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Also diving in the 20 to 30m range, you could "bail out" on EAN50. I know the pO2 is too hi at 25 to 30m. So don't call me a stroke yet. JS. At 00:01 13/01/00 +1100, you 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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