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.........major snip....... > >Now add the possibility that we knew we were going deep, and were using >trimix, and the same scenario happens, the problem becomes even more >complex. > >Will your unit be able to deal with situations as described above? Yes, I suspect that it will. BUT, You must have SOME sort of a plan in mind, and follow that plan in some manner. > >Also, we have rebreathers, so bottom time is not a big issue - i.e. we're >not limited by the amount of gas we carry. Our true limiting factors are >the amount of film in the camera, and how much deco we are willing to >become obligated to. > >Calculating deco on the fly is possible, but not really the most dependable >method, nor the most accurate, especially with large saw profiles during >the dive. > >So, with all that in mind, what do you think? > >Kevin. >HeyyDude > >P.S. I've posted this to the techdiver list, since I believe that it is a >subject that a lot of future CCR divers would be interested in reading. So much for a private conversation <G>... Here is the "Concept" behind our mixed gas computer in a little more detail. Whilst you are sitting in the Coconut lounge with Pyle the night before the big dive you "rough" out a dive plan. For example..... You plan on descending on Nitrox with a set point of 1.3atm You plan on being on Heliox while below 180ft with a set point of 1.4atm You plan on using Nitrox again when above 180 of 1.35atm You plan on decompressing on Nitrox with a set point of 1.5atm All of this information you enter into your Abyss desktop or laptop. You enter your "Target" depths and times as well, so that Abyss has a complete dive profile to work with. After setting all of the other related data for the dive profile you create a transfer file for the submersible. The Submersible, being connected to your CCR via some analog PPO2 unit monitors your PPO2 and determines the O2/N2 or O2/He gas fractions for your current moment in the dive. You, via a manual input indicate which phase of the dive, and which gas combination you are diving. Exp, User enters, Descent-Nitrox, or Bottom-Heliox, or Deco-Nitrox, etc... Lets say that you are now in the bottom phase of the dive. Abyss knows that you are using a Heliox blend of X%O2 and X%He. It knows your current tissue loadings through that moment in the dive. Abyss also knows that you will continue to use Heliox untill you ascend above 180 feet, And that your PPO2 will be at 1.35 when you do so. Abyss also knows that as soon as you enter into Decompression you will switch to a PPO2 of 1.5 for the remainder of the dive. Now, with that information we will be able to make a "Forcast" of total decompression obligation from anypoint in the dive, and this allows you to know for the first time what the direct impact of going deeper or staying longer or ect, etc, etc... will be while you are still in the water. it is the ability to forcast what is going to happen as a result of future gas changes that makes our computer so unique. Now, the obvious question is what happens if the planned gas sequence changes. Lets say that you are not able to swich over to Nitrox at 160 durring the ascent. in that case you will enter into a contingency plan where the computer will allow you to choose between a set of pre-defined (by you) alternatives. Such as, skip the next gas and continue on current till the next planned switch. Change next gas to an alternate gas. Etc... The idea being that you will, with in limits, be able to modify the plan on the fly to reflect emergencies (within limits) as they occur. With a SCUBA diver this process is simpler from an implementation standpoint as their is no outside data to collect from a PPO2 sensor. The diver mearly has to select from his pre-loaded gas list. Idealy, what we would like for the rebreather is the ability to monitor 2 gases (which may happen in the next couple of months as some new sensors make their way onto the market). ====== So, would it work for your scenario, yes I think it would, so long as you remembered to key in the major change points. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Christopher M. Parrett, President Abysmal Diving Inc. 6595 Odell Place, Suite G. Boulder CO, 80301 USA Makers of ABYSS, Advanced Dive Planning Software. Phone: (303) 530-7248 Fax: (303) 530-2808 File Transfer Site: ftp://ftp.abysmal.com/pub/abysmal World Wide Web Site: http://WWW.ABYSMAL.COM ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Rule #1 If We Don't Take Care Of The Customer.....Somebody Else Will. "Its not so much what we do, but how we do it that really matters."
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