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Hello Billyw Hmmm it gets tricky.... If you are also using nitrox as a bottom mix then you don't want to accelerate your OTU's very fast just when you have started your deco stops. I believe air breaks can be handled and calculated much better on your last stop. AND NOT ONLY THAT : lets follow the worst scenario lets say that you have everything on control and on surface you have the symptoms 50% is next to nothing. My humble opinion. Rgds Manos Manoli Cyprus - Limassol bdi@wh*.ne* wrote: > At 08:08 12/01/00 , Manos Manoli wrote: > >Jeff i made many many tests with diferent Ean mixtures belive me > >100% oxygen on 6 meters does a hell of a lot diference than 50% on all stops. > >Plus you can stick with it on board if you screw up thinks. > >To be precise i tested 40% on all deco stops and create an excel table someware > >ill try to find it for you but from my personal experience is that nothing > >compares > >to pure oxygen. > > Manos, on these 'lite' technical dives, you can > get onto the 50 earlier to open the oxygen window. > > With deep stops & 50, you've done more of your deco > earlier, rather than leaving it all for the 02 to > flush-out the bubbles at 6 metres. > > rgrds billyw > > >Jeffrey Swann wrote: > > > > > Dear List, > > > George > > > Are you saying, that you get into deco time with a single tank. > > > This seems to throw away your teachings. > > > I mean, frankly where does recreational and tech diving separate. > > > I do alot of nitrox type diving. > > > That is 20 to 30 m wrecks, multilevel, etc. > > > I use a harness routinely now and practice redundancy. > > > This brings me to the point: > > > What is wrong with carrying a pony with a single. > > > I sling it across my waist, clipped up tight. > > > Reg clipped off, on the harness. > > > Back gas EAN 36. > > > Pony 25 cu ft EAN 50. (or similar) > > > Also, if you do a 25 to 30m dive, George are you just using nitrox, or are > > > you putting some He in that as well. > > > The dive boats we are using for harbour dives, don't lend themselves to > > > using twins. > > > Excepting if I use my twin 55's. > > > Sorry if I am ranting. > > > Anybodys comments welcomed!!! > > > Jeff of Darwin. > > > > > > At 20:09 10/01/00 -0500, you wrote: > > > >Art, I was kind of thinking that the worse shape you are in , the better > > > >that trick would work on a relative basis: the guy who sits on the > > > >backgas and extends the stops will ongas more stuff than he loses( > > > >although in different places) - his only real chance is to force the gas > > > >out and treat himself with the oxygen. > > > > > > > >For the fit diver, helium especially is a great gas even when the ppo2 > > > >is low. Bill Me and I deco out on backgas a lot and don't get hit on > > > >relativlely deep dives with short bottom times. I hate to admit this, > > > >but we do a lot of these on single 80's with no deco gas at all. Now > > > >that should get the weenies howling, but see Weinke's stuff - his work > > > >says it is very doable. > > > > > > > > > > > >Paltz, Art wrote: > > > >> > > > >> I've been following this thread with good interest. Are we saying that on > > > >> this particular profile that had we lost the 50/50 mix that we should > > > >> probably just follow the planned 50/50 stops but use back gas? Then do our > > > >> planned 100% stops as scheduled? I think this probably works if you could > > > >> just come up to 20 foot anyway. Knowing that most people are not in the > > > >> same shape as George, the question is for the normal diver in relatively > > > >> good shape who has done similar dives without having to resort to in-water > > > >> contingency planning (i.e. has not lost a gas) and has had no trouble, > > > >> should they just follow the planned schedule substituting back gas for > > > >> 50/50? Sorry so long but that's just the way it came out. > > > >> > > > >> I think to summarize and simplify, if in descent shape and experienced in > > > >> these types of dives and you loose the deeper gas should you: > > > >> a). Substitute lost gas with previous gas (possibly back gas) and continue > > > >> with planned schedule. > > > >> b). Do to previous gas (back gas in this instance) and try and fudge a > > > >> little by adding stops (probably dangerous on deep stops) > > > >> c). Panic and surface, signal for correct gas and try and go down and hold > > > >> your nuts hoping someone comes to the rescue. > > > >> d). Something else? > > > >> > > > >> The above assumes