The Importance of Deep Safety Stops: Rethinking Ascent Patterns From Decompression Dives

by Richard L. Pyle

An abridged version of this article was originally in DeepTech, 5:64; and the full version subsequently published in Cave Diving Group Newsletter, 121:2-5.

Before I begin, let's make something perfectly clear: I am a fish-nerd (i.e., an ichthyologist). For the purposes of this commentary, that means two things. First, it means that I have spent a lot of time underwater. Second, although I am I biologist and understand quite a bit about animal physiology, I am not an expert in decompression physiology. Keep these two things in mind when you read what I have to say.
Back before the concept of "technical diving" existed, I used to do more dives to depths of 180-220 feet than I care to remember. Because of the tremendous sample size of dives, I eventually began to notice a few patterns. Quite frequently after these dives, I would feel some level of fatigue or malaise. It was clear that these post-dive symptoms had more to do with inert-gas loading than with physical exertion or thermal exposure, because the symptoms would generally be much more severe after spending less than an hour in the water for a 200-foot dive than they would after spending 4 to 6 hours at much shallower depths.
The interesting thing was that these symptoms were not terribly consistent. Sometimes I hardly felt any symptoms at all. At other times I would be so sleepy after a dive that I would find it difficult to stay awake on the drive home. I tried to correlate the severity of my symptoms with a wide variety of factors. I considered the magnitude of the exposure, the amount of extra time I spent on the 10-foot decompression stop, the strength of the current, the clarity of the water, water temperature, how much sleep I had the night before, level of dehydration...you name it. But none of these obvious factors seemed to have anything to do with it. Finally I figured out what it was - fish! Yes, that's right...on dives when I collected fish, I had hardly any post-dive fatigue. On dives when I did not catch anything, the symptoms would tend to be quite strong. I was actually quite amazed by how consistent this correlation was.
The problem, though, was that it didn't make any sense. Why would these symptoms have anything to do with catching fish? In fact, I would expect more severe symptoms after fish-collecting dives because my level of exertion while on the bottom during those dives tended to be greater (chasing fish isn't always easy). There was one other difference, though. You see, most fishes have a gas-filled internal organ called a "swim bladder" - basically a fish buoyancy compensator. If a fish is brought straight to the surface from 200 feet, its swim bladder would expand to about seven times its original size and crush the other organs. Because I generally wanted to keep the fishes I collected alive, I would need to stop at some point during the ascent and temporarily insert a hypodermic needle into their swim bladders, venting off the excess gas. Typically, the depth at which I needed to do this was much deeper than my first required decompression stop. For example, on an average 200-foot dive, my first decompression stop would usually be somewhere in the neighborhood of 50 feet, but the depth I needed to stop for the fish would be around 125 feet. So, whenever I collected fish, my ascent profile would include an extra 2-3 minute stop much deeper than my first "required" decompression stop. Unfortunately, this didn't make any sense either. When you think only in terms of dissolved gas tensions in blood and tissues (as virtually all decompression algorithms in use today do), you would expect more decompression problems with the included deep stops because more time is spent at a greater depth.
As someone who tends to have more faith in what actually happens in the real world than what should happen according to the theoretical world, I decided to start including the deep stops on all of my decompression dives, whether or not I collected fish. Guess what? My symptoms of fatigue virtually disappeared altogether! It was nothing short of amazing! I mean I actually started getting some work done during the afternoons and evenings of days when I did a morning deep dive. I started telling people about my amazing discovery, but was invariably met with skepticism, and sometimes with stern lectures from "experts" about how this must be wrong. "Obviously," they would tell me, "you should get out of deep water as quickly as possible to minimize additional gas loading." Not being a person who enjoys confrontation, I kept quiet about my practice of including these "deep decompression stops". As the years passed, I became more and more convinced of the value of these deep stops for reducing the probability of decompression sickness (DCS). In all cases where I had some sort of post-dive symptoms, ranging from fatigue to shoulder pain to quadriplegia in one case, it was on a dive where I omitted the deep decompression stops.
As a scientist by profession, I feel a need to understand mechanisms underlying observed phenomena. Consequently, I was always bothered by the apparent paradox of my decompression profiles. Then I saw a presentation by Dr. David Yount at the 1989 meeting of the American Academy of Underwater Sciences (AAUS). For those of you who don't know who he is, Dr. Yount is a professor of physics at the University of Hawaii, and one of the creators of the "Varying-Permeability Model" (VPM) of decompression calculation. This model takes into account the presence of "micronuclei" (gas-phase bubbles in blood and tissues) and factors that cause the bubbles to grow or shrink during decompression. The upshot is that the VPM calls for initial decompression stops that are much deeper than those suggested by neo-Haldanian (i.e., "compartment-based") decompression models. It finally started to make sense to me. (For a good overview of the VPM, read Chapter 6 of Best Publishing's Hyperbaric Medicine and Physiology; Yount, 1988.)
Since you already know I am not an expert in diving physiology, let me explain what I believe is going on in terms that educated divers should be able to understand. First, most readers should be aware that intra vascular bubbles are routinely detected after the majority of dives - even "no decompression" dives. The bubbles are there - they just don't always lead to DCS symptoms. Now; most deep decompression dives conducted by "technical" divers (as opposed to commercial or military divers) are very-much sub- saturation dives. In other words, they have relatively short bottom-times (I would consider 2 hours at 300 feet a "short" bottom time in this context). Depending on the depth and duration of the dive, and the mixtures used, there is usually a relatively long ascent "stretch" (or "pull") between the bottom and the first decompression stop as calculated by any theoretical compartment-based model. The shorter the bottom time, the greater this ascent stretch is. Conventional mentality holds that you should "get the hell out of deep water" as quickly as possible to minimize additional gas loading. Many people even believe that you should use faster ascent rates during the deeper portions of the ascent. The point is, divers are routinely making ascents with relatively dramatic drops in ambient pressure in relatively short periods of time - just so they can "get the hell out of deep water".
