First Rebreather Questions

[kensuf]

You could just use an ADV? ^.^

The unit that I had the bad day on was a KISS Classic. The ADV and BOV were both fed from the same gas source, ADV doesn't work when the QC6 is unplugged.

 

[PEDiver]

You could just use an ADV? ^.^

Your incessance around DSV + necklace or BOV only is very interesting to me. I have not met anyone who has really argued the point this much one way or another. I feel like there is really zero extra "drag" or "complication" from having a necklaced regulator + BOV. It is also muscle memory for me to have a necklaced regulator when I dive doubles so the transferability of that configuration just makes sense to me. Even a cursory review of the CCR standards for GUE (taking GUE as an example since I assume they would be more strict than other agencies) does not seem to specify one way or the other (DSV or BOV) but it does specify you must have a backup regulator on a necklace. And from what I understand about the WKPP equipment configuration with the RB80, they also use a BOV with a necklaced backup (taking examples from long-standing use over decades of exploration).

 

[Wibble]

You could just use an ADV? ^.^

Must admit that an ADV** is both useful and a bloody inconvenience on the same dive. Great for the descent when you may be very busy hauling yourself down the shot, clipping off tags, strobes, sorting out lights, scooter, bailouts... all where arms and fingers can be at a premium to inject more loop gas. An ADV also never injects too much on a descent.

However, once on the bottom and definitely during the ascent, an ADV can be a right pain especially with a hypoxic mix where it dilutes your loop and wastes loads of gas as you flush and reset. Which is why an ADV shutoff comes into its own to stop it from injecting. Shut off the ADV on the bottom or just before the ascent. Amazing how much oxygen it saves.


** For newbies to CCR, the ADV (automatic diluent valve) injects diluent into the loop when you suck (hard).

 

[rjack321]

Must admit that an ADV** is both useful and a bloody inconvenience on the same dive. Great for the descent when you may be very busy hauling yourself down the shot, clipping off tags, strobes, sorting out lights, scooter, bailouts... all where arms and fingers can be at a premium to inject more loop gas. An ADV also never injects too much on a descent.

However, once on the bottom and definitely during the ascent, an ADV can be a right pain especially with a hypoxic mix where it dilutes your loop and wastes loads of gas as you flush and reset. Which is why an ADV shutoff comes into its own to stop it from injecting. Shut off the ADV on the bottom or just before the ascent. Amazing how much oxygen it saves.


** For newbies to CCR, the ADV (automatic diluent valve) injects diluent into the loop when you suck (hard).

Yeah same. On my meg the ADV is the MAV, it's all-in-one on those CLs and I find it super easy to flip it on/off as well. Never had to add dil via the BOV on that unit.

On the sidewinder the ADV is terrible. Worst possible design (at least compared to others I've tried). There is no stock dil MAV and the aftermarket MAV options are either clunky, big, or confining in one way or another (extra hoses across the chest).

So at least for me whether the ADV is a positive or negative hinges upon the unit as a whole not necessarily the ADV in isolation.

 

[rjack321]

Your incessance around DSV + necklace or BOV only is very interesting to me. I have not met anyone who has really argued the point this much one way or another. I feel like there is really zero extra "drag" or "complication" from having a necklaced regulator + BOV. It is also muscle memory for me to have a necklaced regulator when I dive doubles so the transferability of that configuration just makes sense to me. Even a cursory review of the CCR standards for GUE (taking GUE as an example since I assume they would be more strict than other agencies) does not seem to specify one way or the other (DSV or BOV) but it does specify you must have a backup regulator on a necklace. And from what I understand about the WKPP equipment configuration with the RB80, they also use a BOV with a necklaced backup (taking examples from long-standing use over decades of exploration).

,Shrugs> having seen someone drown despite their OC buddy having 3 regulators on them, at least two of which had gas, I am not a fan of having a menagerie of "options" which leads to flustered responses by the diver or potentially OOA buddy.

The GUE JJ is a good example of having options which aren't always coherent options based on demonstratively best practices. A gag strap being one of the few CCR practices with actual data supporting its efficacy. A GUE JJ may have a BOV yet no gag strap, and also have a long hose but under the CCR loop.

