OC Gas switch protocols?

[stuartv]

To summarize what I think I've gotten so far:

Agencies that train to switch directly from deco 1 to deco 2 are:

TDI
PADI

Agencies that train to switch from deco 1 to back gas, then switch from back gas to deco 2 are:

GUE

And it is unclear (to me) which way UTD and NAUI teach it.

It is also unclear whether TDI specifically teaches it that way or if that is left to the discretion of the instructor, as my instructor teaches for TDI, but I know his initial tech training was with UTD, and he teaches Method 1 (switch to back gas in between deco gases).

 

[rivers]

In my training, each diver on a team was supposed to do the following upon arrival at the appropriate depth for a switch.

1. Signal to a buddy asking that buddy to watch while you performed the switch.
2. Show the buddy the MOD label on the bottle to which you are planning to switch.
3. Watch as the buddy checks the depth gauge and then gives the OK.
4. Pull out the hose and drape it over the neck.
5. Look at the SPG to make sure the tank is still pressurized. If not, pressurize it.
6. Purge the regulator while looking at the gauge to make sure the pressure dropped while purging, indicating that you do indeed have the correct bottle.
7. Open the valve.
8. Begin breathing.
9. Exchange OKs with the buddy watching you.

After that, your buddy would go through that process. If you are in a team of 3, each of the 3 would go through the process in succession. As I said, in dives outside of training, that never happened.

I do it every dive that requires a gas switch. As does my team.

 

[tbone1004]

I don't recall ever being on a dive where we didn't verify each other's deco gas switches.

It's pretty important.

I know it isn't kosher, but we do not validate each other on the final O2 stop in a cave. We self check and will look at each other after the switch has been made, but do not do a formal gas switch. We all have visually different second stages for our O2 bottles so can check that way. This is part of our style of diving where we are all basically same ocean diving together and choose to be responsible for our own issues. Not everyone feels that way and that's fine, our active GUE buddy is OK with that change and all is well.

basically the O2 pick up goes
Verify it's your bottle
Pick up your bottle
verify it's the right bottle and that the valve is on.
start breathing from it and finish donning the bottle

for me, my first stages are scubapro mk2 style vs poseidon, my second stages are metal dacor and/or scubapro second stages vs jetstreams, i have a green vs black hoses, green vs black tubular webbing on my worm gears, and bright yellow al80's vs brushed or black. If I botch that gas switch, something seriously weird happened.

this is part of the deviation from OW diving where that bottle may be fully stowed and not come unstowed until you start breathing. I choose to skip steps 1-3, and 9 of what was described above as I choose to either solo or same ocean dive where you can't always validate with a buddy that doesn't exist.

 

[PfcAJ]

I'm thinking now about the story (just told casually one day) my tech instructor told about how it went when he was doing his own Adv Trimix cert checkout dives. He described the start of the dive as a hot drop to hit a deep wreck. I remember him saying how they had to switch to their bottom gas as they dropped like rocks towards the bottom, having to stow the hoses and regs from their initial gas as they went. He didn't say one way or another but looking back, the way he described it makes me think that they did not do a formal gas switch (ala the way I have been trained) as part of that. Maybe they did. But, playing the scene in my mind based on how he described it, I imagine 3 divers (an instructor and 2 students) dropping as fast as possible and each one simply switching to back gas/long hose and stowing their reg/hose from one of their deco bottles as soon as they got past 30 feet (or whatever depth they chose).

If you don't do buddy checks/gas confirmation for that switch, what other gas switches do you eventually start doing without a buddy check/gas confirmation? Or is a switch to back gas always okay without that same formal gas switch/check/confirmation process?

When you switch from a deco gas to back gas, prior to then switching to the next deco gas, do you do the same process for the gas switch as when you switch to a deco gas? To what length do you/your buddy go to confirm that the reg you're switching to really is coming from your back gas? What if you had a mistake in an earlier stage and you still have a deco reg hanging around your neck, so you accidentally switch to that? What if it's during a descent and you are accidentally switching to a rich travel gas when you are supposed to be switching to your back gas?

To be clear, I'm not trying to criticize at all. I'm trying to understand what you all, as more experienced folks, actually do to mitigate various potential risks versus things that may seem risky to me but you have learned really aren't risks to be concerned about.

You're really asking me to teach you how to dive hypoxic gases. You need an instructor for that.

On a hypoxic dive like you're describing there's really no condition that would cause you to start a dive with two stage/deco reg hoses around your neck. There shouldn't be any condition where you have two deployed at the same time (going back to the first posts on this thread). A hot drop hypoxic dive is a grownup activity and you've gotta be on your A game.