This, I believe, is where the problem is. Maybe it has to do with the time required for blood to pass all the way through a typical diver's circulatory system. Perhaps it has to do with tiny bubbles being formed as blood passes through valves in the heart, and growing large due to gas diffusion from the surrounding blood. Whatever the physiological basis, I believe that bubbles are being formed and/or are encouraged to grow in size during the initial non-stop ascent from depth. I've learned a lot about bubble physics over the last year, more than I want to relate here - I'll leave that for someone who really understands the subject. For now, suffice it to say that whether or not a bubble will shrink or grow depends on many complex factors, including the size of the bubble at any given moment. Smaller bubbles are more apt to shrink during decompression; larger bubbles are more apt to grow and possibly lead to DCS. Thus, to minimize the probability of DCS, it is important to keep the size of the bubbles small. Relatively rapid ascents from deep water to the first required decompression stop do not help to keep bubbles small! By slowing the initial ascent to the first decompression stop, (e.g., by the inclusion of one or more deep decompression stops), perhaps the bubbles are kept small enough that they continue to shrink during the remainder of the decompression stops.
If there is any truth to this, I suspect that the enormous variability in incidence of DCS has more to do with the pattern of ascent from the bottom to the first decompression stop, than it has to do with the remainder of the decompression profile. DCS is an extraordinarily complex phenomenon - more complex than even the most advanced diving physiologists have been able to elucidate. The unfortunate thing is that we will likely never understand it entirely, largely because our bodies are incredibly chaotic environments, and that level of chaos will hinder any attempts to make predictions about how to avoid DCS. But I think that we, as sub-saturation decompression divers, can significantly reduce the probability of getting bent if we alter the way we make our initial ascent from depth.
Some of you may now be thinking "But he said he's not an expert in diving physiology - why should I believe him?" If you are thinking this, then good - that's exactly what I want you to think because you shouldn't trust just me. So, why don't you dig up your September '95 issue of DeepTech (Issue 3) and read Bruce Weinke's article? I know it covers some pretty sophisticated stuff, but you should keep re-reading it until you do understand it. Why don't you call up aquaCorps and order audio tape number 9 ("Bubble Decompression Strategies") from the tek.95 conference, and listen to Eric Maiken explain a few things about gas physics that you probably didn't know before. While you're at it, why don't you order the audio tape from the "Understanding Trimix Tables" session at the recent tek.96 conference? You can listen to Andre Galerne (arguably the "father of trimix") talk about how the incidence of DCS was reduced dramatically when they included an extra deep decompression stop over and above what was required by the tables. On the same tape you can listen to Jean-Pierre Imbert of COMEX (the French commercial diving operation which conducts some of the world's deepest dives) talk about a whole new way of looking at decompression profiles which includes initial stops that are much deeper than what most tables call for. Why don't you ask George Irvine what he meant when he said he includes "three or four short deep stops into the plan prior to using the first stop recommended by each of the [decompression] programs" in the January, '96 issue of DeepTech (Issue 4)? If that's not enough, then check out Dr. Peter Bennett's editorial in the January/February 1996 Alert Diver magazine; he's talking about basically the same thing in the context of recreational diving. If you really want to read an eye-opening article, see if you can find the report on the habits of diving fishermen in the Torres Strait by LeMessurier and Hills (listed in the References section at the end of this article). The lists goes on and on. The point is, I don't seem to be the only one advocating deep decompression stops.
Are you still skeptical? Let me ask you this: Do you believe that so-called "safety stops" after so-called "no- decompression" dives are useful in reducing probability of DCI? If not, then you should take a look at the statistics compiled by Diver's Alert Network. If so, then you are already doing "deep stops" on your "no-decompression" dives. If it makes you feel better, then call the extra deep decompression stops "deep safety stops" which you do before you ascend to your first "required" decompression stop. Think about it this way: Your first "required" decompression stop is functionally equivalent to the surface on a dive that is taken to the absolute maximum limit of the "no-decompression" bottom time. Wouldn't you think that "safety stops" on "no-decompression" dives would be most important after a dive made all the way to the "no- decompression" limit?
Some of you may be thinking, "I already make safety stops on my decompression dives - I always stop 10 or 20 feet deeper than my first required stop." While this is a step in the right direction, it is not what I am talking about here. "Why not?", you ask, "I do my safety stops on no-decompression dives at 20 feet. Why shouldn't I do my deep safety stops 20 feet below my first required ceiling?" I'll tell you why - because the safety stops have to do with preventing bubble growth, and bubble growth is in part a function of a change in ambient pressure, not a function of linear feet. Suppose that, after a dive to 75 feet, you make a safety stop at 20 feet. Well, the ambient pressure at sea level is 1 ATA. The ambient pressure at 75 feet is about 3.3 ATA. The ambient pressure at your 20-foot safety stop is 1.6 ATA - which represents roughly the midpoint in pressure between 3.3 ATA and 1 ATA. Now, suppose you're on a dive to 200 feet (about 7 ATA) and your first required decompression stop is 50 feet (about 2.5 ATA). The ambient pressure midpoint between these two depths is 4.75 ATA, or a little less than 125 feet. Thus, on this dive you would want to make your deep safety stop at about 125 feet - exactly the depth I used to stop to stick a hypodermic needle in my little fish.
But of course, the physics and physiology are much more complex than this. It may be that ambient pressure mid- points are not the ideal depth for safety-stops - in fact, I can tell you with near certainty that they are not. From what I understand of bubble-based decompression models, initial decompression stops should be a function of absolute ambient pressure changes, rather than proportional ambient pressure changes, and thus should be even deeper than the ambient pressure mid-point for most of our decompression dives. Unfortunately, I seriously doubt that decompression computers will begin incorporating bubble-based decompression algorithms, at least not in their complete form. Until then, we decompression divers need a simpler method - a rule of thumb to follow that doesn't require the processing power of an electronic computer. Perhaps the ideal method would be simply to slow down the ascent rate during the deep portion of the ascent. Unfortunately, this is rather difficult to do - especially in open water. Instead, I think you should include one or more discrete, short-duration stops to break up those long ascents. Whether or not it is physiologically correct, you should think of them as pit-stops to allow your body to "catch up" with the changing ambient pressure.

