What your instructor may not have told you about deep diving

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*Floater*

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I was looking for info on deep diving (just down to ~140fsw/42m) and ran across this article. The full text can be found at this link (highly recommended), but I'll only quote selected bits (due to copyright laws). I'm curious to hear your thoughts about the dangers of responsible recreational diving above 140fsw:

EDIT: This is an old article (1991), so it may be that some of the info in it has become irrelevant or outdated?

A Few Things Your Sport Diving Instructor May Not Have Told You About Deeper Diving
by Larry "Harris" Taylor, Ph.D.

There is an incredible fascination with diving on intact shipwrecks. In the quest for this thrill of diving unmolested wrecks, some divers in the Great Lakes are diving on compressed air in the vicinity of 200 ffw or deeper. A few of these "sport divers" have taken years to develop skills, technique and equipment that allow them to survive these penetrations into that deep, dark, cold and silent world that lies beneath the sport diving limit of 100 - 130 Feet. A few are truly highly skilled diving adventurers. Some would call them pioneers. Others would call them something less dignified. It is true that some walk with a noticeable limp, stand a little funny (numbness in the legs), have difficulty remembering things or seem to have somehow slowed their thinking and speech processes. None-the-less, many of these diving adventurers have seen splendors that not many will ever know. Other diving "adventurers" have found unique pains and death.

Divers new to our sport often do not realize that the successful deep diver has generally taken a decade or more to develop the necessary skills, equipment and technique to survive consistently this deeper diving. Make no mistake; some of these divers are highly skilled and physically fit. That exceptional proficiency, however, was not acquired in only a few days or even years. Although most are self-taught, many of these deep divers were trained when diving courses were longer and discussions on diving physics and physiology was more extensive. Thus, they have had access to information often missing in today's shorter curriculum ... material that is essential to make informed risk/benefit assessments. There are distinct physiological problems associated with deep diving. Since divers do not breathe water, the physiological impairments caused by deep diving can be (and have been) life threatening. Sport "deep diving" courses are simply insufficient training for diving to depths "below the limits." Divers compelled to dive below 100 feet should consider commercial or military dive training - depths below 100 feet are beyond the realm of sport diving...Sport diving equipment and techniques no longer are adequate! In addition, the training agencies will not, for a variety of reasons, address the question of training, at this time, for diving below 100-130 feet.

<snip>

DECOMPRESSION SICKNESS: The risk of permanent tissue injury increases with depth. Many sport divers have been given the impression that "the bends" is a benign disease. That simply is not true. The bends can kill, but most often it cripples. The DAN numbers show more than 500 divers a year now require chamber treatment. After 3 months post treatment, 13% of those treated still show some residual impairment. Severe sport diver bends hits most often show spinal cord involvement. This means that anything "South" of the lesion will be impaired. The spinal cord mediated functions most often tainted are walking, urinating, defecating, and sexual response. So, if you like to walk without a cane or wheelchair, go to the bathroom unassisted or to have sex, it is worth your while to develop some understanding of decompression sickness and its prevention. (A recent national survey reported in Skin Diver magazine noted that approximately 60% of those in the sport diving community surveyed could not recognize the symptoms of the bends and almost every survey of divers done recently suggests that more than 50% of sport divers cannot plan dives using decompression tables.)

A real danger of decompression sickness is that it is often a progressive disease; it may continue to get worse until treated. In North America the time from onset of recognizable symptoms to chamber treatment is often more than 12 hours. It is this delay that can be so devastating. It is believed that the longer the delay between onset of severe symptoms and treatment, the less the chance for total recovery. During the delay the bubbles formed continue to impair or destroy body functions. The key to successful recovery from the bends is immediate recognition of symptoms and the prompt administration of the highest possible concentration of O2 (preferably by demand mask). Medical consultation/treatment should always be sought. Not recognizing or ignoring the symptoms may allow the disease to do more damage. Although there are anecdotal stories of acute relief of decompression sickness symptoms without medical treatment, there is a lingering question of the potential for long-term damage even though immediate clinical signs were absent or simply went away.

