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(a short novel by Jess Armantrout) As a result of the recent deep stop thread, several people have asked me to explain what we (WKPP) do for deco. Rather than reply to each individual, I will make this post. It is going to be long, so if you are not interested, go to the next message. I suggest you print it out if you can...it will be easier to digest. This is what I do. I do not suggest anybody attempt to duplicate this and assume no liabilty for any harm you do to yourself trying to copy this. DO NOT TRY THIS AT HOME. Also, I do not speak for the entire WKPP. This is what I do and I do not claim it is right for everybody. First, you all must understand that explaining deco is like explaining the El Nino phenomenon. You can get a pretty good handle on what is going to happen, make some predictions on when, even create a model to say where. But there are just too many variables and when it actually starts to rain, you have to reevaluate the new data coming in. The same is true with deco. The next thing I must make clear is that I hate physiology. I get faint at the sight of blood, queasy at the discussion of medical stuff and just flat hate biology. That is why I got a degree in electrical engineering. What does that mean? I do not understand all of the medical aspects of decompression nor do I wish to. Quite frankly, I hate that stuff, so don't try to ask me about it or argue with me about it. However, my engineer side can listen to people with that kind of info and make decisions based on what I hear. I then go out and do test runs and evaluate the results. For example, Bill Mee is our main source of biology info. He knows that stuff. He want thru a long explanation of why I needed to take antioxidants and I understood none of it. I did get the point that antioxidants are important so I began implementing them a few days before a dive, during a dive and just after a dive. Now a bunch of you are going to jump up and say antioxidants are bullshit and give me all kinds of reasons why you think that. Don't waste your time. My *experience* says they help and until your *experience* demonstrates they hurt, well I just don't care. The other thing we have going for us is a tremendous amount of empirical data from which to pull. George Irvine, WKPP project director, has spent a huge amount of money buying data and tables from the commercial guys. Then there is the team itself. On any given weekend we have 10 to 20 dives that are pretty much considered from ridiculous to flat out insane. Before and after the dives, Ma Bell makes a small fortune as we all call each other and talk about what we did last time, how we felt, what we are going to do this time, etc., etc., etc. Then, the other source of data is what Jimmy Buffett calls the "Coconut Telegraph" a.k.a. the grapevine. Most if not all of the serious players throughout the world exchange data with the WKPP via e-mails, phone calls, faxes, etc. Even guys we may not get along with share data. Another thing we have available to us is some of the top medical guys. Bill Hamilton evaluates what we are doing although I think most of the time he is just shaking his head in amazement that we are not all in wheelchairs. And for our last big dive of the season, Dr. Chimiak form the Navy came down to doppler us. He too seemed amazed. These guys and others collect our data and try to figure out why things are working for us. Now a lot of people complain that we don't make all of this info readily available. Guys, this is not a static process...it is a dynamic process and it is changing so rapidly, like weekly, that nobody has time to write it all down in one place. Each guinea pig, er, I mean WKPP diver would need to keep detailed logs of how much they slept, ate, drank,exercised, etc., before a dive, then detailed descriptions of the dive profiles would need to be kept, detailed descriptions of the deco profiles used would need to be compiled and finally detailed descriptions of how we felt after the dives would need to be kept. Quite frankly, we are too busy/lazy/tired to do all of the that. So, having made the previous page or so of preface, what are we doing? Let's take my last big dive of the season as an example. The plan was 285' for 150 minutes (real bottom time calculated from the time we left our 190' switch to helium on the way in to the time we got back to our first deco stop at 240'.) The first thing I did was run DECOM to get a template or guide to the anticipated deco. By the way, guys, that is all those programs are... templates. Anyway, tabulated below is what DECOM (set at 0 and 0 safety factors) called for as well as what I actually did. (I actually wrote this down as I was doing the deco to give to Hamilton and Chimiak...Hamilton told me I was bent.) DO NOT TRY THIS. THIS SCHEDULE IS FOR DISCUSSION PURPOSES ONLY. ANY ATTEMPT TO PERFORM THIS DIVE MAY RESULT IN DECOMPRESSION SICKNESS OR DEATH. 285' for 150 minutes depth DECOM actual (10/60 trimix) 250 2 (18/35 trimix) 240 2 230 3 220 1 4 210 1 4 200 1 5 (20/25 trimix) 190 1 5 180 2 6 170 4 6 160 5 7 150 7 7 140 9 8 130 8 8 (35% nitrox) 120 10 10 110 9 8 100 15 13 90 14 12 80 23 20 (50% nitrox) 70 21 21 60 35 30 50 38 33 40 67 60 100% o2 in habitat with 10/60 trimix gas breaks as needed. After 30 foot stop, 1 foot per minute ascent to surface on 35%. 