 

[flymolo]

,Shrugs> having seen someone drown despite their OC buddy having 3 regulators on them, at least two of which had gas, I am not a fan of having a menagerie of "options" which leads to flustered responses by the diver or potentially OOA buddy.

The GUE JJ is a good example of having options which aren't always coherent options based on demonstratively best practices. A gag strap being one of the few CCR practices with actual data supporting its efficacy. A GUE JJ may have a BOV yet no gag strap, and also have a long hose but under the CCR loop.

I think the rationale behind the long hose being underneath the loop is two fold:

1. where else would you stow it?
2. if you are diving in a ccr team it seems unlikely a gas donation would be a completely unexpected event so you'd have time to get the long hose over the loop. even with the long hose under the loop you can still get it deployed relatively quickly. this is also where practice comes in handy.

if you are diving a mixed team you can just keep the long hose over the loop if you choose

 

[PEDiver]

I think the rationale behind the long hose being underneath the loop is two fold:

1. where else would you stow it?
2. if you are diving in a ccr team it seems unlikely a gas donation would be a completely unexpected event so you'd have time to get the long hose over the loop. even with the long hose under the loop you can still get it deployed relatively quickly. this is also where practice comes in handy.

if you are diving a mixed team you can just keep the long hose over the loop if you choose

I think this opens up an argument for the pros/cons of BM vs SM bailout when using a BM CCR. In the GUE configuration, you have the long hose under the loop which requires the diver to remove the loop from their mouth to donate the long hose in an emergency. In a SM bailout configuration, you can easily stow the long hose and clip it off to your chest d-ring (or even leave it stowed without clipping) which does not require the diver to first manipulate their own loop to donate.

I have not tried to dive my CCR with the long hose over my loop...that idea seems really funky to me. If I need to bailout from the loop and ascend, with the loop now above my head, I can visualize the long hose getting in the way of or hampering my ability to vent the loop as I ascend. Seems like a weird compromise to me based on other possible configurations.

 

[flymolo]

I think this opens up an argument for the pros/cons of BM vs SM bailout when using a BM CCR. In the GUE configuration, you have the long hose under the loop which requires the diver to remove the loop from their mouth to donate the long hose in an emergency. In a SM bailout configuration, you can easily stow the long hose and clip it off to your chest d-ring (or even leave it stowed without clipping) which does not require the diver to first manipulate their own loop to donate.

I have not tried to dive my CCR with the long hose over my loop...that idea seems really funky to me. If I need to bailout from the loop and ascend, with the loop now above my head, I can visualize the long hose getting in the way of or hampering my ability to vent the loop as I ascend. Seems like a weird compromise to me based on other possible configurations.

I don’t leave the loop floating over my head during a bailout I pull it down underneath my chin. Would rather not have it floating high above me and exposed to getting caught on stuff.

In sidemount bailout config I still route the long hose the same way (underneath the loop)

 

[Wibble]

Longhose under the loop with an elbow on the reg, the mouthpiece inserted into a rubber necklace. The excess hose is looped under bungees on the bailout cylinder on the LHS.

The main use is for my safety when the rebreather fails. It is very simple—and practiced on every dive—to exchange the loop and breathe from the necklaced regulator.

A very secondary use is to donate to another OOG diver. This is two phases: I grab the regulator, pull it from the necklace, and thrust it towards the OOG diver whilst pulling the stowed hose from the bailout bungees with the other hand. Once stabilised, remove loop and lift hose over my head (possibly wearing a helmet), then back on the loop.

 

[rjack321]

I think the rationale behind the long hose being underneath the loop is two fold:

1. where else would you stow it?
2. if you are diving in a ccr team it seems unlikely a gas donation would be a completely unexpected event so you'd have time to get the long hose over the loop. even with the long hose under the loop you can still get it deployed relatively quickly. this is also where practice comes in handy.

if you are diving a mixed team you can just keep the long hose over the loop if you choose

Or you could recognize that a gag strap is a proven CCR safety device (one of very very few in the CCR universe) which means you either put the long hose over or stuff it.

I kinda question if a gag strap+DSV is really that good a combo vs gag strap+BOV but that question hasnt been tested