So you'll have three 2nd stages on that BO bottle? A bungied stage to in theory donate, a necklace, and the BOV? You won't be handing that off with a loop in your mouth and necklace around your neck. But more importantly why?
My diving is very far from extreme, but I plan to continue running just a BOV that has a QC6 somewhere on its feed line, and leave stage regs banded onto all stages, with no extra necklace reg. Very easy setup, bailouts, handoffs, and breakdown
For most diving scenarios, the risk of zero-warning caustic happening before I've made a decision to bail out onto either the BOV or the stage reg is not at the top of my list of hazards.
Seems a reminder that bailing out early matters, especially if there are signs of flooding or a compromised loop, and perhaps also if someone else is having an emergency. BOV makes it more likely to make that early decision, incurring even less physical or psychological effort than switching to a necklace reg. BOV also reduces risks of loop flooding via the DSV, because turning the BOV also seals the loop, eliminating some of the flooding mistakes that can happen while changing mouthpieces. Someone panicking is probably more likely to flood a mismanaged DSV while going onto the necklace reg, versus simply turning a BOV valve. A flood/caustic situation could even arise directly from errors during repeated CC/BO switches between the loop and independent bailout regs.
But let's forget about BOVs for second
The other question I'm asking is: if there's a necklace reg in conjunction with a rebreather, might it not be quicker to setup, stage, hand off, and de-rig the cylinder if there is a QD involved somewhere, rather than taking off a hard-hosed necklace reg past the loop, mask, mouthpiece retaining strap, etc (or yanking it free), for any of those actions? I guess that's merely hypothetical, unless someone has done a field comparison.
There are some issues with established OC DIR reg/hose approaches when included in rebreather setups, and that includes both sidemount tech and twinset-based approaches. These have gotten married to a certain way of doing regs and hoses, which were developed and engrained without ever taking rebreather loops into account. It can get awkward, yes there are extra drills to manage passing hoses past loops and such, but it brings up problems that deserve a re-think of the whole approach.
Huh? Why would you ever have a stage bottle or BO reg dangling around your neck that wasn't in your mouth? You stow the reg after using it and do a complete verification if you want to breath it again. That is basic gas management to ensure that you never breath the wrong gas.
Here I was just wondering how the necklace reg approach first evolved. Did necklaced regs always exist? Whom should we credit for making it canonical in open circuit tech? Did nobody in history ever just drape a reg behind their neck/around their body as their backup, before bungee necklaces became standardized? Probably.
), four or more times (during setup, tank donate, tank receive, post-dive). But there would be risks of forgetting to replug etc
