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What if using two computers is convoluted solution to a non existent problem and thus makes you a stroke? THOMAS > -----Original Message----- > From: Ian Puleston [mailto:DiverIan@pa*.ne*] > Sent: Monday, June 12, 2000 1:18 PM > To: techdiver@aquanaut.com > Subject: RE: Oxygen Toxicity - using 100% in open water > > > What if a battery dies? The separately powered redundant backup > system takes > over. What if the display dies? You flip it over and use the redundant > display on the back. How does the backup know about your gas switches? The > primary passed that info to it whilst they were both operational. What if > you lose a gas? You hit the "Lost Gas" button. Pyle / WKPP stops? Download > the relevant software to the computer (note the Abyss Explorer is going to > be downloadable - hopefully it'll start a trend). > > All the problems you've brought up could be solved by a well designed > computer today. Like I said - the right computer for tech diving > doesn't yet > exist, but that doesn't mean that it won't one day. > > > How useful are your 2 computers when the deco that the > computers suggests > > is wrong anyway? > > What's the alternative - cut tables using software on a PC. What if its > wrong? What if you made an error copying the tables to your slate? What if > you lose your slate? > > > -----Original Message----- > > From: ScottBonis@ao*.co* [mailto:ScottBonis@ao*.co*] > > Sent: Sunday, June 11, 2000 4:28 PM > > To: se2schul@uw*.ca*; donburke56@ya*.co*; techdiver@aquanaut.com > > Subject: Re: Oxygen Toxicity - using 100% in open water > > > > > > In a message dated 6/11/00 3:03:53 PM, se2schul@uw*.ca* writes: > > << Scott, > > > > What if you lose a gas? You can't reprogram you computer in the > > water. You > > > > computer schedule becomes invalid. What then? >> > > > > Hi Steve, > > Thanks for raising some good points that are worth discussing. > > If you loose > > a gas during a dive, the situation is then the same as if you > > lose a gas with > > any predetermined dive plan. You pull out the waterproof dive > > tables, use > > the computers as depth gauges / bottom timers, and figure a worst > > case (depth > > and time) plan for deco. with the gasses you have available. > > > > > > << 2 computers sounds pretty expensive, and about as useful as > > diving with 2 > > > > wings. You just fixed a problem (unreliable dive computer) by adding a > > > > second computer. Now the problems are compounded. >> > > > > I really don't think anything is compounded. One computer can be > > tucked away > > in a pocket so it is not even seen unless it is needed. And if > > it is needed, > > then the other computer has failed and so is ignored. Both > > computers contain > > the same information so what's to compound? And as far as expense is > > concerned, when the cost of life support equipment becomes a strong > > consideration in technical diving, then perhaps it's time to > > consider some > > other avocation. > > > > > > << How useful are your 2 computers when the deco that the > > computers suggests > > is > > > > wrong anyway? Steve >> > > > > Remember please that I'm not proposing the use of wrist > computers at this > > time, for extended decompression diving. I'm only pointing out > > that a number > > of the arguments against them are really not valid. However, I > > do completely > > agree with this last point of yours in many cases. But it has been my > > experience that the wrist computers are simply more conservative, > > rather than > > being "wrong." And as time goes on, I imagine the algorithms > > employed in > > these units will get more realistic and then perhaps the wrist > > computers can > > be useful. I just don't like eliminating their use with a wave > > of the hand > > and a number of invalid arguments. > > > > Thanks for the response to my thoughts. > > > > Take care and safe diving, Scott > > > > > > ----- Original Message ----- > > > > From: <ScottBonis@ao*.co*> > > > > To: <donburke56@ya*.co*>; <techdiver@aquanaut.com> > > > > Sent: Sunday, June 11, 2000 1:00 PM > > > > Subject: Re: Oxygen Toxicity - using 100% in open water > > > > > > > > > Hi Don, again, > > > > > > > > > > While I need to emphasize that I am definitely not recommending > > the use of > > > > > wrist computers for extended decompression diving, the reasons you are > > > > giving > > > > > for not using them are, IMHO, not valid reasons for eliminating > > them from > > > > > consideration. I say again that simply carrying a second > computer will > > > > > protect against any possible failure of your primary unit. > > > > > > > > > > But "what about informing two computers of my gas changes > > during the dive?" > > > > > you say. Well actually, it is not necessary. Consider for > example, the > > > > > Cochran three gas computer. It is not a trimix