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Who said anything about using two computers? Not me. This is a theoretical ideal tech diving computer that could (but probably wont) exist in the future. My point is that the arguments against using a computer are based on shortcomings of those currently in existence, and shouldn't preclude their use in future if those shortcomings could be overcome. "Current computers are not really suitable for deco diving" is a valid reasoned argument, but "Computers are a bad thing" (what started all this) is a short-sighted statement. Ian > -----Original Message----- > From: Thomas Tukker [mailto:thomas@ha*.ne*] > Sent: Monday, June 12, 2000 5:43 PM > To: Ian Puleston; techdiver@aquanaut.com > Subject: RE: Oxygen Toxicity - using 100% in open water > > > 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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