but the bottom line is that if someone is spazzed to the point that they aren't going to calm down then you may be put in the uncomfortable position of choosing between one death and two, with the latter including yourself.
I hope to never encounter that choice.
Its not just a matter of a polaris ascent. Its also the possibility that by flailing around they will do harm to your stability in the water; since you are their "rescuer" it is paramount that your ability to maintain YOUR cool not be destroyed.
Yes, you can stop them from kicking, but can you stop the flailing of arms or body reliably enough to insure that you are not put in (further) danger?
I also understand the reason for the 7' hose and where it originated - and in that it makes perfect sense.
A regular octo hose is ok in terms of the separation it allows. My point is that the regular primary is WAY SHORT in that regard; you're almost kissing each other if you give that away and go to an Air2 for yourself, and if there is ANY kind of lack of control on the part of the other diver you may have an extremely dangerous situation on your hands.
Now let's say you're going to use any kind of secondary air source that is for you (whether a bungied backup or an Air2-style unit)
With that decision made, how long a hose do you want on your primary?
It MUST be long enough for it to reach someone else's mouth. Both the regular hose and Octo-length fit that bill, but the former JUST BARELY does, and with some people (particularly if they have a lot of "stuff" on their chests, or if they're physically large) it might even be next to impossible for you to donate air to them with a "regular" length hose.
Remember, we're talking (typically) 29" here, end-to-end, one end has to make a 90 at your reg and the other a 90 at the donated reg, AND it has to cross in front of your mouth (since the reg feeds "backwards" when you donate it from your perspective) When I did these exercises with my "assigned class buddy", who WAS relatively large, we just BARELY were able to do it and remain in control of the situation - there was no extra length available at all.
The obvious "non-DIR" solution is to use the octo-length (typically 39") hose on the primary. But now you bought yourself a second problem, which is how to route that hose. Its a non-solvable problem in my experience; I tried and failed
So where does that leave you?
I believe that those who are going to choose to have a backup reg for themselves should think through how their buddy will get air, and how they will manage the situation, if they need to donate that primary reg. I also believe that this pretty much dictates that you have something longer than 29" of hose between your regulator post and the inlet of that primary, unless you are diving with people who you KNOW can be provided air with the "shortie", and that you've practiced that.
The remaining question is then "how long", and that, for open water use, is simply a matter of your routing comfort. If you can figure out a way to route your primary in that it is secure and yet reasonably easy to deploy when you need it, then for OW use that is (IMHO) perfectly fine.
(Personally, I find the "long hose" routing WAY more comfortable than the "conventional" setup, in that the half-wrap around the neck serves to keep the angle on final approach to the reg constant. This keeps the reg from "pushing" or "pulling" as your turn your head, which is a very nice departure from the "usual" configuration!)
