Need more gas - now what?

[AfterDark]

These are choices I made years ago. I use BM ID's of various sizes to suit the dive(s). Any of the tanks I use for ID's can be used as single tanks or used in a combination of single tanks to fit the dives.

I've found one of the biggest side benefits of IDs is as I get older and my gear gets heavier I can carry each tank as a single. My tank size choices reflect how long ago I made these choices. I use 2 50cuft steel tanks made 1965, 4 72 cuft steel tanks made in the 1970's , 2 94 cuft steel tanks made 1980's.
This system has worked for me and my diving needs here in RI. I don't travel much if at all so travel gear is not part of the equation. Any traveling I do for diving is by car so my gear comes with me.

 

[Dan_P]

These are choices I made years ago. I use BM ID's of various sizes to suit the dive(s). Any of the tanks I use for ID's can be used as single tanks or used in a combination of single tanks to fit the dives.

I've found one of the biggest side benefits of IDs is as I get older and my gear gets heavier I can carry each tank as a single. My tank size choices reflect how long ago I made these choices. I use 2 50cuft steel tanks made 1965, 4 72 cuft steel tanks made in the 1970's , 2 94 cuft steel tanks made 1980's.
This system has worked for me and my diving needs here in RI. I don't travel much if at all so travel gear is not part of the equation. Any traveling I do for diving is by car so my gear comes with me.

Thanks for sharing.
There's of course been a lot of talk about indies versus manifolded in backmount before, I'm sure you'll have read/heard a lot of that at some point(s).
For me, the need you describe is exactly what I mean by scalable in the system that I use, where I can plug in one small tank, a larger one, multiple tanks or swap in new ones during the dive, and whichever tank I choose, feeds the whole system - both regulators, BC, drysuit.
That way, whatever tank I need, I bring and everything is consistent, 100% of the dive.

One of the issues that is often brought up with individual tank configurations (both sidemount and backmount), is that one needs to swap regulators often throughout the dive, to balance the tanks.
This means there's a myriad of options to address in terms of routing/configuration/protocol, none of which fully work for my personal needs. There just always is some area of diving where it seems to not work well enough, no matter which coniguration I'd opt for.
There is also a gas planning consideration when using a tank configuration with decreased compartmentalization options, compared to ex. a high-pressure manifolded doubles rig.
For me, it's mainly the regulator swapping and the impact it has on configuration versus protocol.

But, if I were a solo diver, I'd opt for some individual option, to avoid any risk of a single point failure (manifold).
It's just that for me, I'm not choosing to accept the risk profile of solo diving, so I prefer manifold.

 

[tbone1004]

scaling with al80's isn't very efficient, just isn't no matter how you skin it.

In cave diving, where it really matters, I have 3 tank sizes that I use, all filled to 3600psi/250bar for refernce
LP50/8l-for when I can't fit with the big tanks or just want some super light bottles
LP85/13.-for "normal" diving
LP121/19l-when lp85's+1 stage aren't enough, I go to 121's

Most of my cave dives now are using 121's and 2 stages. If I were to do this with AL80's, I'd have 6 bottles, and that is very annoying to tote around in a cave. That is the reason that Mexico style sidemount diving doesn't work in Florida.

The issue with the Z-manifold is that while it is scalable and consistent within a UTD team *which is what you plan on because that's what UTD is*, and while many of us including myself like the system in theory, it actually has some very real and very large safety issues within a cave diving environment that I haven't seen talked about. That safety issue is one of the bottles not having a second stage regulator on them in addition to the QC6. There have been several instances where divers have been coming out in an emergency and would have died if the bottles that they came up to where rigged with a Z system. These bottles weren't theirs, they were either safety bottles that were staged there, or someone else's bottles, but had they come up to that bottle without a second stage on there, they wouldn't be here to talk about it. The KUR, WKPP, etc. all have QC6's to be able to plug into their rebreathers, but all of those bottles ALSO have a normal second stage on there.

Now, you talk about consequence vs. probability of failure. One very low probability, but VERY high consequence is that you experience a failure of the isolation valve in the UTD manifold. It is the same valve that is used on scuba tanks, and there is a single o-ring that likes to get worn and can fail. If that fails, or since you have to plan for 2 catastrophic failures *in this case both female QC6 connectors*, what do you do? UTD says carry a spare second stage with a QC6 in a pocket. While now you have a system that already costs $750 more than a standard sidemount or backmount system *yes that number is real*, and you now have to add another $300 on top of that? Made worse by how uncomfortable a long exit would by with the size and weight of the QC6 system because UTD has decided that they want to go the cheap and easy way on the QC6's instead of "Doing it Right"? You do know that you can get regulator fittings for the QC6's instead of using NPT to regulator adapters yes?

This is UTD's "oh sh!t" solution when the Z-system breaks.

this is their implementation of the QC6 using NPT adapters instead of doing it right and having them made with regulator adapters

SF2 decided to actually "Do it Right" and this is the exact same MAV's, with QC-6's on them, but they instead had it done properly without adapters

So now I have a less than ideal implementation of a quick disconnect, have had to spend over $1000 over what we would have spent on a comparable system using normal regulators, and the only thing we really have done is allow you to share gas on the same tank with a buddy. If you are diving properly, that is really a pretty remote possibility, and if you are concerned about it for decompression, it is cheaper/easier/better to just bring an extra bottle with you so you aren't tied to your buddy

 

[Dan_P]

I never really meant the video to push Z-system but rather explain the pro's and con's of various ways to manifold...