The problems linked to decompression sickness can primarily be called "bubble trouble." Whenever bubbles form, they obstruct normal body function. This may prevent normal exchange of nutrients and oxygen and allows waste products to accumulate. This can, over time, create destruction of body cells. Medical evidence is beginning to accumulate that suggests there may be gradual deterioration of nervous system tissue upon repeated exposure to deep diving. It is believed that this damage can occur without ever showing gross clinical signs (i.e. joint pain, etc.) classically associated with decompression sickness hits. Although still far from complete, early studies seem to imply that there is a marked deterioration in short-term memory and reasoning skills in commercial divers aged 24-39. Autopsy studies of three deep divers who died of non-diving related causes indicated that there was a marked degradation of spinal cord tissue. It is believed that the spinal cord lesions were created from diving. Although controversial, there is some evidence that deep diving can block retinal blood flow and create vision problems due to a damaged retina. Additional studies measuring blood chemistry and urine of divers imply that the liver, as well, may be damaged in divers diving as shallow as 30 meters (98 feet).

The body is a remarkable biochemical machine with much redundancy. It can sustain some tissue damage that can be compensated for by this redundancy. However, repeated exposure to tissue-damaging conditions will ultimately result in loss of function.

Bottom line: The DAN numbers suggest that diving below 80 fsw is a significant risk factor for sport divers (more than 70% of DAN treatments involved sport dives to depths below 80 fsw). The deeper and more often this deep diving occurs, the more the risk for long-term neurological damage. It is not possible to predict the type and severity of this physiological impairment.

<snip>

There are other problems that could result from the practice of breathing pure O2 at depth (during decompression stops?). There are some medical authorities who consider 100% O2 at elevated pressures a cellular toxin. Breathing pure O2 at elevated pressures for extended times can induce abnormalities in the red blood cells that carry O2 to the body. High O2 concentrations can constrict blood vessels in the eye and lead to visual problems. In addition, high O2 can create a mild hearing loss that may appear hours after the dive and take a day or so to disappear. High p O2 has also been proposed as contributing to dysbaric osteonecrosis ("bone death"- usually seen in deep diving commercial divers; this malady may eventually require surgery to replace bone joints with artificial devices.)

Bottom line: The potential for grand mal seizure and subsequent death caused by oxygen toxicity makes diving below 180 fsw in sport diving equipment on compressed air an extremely high risk activity. Below 200 fsw many diving authorities believe that oxygen toxicity poses a greater risk to the diver on compressed air than nitrogen narcosis.

<snip>

[continued in the next post]
 
the rest...

[continued from previous post]

RISK: REAL OR THEORETICAL? There is a wreck, the Gunilda, which lies at 256 ffw in the Great Lakes. Since it has historical significance and lies close to the Canadian shore, the diving activity on this vessel has been monitored. To date, there have been 26 divers who have visited this wreck. Twelve of these divers (operating under commercial-type protocols) account for 136 dives on this vessel. Within this group, 1 dive required treatment for severe decompression sickness (to a diver who had 34 dives on this wreck) and there were no fatalities. There have been 14 sport divers on compressed air that have accounted for 33 dives. Of these 33 dives, 9 (27%) have resulted in severe decompression sickness that required chamber treatment, 5 dives (15%) were aborted due to severe narcosis that required the diver to be rescued, and there were two fatalities (6%). In addition, two of these surviving divers, one from each group, have subsequently died on another deep wreck.

<snip>

FINAL THOUGHTS: No one has the right to restrict your personal style of recreational diving. Lee Somers, Ph.D., Diving Safety Officer for the University of Michigan and one of the Founding Fathers of our sport, calls this "THE RIGHT TO DIvE!" Dan Orr, Training Coordinator for DAN, calls deep sport diving "an exercise in natural selection." The decision to risk life and spinal cord for the sake of recreational adventure rests with each diver. This risk (loss of life or maybe only a slight compromise in mental faculties, the ability to walk, go to the bathroom unassisted or to have sex) / benefit (adventure, thrill, status, or fame) decision should, however, be based on knowledge and evaluation of the actual risks incurred and not solely on the perceived status of survival.