This is why you need solid procedures from the beginning.

I'm sure you can come up with some scenario where you've got a bunch of regs deployed (Sherwood Schile) and run into trouble. Always revert to the basics and take the time to do it right every step of the way.

 

[PfcAJ]

I know it isn't kosher, but we do not validate each other on the final O2 stop in a cave. We self check and will look at each other after the switch has been made, but do not do a formal gas switch. We all have visually different second stages for our O2 bottles so can check that way. This is part of our style of diving where we are all basically same ocean diving together and choose to be responsible for our own issues. Not everyone feels that way and that's fine, our active GUE buddy is OK with that change and all is well.

basically the O2 pick up goes
Verify it's your bottle
Pick up your bottle
verify it's the right bottle and that the valve is on.
start breathing from it and finish donning the bottle

for me, my first stages are scubapro mk2 style vs poseidon, my second stages are metal dacor and/or scubapro second stages vs jetstreams, i have a green vs black hoses, green vs black tubular webbing on my worm gears, and bright yellow al80's vs brushed or black. If I botch that gas switch, something seriously weird happened.

It's just weak procedure. Doesn't scale, has potential to break down if you have to borrow a reg, and is generally just lazy.

All you have to do is move your eyeballs to look at your buddy. It's seriously easy. Some dumb **** might go down like inhaling a rock, switching to a dead reg or a stage, or something that's just a minor annoyance like a hose gets jammed up by the boltsnap. You're unable to lend a hand because it's too hard to look at your buddy?

I can't even relate to this.

 

[lv2dive]

Personally I just do not understand the different color hose/reg plates, even as a back up. What happens when you have a problem with a hose or second stage and have to borrow someone else's and all of sudden that visual verification is gone? Or you are in murky water and the color is obscured? Use a verification process independent of colors or caps on regs or other creativity, then validate changes with buddies/s, boom... problem solved.

 

[barth]

In my training, each diver on a team was supposed to do the following upon arrival at the appropriate depth for a switch.

1. Signal to a buddy asking that buddy to watch while you performed the switch.
2. Show the buddy the MOD label on the bottle to which you are planning to switch.
3. Watch as the buddy checks the depth gauge and then gives the OK.
4. Pull out the hose and drape it over the neck.
5. Look at the SPG to make sure the tank is still pressurized. If not, pressurize it.
6. Purge the regulator while looking at the gauge to make sure the pressure dropped while purging, indicating that you do indeed have the correct bottle.
7. Open the valve.
8. Begin breathing.
9. Exchange OKs with the buddy watching you.

After that, your buddy would go through that process. If you are in a team of 3, each of the 3 would go through the process in succession. As I said, in dives outside of training, that never happened.

I think I did learn it a bit different.

1 switch signal
2 clip primary light off and stow light cable under longhose and under belt
3 left hand on stage valve
4 check depth
5 Check mod on tank.
6 deploy stage hose
7 purge regulator and check spg
8 buddy checks depth
9 buddy checks mod at tank
10 buddy must see if the regulator is connected to the right tank and follow hose from regulator to tank
11 buddy give switch signal. Ok signal is nog enough, you want to be sure it is possible to switch. Communication should be clear.
12 put stage hose behind neck.
13 check depth
14 put stage regulator in mouth breath 2 times
15 clip longhose off
16 put primary light back on hand

 

[stuartv]

On a hypoxic dive like you're describing there's really no condition that would cause you to start a dive with two stage/deco reg hoses around your neck. There shouldn't be any condition where you have two deployed at the same time (going back to the first posts on this thread)..

I am not talking about starting a dive with 2 deco regs around your neck. I'm talking about starting with 1 and then asking about the possibility that you would somehow make the mistake of forgetting to stow it. Then, later, you do a switch that is supposed to be to your back gas, but you accidentally switch to that deco reg instead. Say, a buddy has some kind of emergency and you donate your long hose and switch to what you think is your alternate back gas reg.

I'm not asking you to teach me how to dive hypoxic mixes. I'm trying to understand the different ways people do gas switches and the pros and cons of them - which includes how they scale up to bigger dives. Obviously, it seems better to use a protocol from the beginning that will still work even on really big dives.