30 61 180 20 110 10 117 total deco 559 484 From this you should be able to see that I lengthened the deep stuff significantly, left the 160 to 120 stuff pretty much alone, started shaving the intermediate stops then chopped the last three stops down considerably followed by a very slow ascent to the surface, 30 minutes to get up from 30 feet. This was to eliminate the oxygen and reduce that chance of oxygen bends, again something the "experts" on these lists tell me I can't get but I always do get if I don't do this super slow ascent. This slow ascent is included in the total deco by the way. Why do I do this? I don't know. I take into account everything...was the dive easier or harder than expected? Was it a flat profile or lots of ups and downs (pad for ups and downs)? Could I ride on the roof or did I have to stay on the line due to bad viz? Am I rested? Am I hydrated? Am I in shape? How does my right elbow feel? What time does Outback Steak House close? Do I have statistical proof to say it is correct? Nope. But after a lot of trial and error, of listening to what works for my teammates and, most importantly, listening to my body on pervious and current dives, this is what I have arrived at. And that seems to be another key...lots and lots and lots of diving. I dive deco dives three weekends out of four and would do more if I thought I would not be divorced. It is perfect? I doubt it and I am looking forward to the new season to refine it. By the way, all three guys on my team did exactly this profile and all were fine. In short, we believe the Buhlman algorithm to be incorrect in that the shallow stops are too long and the deep stops are too short, thus making the shape of the deco incorrect. This is based on our collective experience. Now, there are several keys to being able to get away with this deco, and guys, that is exactly what it is...getting away with it. Every time I successfully finish a deco I consider myself lucky because there are so many variables. The most important thing is to avoid getting bent deep. If you blow past your deep stops and a bubble forms, it is too late. You may as well get out of the water and go to the chamber. If a bad bubble forms, all the deco in the world won't help until you recompress. So make sure to take care of the helium bubbles. You also have to think "what if I have to abort my deco?" By getting rid of as many bubbles as possible deep, where they come out easier and tax the lung-filter less, you increase your chances of surviving an aborted deco. If you are constantly right up against your deco ceiling (what the Buhlman algorithm calls for) and blow up, you are screwed. Deep stops allow you to move your ceiling up. The second most important thing is don't fry your lungs. We start back gas breaks as soon as we start deco. In other words, my first gas break was after 25 minutes deco at around 190 feet, for 5 minutes on 10/60 and then again at least every 25 minutes. Do not penalize yourself and not count this time in your deco which is what the agencies teach and which is wrong. This is the second most important aspect of deco after deep stops. Again, if you fry your lungs (pulmonary tox) you may as well get out of the water because gas exchange ceases and you are just wasting time. By the time deco ends, as much as 50% of the time or more is spent doing gas breaks. The third most important aspect is hydration. I drank one entire gallon of fluids prior to this dive and stashed two gallons along the deco. I use quart jars of Powerade myself. Others use different stuff. There are some concerns with drinking drinks with sugar in them, but I do not seem to have any problems. I took 4 Advil the night before along with an antioxidant supplement, repeated this the morning of the dive, 4 Advil when I got back to deco, 4 more when I got into the habitat and 4 more and another antioxidant when I got out. Most of the guys dissolve the Advil in their drinks that they stash at deco. I will do that this season. The Advil is a preemptive strike against inflammation. With all this drinking, it is very important to make sure you P tube does not get kinked. Also, on a dive of this length, no. 2 is a concern. I hate coffee, but have learned that a cup first think in the morning helps get the bowels moving. Thermal considerations are probably the next key. We of course all dive DUI drysuits with C-4 thinsulate or equivalent (the Bare underwear looks promising as well). I add a set of thinsulate thermal ski underwear and a polartech vest. We use argon for suit inflation. This dive was done on rebreathers so we had the added warmth of the exothermic reaction of the scrubbers to help. And believe me, that makes a big difference. Now, a lot of people argue that a fixed PO2 rebreather or more deco gases that would allow you to keep your PO2 higher would be better. We say bullshit. We believe the WKPP deco gases as listed above and developed by Hamilton are the best balance of high PO2 and not frying your lungs. What good is a fixed PO2 if it has to be at .8 to avoid pulmonary toxicity problems. The temporary spike to 1.6 that occurs with each gas switch is quickly relieved as we move up lessening both pulmonary and CNS problems. Again, until somebody else does it, I really don't want to hear about the advantages of fixed PO2 for deco. Even the usdct guys were not stupid enough to try that with the Cis Lunar during their stay at Wakulla. Fitness is of course very important to being able to pull off these decos. It helps the circulation, reduces fat and helps keep fatigue down. Again, until an HFS does this, I will keep running and swimming. Rest is important. On dives where I drive from Mobile to Tally just before a dive, I always deco worse than when I drive in the night before. This is part of the reason stuff like the Doria would be hard for me...I don't think I could rest well. Finally, as much or more than anything, the selection of your parents may be the most important factor in preventing DCS. I don't know why, but some people just don't get bent, while others, all things appearing equal, do. Don't fight nature. If you do get bent, don't do this kind of diving. One of my best friends in the world and an excellent diver, Steve Dittner, gave up this stupidity because nature was against him. He did everything right, saw all the doctors who said he was fine and he still got bent on a regular basis. This stuff is not worth that. I am sure there is a lot more to say, but I am going diving. Good luck to all and be careful, Trout -- Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.
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