Posted by RaiderKarl on March 13, 2001 at 15:25:05:
In Reply to: Re: Dive tables vs. computers: only a $ difference? posted by AADIVER on March 13, 2001 at 14:42:05:
When I bought my dive computer, it was because I wanted a digital depth gauge that was more accurate than my ScubaPro analog diaphram depth gauge, which is marked off in 5s and 10s of feet down to 250 feet. I also wanted a buzzer or blinking light that would tell me to slow down if I was ascending too fast.
I had just come from a deep dive to 130 feet (not deep for you tekkies here, I know!) and I had gotten really narked on that dive, and so it was difficult for me to egress safely using my own analog instruments at the time.
I went to one of my favorite dive stores and got a nice song and dance from the salesperson there about models and algorithms and features, and I bought what I determined to be the best dive computer available at that store at that time, the Suunto Vyper.
I have been using it for several months now. I got everything that I wanted, except it didnt come with any printed tables like PADI or US Navy/NOAA, and so I usually keep it in "gauge" mode for the specific reason that it gives read-outs for dive planning that are different than BOTH the Navy tables and the PADI tables.
For deep dives, I simply cannot trust the computer to do the NDL and deco calculations for me, because whatever the built-in parameters it may have, I have no way to compare them with Navy or PADI. Mike K, I will go ahead and study that web site you gave me info on, to see if that answers the questions I have and addresses the fundamental issue, which is this:
If DSAT came up with one thing in their research, and if the dive computer manufacturers chose to use something else, then it seems to me SELF EVIDENT that that the dive computer manufacturers either owe us a set of dive tables consistent with their electronic products, or else they need to tell us which set (PADI, NAUI, SSI, IANTD, NASDS, or CANADA) they did build into their product.
For dive planning purposes, you should get consistent data from the dive computers and the tables. IF you can calculate dive plans both ways, using both computers and tabular products that are consistent with each other, then it doesnt matter if your dive computer dies on a dive vacation, because you should be able to switch over to the tables using your written dive log (if you wrote everything down each night to be safe), and you should get the same answer.
Most people cant calculate anything too good! So they just buy a dive computer and try to squeeze bottom time out of it. That is an experiment, in my opinion, and their body is the lab. A lot of people dont even log their daily dives. That is laziness which could lead to miscalculations when on a dive trip or vacation.
In a sport like diving, where the gas laws of Boyle, Charles, Dalton, and Henry come intimately into play, relying solely on an electronic dive computer without comprehending why, is a lot like putting your life into someone else's hands. We tolerate people doing it after their open water certification courses, but it is inconsistent with sound logic, safety, and good sense.
That is why you get questions here on this web site like "how can I squeeze more bottom time out of my dive computer" when its not the dive computer they are squeezing bottom time out of, its the blood and organs and tissues and nerves of their own bodies that they are squeezing bottom time out of, in reality.
The "business of diving" has managed to get a whole lot of people into the water and diving who probably do not pack all the gear to be doing so. Thats why we have one-liners in recreational diving like "never hold your breath on scuba ... what part of never do you not understand" and/or "never dive under 130 feet" etc. As I grapple with the issues involved in working with the public and with professional scuba certification, this is what worries me. So I am worrying out loud.
I appreciate the feedback and info that the rest of you have shared. Thanks.