Quote: (Originally Posted by
dave t)
It was to highlight the fact that the white paper (or maybe it was the advertising blurb) says and I quote "forget about po2"
I think that was in the brochure (definitely not the whitepaper). And yes, I cringed when I read that for the first time also (at DEMA). But in Poseidon's defense, I think the point (maybe a bit lost in translation??) was that the system design is intended to be more reliable than a "well-trained" rebreather diver, and as such it may not be as important that the diver monitors the PO2, as much as it is important that the diver reliably responds to an abort signal correctly.
There are two basic ways the system can fail:
1) It doesn't send the diver to the surface on OC when it should;
2) It does send the diver to the surface on OC when it should not.
From my perspective, #1 will kill divers, and #2 will simply annoy divers (thereby hurting the reputation of the rebreather). Thus, #1 is by far the more important of the two.
Next, we have to determine how rarely the system fails #1, compared to how rarely a well-trained diver fails #1. Obviously, a well-trained CCR diver will succumb to failure #1 less often/less likely than a poorly-trained CCR diver will. But if the system matches or exceeds the reliability of the well-trained CCR diver, then the playing field is leveled.
Of course, there are a MILLION ways the diver can fail, even when the system doesn't (i.e., all the alarms work as they should, but the diver fails to respond to them). But the same is true for OC scuba, driving on the freeway, and just about any other activity any of us ever does.
Quote: (Originally Posted by
dave t)
Indicating (to me at least)the knowledge level of the divers needs only to be at basic sports level yet here we are already with a need for the "sports" diver to understand how to analyze and interpret the various processes of determining the o2 content of his rebreather cylinder and to further understand the reason for inputing the said result into the rebreather electronics and the impact it will have on his breathing gas.
Not true at all -- the diver only needs to know this stuff if the diver wants to *intentionally* dive with oxygen that is not within tolerances of proximity to 100%. The basic sports level diver will simply get a "Do Not Dive" alarm, and will be pissed off, and will send Poseidon a nasty letter -- but will at least be alive.
Now, it may well be that there are parts of the world where sufficiently pure O2 is simply not available -- in which case the diver cannot dive. Period. (At least not safely). But this is true of ALL rebreathers -- the difference is that the MK-VI is capable of *determining* that the O2 is out of tolerance, and is thus capable of alerting an otherwise naive diver of the problem.
Aloha,
Rich
P.S. Back to work for now -- more later....