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Dave, Your experience with the Commander NITROX is very similar to mine. Mine has been back to Cochran 3 times now (about once a year). Always seems to be "just another software re-load". This last time it totally crapped out and would not start. I dive tables anyway so I just use it as a really expensive bottom timer. For no decompression dives or single, not too deep" dives it seems to be fine. Forget repetitive dives especially those requiring even the smallest amount of deco. I'd still be in the water from last weekend if I followed it. It does give nice big "dive time" numbers when decompressing though! :-) Art. -----Original Message----- From: Deep1dave@ao*.co* [SMTP:Deep1dave@ao*.co*] Sent: Tuesday, June 13, 2000 4:50 PM To: techdiver@aquanaut.com Subject: Deco diving: Dive Computers vs. Bottom Timers Greeting list, Lately there has been a lot of posts regarding computers Vs bottom timers for deco. I found a good summary that was posted by Jarrod Jablonski last February. I have recently switched to diving with decoplanner tables, and a bottom timer. At first, it was awkward to have to look at a table during deco. Now I have many of our typical profiles with the appropriate mixes memorized, and my deco doesn't depend on a computer. Even if I loose my slate, I can do the deco. During my normoxic trimix class, I dove with both a 2 gas Cochran Commander, and a bottom timer with tables. I wanted to see what the Cochran would do since it only new about the 50% switch at 70fsw. Well, on shallow dives, say to 160fsw for 20min, the cochran would clear at about the time the table had me out of the water. However, on the 200fsw for 20min dive, the Cochran would bend it self, and lock me out, at the 20fsw stop. In addition, on one of the dives, the Cochran really went south and gave me a ceiling of 20fsw when I actually hadn't completed my 50fsw stop. That's when I really became convinced that we can't safely deco on dive computers. Deep diving is not a "by the seat of the pants" event. One is forced to plan the dive for gas consumption and deco. Understanding and familiarizing your self with your deco is just part of it. Below is the post of Jarrod's. Hope it helps, Dave " 1) Dive computers tend to induce significant levels of diver dependance, eliminating the awareness so common and essential to all diving but particularly obvious when diving tables 2) Dive computers do not allow proper planning as divers can't properly "study" the impact of various mixture and decompression choices. 3) Dive computers are of very limited educational benefit as they do not induce questioning, or proper planning discussions as can be found with tables and most particularly with deco programs 4) Dive computer programmers often play games with computational process so that they can take insulate themselves from the risk of taking largely square profile data and utilizing it on a multilevel dive. These games tend to result in odd and often ridiculous levels of conservation. 5) Dive computers are expensive and in some cases leave divers with limited resources carrying equipment that is of far less benefit than other equipment that may have been purchased. 6) Dive computers significantly limit the likelihood that divers will track their residual nitrogen groups. 7) Dive computers do not allow for Helium diving in any formats but the bulkiest and most questionable format. 8) Dive computers will often generate longer decompressions than could be figured by an astute, well educated diver with experience. 9) Dive computers often create confusion by giving the user to much useless information, sometimes even obscuring depth and time in favor of blinking CNS and/or deco limitations. 10) Dive computers can become very difficult to properly if a deco stop has been violated. Some computers lock up completely while others just beep or generate erroneous and distracting information. Divers using mixed gasses are likely to often violate computer profiles. 11) Dive computers do not allow for the educated diver to properly modify their decompression to account for advancing knowledge such as the use of deeper stops in a decompression profile. 12) Dive computers do not offer divers as much flexibility in the generation of profiles with varying conservation. For example the right mix would allow 100 min at 60 vs 60 at 60 but I might prefer to do one or the other and indeed might like a compromise. Computers confuse this issue by not providing divers with the proper information. 13) Dive computers users often ignore table proficiency and therefore do not learn tables properly. When confronted with a situation where they can't dive the computer (failure, loss, travel etc) these divers are at a serious handicap. Jarrod Jablonski President- Global Underwater Explorers www.gue.com CEO Extreme Exposure www.extreme-exposure.com VP Halcyon Manufacturing www.halcyon.net, www.browniedive.com, www.tankfill.com" Global Underwater Explorers www.gue.com GUE is a non-profit educational, research, and exploratory organization with hundreds of dedicated members around the world. Extreme Exposure www.extreme-exposure.com Extreme Exposure and Halcyon manufacturing produce some of the scuba industries most novel and robust diving equipment designed by many of diving's most active explorers. -- 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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