This specific question is really about whether you treat a switch to back gas exactly the same way as you treat a switch to a deco gas. Does your buddy verify that you switched to the correct gas (when you switch to back gas)? Does he literally view the entire length of the hose? Do you fully deploy the long hose so that you/your buddy can see the whole thing to verify that you are switching to back gas? Or do you assume that you would only have one deco reg around your neck, and if you're breathing from it, then the other regs around your neck MUST be back gas, so they are safe to switch to without verifying them the same way you verify a switch to deco gas?

This seems like it would particularly relevant if you happened to end up in low viz. If you forgot to stow your deco reg that you were using on initial descent, your buddy might not even be able to see you well enough to notice that you have that extra reg hanging there.

Y'all were talking about Jim Miller's death. What I got from your discussion was that he died because he switched to "back gas" (or so he thought) and neither he nor any of his buddies actually verified the gas he switched to. Did they all make that mistake because there is a mentality that switching to back gas doesn't need a verification? I understand that he switched to a bottle that wasn't a back mounted "main" cylinder. But, it still begs the question, is there a mentality that says "I only have to check switches to deco gases" that lead to that failure of process for him and his buddies. And is that appropriate? If not, should ALL switches, including to back gas, be treated exactly the same way? Or is this a case of teaching and continuing to teach "just don't be an idiot"?

 

[boulderjohn]

What I got from your discussion was that he died because he switched to "back gas" (or so he thought) and neither he nor any of his buddies actually verified the gas he switched to. Did they all make that mistake because there is a mentality that switching to back gas doesn't need a verification? I understand that he switched to a bottle that wasn't a back mounted "main" cylinder. But, it still begs the question, is there a mentality that says "I only have to check switches to deco gases" that lead to that failure of process for him and his buddies. And is that appropriate? If not, should ALL switches, including to back gas, be treated exactly the same way? Or is this a case of teaching and continuing to teach "just don't be an idiot"?

As I understand it, according to their procedures, each switch should have been verified.

 

[PfcAJ]

I am not talking about starting a dive with 2 deco regs around your neck. I'm talking about starting with 1 and then asking about the possibility that you would somehow make the mistake of forgetting to stow it. Then, later, you do a switch that is supposed to be to your back gas, but you accidentally switch to that deco reg instead. Say, a buddy has some kind of emergency and you donate your long hose and switch to what you think is your alternate back gas reg.

I'm not asking you to teach me how to dive hypoxic mixes. I'm trying to understand the different ways people do gas switches and the pros and cons of them - which includes how they scale up to bigger dives. Obviously, it seems better to use a protocol from the beginning that will still work even on really big dives.

This specific question is really about whether you treat a switch to back gas exactly the same way as you treat a switch to a deco gas. Does your buddy verify that you switched to the correct gas (when you switch to back gas)? Does he literally view the entire length of the hose? Do you fully deploy the long hose so that you/your buddy can see the whole thing to verify that you are switching to back gas? Or do you assume that you would only have one deco reg around your neck, and if you're breathing from it, then the other regs around your neck MUST be back gas, so they are safe to switch to without verifying them the same way you verify a switch to deco gas?

This seems like it would particularly relevant if you happened to end up in low viz. If you forgot to stow your deco reg that you were using on initial descent, your buddy might not even be able to see you well enough to notice that you have that extra reg hanging there.

Y'all were talking about Jim Miller's death. What I got from your discussion was that he died because he switched to "back gas" (or so he thought) and neither he nor any of his buddies actually verified the gas he switched to. Did they all make that mistake because there is a mentality that switching to back gas doesn't need a verification? I understand that he switched to a bottle that wasn't a back mounted "main" cylinder. But, it still begs the question, is there a mentality that says "I only have to check switches to deco gases" that lead to that failure of process for him and his buddies. And is that appropriate? If not, should ALL switches, including to back gas, be treated exactly the same way? Or is this a case of teaching and continuing to teach "just don't be an idiot"?

Your long hose is clipped off to your chest. You can't just leave a reg dangling around your neck. You're literally asking me to teach you the entire procedure from normoxic trimix all the way up to hypoxic trimix hot drop and every detail along the way. No, sorry. There's too many nuances and considerations that need to be assessed for a dive like that. If we aren't even on the same page about something as simple as what do to between deco gases there's no way we can really have a meaningful discussion about what to do when you make a 200fpm descent to 270' and what to do along the way.

Jim erroneously switched to a deco bottle thinking it was a bottom stage. Stage and deco switches need to be verified. Potential for error is high.

One reg deployed at a time. Regs are either off and stowed or on and in your mouth. Backgas is either clipped off or on your mouth. Keep it simple. Revert to basic procedure. Don't complicate things.