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I do not know if the calculations are correct, but I do know that the brain chmistry gets severely depleted. I break < every 20 minutes to back gas no matter where I am in the deco, and I do a "clean up" 20 minute back gas stretch before I go to the 70 bottle and again at 50 feet on long ( > 2 hour ) bottom times. Whether or not that is bullshit is a bet I am not wiling to make. I also reduce the ppo2 of th eb ack gas according to bottom time, generaly under 1.0 for long dives. Anectodatal commercial diving experiecnes say this is all correct. The CNS "clock" is merely Hamiton's attempt to put numbers to it. I do not use number for any part of my deco, but I do understand how to do all of it - much more important. If you are asking whether I add breaks to deco, the answer is NO. Breaks are not added to deco time, thery are substituted for it. It is all part of the game. Paltz, Art wrote: > > George, > > Sorry about taking so long to get back but my companies email system has > been down from Thursday until now on Sunday. What I was referring to in > particular is the CNS clock, not that toxing isn't a real issue. > > Thanks for the info! > > Art. > > -----Original Message----- > From: kirvine@sa*.ne* [SMTP:kirvine@sa*.ne*] > Sent: Thursday, December 30, 1999 9:41 AM > To: Paltz, Art > Cc: Shimell, David (shimell); QUEST@GU*.CO*; techdiver > Subject: Re: SAMPLE DECO DIVE - 220 FOR 25 > > Sure , Art - the only two issues are that 1) Navy found an increased > chance of toxing after multiday elevated ppo2 exposures ( like > nitrox > diving every day or deco diving every day ) with the MK16 divers, > and 2) > the lung damage and such are obvious and cumulative. The lungs tend > to > scar and build "callusses" , decreasing vital capacity. > > Art , I do not know what I said about anything being bullshit > unless it > is what the agencies teach, and that is solid bullshit, but I take > oxygen exposure very, very seriously, and to me it is the biggest > risk > in tech diving outside of violating Rule Number One. > > Paltz, Art wrote: > > > > George, > > > > Can you elaborate on Oxygen Exposure? I remember you saying many > times that > > OTU's and CNS clock's are BS. How do you track this? What about > repetitive > > dives? > > > > If you covered this before in the thread I apologize, I must have > been > > snoozing... > > > > Thanks, > > Art. > > > > -----Original Message----- > > From: kirvine@sa*.ne* [SMTP:kirvine@sa*.ne*] > > Sent: Wednesday, December 29, 1999 2:26 PM > > To: Shimell, David (shimell) > > Cc: QUEST@GU*.CO*; techdiver > > Subject: Re: SAMPLE DECO DIVE - 220 FOR 25 > > > > I ignore the first dive - in this case you have mushed the > bubbles > > anyway. After enough time, I ignore any first dive other > than as > > regards > > the oxygen exposure - that is where the risk lies. > > > > Shimell, David (shimell) wrote: > > > > > > George > > > > > > Here's another question. > > > > > > Say you do your 220' for 25 and then ascend to do a > multi-level > > dive to say > > > 90' for 25. How would you calculate the deco for this? > I recall > > you once > > > talked about superimposing one table on another but I > had it on my > > list of > > > things to look at. > > > > > > David Shimell > > > Email: shimell@se*.co* <mailto:shimell@se*.co*> > > > Project Manager, IBM NUMA-Q, Sequent Computer Systems > Limited, > > > Weybridge Business Park, Addlestone Road, Weybridge, > Surrey, KT15 > > 2UF, UK > > > registered in England and Wales under company number: > 1999363, > > registered > > > office as above > > > > > > -----Original Message----- > > > From: kirvine@sa*.ne* [SMTP:kirvine@sa*.ne*] > > > Sent: Friday, December 24, 1999 12:43 PM > > > To: QUEST@GU*.CO* > > > Cc: techdiver > > > Subject: SAMPLE DECO DIVE - 220 FOR 25 > > > > > > Let's run through a sample dive. I will throw out the > parameters > > and > > > the standeard deco on one side, and my changes and why > on the > > other ,and > > > then we can discuss it. > > > > > > We can then build the dive into a longer dive, a deeper > dive and > > we can > > > add more gasses and more stituations, and then the > equipment to do > > it. > > > > > > Let's start with this and get the discussion going that > way. I > > need all > > > questions, no matter how sophisticated, so we can get > out the > > rock. > > > > > > ***PROFILE 220 FOR 25 CHANGES > > > ***GAS 16% OXYGEN 50% HELIUM 1.2 PPO2 > > > 85 AED > > > > > > REASON FOR GAS CHOICE: the more heluim, the > better . It > > is > > > easier to breathe at depth, and it is easier to > decompress from, > > > contrary to what you have been told elsewhere. The > reduced narc is > > > obvious. I chose the 50% heliuum for this , but the more > the > > better. The > > > oxygen ppo2 should be kept intentionally low. The reason > is that > > you do > > > not want to unnecessarily deplete brain chemistry to > pick up > > "perceived" > > > deco advantage, expescially in light of the fact that we > have > > boosted > > > the helium which reduces the nitrogen damage and > loading, and thus > > the > > > deco requirement. While inert gas is inert gas for > purposes of > > this > > > discussion ( or said another way, the oxygen window is > the oxygen > > > window) the reality is that helium changes the > physiological > > factors > > > that are as real in deco as the straight compartment > loading and > > > unloading factors. Very important to us in our diving, > and more so > > as > > > the dives get more severe or repetitive. We also do not > want to > > burn the > > > shit out of our lungs with high PPO2's either, and keep > in mind > > that > > > depending on the bottom time, we are going to be forced > to expose > > > ourselves ot elevated oxygen to decompress. > > > > > > It is critical