OK to Bounce Dive to 220 Fsw as...
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That's insane. Notice the amount of diver support the guy had, though. Good planning - turns out he didn't need it, but definitely a far cry from a bounce profile by a newbie.
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...that being said, I have 430 dives and only 10 are deeper than 130 ft with a maximum of 153 ft. On the other hand, I have 112 dives between 100-130 ft. I always had a good reason for diving deep and planned and executed those dives very carefully. I'd have to have a very good reason to consider a short dive to 220 ft.
I do not want to appear to minimize the risk but the decision and risk are personal.
Good diving, Craig
Yes, the question of doing a 220 foot dive safely basically precludes freediving because there are variables that cannot be controlled. The United States Navy's official study on breath hold diving once put a 1 minute time limit as the safe zone for a breath hold. After that, it is a crap shoot. With times between 5 minutes and 5 minutes and 38 seconds being my longest comfortable breath holds with no chest contractions, and my average times between 3:30 and 4 minutes, I was shocked when I erxperienced a blackout at 2:38 in a pool. Doctors ruled that episode to have been aggravated by poor gas exchange in the lungs due to a chest infection that I didn't know I had. However, I wonder if that infection could have been caused by the aspiration of a small quantity of water since the fever,congestion and blood gas analysis followed the blackout and I felt fine prior to entering the water for training. I suffered two other blackouts in my career. One was in deep water while the other was a classic shallow water blackout.
Once, when sitting at Bill Rennaker's shop while cave diving, Bill compared cave diving in your youth to driving a muscle car. As teenagers, we tend to drive fast and recklessly when we feel invincible. As we get older, we tend to slow down, but we'll still place ourselves in danger on icy and rainy roads. Finally, we have the good sense to stay home when the roads are treacherous and we think back to that first muscle car we had and think, "Dang, that beast could've killed me." At age 41, I can think back to the days of having my 1978 Firebird Esprit and recalling how I totalled two Camaros, but somehow my car got to live to be sold to another teenager when I was a senior in college and how lucky I am to still be breathing with the amount of deep and solo freediving I did. Just like deep air divers who realize the benefits of Trimix, I now limit freediving depths and times and prefer to use the right gas and scuba. I still believe in freediving and that it is an essential skill to be a diver. But, without the right amount of support and training, it is a stunt much like deep air bounces. Safer freedives can be managed by scuba equipped bottom teams that can become a bailout option for a freediver. The ability for the freediver to be handed off to another freediver for a quick trip to the surface for medical attention is also important since underwater resuscitation in a deep blackout is incredibly difficult. Teams of deep, intermediate, and shallow support scuba and freedivers are the ideal for safety.
ScubaInChicago
Contributor
You learn something new everyday, even from the beginnings of a trolling thread...
I've heard of shallow water blackouts but thought it was from the hyperventilation most freedivers do to attempt to expel C02. I haven't read anything much on the science behind freediving but think the thought of having a bad day and blacking out at depth spells a recipe for disaster. Pardon my ignorence...
The most basic danger of hyperventilation is the practice will cause the CO2 levels in the blood to drop. As it is CO2 that stimulates the urge to breathe, a diver may black out as the oxygen level in the blood drops before taking a breath. That is the scenario most all divers become familiar with at some point during their training or when reading a diving manual.
This is further complicated by the fact that hyperventilation actually spikes the heart rate prior to the heart rate slowing down due to bradycardia (mammalian diving reflex) during the dive. Further still, as the blood moves away from feeding the extremities and as tissues such as the lungs are compressed during the dive, the oxygen partial pressure will increase with depth and the reduced areas that it feeds. As the diver ascends and the lungs and other tissues expand, blood will be drawn back into these tissues while at the same time the partial pressure exerted on the oxygen in the body will drop with decreasing depth. This will lead to that classic "shallow water blackout" scenario. Many divers are familiar with this as well.
However, any form of breathe-up associated with freediving is believed to trick the body in much the same way as hyperventilation. I was able to discuss this subject at length with the DAN researchers who made a presentation on freediving at DEMA in Vegas and they believe that breathe-ups are just, "a rose by any other name ..." What is certain is that the more active the body is the more oxygen will be required to feed the machine. Muscle exertion will surely demand oxygen, but even active thoughts or a busy mind will require oxygen as well. Relaxation is the key to freediving and the mind must be as relaxed as the body if not moreso. Eventually, no matter what technique we use to prepare for a dive, without being able to replenish the oxygen, it will be used up. Some divers may fight the chest contractions associated with the rise in CO2 demanding the diver breathe. Even if that diver did not hyperventilate, fighting the urge to breathe is simply mind overriding body rather than tricking the body through hyperventilation. Either way, a diver will only have so much time before the oxygen level decreases to the point of not being able to sustain consciousness. This may happen at depth or even if a diver is on the surface with the face submerged as in static apnea.
Depth in itself is a mystery. A Canadian freediving champion experienced paralysis several times for brief periods at depth as he tried to fin upward. Comparing this to deep air diving, Sheck Exley, was no stranger to the body shutting down at depth and having to fight deep water blackout on scuba. One of my cave diving instructors who also did end of the line deep air diving came close to deep water blackout. While we focus on oxygen, nitrogen, carbon dioxide, and even helium and other trace gases as partial pressures increase on both freedivers and scuba divers, much of the narcotic effects of gases are not well-understood nor is the behavior of gases under intense pressure within the body. Freedivers have reported everything from narcosis to DCS.