Here is my method for incorporating deep safety stops:
1) Calculate a decompression profile for the dive you wish to do, using whatever software you normally use.
2) Take the distance between the bottom portion of the dive (at the time you begin your ascent) and the first "required" decompression stop, and find the midpoint. You can use the ambient pressure midpoint if you want, but for most dives in the "technical" diving range, the linear distance midpoint will be close enough and is easier to calculate. This depth will be your first deep safety stop, and the stop should be about 2-3 minutes in duration.
3) Re-calculate the decompression profile by including the deep safety stop in the profile (most software will allow for multi-level profile calculations).
4) If the distance between your first deep safety stop and your first "required" stop is greater than 30 feet, then add a second deep safety stop at the midpoint between the first deep safety stop and the first required stop.
5) Repeat as necessary until there is less than 30 feet between your last deep safety stop and the first required safety stop.
For example, suppose you want to do a trimix dive to 300 feet, and your desktop software says that your first "required" decompression stop is 100 feet. You should recalculate the profile by adding short (2-minute) stops at 200 feet, 150 feet, and 125 feet. Of course, since your computer software assumes that you are still on-gassing during these stops, the rest of the calculated decompression time will be slightly longer than it would have been if you did not include the stops. However, in my experience and apparently in the experience of many others, the reduction in probability of DCI will far outweigh the costs of doing the extra hang time. In fact, I'd be willing to wager that the advantages of deep safety stops are so large that you could actually reduce the total decompression time (by doing shorter shallow stops) and still have a lower probability of getting bent. Until someone can provide more evidence to support that contention, you should definitely play it safe and do the extra decompression time. One final point. As anyone who reads my posts on the internet diving forums already knows, I am a strong advocate of personal responsibility in diving. If you choose to follow my suggestions and include deep safety stops on your decompression dives, then that's swell. If you decide to continue following your computer-generated decompression profiles, that's fine too. But whatever you do, you are completely and entirely responsible for whatever happens to you underwater! You are a terrestrial mammal for crying out loud - you have no business going underwater in the first place. If you cannot accept the responsibility, then stay out of the water. If you get bent after a dive on which you have included deep safety stops by my suggested method, then it was your own fault for being stupid enough to listen to decompression advice from a fish nerd!

