DIR and SPG

[Meng_Tze]

I
The whole "show the SPG" step (which is no longer taught by GUE) was a kind of "marriage" between two schools of thought regarding gas sharing.

Originally, some of the GUE tech folks were teaching students to show their SPGs, while the cave folks were not...

Checking the available gas helps in the decision process on what to do next.
.. Stopping to check the gauge at that point doesn't really tell you anything useful, IMO (speaking as a "primarily cave" diver)...

At any rate, when it came time to standardize the curriculum, the cave guys conceded on the "check the SPG" step, as a way of forcing students into a more measured response to the emergency. They were already teaching the cave students to take a few seconds to calm everyone down before exiting, and stopping to check the SPG kind of fulfilled that requirement, so that's what they all agreed to do...

In Kevrumbo's scenario (three person team, restricted passage), I agree that the team needs to evaluate their remaining gas supply before entering the restriction....

The currently donating diver needs to be sure that he will exit the restriction with sufficient gas to get him or her the rest of the way out...

At that point, however, it is a team decision, and not just for the benefit of the diver who is OOG. The currently donating diver will need to have a good idea of how much gas he will need for the exit, and will need to advise the remaining team members that the OOG diver needs to switch........

..So I don't really see how checking the gauge helps in that situation - if anything, it probably creates even more stress...

OW diving is a slightly different animal though - if your only option to is to surface immediately (like in the cave scenario), then there's not much point to an SPG check, as far as I can see. However, if an SPG check helps your team with "what to do next", then maybe there is some merit to adding that step.

I agree at a high level with your assessment on this, but I think there is a difference between checking a gauge and 'checking and showing' a gauge. I see the two intertwined above.

I would as a donor always check the gauge even if it is to create a 'force of habit'. This way we can change plans (if possible) along the way should consumption be more than expected.

But as mentioned before, the recipient effectively does not need to know and adding the step to have the recipient see and verify adds time and possibly stress. (try to do this in single file scenario, or even in a wreck with heightened stress levels and silt on the floor...and let me know). Gas rules are there to manage available gas for these scenarios, the donor merely verifies that all is going according to plan and makes changes if required/needed/possible.

ps: i edited the quote to focus on the check vs. check and show.

 

[rjack321]

Despite the fact that GU no longer teaches gauge checks (or at least mutual checks). I found myself checking the gauge after donating in Cave1 last month. If for no other reason than to charge the glow background for the eventual disappearance of all lights. Chris LM was not critical of this approach (actually it was never mentioned).

In a cave I see little need to develop muscle memory right at the beginning of an air share to check the gauge. Before a restriction or after a short while - sure that a good idea. Esp in a 3 person team.

In OW or another scenario where you have exit options, checking the gauge is prudent to ensure you have sufficient gas for your chosen approach/exit. But whether you need to do this as part of an air share drill is debatable (obviously) IMO.

 

[Ben_ca]

I didn't read what Kevrumbo wrote in the same way that you did and that may be the answer.

I read the terms primary, secondary and tertiary as descriptive of the "failures" in that sentence and not the "lights". So, you'd still have a primary and 2 backup lights, but you would experience primary, secondary and tertiary light "failures".

I think that Andrew still refers to the lights themselves as primarys and backups and that the terms "primary, secondary and tertiary" were simply being used by Kevrumbo to describe what happened.

This is all speculation of course.

Christian

Clarification note: Kevin refered to the lights with those terms... It wasn't Andrew. I believe that Kevin was refering to his latest class (In Subic Bay, Phils) when he was talking about light failures

 

[DIR-Atlanta]

I agree at a high level with your assessment on this, but I think there is a difference between checking a gauge and 'checking and showing' a gauge. I see the two intertwined above.

Actually, I agree with you, and I guess I blurred the distinction between my personal feelings on the matter, vs what may or not work in practice. I'll try to clarify that.

I would as a donor always check the gauge even if it is to create a 'force of habit'. This way we can change plans (if possible) along the way should consumption be more than expected.

But as mentioned before, the recipient effectively does not need to know and adding the step to have the recipient see and verify adds time and possibly stress.

Personally, I agree 100% with both of these statements. If the gas is planned and managed correctly, then there is sufficient gas available to get the team out. Therefore there is no real need for the OOG diver to see the gauge prior to beginning the exit. However, there might be a reason to show the gauge, and I would certainly communicate the remaining gas info to the other team members if they requested it.

As the OOG diver, I would never ask nor expect to be shown the remaining gas supply. In an overhead environment (which is where I mostly dive), that is a waste of time. I have complete faith in mine and my team's ability to plan and manage the gas requirements for the dive, and I know that we have adequate reserves to get us out. If for some reason we don't, my knowing about it won't matter anyway, and will likely only add stress to the situation.