in multiday exposure that you reduce the > oxygen > > dose, and > > > we will show how to do that in each decompression. > > > > > > STANDARD DECO FROM A PROGRAM REAL LIFE DECO > > > > > > DEPTH TIME GAS DEPTH TIME > GAS > > > 160-120 1 MINUTE > EACH ON > > BG > > > 110 1 16/50 110 1 > > > 100 3 100 1 > > > 90 4 90 1 > > > 80 5 80 1 > > > 70 3 50/50 70 5 > 50/50 > > > 60 4 60 2 > > > 50 5 50 3 > > > 40 9 40 5 > > > 30 11 30 8 > > > 20 17 OXYGEN 20 13 > OXYGEN > > > 10 26 20-0 8 > > > > > > TOTAL 88 TOTAL 60 > > > > > > REASONS FOR CHANGES > > > > > > 1) we start our deco at 80% of the profile in > atmospheres, or in > > this > > > case , around 160 feet. We are not changing gases yet, > so no > > reason to > > > sit on these stops. The ascent rate is 30 fpm, or the > equivalent > > of a 20 > > > second stop every ten feet from the bottom, so we are > really only > > adding > > > 40 seconds per "stop" from 80% of the profile. This > actually > > "maxes out" > > > at about 5 minutes per "deep stop" in anything > approaching > > saturations, > > > which I call 150 minutes for the purposes of > decomprssion reality > > as > > > opposed to trying to decompress a whale. In a long dive, > we also > > use the > > > first deco gas at 80% of the profile . Not in play here. > > > > > > 2) moving up we do not extend these stops per Bulhmann, > since we > > have > > > already moved the "ceiling" quite a long ways above us, > and are > > not yet > > > really pressing the gradient ( in percentage or relative > terms, ie > > the > > > ratio of the atmospheric change deep a opposed to > shallow). We > > need to > > > get to a deco gas first and spend some time, so...... > > > > > > 3) we "SIT" on the 70 foot stop for quite a bit longer > than is > > suggested > > > by theory. The reason is we want to use that wide open > oxygen > > window for > > > all it is worth down there to both clear the slate as > much as > > possible, > > > and to move that ceiling again quite a bit so that we > can > > abbreviate the > > > stops above as their ppo2 declines, rather than > lengthening them > > as > > > either Bulhmann or bubble mechanics would indicate - > real life > > says we > > > are correct. In fact, I have SKIPPED up to 100 minutes > of our 40 > > foot > > > stops with no repercussions, and Lucy Ho can vouch for > me on this > > ( and > > > the doppler says so). The other reason is that we want > to give the > > blood > > > a chance to totally circulate with the new gas. While it > hits the > > key > > > body parts immediately ( spine, heart, brain), it takes > a couple > > of > > > minutes to get to everything properly. We do not want to > hammer > > high > > > popo2's, we want to use them to our advanntage. > > > > > > 3) since we have done our deep stops and our high > ppo2's, both > > moving > > > our ceiling and shortening our upper time, we can go > ahead and > > press the > > > gradient as it condenses, and shorten the next few stops > and get > > to that > > > oxygen. > > > > > > 4) the oxygen does not have to be hit too ahrd. I like > 12-13 > > minute > > > stints with 6-8 minutes off. The reasons are that it > takes almost > > no > > > time to saturate with oxygen at any ppo2 once the > immediate > > offgassing > > > slows - a few minutes - and the damage starts to accrue > after > > about > > > 16-20 minutes in our experience, depending of course on > the > > dosages > > > already taken on the way up to this point. The swelling > of the > > lung > > > tissue picks up after a few minutes, and the gas > transfer process > > is > > > severely hampered. Vasoconstriction gets worse, and you > are > > pissing in > > > the wind honking on the oxygen. You need to break to > back gas, or > > in > > > this case , just move up and get out. > > > > > > 5) slow final ascent - the last move up to the surface > is one of > > the > > > most critical. No matter how long you sit on a stop with > the > > window wide > > > open, there will still be gas that will not be displaced > by this > > method. > > > When you increase the gradient by trying to surface, the > last of > > the gas > > > comes out rapidly and does so in bubble form. You must > do a slow > > ascent > > > to reduce the risk of this, and for long dive it is one > foot per > > minute > > > to the surface, for this dive it is more like 2.5 - 3 > fpm. > > > > > > 6) at the surface, sit still for a bit and try not to > exert for > > about 30 > > > minutes thereafter. Bubbles forming at this time will > now grow as > > they > > > pick up offgassing nitrogen ( the helium is long gone) > and will > > become > > > problematic later, and severely so if you have a shunt > that can > > then be > > > opened by the in increasing pressure on the cappillary > beds of the > > > lungs. > > > > > > OK - let's take it from here and get the discusion > going. Please > > do not > > > copy back the whole message or it will become a mail > bonb - just > > cut and > > > paste the parts you want to discuss, and lets discuss > one item per > > > email, SVP. When we expand this to a long dive, then I > will cross > > copy > > > it to WKPP@eg*.co*, and we will bring in the big > guns ( Rose, > > Mee > > > ,et al). > > > > > > Let's go . > > > > > > -- > > > Send mail for the `techdiver' mailing list to > > `techdiver@aquanaut.com'. > > > Send subscribe/unsubscribe requests to > > `techdiver-request@aquanaut.com'. > > > > -- > > Send mail for the `techdiver' mailing list to > > `techdiver@aquanaut.com'. > > Send subscribe/unsubscribe requests to > > `techdiver-request@aquanaut.com'. > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: quest-unsubscribe@gu*.co* > For additional commands, e-mail: quest-help@gu*.co* -- Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.
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