Braunbehrens once bubbled...
If you jump in with your tank turned off you reach back and turn it on.
The simple fact is that there is a lot more that can go wrong on a rebreather, and again a lot more on an electronically controlled one.
There is simply no question that rebreathers are subject to all the failures of OC in ADDITION to the failures of rebreathers.
The warning system for many of these failures is what I like to call the "St. Peter" system.
Everything seems to be fine, and then you are greeted by St. Peter.
Diving is all about evaluating and accepting or rejecting risk. Rebreathers are a risk that I chose to reject. Others may chose to accpet this risk, I have no problems with that...if it's a friend of mine, I try to talk them out of it, but in the end we are all responsible for our own actions.
I also won't dive with a rebreather diver, due to the risk to me as a buddy.
A properly trained , experienced and equipped RB diver is in most liklihood a safer buddy than another OC diver..
I know that on more than one occassion I have donated bottom gas (just handed off a sling) and deco gas (same way)..
If you have a gas problem, I should have more than enough gas to hand the entire bottle over to you and not compromise my safety(and you can do your thing).. If I calculate my bailout right, I have enough gas to easily get a diver (myself or a buddy) out of trouble..
"if you jump off with your doubles turned off you can turn them back on"
You can actually do this MUCh faster on a most RB(since most invert the tanks), and if the diver is doing his checks he SHOULD check his guages immediately upon hitting the water (and before jumping in). Unless you are a total idiot you should have more than enough time to correct the situation..
There are other things that can be done to prevent thius and give a longer reaction time... I usually do an o2 flush of my loop before entering the water(I don't go overboard just try to get it as high as possible).. if the loop volume drops I manually add a bit of o2.. in this way the electronics aren't even an issue at this critical time.. If I had my gas off, The loop would become more difficult to breath (but still supply gas) at this point I knwo the [rpbl;em immediately... Probably every "danger" you can come up with a properly experienced RB diver has a way to eliminate that potential risk..
ANy diver whether it be on an RB or OC deserves whatever they get if they don;t do predive checks and proper gear checking upon entering the water.
A new RB diver without experience probably isn't that good of a buddy since the person's attention will be totally focused on the hardware.. One you know your body, you become aware of everything the RB is doing without checking the controllers.. I know what I expect the controllers to say when I check them.. Nothing happens quickly on a CCR RB you have time for everything.. The most dangerous time is when you are near the surface, while at depth unless you suspect a high PO2 or CO2 breakthrough (proper prep and following guidlines should avoid this) you have much more time than an OC diver to make a reasoned out choice on the best coarse of action.. not this instinct triggered reaction that is necessary when on OC.
If unsure just flush the loop or switch to your bailout for some sanity breaths..
I wouldn't say RB failures have all the failuures of OC... running out of gas is pretty unlikely on a ccr (you really have to be a fool to do it), batteries dying are likely if you don't always change them and track their time (but thats what backup controllers / displays are for)
I have done some deep wrecks with penetrations, on one occasion my guidline was cut and due to some inept divers there was zero viz towards the way out (poor fin control and exhaust bubbles from the oc regs).. on OC this would have been a BIG problem, running out of gas would have been a likely event.. I just rose towards the ceiling and hung out... after a few minutes the silt started to settle and I was able to get my bearings.. I had a little longer deco than planned but so what, I did it all and didn't dirty my drysuit...
