depth for the nitrox mix being used. A rebreather diver must be a more disciplined individual for more than just the above reasons. Rebreathers have prescribed checkout procedures that can not be ignored. Unlike open circuit, a rebreather can become very unfriendly. They have, in short, been the nemesis for the shortcut enthusiast. One example is that with a SCR you can run out of gas and keep on breathing until the oxygen in the system is used up and you pass out and drown. The key to sucessful rebreather diving is the acronym EARP: Education, Attention, Responsibility, Practice
As a recent article in the May 2000 issue of Dive Training asked: Is there a rebreather in your future? Well you will never know if you dont try one. They do have some drawbacks but they have some real pluses as well. If you are interested please contact us for a rebreather experience. We will take you to a local pool and outfit you in one of our units and let you experience one of these awesome machines.
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