I once asked a very highly skilled and well-known Great Lakes deep sport diver about diving to extreme depths on compressed air without the redundancy of commercial equipment and personnel. My question, "What do you do alone at 250 feet under the influence of narcosis to deal with an equipment emergency?" His answer, "I die!" Enough said! The decision to dive to "adventurer depths" rests with the individual diver. Choose wisely!
 
*Floater*:
the rest...
Hopefully, sport divers know........one can only make an informed choice, if fully informed..........the information is out there, you have to seek it, and understand it.
 
Larry "Harris" Taylor, Ph.D. is well known for his high drama, "OMG you could die or be crippled or gawdknowswhat if you scuba dive" threatrical rantings. If you want to listen to him, feel free, but most people shrug him off as sensationalist (and I'm being kind). This is the same sort of rantings PADI et al used to do about Nitrox, if you can believe it, and not all that long ago.

Look, make up your own mind, but a lot has changed in technical and recreational diving since the early 90's. Nobody -- with any brains anyway -- does deep air dives, the decompression models are MUCH better (and lets save the modified Buhlmann vs. RGBM vs. VPM-B arguments for another thread, they are all better than the Navy tables), the equipment is more reliable. Diving is safer today than its ever been, if you are properly trained. Any good Deep course worth its salt will teach important skills in addition to just being an adventure/experience type of dive.

Listen to that nutjob from a different era if you want, I'm going diving! :D
 
"deep diving" is more of a risk, requires more knowledge/skill and equipment. But, I know lots of divers who have dived VERY deep many times over a period of many years and walk, talk and think just fine. Whether or not there is gradual deteriation or ot probably isn't known for certain. One thong I do know is that there seems to be a gradual deteriation with age and it always results in death.

I only skimmed the artical but the one area that I'll disagree with completely is what he said about training. As far as I know, there isn't anything about commercial or military dive training that will prepare you for deep sport diving. They are completely different animals.
 
First let me say I agree with Stsomewhere's post. Well put.

Lets look at the "case study"

1. Better Trained Divers, with more experience had many fewer problems. Really? No kidding?

2. Deep Air Kills. Really? No Kidding?

This 1991 article cites stats from ~1980-1990, I'd guess. Remember this is the period when the large agencies position was "stick to the rec limits, beyond that is bad" People seeking more were forced to experiment on their own, "tech diving" was an underground movement. Things have improved, but people still do stupid things occassionally.

Good training is now available to those with the time and money to pursue it.


Tobin
 
MikeFerrara:
I only skimmed the artical but the one area that I'll disagree with completely is what he said about training. As far as I know, there isn't anything about commercial or military dive training that will prepare you for deep sport diving. They are completely different animals.

I've had no commercial or military dive training, but I'd guess that he may be referring to the Mixed gas portion. It's only fairly recently that info and tables for He have been readily available outside commercial / military diving. If the author is looking at stats from the 1980's the commercial / military guys were well ahead in this area.

Just my guess,


Tobin
 
MikeFerrara:
"deep diving" is more of a risk, requires more knowledge/skill and equipment. But, I know lots of divers who have dived VERY deep many times over a period of many years and walk, talk and think just fine. Whether or not there is gradual deteriation or ot probably isn't known for certain. One thong I do know is that there seems to be a gradual deteriation with age and it always results in death.

I only skimmed the artical but the one area that I'll disagree with completely is what he said about training. As far as I know, there isn't anything about commercial or military dive training that will prepare you for deep sport diving. They are completely different animals.

...my commercial diving education & my years of commercial diving prepared me for deep sport diving in several ways:

> an intimate knowledge of narcosis

> the joys of switching from air to HeO2

...and, most importantly,

> a healthy respect for the marine environment.

Having said that, Mike is esentially correct; consider that a surface-supplied diver is tethered, gassed, communicated, directed & sometimes heated to/by & with a central surface control; it must be this way so that the diver may concentrate their full attention on the task(s) at hand.

The deep sport diver, essentially, is on his/her own, thus the term of the day is "self-reliance."

Regards,
D.S.D.
 
https://www.shearwater.com/products/perdix-ai/

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