Maybe eCCR's really aren't the wave of the future for recreational divers?

(1): There's no elegent way to add a 4th cell to a Meg. You either cut the inhale hose and add a "T" or add a P-Port into the inhale counterlung. Neither is optimal.

Dave

(1): There's no elegent way to add a 4th cell to a Meg. You either cut the inhale hose and add a "T" or add a P-Port into the inhale counterlung. Neither is optimal.

(2): Solution: Bin the Shearwater idea. Use three cells: Run (2) to a rEvodream for 2-cell HUD and handset, and the 3rd to a totally independant VR-3 and you'll have all you ever wanted..... it'll be a perfect setup.



Dave

Eccrs are by nature, inspire operator complacency. The problem with the current designs are the hand off nature of those designs. the basic thought behind the three cell system is that if a single cell fails we will be able to determine what cell has failed. but this does not take into account environmental conditions ,IE. condensation that could take out two cells at the same time.
controllers are just like a regulator if it fails you are done with it this dive.

we as consumers demand that the next piece of equipment has more bells and whistles then the previous piece. this is stupid. do we really need a car that can parallel park itself? gill you said that you where disappointed that the inspro would not allow you dive the with a broken solenoid. my question is why would you want to risk your wifes life with a piece of broken equipment to save a dive. you would let her enter the water with a free flowing regulator, no. so why would you allow her to dive with a broken controller. rick

Some months ago I was convinced that mCCRs are much safer than eCCRs and was leaning to purchase a COPIS. (my reasoning was mostly based on the “statistics” and the failures I kept hearing/reading about)

My decision to finally go for a eCCR and not for a mCCR was made after carefully considering my specific diving needs (cave diving) and why I really wanted a rebreather.

In normal situation the diver SHOULD closely and frequently monitor his handsets (or HUD) . No major deference’s here between mCCR/eCCR
In normal situations a properly tuned mCCR needs minimal intervention (manual additions) so no major differences in task loading between mCCR/eCCR.
The preparation/calibration / setup time that some people mentioned was irrelevant for me.

Where I saw a big difference was in the very few and rare occasions where “the shit hits the fan”. In these very few occasions where you get stuck in a restriction, up side down, with both your arms stuck and in zero visibility and high flow while you loose your mask and ...(ok ok I stop you get my point). This of course happens once in hundreds of cave dives BUT this is when you really need a eCCR to keep you alive even if your O2 consumption escalates and you can see nothing.

One of the (main) reasons why I finally chose a Rebreather versus OC for my caveding is that if you run into trouble the RB gives you more time to solve the problem. I believe this is done best when there is something making sure you are on setpoint and during this extreme high task loading moments you have one less thing to worry about.
Now if you are unlucky enough and your controllers fail at that particular point then that’s it…finito! But you must be really unlucky…


PS. In my worst experience in cavediving (zero visibility AND lost line due to a cut line (!) at around 60 meters depth) I calculated afterwards that I had 7 (seven!) minutes left to find the line before running out of gas. I would have loved to have a Rebreather back then….This was one of my main arguments for choosing to cavedive with a RB.

I also think whether the evodream HUD is classed as a primary depends on what you mean by Primary - for me Primary means it shows me the exact PPO2 of every cell.Stuart

Gill,

It goes to the root of human nature. Most HUD.s, rEVO included, are really secondary displays. Raw info has had decisions made on status etc. When it dispays different pulse rates, colors, etc, these indications are based on internal settings the machine makes, not you. i. e. rEvo assumes that if the PO2 is under .5 for 5 minutes, it shuts down.

Maybe, I am running that PO2. That would be my decision, and as long as it remains where I want it, my business.

I believe that the decision making is the divers responsibility, not a third party. I use two independent primary displays, both of which I can view simutaneously. If I could not view them at the same glance, then by human nature, I would probably start to rely on the one I could access the easiest and by default it would become a primary/secondary display configuration.

HUD's and displays like the rEvo funnel both cells to one controller. I would use the HUD as my primary display (human nature) and rely on the digital screen as a secondary. But, the HUD is being driven by the same circuitry, therefore no isolation between cells. If the controller goes awry, you loose all.

Don't get me wrong, the rEVO looks like a well thought out design and package, but IMO it is hindered by the funnel.

Using a system like the one I put together is two completely independent systems. Even the common case is devided into independent sections. The set points are run by me with real numbers, which translate into real values to my brain as regards PO2.

I have stated before and I might as well say it again, if you give a guy a crutch, he more than likey begin to rely on it. Buzzers, horns and other types of indicators are just such devices. One will dive and rely on the outside system to warn him of impending disaster.

Constat monitoring your PO2 is important to spot certain failure modes. I don't want to wait until the unit is telling me, OH, BTW, you have a problem.

I hope this hasn't been to confusing an expanation.

Dale

All this time I ran the unit manually and I can tell you it was hard work and the PP02 track will NOT look pretty.

Hey Mark, Sounds like a good day. Time for a well-deserved beer. You guys ought to get into the habit of serving it cold though...

What 02 flow are you using? It sounds like you could jack it up a "little" for what you are doing if you are needing to manage the rig often enough for it to be a bother. And what tolerances are you trying to hold? Within 0.2 is close enough for anything deco-wise and is far closer than you need to hold for physiological reasons not associated with deco. This is one of the "new mindsets" when moving from eCCR to mCCR's: Letting the PP02 flux up and down thru *your* desired limits. I use 0.2 high/low from "setpoint" and that's plenty close enough.


You are DEAD ON with your analysis of the HUD, and it's "Primacy" among displays. Well said, and have some green along with your beer.


Best,

Dave