References:
Bennett, P.B. 1996. Rate of ascent revisited. Alert Diver, January/February 1996: 2.
Hamilton, B. and G. Irvine. 1996. A hard look at decompression software. DeepTech, No. 4 (January 1996): 19- 23
LeMessurier, D.H. and B.A. Hills. 1965. Decompression sickness: A thermodynamic approach arising from a study of Torres Strait diving techniques. Scientific Results of Marine Biological Research. Nr. 48: Essays in Marine Physiology, OSLO Universitetsforlaget: 54-84.
Weinke, B. 1995. The reduced gradient bubble model and phase mechanics. DeepTech, No. 3 (September 1995): 29-37.
Yount, D.E. 1988. Chapter 6. Theoretical considerations of Safe Decompression. In: Hyperbaric Medicine and Physiology (Y-C Lin and A.K.C. Niu, eds.), Best Publishing Co., San Pedro, pp. 69-97.

I would like to thank Eric Maiken for explaining bubble physics to me and for adding some theoretical foundation to my silly ideas.

Doing It Right Gear Configuration

by George Irvine

A good SCUBA equipment configuration needs to carry through all of your diving, from open water to cave in such a fashion that the addition of items necessary for each dive does not in any way interfere with or change the existing configuration. Diving with the same configuration allows the same response to emergency at all times while reducing effective task loading due to familiarity . In other words, it not only helps solve problems, it prevents them.
Let's start with the backup regulator ( not the "safe second" or "octopus", the BACKUP). The backup must be instantly accessible. We hang it around the neck on surgical tubing or bungee which is held on by the tie wrap that holds the mouthpiece to the regulator. It must be up close to the neck in order to minimize the venturi effect on the reg, and to provide a strap to hold that reg tightly in the mouth when necessary.
That reg must be a non air balanced, low performance reg. The intermediate pressure of all regs should be held to a minimum to prevent free flow and stress on the second stage and hoses. Since most regs feed right to left, we initiate this regulator from the left post of the manifold, with its hose short enough so as not to "flap in the breeze" and wear out the swedge fitting. As with all hoses, we use a strain relief. We do not use "upstream" valve regulators, regulators that get water in them when scootering or in a current, or regs that require custom hose fittings. We use regs that can be taken apart and cleared underwater. We use regs that operate at low IP's. We leave them loose so that they can be changed underwater. For open water configuration assume that all hoses are off of the one reg, rather than the manifold doubles.
For manifolds we use the dual port style with a center shutoff for redundancy and to be able to solve the most common failure mode: loss of knob followed by a free flow, or roll-off followed by loss of the knob. Manifolds should have barrel style o-rings, no face seals, and should be adjustable. The ports would be 300 bar for more thread depth, and should be straight facing ports, no angles which end up breaking off DIN connections. Knobs should be spring loaded and soft with a metal insert so they do not strip out - no metal knobs. Metal dents and will lock off or on, and are hard to turn in a pinch. Burst ports would contain higher working pressure plugs, and be changed often.
The primary second stage reg is then on the right post for redundancy and ease of gas sharing. This is the long hose in any configuration. It runs straight down behind the wing, under the light ( if a light is worn - around the knife or tucked into the belt if not ) and back up the left side , behind the neck and into the mouth. When not in use, as in staging or deco, this reg is clipped of on the right chest d-ring using a breakaway clip. While you always must be willing to donate the reg that is in your mouth, switching to the long hose donation for traveling is a must. You NEVER put the primary reg on the left post due to the roll-off , break-off failure mode, the effective shortening of the hose for sharing and comfort of routing, and the oblique angles created in a traveling share that will restrict gas flow by being on that post. Hoses float, and since the diver should always be in a supine position for purposes of gas exchange and general good form, the hose will be held against the body and stay in place. This treatment of the hose solves several problems at once while not creating any and not interfering with the rest of the rig. To make the long hose breath the way you like it, adjust the intermediate pressure of the first stage, but keep it as low as you can. Today, we all use helium for deep diving, so the ease of breathing is greatly increased, allowing for lower intermediate pressures.
The pressure gauge is from the left run straight down the left side to the left side d-ring where it is clipped off. This has no boot , no console , and no other clap trap on it. The hose should be short enough to stay out of the slipstream and long enough to view when unclipped. It is read on the fly with the left hand. The inflator from the wings runs over the shoulder and through a small bungee attached with the left chest d-ring. This keeps the inflator where it can be located instantly. The inflator must be long enough that it can reach the mouth, the dry suit inflation valve, and the nose for ease of operation with one hand controlling all three maneuvers. It must be long enough that it can be breathed by holding both buttons down at once (never "rebreathed", only breathed). The low pressure hose to it must come from the right post. This then acts as a second backup or third regulator which can be used if the left post knob either gets rolled off or rolled and broken off.
