Rockjock, Mania, et al,
Sorry if I seemed to be coming down on everybody like a ton of bricks, but there seems to a vast store of mis-information and myth in the general diving community about re-breathers. Some of that comes from the fact that there are few of them around, compared to OC equipment. Some of that comes from self-appointed experts like George Irvine, who foam at the mouth on the internet, calling those who have died in accidents a lot of vile names. (Such behaviour for a "so-called expert" is beyond the pale for civilized individuals.) A lot tends to come from the media. (After all of these years, and shows from Sea Hunt to Discovery Channel, reporters cannot figure out that OC divers do not dive with "oxygen tanks". I don't know about you, but it does not give me much confidence in the quality of their information.)
Let me see if I can dispell a few myths for everyone's information and reading pleasure.
(1) Rebreathers
are more dangerous than OC gear, in this sense alone. They require more training, and a more mature outlook on what you are doing than many people are willing to acquire.
I liken re-breathers to flying, for a very good reason. The process is the same. You pre-flight the machine. You watch your gauges while you fly. You have a back-up plan that you have practiced for emergencies. When you finish, you post-flight your machine.
What are your rewards for this extra effort? You get higher performance! Simply put, you can get much, much more bottom time, and isn't that what we are all here for?
(2) There
are ways that a re-breather can kill you. In most cases they are very gentle ways. You just go to sleep. The way around this is to monitor your gauges and warning systems. (Remember, this IS more like flying.)
(3) Do re-breathers cause heart attacks? Only in the sense that if you go to sleep, as mentioned above, your mouth-piece comes out of your mouth, you drown, and your heart stops. Is there something specific about them that causes heart attacks? Simply put, NO! There is a condition called hypercapnea, which is having too much carbon dioxide in the system. If this happens, your heart will race, among other things, and if your heart is weak, it might trigger a heart attack. You could do this just as easily, however, by swimming too fast on OC.
If you find yourself becoming hypercapnic, you just reach up and twist the bail-out valve (BOV) and start breathing on OC while you figure out what is happening. Then, if it is fixable, you go on about your business. If not, you go back to the boat. No big deal.
If you are interested in finding out what re-breathers are really all about, look in Advanced Diver Magazine (Great mag!) and look for one of their "Intro to Re-breathers" sessions coming to a pool near you!
In the interests of full disclosure, I teach the Inspiration Rebreather for IANTD. I am also involved in bringing a military re-breather to the civilian market. I have also been featured in Dive Training Magazine during one of my instructional sessions in the Cayman Islands. (Not trying to blow my own horn here. Just establishing my bona fides, as they say.)
Cheers!
Rob