Early in the season, or when an experienced freediver is not properly warmed up by making a series of progressively deeper dive, injuries like thoracic squeeze may occur. I suffered one in 105 feet of water when I only made 2 warm up dives. A friend, who had just made a near world record dive reaching 250 constant ballast at the time, suffered a thoracic squeeze a week later when helping me teach a course in the same location. He dove to place a descent/ascent line for my students at 100 feet the second day of their course, skipped his warm-up dives and returned coughing up blood like I had with only 2 warm-ups. I have been highly successful in teaching students to reach 100 feet in a constant ballast freedive in 2 days simply by the amount of time we spend in the water and the number of dives we make in class. The first day we will spend the first session working on form and technique for static, dynamic and depth to just 15 - 20 feet. After a rest we will do several warm-up's and continue to reach 50 feet. The second day we try to increase static times, dynamic distances, and work on negative dives (exhale air out of lungs and descend) in this 15 to 20 foot range, we'll cover rescue techniques in the second session and in the third session move into 60 - 100 foot dives after an adequate warm-up. The trick is to dive deep once properly warmed-up, but to catch the mental motivation and physical performance at the apex. Deep dives, as the brain and body fatigue, are not only going to be far more work, but will create negative thoughts and possibly be dangerous since the body's ability to perform and the mind's ability to relax, yet be aware, will be hampered by the fatigue. In this manner of making many dives while avoiding fatigue, I've been able to safely help divers reach 100 feet on a breath-hold without injury. Many freediving courses do not allow the students to make enough dives to be adequately prepared. But, the student must also be fresh enough to dive without being tired physically, emotionally, or mentally.
While freediving might seem like a physical sport, it is much more mental than even technical diving, but the mind must be trained to be as empty as it is full. I've found the best way to achieve this isn't through yoga, mysticism or ritual. The best way to achieve this is to freedive. As one becomes better, the information that once required concentration becomes both muscle memory and automatic behavioral response. Freediving is sensual, and as a surfer, I believe that freediving has more in common with surfing in the pursuit of depth, distance or time than it does with diving. While surfing may be the expression of one's innermost self in an aqueous medium, freediving is about becoming one with that medium as you explore yourself inwardly. As a wave is a tool, or better, a partner that helps you find yourself, so is the process of a freedive.
Any freediver who has had to perform work underwater such as retrieving an object or freeing an anchor will often feel like he or she had to work hard to accomplish the task, because that spiritual needle in which you insert yourself into the sensuality of the experience will have been broken by the need to actively engage the mind. I've done a lot of work underwater on breath holds and even minor work at 70 feet is much harder on me than a dive to 170 feet.
What is often lost on scuba divers, today, is the comfort one develops in the water as a breath hold diver to find peace in the environment without conquest, without trophy, without fear, without worry, without thought. Once you reach this state, the comfort you feel compels you deeper, farther, longer and the trophies come. Yet, most freedivers shun competitions and numbers. Much like in the movie North Shore with Gregory Harroson and Matt Adler, competitions don't mean anything to soul-surfers.
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ucfdiver
Contributor
Might want to read up on the most recent Eagles Nest fatality. I think you're sadly misunderstanding the difference between confident and competent.
http://www.iucrr.org/20081112_01.htm
boomx5
Contributor
Lol...I haven't seen that movie in years. It was actually on HULU a few months ago.
You know, Scott, our teachers and professors tried their best to fill our minds with ideas that were captured in critically acclaimed films, great literature, and masterful works of art, yet, whenever we need to find our own brand of ABC After School Special wisdom, it usually comes from a B movie. Know what I mean?
Here are some titles of obscure B-movie diving films to add to your collection. Have you seen:
1. Amsterdamned -a diver is killing people Jack The Ripper style in an around the canals of Amsterdam. Foreign. Dubbed in English, but pretty outstanding police investigation and slasher flick, especially since it is foreign, dubbed, and involves a diver killing people Jack The Ripper style in and around the canals of Amsterdam.
Lesson: Foreign, dubbed films involving a diver killing people Jack The Ripper style in and around the canals of Amsterdam don't necessarily suck.
Lesson number two: BIG DIVING KNIVES have their uses.
2. The Dive - commercial divers are trapped in a diving bell in the North Sea. Michael Kitchen from the James Bond films with Pierce Brosnan stars in this Norwegian/British production. Kitchen also does a deep bounce dive on scuba with expected results.
Lesson: Deep air bounce dives and full Cressi face masks do not mix.
3. Oceans of Fire - Gregory Harrison is back as a commercial diving supervisor who hires convicts who have been receiving training in commercial diving as a way of rehabilitating them and finding work once released. They go to work on an oil rig south of the border.
Lesson: If you really want to find a job, keep swimming and don't quit.
4. Namu: The Killer Whale - a marine biologist doesn't believe orcas are killers and protects one from ignorant PNW fishermen. Good one for the kids.
Lesson: Yep. Fishermen are still ignorant.
5. Assignment Underwater - TV series with 30 minute episodes of Sea Hunt-like adventure with a professional diver who is a single dad raising his daughter on a boat. Black & White.
Lesson: Men will do ANYTHING to save their daughters and it only takes a man 30 minutes to accomplish any task with a knife or a speargun -unlike soap operas in which the problems have outlived the original cast.
BDSC
Contributor
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