Mailing List Archive Mailing List Archive
> I'll bite Richard, why does it take such extraordinary time to be skilled > at diving a rebreather enough not to have safety divers at 15 ft? I read the > thing about not being able to make small changes volume/bouancy changes with > your breathing. That would be some what of a help for me as I can't take a > full breath of gas or exhale fully w/o a big change. Can you elaborate on > the other problems? Surely depth control isn't that difficult or why is it? Depth control takes a short time to get used to - that's not the problem. The problem is making sure that the gas you inhale will sustain life. This may not be as big a deal for semi-closed systems (I honestly don't know, I've never been on a semi-closed system), but it is by far the biggest deal with a fully closed system. There is no single rig design or electronic gizmo that will absolutely ensure that the automatic control will continue to function properly. Like I said, I think all rebreather divers will have to enter the water as if they need to manually operate the rig. If the rig is built well, they may never need to, but they must always know how to just in case. More importantly, they need to know how to verify the validity of the O2 sensor readings, and the computer's response to those readings. A good rebreather design will provide the tools to do this, but the tools require practice and experience to correctly use and interpret results. Without these skills, all the bailout options in the world will be superfluous. Other skills, like flooding the loop with water and clearing the water to recover the rig require time and practice. Bailout options require practice. Understanding cause/effect relationships for things like depth changes and manual gas additions on PO2 values takes practice. Habits need to be developed. Divers must learn to check the PO2 with as much instinctivity and with greater frequency than they now check their pressure gauges (PO2 can change more quickly than cylinder pressures). Divers need to become so familiar with the clicking solenoid that they notice when it hasn't clicked in a while. They must learn to distinguish between solenoid firings with no oxygen injection (i.e., out of O2 or a cut-off valve was inadvertently left shut) and solenoids with oxygen injection. Divers must learn to always look at PO2 readings with skeptecism; and if there is ever a discrepency between the sensors, how to figure out why there is a discrepency and which sensors to trust. All this requires time in the water. Also, because during this time the divers are likely to make mistakes, this must all be done in shallow water so that if something goes awry, they know that they can always hit the manual O2 addition and not get a toxic mix. Tenders need to be present so that if the diver goes hypoxic, the tenders can quickly add O2 to the loop and bring the diver to the surface. No one component or diver protocol will ensure that an accident does not occur; it is the summation of all the rig components and the diver's skills that will decrease the chances that s/he will die using it. There are many, many more things, some of which I haven't even learned myself yet. But I think I'm making my point, so I'll stop here. Incidently, if I were a rebreather instructor (and I never intend to be one), I would make all of my students do their first 10 hours on manual mode without any batteries in the unit. Only later would I let them turn the power on. Hope that helps.... Aloha, Rich P.S. One more thing...many/most of these skills will be rig-specific. I would approach a diffent rebreather model with as much caution as I would approach a rebreather for the very first time. Richard Pyle deepreef@bi*.bi*.ha*.or* ******************************************************************* "WHATEVER happens to you when you willingly go underwater is COMPLETELY and ENTIRELY your own responsibility! If you cannot accept this responsibility, stay out of the water!" *******************************************************************
Navigate by Author:
[Previous]
[Next]
[Author Search Index]
Navigate by Subject:
[Previous]
[Next]
[Subject Search Index]
[Send Reply] [Send Message with New Topic]
[Search Selection] [Mailing List Home] [Home]