(The right knob can get broken off, but will roll "on", so would be broken off in the "on" position.) Also, you never want to discover you have a roll-off by not being able to inflate - an invitation to further problems. The inflator mechanism itself must not be air balanced or high speed - it must be a slow inflator so that runaways are easier to deal with. The diver must anticipate his inflation needs, part of good form which is the hallmark of the safe diver.
Wings must not be too big or too small. A diver must start with a balanced rig which gives him every chance to deal with emergencies. In ocean or lake diving, steel tanks should never be used without a
drysuit. Double wings are an invitation to a disaster - do not use them. Elastic wings are a disaster waiting to happen. They can not be operated safely by mouth, they lose their gas if ruptured, they can not be breathed like normal wings, and they cause more drag than normal wings. For ocean, aluminum 80's are the tank of choice. If more gas is needed, take an aluminum stage, but don't risk your life being over weighted at the beginning of the dive. The buoyancy characteristics of aluminum,
especially when using helium , are such that a weight belt and or canister light will provide the necessary ballast which can be dropped in an emergency, making the rig only reasonably negative when full, neutral when empty, but swimable by dropping the weight. In cave, steel must be used with a drysuit and they must be negative enough to allow the diver to stay down in a low on gas emergency. There is nothing worse than being too light to stay off the ceiling while low on gas and then struggling. For this reason, the rig must be balanced to a no gas situation prior to cave use, and weighted accordingly.
The diver's harness is rigged from one piece of webbing - no buckles or disconnects or other failure points. One d-ring is on each chest, one on the left side. The crotch strap is also one piece, and has a loop in the front the the belt passes through. The belt buckle must be to the right side so as not to get opened by the crotch strap. This strap is necessary to hold the rig in place whether scootering or not. Any upward pressure on the diaphragm crated by unstraped rigs increases the breathing rate and discomfort of the diver markedly. The crotch strap has a scooter d-ring just below this loop. We never use a quick disconnect here. The knife is in an open sheath on the waist belt left
of the crotch strap, where it can be pulled like a gun. The backup lights are attached to the two chest d-rings and held to the strap by a bungee. This puts them under the shoulder and out of the way.
The light is worn to the right side on the waist belt, and is held on either by the same buckle that fastens the waist belt, or by a second buckle slipped on. The light head is held in the left hand , or clipped of to the right chest d-ring when not in use or when changing stages. There are no d-rings on the right side, but if a bottle is carried there for some reason, a piece of bungee cord on the belt will suffice if the bottle has the correct stage bottle buoyancy characteristics. The light is part of your weight and balance, should never be on the butt, and is under the shoulder where it is protected and out of the flow, and can be conveniently operated or removed if necessary.
Stages should be aluminum 80's. These swing equally from negative to positive with air, less negative with gas, by the amount of the air or gas carried. They are rigged with stainless steel bolt snaps, the size of which is determined by whether or not your diving requires gloves, and those are attached by a piece of 1/4" line run under a hose clamp halfway down the tank and tied to the neck. The upper clip should be tight to the break of the neck, the lower clip should have plenty of tail to work with. The bottle needs to be held close in the front and lose in the back to prevent drag. There should NEVER be any metal to metal connections of any part of your rig.
Stages need to be permanently marked as to their maximum operating depth in three inch high letters placed horizontally in the orientation of the tank on either side so that the diver can see what he is breathing, and so can his buddy, no mater where the tank is. The stage reg is rigged with a short pressure gauge which is bent back on itself to face the diver and held in place by bungee cord at the first stage, The reg hose must be the octopus length. The stage regs are always parked on the bottle and the bottle turned off unless in use. Stages are generally worn on the left side for streamlining, and because of the position and balance of the rest of the gear and the other hoses so as not to interfere with the operation of any other gear, as well as the scooter , which is driven with the right hand, favoring the right side.
To deploy a stage, we look for the correct depth marking, we put the reg around our neck, we then turn on the bottle , put the reg in our mouth, and if we can breath, we are breathing the correct gas. It is just that simple. No other convolutions are necessary, and would only add to the chance for error.
Gauges and compasses are worn on the wrists. These must be situated according to need. In the ocean, the compass is paramount, and needs to be viewable and held in its correct orientation without interfering with other activities - that means the left hand, away from the scooter. The depth gauge and timer needs to be viewable all the time, so is on the right hand. Fins straps and mask straps should be replaced with springs and stretch material that will not rot and break on a dive.
To quote Bill Gavin regarding gear, a diver must "settle for nothing less than perfection. Those who do will discover on their own the value of such effort. Those who do not will never understand what the others are talking about". What we have presented here is called the "Doing It Right" system, and is a platform that is integrated completely and accommodates all contingencies and additions, but no phobias. Use it accordingly with one caveat - "never break Rule Number One", which is "Don't dive with strokes". A "stroke" is somebody with an unsafe attitude.

