Posted by Eins on April 07, 2001 at 21:28:27:
... instead of the back up.
In every explanation, DIR talks about the reason being that the primary is proven to work. I always had a feeling that something is wrong with that explanation, and now I know why:
It implies that the back up may be not working. That does not sound like DIR to me at all. And, in all honesty, which diver in an emergency would give up his only working regulator? Or who would knowingly risk being stuck with a reg that just might not work.
OK, it may be a psychological aspect for the OOA diver to know he is getting a working reg, but at the point of such an OOA emergency, I bet no-one will deliberate whether this donated reg may possibly work or not. All they care about is to get air, quickly. And they will most likely not have a chance to give the donating diver a heads up before they reach him in dire need of air. So, the first logical thing for a distressed diver is to grab the reg that he sees will give him air (not because it is flawlessly working, but because it is there and obviously connected to an air source).
All the other rationales make a lot of sense: it is easier for the distressed diver to see and to grab than a somewhere attached back up. In the DIR configuration, it is therefore the better reg to be on a longer hose, and the back up may as well be unuseable for the OOA diver, being necklaced and on a very short hose.
So, bottom line, the system works flawlessly, but some of the reasons seem to be nonsense.
Eins