With Kevrumbo's scenario (three person team, restricted passage), it's obviously important for the donor to keep track of the remaining gas supply, and I agree that technically, the donee does not need to know. However, it might be nice for him or her to know, particularly when you reach the point in the dive where they need to switch donors. In that situation (as donor), I would probably just indicate that I was low on gas, but if the donee wanted to see, then I certainly would not mind showing them.

To me, the only time that it makes any sense at all to show the gauge is on an OW dive, where you have the option of surfacing immediately, or swimming a short distance (possibly to a more favorable exit point). This obviously needs to be a team decision, so I think all team members need to have all the info. If (as donor) I am lobbying for a swim, then I might need to show the gauge to assure the donee that we have sufficient gas to do that. If we are surfacing though, then I see no benefit to showing the gauge.

I think the issue here is that for the OOG diver, it's a bit of a "head game" - they are placing a great deal of trust in the rest of their team, who are effectively managing their gas for them. I think it's a bit of an oversimplification to say "there is never a need to show the gauge, so you should not do it" vs "there is always a need to show the gauge, so you should always do it". Different situations may call for different strategies, and I think it's important to remain as flexible as possible in dealing with the emergency.

 

[TSandM]

I think it's a bit of an oversimplification to say "there is never a need to show the gauge, so you should not do it" vs "there is always a need to show the gauge, so you should always do it". Different situations may call for different strategies, and I think it's important to remain as flexible as possible in dealing with the emergency.

Thinking divers. After all discussion, that IS one of the central tenets of DIR. We practice a sequence, but should always understand the reasoning behind it, so we can recognize when an exception to the rule has been encountered. Otherwise, we are blindly following protocol without comprehension.

 

[Kevrumbo]

A gas-sharing egress at nearly the furthest point of penetration, followed by a total light failure for the 3-man team is one of the most difficult & arduous drills to perform in an overhead class. However unlikely and improbable this occurrence may happen for real, the Drill illustrated an obvious point for me: everyone's gotta know how much gas that initial donor has. You have proper gas management and rock bottom reserve so at least you have a basic idea --how hard is it to just confirm it with a quick show of the SPG (right before the cascade of primary & secondary light failures in this Drill begins)? Also, a lights-out gas sharing egress in total darkness can take almost twice as long to effect an exit. A donor switch in this situation may therefore be inevitable.

Be consistent in practice, be prepared for the worst possible contingency. Always show your SPG on any Gas-Sharing Drill. . .

 

[rjack321]

A gas-sharing egress at nearly the furthest point of penetration, followed by a total light failure for the 3-man team is one of the most difficult & arduous drills to perform in an overhead class. However unlikely and improbable this occurrence may happen for real, the Drill illustrated an obvious point for me: everyone's gotta know how much gas that initial donor has. You have proper gas management and rock bottom reserve so at least you have a basic idea --how hard is it to just confirm it with a quick show of the SPG (right before the cascade of primary & secondary light failures in this Drill begins)? Also, a lights-out gas sharing egress in total darkness can take almost twice as long to effect an exit. A donor switch in this situation may therefore be inevitable.

Be consistent in practice, be prepared for the worst possible contingency. Always show your SPG on any Gas-Sharing Drill. . .

After Tech1 and learning AGs approach to blind line following, I'd have agreed with you.

After Cave1 with Chris LM, I no longer agree that you should or need to be tracing every last mm of line around a tieoff. You have to get out, check each tieoff with a quick swoosh of the hand all around the point. If you find another team his broken protocol and placed another line there, start tracing carefully. Otherwise get moving again.

Using this more cursory method we exited over 1000ft of passage, blind, sharing gas FASTER than we entered. This was a 2 person team. But with a 3 person team having everyone check every last mm on line is a waste of precious time.

You have to get out, slowing down on the exit to exhaustively check for a highly unlikely new T in the line is a misprioritization of risk IMO.

 

[Kevrumbo]

I agree, it is tough!!! You've gotta move as quickly as possible as a team on the egress, but at the same time you don't want to inadvertently blunder onto a wrong line leading away from the exit. A bad dilemma to be in for a Drill, a terrible experience to be in for real. . .

 

[rjack321]

For me, this drill was the tipping point on Cave1. I realized if I could handle that (BTW I didn't show the SPG, just checked it) I could handle anything less than being lost.

So now my greatest paranoia is being lost, not OOA on the line in the pitch dark.

 

[limeyx]

I agree, it is tough!!! You've gotta move as quickly as possible as a team on the egress, but at the same time you don't want to inadvertently blunder onto a wrong line leading away from the exit. A bad dilemma to be in for a Drill, a terrible experience to be in for real. . .

Also got to remember that in a cave you could have significant flow (for or against you). In a wreck, maybe not so much.

I get the CLM treatment in Jan, and then some AG treatment in feb, so I'm sure I'll know far more about it than I might want by then (if I haven't chucked the whole thing in)