that "previous gas" is probably better than just saying > > > >> bottom mix. Correct me if I'm wrong but I would assume that if you were > > > >> using say 35% Nitrox, 50/50 and O2 in the schedule you should use the > > > >> remaining 35% for the 50/50 stops if you lost the 50/50 gas. Maybe on a > > > >> profile where you're necessitating more than 2 deco gases the answer > > > >> changes. > > > >> > > > >> Thanks, > > > >> Art. > > > >> > > > >> -----Original Message----- > > > >> From: kirvine@sa*.ne* [SMTP:kirvine@sa*.ne*] > > > >> Sent: Monday, January 10, 2000 10:14 AM > > > >> To: Shimell, David (shimell) > > > >> Cc: Ian PINKSTONE; techdiver@aquanaut.com > > > >> Subject: Re: I think I understand > > > >> > > > >> Move up = shallower. You can do the 50% as if it were oxygen > > > >> timewise, > > > >> and if you lose that you can do the backgas as if it were 50% > > > and go > > > >> to > > > >> the oxygen. What I am saying is do not extend the table because you > > > >> have > > > >> the wrong gas - the upper deco steps can be screwed with > > > >> unmercifully > > > >> without any real consiequnces, it is the deep ones that you must so > > > >> corectly. > > > >> > > > >> I'll let you in on a little secret - you could do this dive and > > > come > > > >> right to 20 in quick steps , do 20 minues on oxygen and get out > > > >> clean - > > > >> done it, and done al ot worse and gotten away with it. These are > > > the > > > >> real measures you take in an emergency. > > > >> > > > >> Shimell, David (shimell) wrote: > > > >> > > > > >> > George > > > >> > > > > >> > Most interesting stuff... > > > >> > > > > >> > >In real life, you are btter off moving up and taking the > > > gradient > > > >> > >offgassing as bubbles while still underwater than you are > > > sucking > > > >> on the > > > >> > >wrong gas and lengthening the stops, > > > >> > > > > >> > Going pack to your suggested deco profile: > > > >> > > > > >> > Profile 220' FOR 25 > > > >> > 16/50, 50% and O2 > > > >> > > > > >> > DEPTH TIME GAS > > > >> > 160-120 1 MINUTE EACH ON BG > > > >> > 110 1 > > > >> > 100 1 > > > >> > 090 1 > > > >> > 080 1 > > > >> > 070 5 50/50 > > > >> > 060 2 > > > >> > 050 3 > > > >> > 040 5 > > > >> > 030 8 > > > >> > 020 13 OXYGEN > > > >> > 20-0 8 > > > >> > > > > >> > I would like to better understand what you mean by "moving up". > > > >> > > > > >> > Following a failure of the 50%, are you suggesting that you > > > >> continue the deco > > > >> > as if 50% had been available i.e. follow the schedule but on BG. > > > >> > > > > >> > Or are you saying that 16% is so worthless that you would skip > > > the > > > >> stops and > > > >> > go straight to O2 at 20', if so what kind of ascent would you do > > > >> from 70' to > > > >> > 20' to give your system a chance to cope with the bubbles? > > > >> > > > > >> > 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: Thursday, January 06, 2000 4:48 PM > > > >> > To: Ian PINKSTONE > > > >> > Cc: techdiver@aquanaut.com > > > >> > Subject: Re: I think I understand > > > >> > > > > >> > Ian, these decos are so severely overstated that a loss of a gas > > > >> is > > > >> > insignificant. I did a whole Wakulla deco on my 190 bottle right > > > >> through > > > >> > 20 feet on a 30 minute bt at 300 and never got hit, using a > > > >> schedule for > > > >> > switching. I kept screwing up the gas switch and not knowing > > > it. I > > > >> only > > > >> > found out when I got to 20 feet and my O2 was not there, and I > > > >> then saw > > > >> > that my 120 and 70 bottle were both untouched, and that I was > > > >> about out > > > >> > of gas on my 190 bottle. So much for deco. > > > >> > > > > >> > In real life, you are btter off moving up and taking the gradient > > > >> > offgassing as bubbles while still underwater than you are sucking > > > >> on the > > > >> > wrong gas and lengthening the stops, and in real life if you have > > > >> > anything approaching the deocompression time that you are > > > >> suggesting > > > >> > here, you not only have support with extra gases available, you > > > >> have > > > >> > buddies to share with. I just did a dive wher I shared the 70 > > > >> bottle > > > >> > with my dive partner last Sunday, and it worked fine. > > > >> > > > > >> > -- > > > >> > 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'. > > > > > > > >-- > > > >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'. > > > >-- > >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'.
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