Distribution block question.....

[amascuba]

I've never taken a class. If think that if I were in a team envionment that I'd get gas from a team mate, then turn off both tanks in the event of a o-ring failure in the manifold system. This would allow you to preserve as much gas as possible while you deal with the failure enough to start using the gas again. It could also just be easier to make an ascent on your team mates long hose. However, If your in some position where you're not able to easily able to get gas from a team mate, the it would be easier to disconnect one tank, attach the second stage or deploy a stage rigged second stage, then turn off or disconnect the second tank (depending on which tank was turned off). I'm just thinking through scenarios and solutions. Either way, you shouldnt be without any gas at any time, typical team based rock bottom planning would work,
and you don't have to dense to determine that their is a solution. I don't think that it's necessarily any more complicated than dealing with the 9 valve failures, but do require somewhat of a different process. Again, just thining it through shoulldn't be that difficult.


And again, I still think that a traditional sidemount set up is still the best current solution, particularly for true sidemount passages where you'd likely be scraping the manifold against the ceiling regularly. However, I wouldn't hesitate using a z system for some types of diving.

 

[billgraham]

I've never taken a class. If think that if I were in a team envionment that I'd get gas from a team mate, then turn off both tanks in the event of a o-ring failure in the manifold system. This would allow you to preserve as much gas as possible while you deal with the failure enough to start using the gas again. It could also just be easier to make an ascent on your team mates long hose. However, If your in some position where you're not able to easily able to get gas from a team mate, the it would be easier to disconnect one tank, attach the second stage or deploy a stage rigged second stage, then turn off or disconnect the second tank (depending on which tank was turned off). I'm just thinking through scenarios and solutions. Either way, you shouldnt be without any gas at any time, typical team based rock bottom planning would work,
and you don't have to dense to determine that their is a solution. I don't think that it's necessarily any more complicated than dealing with the 9 valve failures, but do require somewhat of a different process. Again, just thining it through shoulldn't be that difficult.


And again, I still think that a traditional sidemount set up is still the best current solution, particularly for true sidemount passages where you'd likely be scraping the manifold against the ceiling regularly. However, I wouldn't hesitate using a z system for some types of diving.

How about, there is no manifold and you just stick the other reg in your mouth and shut down the tank with the problem? As for making an "ascent" on your buddy's long hose, how well is that going to work if the only way out is several thousand feet in the other direction? Whatever emergency reserve gas plan you had goes out the window when it takes twice as long because you're clumping along, bonking into each other. One of the greatest safety advantages of sidemount is that the tanks are completely independant. To me, this seems like an overly complex way to make sidemount diving warm and fuzzy for backmount/manifolded doubles people.

 

[MXGratefulDiver]

Not only gross unfamiliarity . . . but just gross *period*. . .
<ba dum tiss>

How so?

When I first became exposed to DIR, the standardized approach to fixing the clip to the long hose was by using an o-ring as a breakway point. Many DIR-trained divers I know still use this approach, because it's how they were trained.

In a typical sidemount setup, where a long hose is attached to the right cylinder, the same approach is used in order to facilitate long hose donation in the event that the diver is already breathing their left cylinder (and thus the long hose is clipped off).

The clip I use serves the exact same purpose, in the exact same way ... it only adds the advantage that if you need to restow the long hose for any reason, you don't first have to replace a broken o-ring.

So what do you see as a downside?

... Bob (Grateful Diver)

 

[MXGratefulDiver]

Team protocols. turn off both tanks, signal oog to team mate, share gas, deploy stowed second stage, and breath off it. Same minimum gas / rock bottom for any team based diving - enough to get you and a ream member to the surface while completing any deco.

... and if you're in a restriction ... where your team mate cannot hand you their second stage ???

... Bob (Grateful Diver)

 

[SuPrBuGmAn]

If think that if I were in a team envionment that I'd get gas from a team mate, then turn off both tanks in the event of a o-ring failure in the manifold system.

Team environment or not, your first step after a your primary(defined by whats in your mouth) quits delivering gas(or takes a dump in any other way) should be to get on your own personal redundant regulator. This should be an incredibly easy thing to do, pop the available/easy access regulator in your mouth and start breathing.

 

[amascuba]

Team environment or not, your first step after a your primary(defined by whats in your mouth) quits delivering gas(or takes a dump in any other way) should be to get on your own personal redundant regulator. This should be an incredibly easy thing to do, pop the available/easy access regulator in your mouth and start breathing.

Bubbling doesn't automatically mean a failed regulator. You don't automatically swap second stages on manifolded doubles. In manifolded doubles, if you hear bubbling behind your head, your first quick move is to determine which side is bubbling and shut down that side. If you are unable to determine quickly, default to the right side, breath down the second stage, swap to the necklace, and listen for bubbles. If they haven't stopped, then isolate and call a buddy to look at the problem. At this point it could mean a few different situations - left bubbling mistaken for right, left/right isolator, protruded neck o-ring, or something like needing to reseat a DIN o-ring.