What is stroke ?

by George Irvine

Very simply put, a "stroke" is somebody you don't want to dive with. It is somebody who will cause you problems, or not be any use to you if you have problems. Usually, this is a reflection of the attitude of a stroke, but that can be inherent in the personality of the individual, or others can teach it.
For instance, if somebody is taught that diving is an "every man for himself" sport, that you "can't help somebody deep," that "my gas is my gas," or "know when to leave your buddy," then that is somebody you do not want to be in the water with. Some people are natural strokes, but all too many are created. Unfortunately, people believe best what they hear first, and given the low-level food chain structure of dive instruction, most strokes are man-made, and are then hard to fix.
Obvious strokes are not so bad - you can see them and you know to avoid them. Frequently they will give it away with their choice of gear and gear configuration. If you see something that is a complete mess, makes no sense, is less than optimal, or is designed to accommodate some phobia while ignoring all else, you are dealing with a stroke. If the stroke is pontificating about how he can "handle" deep air diving, or obsessing about depth, or appears to be trying to compensate for internal fears, this is an obvious stroke and you merely avoid them.
The really insidious strokes are those who pretend to be squared away, but are in this game for all the wrong reasons. Usually they wish to prove something to themselves or others, or to overcome some internal fears. These tend to try to do things that they are not ready to do, and when something goes wrong, they flee for their lives.
Diving is not an intuitive thing. It is not a natural thing. Natural reactions of human beings on dry land do not work underwater. To be a good diver, you have to control your natural responses, and know that they can only hurt you, not help you. A stroke cannot do that. A stroke is driven by fear, ego, bullshit and self-concern.

