Breather and risk vs benefit

[Retardboy]

It has been to quiet on the site for some time, so I tweaked my brain to come up with a theme for some discussion:) here it is!

In the dir system, breathers should not be used unless you are beyond the capabilities of OC, that is something most dir-divers know. When I read on different forums and web-sites, it seems like the limit in open water where a gas-extender is beneficial (i.e risk vs benefit) is fairly deep (say 70-80m and beyond). What came to mind when reading this was; what about the benefit of reduced heat loss? We are diving in cold water almost all year round (4-8c), a lot of divers don`t. So the question is; do you think that this alone could justifie the use of a rebreather on less agressive dives than what is commonly "accepted" as the standard for when it should be used? I know from some really cold winters in the army that beeing only moderately chilled for some time significantly reduces awareness and reaction time. I`m sure several of you breather-boys have some thougts about this!:)

Håvard

[Chrisch]

..When I read on different forums and web-sites, it seems like the limit in open water where a gas-extender is beneficial (i.e risk vs benefit) is fairly deep (say 70-80m and beyond)....


What are the extra risks though Håvard? Most RB divers I know would argue that there is an extra cost - additional training and capital outlay, but the risk is very subjective.

Chris

[Retardboy]

My impression as that the devil is in the details, as with so many other things:) Mushroom valves that can fail, CL`s that can jam/rupture, a little increased risk switching gases as two hoses can be connected to the switchblock at the same time ( I am not trained at all in the use of the RB80, nor am I familiar with the procedures for gas-switch, so I might very well be wrong on this one.)
Even if its made by halyon doesn`t make it fail-safe (nothing is, so it has nothing to do with the manufacturer), and I suspect that most of the dives done on the unit COULD have been done OC. However, there must be a reason why people choose to use them where other things could do the job. So, that is part of the reason I asked about the benefit of reduced heatloss and the impact that has on awareness and general safety. Btw, are you a rb-diver Chris?

[Chrisch]

.. are you a rb-diver Chris?

No. However we had all our OC gear stolen last year and looked very hard at whether to replace with new OC or an RB. In the end we went back to OC because the initial outlay was cheaper, even though you spend more on gas.

I read a lot of arguments about safety but no-one ever quoted any hard statistics. Commonsense tells you that all mechanical devices can fail but the failure rate for RB doesn't appear to be different to OC. Most of the discussion I read was based around people's ideas rather than fact. Or emotional rubbish. Or indeed about why a KISS or whatever is not DIR.

There are some safety issues if the RB training is not adequate. But then that is true of OC - why else would DIR exist?

In the end we came to the conclusion that for dives to 50m OC is acceptable and that if you dive beyond that more than a few times a year an RB is better. My wife and I don't have the chance to do many dives beyond 40m so we stuck with OC. We also don't have a suitable dive shop nearby to get lime and O2.

If we lived somewhere else I think the decision would have gone the other way.

Chris