Basically, all you're doing is treating the z systems manifold like manifolded doubles, with two exceptions; (1)Instead of using an isolator knob to isolate the tanks in a gas loss situation, you disconnect the tanks from the manifold and (2)One tank turned on at a time and using sidemount gas strategies to evenly consume gases from the tanks. At the point where you need to isolate the tanks, you will require a stage rigged second stage or a QC6 rigged second stage to continue breathing from the tanks. Of course, traditional sidemount rigging is simpler, as are manifolded doubles in a situation where you're dealing with a gas loss situation. However, with practice, I believe that a competent diver can handle easily handle the situation.

In a small sidemount tunnel, I think that you're absolutely correct in saying that the z system manifold and hose connections are typically going to be the first point of contact against a cave ceiling. That contact could wear down and break the hose connections to the manifold and like I've said this entire time, I still think that a traditional sidemount configuration would be best here. And especially in that type of situation, I think that team responsiveness would be slower due to the restrictiveness as well as most likely lowered visibility and that this situation would require more of an on board method of redundancy and self rescue.

EDIT: You still have the option of swapping to your necklace if your primary stops delivering gas. You also have the option of using a different second stage by turning one tank on and the other off. Most everybody that I know uses downstream second stages, so instead of not working, they typically fail open and bubble, so with that in mind, if your primary stops working it's usually because you're out of gas and would need a donation regardless (with manifolded doubles and z system sidemount - unless you had a roll off while breathing your necklace on backmount doubles)

 

[amascuba]

... and if you're in a restriction ... where your team mate cannot hand you their second stage ???

... Bob (Grateful Diver)

I've never taken a class. If think that if I were in a team envionment that I'd get gas from a team mate, then turn off both tanks in the event of a o-ring failure in the manifold system. This would allow you to preserve as much gas as possible while you deal with the failure enough to start using the gas again. It could also just be easier to make an ascent on your team mates long hose. However, If your in some position where you're not able to easily able to get gas from a team mate, the it would be easier to disconnect one tank, attach the second stage or deploy a stage rigged second stage, then turn off or disconnect the second tank (depending on which tank was turned off). I'm just thinking through scenarios and solutions. Either way, you shouldnt be without any gas at any time, typical team based rock bottom planning would work,
and you don't have to dense to determine that their is a solution. I don't think that it's necessarily any more complicated than dealing with the 9 valve failures, but do require somewhat of a different process. Again, just thining it through shoulldn't be that difficult.


And again, I still think that a traditional sidemount set up is still the best current solution, particularly for true sidemount passages where you'd likely be scraping the manifold against the ceiling regularly. However, I wouldn't hesitate using a z system for some types of diving.

.....

 

[amascuba]

How about, there is no manifold and you just stick the other reg in your mouth and shut down the tank with the problem? As for making an "ascent" on your buddy's long hose, how well is that going to work if the only way out is several thousand feet in the other direction? Whatever emergency reserve gas plan you had goes out the window when it takes twice as long because you're clumping along, bonking into each other. One of the greatest safety advantages of sidemount is that the tanks are completely independant. To me, this seems like an overly complex way to make sidemount diving warm and fuzzy for backmount/manifolded doubles people.

I don't know about your cave class, but in ours, we were required to exit at the same speed or faster that we went in while sharing gas in a zero-vis scenario. If you're taking twice as long, then something is very wrong.

 

[gsk3]

In a small sidemount tunnel, I think that you're absolutely correct in saying that the z system manifold and hose connections are typically going to be the first point of contact against a cave ceiling. That contact could wear down and break the hose connections to the manifold and like I've said this entire time, I still think that a traditional sidemount configuration would be best here. And especially in that type of situation, I think that team responsiveness would be slower due to the restrictiveness as well as most likely lowered visibility and that this situation would require more of an on board method of redundancy and self rescue.

So here's where we disagree:
-I don't consider either "onboard" redundancy or self-rescue to be optional in any technical environment.
-There's little point in messing with a time tested configuration (backmount doubles) unless the new configuration offers clear benefits. For sidemount, it does in specific environments (sidemount caves, and to save weight on the back in environments where tanks can be staged). Why design a sidemount system that has two major flaws for its primary use? Should we now have to learn four systems (backmount, z-system, sidemount, CCR) for their appropriate environments? Viewed that way, the range of environments where the Z-system is ideal looks pretty slim.

 

[MXGratefulDiver]

amascuba ... That's a pretty convoluted solution ... and one that may not be practical or achievable in a tight hole.

... Bob (Grateful Diver)