My 77th Cave Dive

by George Irvine,

When I logged this dive in my book, I wrote, "this might be my last cave dive". It was my 77th cave dive, but someplace up near my 1000th "tek" dive, and I was still scared cave diving. Up to this point, I was always overwhelmed with joy at making it out of a cave alive, and empathized with Rob Palmer's mention of the "grass always looking greener and the sky more blue" after each dive in his "Blue Holes of the Bahamas" book, a story of exploration and adventure which describes accurately why we keep coming back. I had only been a minor WKPP support diver up to this point. My instructor, who was also Director of the WKPP, extended my time to getting a cave card out for a full year, and I had received that card from him on the plane down to Mexico on the way to do some diving in a system that I had been exploring with some other WKPP Divers.
Lamar English had taken me under his wing immediately after I started the initial cave class, and I had found Jarrod Jablsonski right away, so I had hit the ground running and was averaging about two cave dives per week. This day was to be my first support dive of any distinction in the WKPP. Parker and Bill Gavin were to do a dive to the end of Indian Springs to try extending that cave out past where Exley had left off in his exploration in a lead Gavin had spotted on an earlier dive. The system had been down for months, and was now finally diveable. Parker had basically invited all his friends to come dive, and made up dives for us that were really unnecessary, but he wanted to get the team moving again. Lamar English and I were to put in the deep deco bottles and ride out a ways to mark unexplored leads. Bill Main and his dive partner were to put in the intermediate bottles and do the same behind us. Everyone else was supporting on land and in the basin, or just doing a dive.
Right from the start , things went strangely. Parker appeared distracted, and was not feeling well. Most of the more experienced WKPP divers were all sick and in street clothes, so could not dive and were running the surface, so I offered to do the dive in Parker's place. Parker said, "Don't you think that would be a bit much to bite off right now?". His stages were not all the way full, and he had a 3x Tekna scooter (Gavin had a Gavin). I offered my full bottles and more powerful scooter. He said, "No, it's too late". He then asked me for the keys to my car. I had a built in phone , and a month later when I got the phone bill, I saw he had phoned his house.
That was November 17, 1991 - I don't need to look at my log to remember that. His wife later told me that he called her to tell her he loved her. I had mixed the backgas for both Lamar and myself, but had done so based on the wrong depth - we did not know the cave went deeper than 150. We dropped down to 110 feet and clipped off deco bottles for Parker and Bill, then took off upstream. Bill Main and his partner entered a few minutes later. Behind us, Main had called his dive about 1200 feet in and turned. Lamar and I rounded a corner about 3500 feet in and the depth crossed 150. I looked at my gauge when I had to clear my ears, and let off the trigger. I saw Lamar's blades stop spinning at the same moment. We were floating there, looking at the white tunnel in front of us. I reached for my wetnotes, try to figure out how I was going to tell Lamar that the analysis had come out two points over spec and that we had to turn - it was always me who weenied on the long dives he liked to do, but he turned to me with the scariest look in his eyes I have ever seen, and took my notes from me. He wrote, "Bubba, we are a little deep for this mix", and I was off the hook, but the look sent chills through me. Now I was scared, but I did not know why.
We turned and scootered back towards the entrance, and came across Bill Gavin and Parker nearing the stage drop. Gavin was really something to see in the water, so we stopped about 75 feet away and turned to watch them make the switch. Gavin floated methodically and executed the perfect drop and switch. Parker turned back and scootered a few feet towards me, let go of his scooter, switched his light to his right hand, held his left hand out to the side in an "OK" signal and shined the light on his hand. I returned the signal. He then went back to where Gavin was waiting and dropped his stage.
Lamar and I continued out, but never saw Bill Main - he must have turned right before we reached him. At the upstream/downstream T, Lamar stopped and checked his gas, pointed downstream and gave me the "little bit" signal. I checked my gas and gave him the "OK" signal. Again he suddenly stopped and that look came back, only this time he showed me the thumb. Now I was scared again. We scootered back to the restriction and moved through. I was felling a lot better now, we were out of the cave. I checked Parker and Bill's bottles - everything ok - and we started moving up to where Bill Main and his partner were decompressing above us.
At fifty feet, my computer wanted some unrealistic deco, so I took it off, strapped it to my scooter, and dropped the scooter to the floor below. It had been about 4 minutes since we cleared the restriction. Suddenly , everything cut loose. The water went rushing past us from above and the cavern blitzed in an underwater sandstorm. Bill Main and I both went instinctively to the ceiling to try to recapture what we thought was my runaway scooter - we both figured it had to be the scooter trashing the place and blowing the water on us from above. We could not see it sitting below us peacefully on the floor. What was really happening was that the water was rushing in from holes in the ceiling above, pulling sand and silt in with it, and in from the entrance to the cavern. What we did not know is that someplace in the system an aquaclude had cut loose turning the cave into a violent syphon which lowered the water level in the basin by a full foot and pulled whitewater rapids backwards up the spring run. The rushing water pulled sand and debris over the restriction at the entrance of the cave and the movement suddenly stopped. All of the silt and sand water had been sucked into the cave, so amazingly we were sitting in clear water again. I dropped down to my scooter , still not believing it was not responsible, only to find it untouched. I noticed that the deco stop was gone from the screen - it had been four minutes that the cave flowed backwards. None of us got it. Nobody on the surface got it. Nobody came in to check on us. This would be a day that ended the easy going "volunteer" WKPP of old, if it did not end it for ever. In fact, that day all but four of us quit the Project and most quit cave diving for good. Gradually, the cavern started silting out again. Lamar and I were getting uncomfortable about it, but we still did not know why. Bill Main and his partner had already long gotten out. We were at 20 feet. I decided to check on Parker and Bill, so I dove back down to 110 feet. Everything appeared the same, but I did not go far enough to see the restriction, which was no longer there. The bottles were untouched in the same place I had put them , clipped to the line. I began wondering about the length of the dive relative to the gas supply, but these guys were the pros. I came back up to Lamar, and did not see the support divers come past me in the silted out cavern, but figured they must be there and must be silting it out.