computer but > will handle > > > > > three nitrox / air mixes and automatically switch to the deco > > gasses at the > > > > > correct time. All I need to do is to program into the computer > > the depth at > > > > > which I plan to switch to my second deco. gas and the computer > > then does the > > > > > rest. In fact, I cannot change the programming of the computer > > after I have > > > > > entered the water. > > > > > > > > > > Consider for example, a dive to say, 100 feet on air for a long > > time and > > EAN50 > > > > > and O2 as the deco gasses. I would need to program in 20 feet as the > > > > > depth to switch to my second deco gas (the O2). The computer > > would then do > > > > > the rest. > > > > > > > > > > "How does the computer know when to switch to the deco. > > gasses?" you ask. > > > > > Good question. Magic!!! No not really, the computer is an air > > integrated > > > > > unit connected to the back tanks. It keeps track of my breathing rate > > during > > > > > the dive. And when that breathing rate goes to zero, it knows > > that I am no > > > > > longer breathing off of the back tanks so it switches to the > > first deco. gas > > > > > (the EAN 50 in this example). Then, later in the deco > > schedule, when I have > > > > > progressed up to 20 feet, it knows to switch to the second > > deco. gas (O2 in > > > > > this case). > > > > > > > > > > As you can see, no "informing the computer" during the dive is > > necessary, so > > > > > a second computer stowed away conveniently, serves well as a > > backup should a > > > > > failure occur in the primary unit. Of course a set of waterproof deco > > tables > > > > > must be taken also (with the computers serving as depth > gauges / bottom > > > > > timers), to serve as a second backup should something unusual > > occur during > > > > > the dive. After all, the well trained and experienced human > > brain is still > > > > > the best dive computer around, by far. > > > > > > > > > > So as I said previously, I need to emphasize that I am certainly not > > > > > recommending using wrist dive computers for extended > > decompression dives at > > > > > this time. But I believe the reasons you are stating for not > > using them are > > > > > not valid reasons to preclude their use. I do agree with you > > however, that > > > > > sometime in the future these computers may have reached the state of > > maturity > > > > > where we will be able to depend on them for extended > > decompression dives. > > > > > > > > > > Take care and safe diving, Scott > > > > > > > > > > > > > > > > > > > > In a message dated 6/11/00 8:08:25 AM, donburke56@ya*.co* writes: > > > > > > > > > > << DB>A computer failure on a deco stop dive isn't nearly > > > > > that easy in that vital information about your deco > > > > > obligation went away with the computer. Perhaps one > > > > > day there will be a computer with an independent, > > > > > redundant system that can fix this properly. There > > > > > are other issues as well. > > > > > > > > > > SB> I can't speak to the "other issues", but this one > > > > > is a non-problem. Simply take a second computer. And > > > > > remember, there may be no significant difference > > > > > between the failure rate of dive computers and the > > > > > failure rate of the electronic depth gauges / bottom > > > > > timers commonly used in technical diving. > > > > > > > > > > > > > > > Scott, > > > > > The rub here is the gas changes. The Nitrex (I > > > > > think that was the name) computer needs to be told > > > > > about each gas change. IMO doing this on two > > > > > computers during a dive is a bit much. Two computers > > > > > in the same case, (but independent pressure housings) > > > > > operated by a double set of switches might fill the > > > > > bill. > > > > > > > > > > Make no mistake, I _really_ like the display on my > > > > > Oceanic but I have been screwed by electronic devices > > > > > too often to bet my life on one. > > > > > > > > > > The digital depth guages can be backed up with your > > > > > reel and bottom timers can be backed up with your > > > > > watch. It's also pretty easy to find a home for an > > > > > extra watch or an extra depth guage (like maybe on > > > > > your buddy). Since you don't need to look at these > > > > > devices until the primary fails, they can be stashed > > > > > away. Not so with a computer that must be informed of > > > > > gas changes. > > > > > > > > > > There are some watches out there that can give you > > > > > depth, so there's a possible backup to backup. > > > > > > > > > > The fact that I'm paranoid doesn't mean these devices > > > > > aren't out to get me. :) > > > > > > > > > > SB>Take care and safe diving > > > > > > > > > > Same to ya >> >> > > > > -- > > 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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