What was really happening was that the cave had blown the restriction back open again, and the silt cloud inside was flowing out. Lamar and I surfaced. Lamar was right up against me on the surface, and he had that look again. We were out of earshot of everyone. He asked me if I saw Parker and Bill went I had gone back down. I said "no, their bottles are still there". He floated there thinking . Then the support divers popped up by the dock. Steve Irving asked them if everything was OK. One said, yes. Steve said, "Did you see them both, where are they?". One said , "I saw Bill". the other said, "I saw Parker, he waved at me". The other said, "That was not Parker, that was me". Lamar got real close to me and whispered, "Bubba, something is not right. I am going to go check". He dropped down, and reappeared about two minutes later, again whispering, "Parker is screwed I found his tanks on the line with his light on and he and Bill are not there". I deflated my wings and dropped down, scootering down the now blacked out cavern to 110 feet. I passed one intermediate bottle clipped to the line and then I saw one deep bottle still clipped to the line.
I clipped in with my spool and hit the inflator, going to the ceiling. I kept trying to remember what that cavern had looked like, but I had never really taken a good look. I was amazed at how far up it went. I then started sweeping in the zero vis, banging along the ceiling of the cavern. I ran smack into Gavin. I could not tell who it was at first, and was feeling all over him to see if he was alive. He did not move, but I could hear him breathing. I found his pressure gauge and held it up to my mask it read zero. I grabbed his stage gauge and saw he had gas, He was on his shallow bottle. He had used the deep bottle and jettisoned it apparently, and was still sitting on the ceiling, off the line, silted out on the second bottle.
He passed me a little tiny slate. I could not read it. I pressed it up to my mask and shined my light at the side of the clear silicone skirt - "Parker is dead". I felt like my heart stopped. I kept holding the slate to my mask. I woke back up - I had to get Gavin to some gas. I asked him if he knew where his oxygen was. He said yes. I did not believe him. I don't think he cared where it was. I realized he was not in a good space. I could not get him to move. I tied my reel to him, then ran it to the trough, then out and to the surface , over to the dock and tied it off to a piling.
Everyone stopped what they were doing and looked down at me from the dock. I tied to get myself together to speak. "Parker is dead", I could hardly get the words out. Bill Main started pacing back and forth. He said, "That is not supposed to happen". I said, "Bill, you have to go down and get Gavin - he won't move". I tied off to him. Just follow the line and get him up to the trough. Lamar went down my line and Bill had his tanks on in seconds. They followed the line to Gavin, moved him to the trough and sat there with him for nearly four hours. I never asked what went on, but I didn't have to and didn't want to know. Bill Gavin was beyond upset.
When I saw that Bill Main and Lamar were on it, I went back down the main line, tied in and began sweeping again. I did this nine times with stages and backgas until I ran out of gas. I could not find Parker. I forgot to decompress, and just got out when the gas was gone. I was sick. The cops were there and it seemed like 100 other people were streaming in. I remember Tara Tanaka showing up and a bunch of other cave divers, like they appeared by some magic call. Everyone kept asking me if he could be in an air pocket on the ceiling, and I kept telling them that the ceiling was well under water. I got sick of telling them that and went to my car and called Alton. Alton loved Parker and so did I. Bill Main and Sherwood Schile got in the car and drove over to tell Penny Parker, not the kind of thing you ever want to have to do, and they were the only ones among us who could do it that day. We told the cops we needed to go reload our gas and come back to look for Parker. We all went back to Steve Irving's house where the compressor was. Bill Gavin parked his van outside and sat there all night, while Carlyanne Johnson stayed with him.
We went back down the next morning, and Gavin laid out the plan for clearing the restriction and bringing out Parker. Then the cops showed up and told us they had done it at 6:00 am. Parker had trained them to cave dive and do body recoveries. They did not want to leave him in there. Gavin and the rest then got ready to go in and retrieve all the gear that was behind the restriction. I did not want to get back in the water for gear, even with the light duty Gavin assigned to me. I got in my car and left for Ft Lauderdale. I cried all the way to Perry. I don't know whether it was because of Parker, or because four more minutes later would have meant all of us.
Gavin later told me that he and Parker had reached where the restriction was supposed to be and the line just disappeared under the sand, and that the main tunnel was totally blacked out. Parker's scooter had failed and Bill was towing him. He got Parker to wait while he scootered back to the upstream/downstream T to see if maybe he had gone the wrong way. Imagine what was going through the mind of an 18 year veteran cave diver diving in a place he knew like his own house. He came back to the restriction. For 45 minutes they tried to find a way out, tying in their spools to where the line was buried and searching forward. Gavin told me they were down to almost no gas, and he knew they were going to die. He said he did not want to see Parker die so he moved over to die by himself. At that moment, they felt the water flowing, and followed it. Parker had taken his tanks off and was dragging them behind him. Gavin left his on. Both had hit the entrance as it blew open with less than 100 psi in their tanks. Without his backtanks for weight, Parker must have been struggling to stay down, used the last of his gas and blacked out. The ceiling on the other side of the restriction is at least 30 feet above the floor, and he could not hold on .
Gavin made it the few feet to his bottle and got the deco gas just as he ran out. Gavin told me that knowing you are going to die is the most desperate feeling there is. He said you don't ever want that to experience that. All of our worst fears in cave diving demonstrated. I called Jarrod. He said, "you have to get back in the water". I did not even want to take a shower, let alone go cave diving. A few weeks went by, and Jarrod told me to come up to High Springs and he would go diving with me. I called Lamar, and got him to meet us at Ginnie. We were both freaked, but JJ stayed real calm with us. JJ told me, "We'll just do an easy dive, you have to get back in". We geared up, and then Lamar stopped, "I just can't dive right now", so JJ repeated to me, "you have to get back in the water", so I went. He started out real slow and easy, attentive as always, no stress. The cave was clear and beautiful. It was night and nobody was there. We dropped our stage at the Hinkle and dove all over the back of the cave, in ever squirrelly, crazy place JJ knew, and came back out about 90 minutes later with one of the best cave dives I had ever done. JJ got me back. A couple of months later I called Bill Gavin and got him to go to Mexico with me. Parker had told him he needed to see the stuff that we had seen, so we took a couple of weeks and did the tour. By the end of the trip, Gavin was back and talking about moving to Mexico, but that experience never let him alone. In the film NHK made about the WKPP, in an interview with Gavin, he said, "A day has not passed that I have not thought about Parker".