That is the reason that Mexico style sidemount diving doesn't work in Florida.

I think it makes sense to have a system that works well everywhere, is consistent and scalable, rather than have a system for this environment, one for that, a tweaked gas donation protocol here and there in case this and that, etc.
That consistency, in my view, has a significant positive impact on safety.

The issue with the Z-manifold is that while it is scalable and consistent within a UTD team *which is what you plan on because that's what UTD is*, and while many of us including myself like the system in theory, it actually has some very real and very large safety issues within a cave diving environment that I haven't seen talked about. That safety issue is one of the bottles not having a second stage regulator on them in addition to the QC6. There have been several instances where divers have been coming out in an emergency and would have died if the bottles that they came up to where rigged with a Z system. These bottles weren't theirs, they were either safety bottles that were staged there, or someone else's bottles, but had they come up to that bottle without a second stage on there, they wouldn't be here to talk about it. The KUR, WKPP, etc. all have QC6's to be able to plug into their rebreathers, but all of those bottles ALSO have a normal second stage on there.

We do agree that divers should aim to leave other diver's staged tanks alone, right?
What kind of scenario leads to this eventuality - if we're planning for this, then with all the acumen for feathering and other exotic solutions regarded as valid, I'm comfortable that you'll have to make do with thumbing a QC6 for gas if you're snatching my stage tanks

Now, you talk about consequence vs. probability of failure. One very low probability, but VERY high consequence is that you experience a failure of the isolation valve in the UTD manifold. It is the same valve that is used on scuba tanks, and there is a single o-ring that likes to get worn and can fail. If that fails, or since you have to plan for 2 catastrophic failures *in this case both female QC6 connectors*, what do you do? UTD says carry a spare second stage with a QC6 in a pocket. While now you have a system that already costs $750 more than a standard sidemount or backmount system *yes that number is real*, and you now have to add another $300 on top of that? Made worse by how uncomfortable a long exit would by with the size and weight of the QC6 system because UTD has decided that they want to go the cheap and easy way on the QC6's instead of "Doing it Right"? You do know that you can get regulator fittings for the QC6's instead of using NPT to regulator adapters yes?

Not really. By that logic, you couldn't use a manifolded backmount rig either, because what if two divers both lose their manifold?
At least with a Z system, you keep all your gas so you can rotate your tanks on to your donor's system.

Indies are a fine tool for the alpinist solo explorer, but I think that's about it. How they stand idly by and say nothing while the mainstream scuba agencies push that configuration to new open water divers for a buck, is beyond me.

And what's with the QC-fitting? UTD doesn't say one way or the other, most of the Z rigs I've seen have your "doing it right"-fittings on them. It's just an incorrect inferrence based on a picture on the internet.

And the spare regulator hasn't been standard issue since the isolatable manifold came about, which is ancient info by now.

So now I have a less than ideal implementation of a quick disconnect, have had to spend over $1000 over what we would have spent on a comparable system using normal regulators, and the only thing we really have done is allow you to share gas on the same tank with a buddy. If you are diving properly, that is really a pretty remote possibility, and if you are concerned about it for decompression, it is cheaper/easier/better to just bring an extra bottle with you so you aren't tied to your buddy

You think the only thing done is share gas on the same tank with a buddy? Look, you can present any indies configuration, and I'll show you where it falls apart. Most likely, it'll be in a gasshare.
And I think your $1000 (which we've established is a hyperinflated number) is saved better by having just one rig for all your diving, throughout your progression.

Again, I wasn't aiming to post the video for the reason of peddling Z-system, but in the face of criticism, I think it's fair game to insist that the criticism is at least somewhat correct.

 

[tbone1004]

@Dan_P you can't talk about how a low pressure manifold system is superior to a high pressure or lack of manifold while decked out in UTD gear, posting from an official UTD youtube channel and not have everyone go straight to the only low pressure manifold system on the market. It is about the Z-system, whether you think it is or it isn't, it is the only option out there and you happen to teach for the only agency that uses or promotes it.

the picture on the internet is from the UTD web store and is what is shown by AG in all of the UTD videos. If you guys in Europe are using the proper ones, then that's fantastic, but the UTD website specifically sells the NPT to regulator adapters as an extra cost option and there is nothing in there for the proper fittings.

Swapping tanks should never be a planned procedure with anything other than al80's, and those tanks are not practical for most true technical diving.

Use of others stage bottles is certainly not something you should ever do, however it does happen in rare circumstances, and there are individuals that would not be with us if those tanks did not have second stages on them. The KUR has second stages on all of their stage bottles despite having what is essentially a LP manifold attached to their rebreather because if they hadn't, at least one of their team members would have been dead because of it...

Low pressure manifolds are a great system in theory, but the practical applications of them just don't really make sense because by your own logic, the probability vs consequence of failure doesn't balance out to warrant the extensive added expense of that system nor the annoyance of having to open and close valves on a regular basis.

Surprised that one thing you hadn't mentioned as a con of that system is salt water ingress into the system. QC6 does not have a lot of water come in when you plug it in, but it does have some, and when diving in salt or any sort of contaminated water, you are blowing that all through the hoses/manifold/adapters/regulators and it does have a very real impact on how frequently you have to service regulators. I have seen the inside of some second stages from a guy that uses the z-system in salt water and it was UGLY. This was after the manufacturers recommended interval not an extended service interval. It is a concern that all CCR divers have and is part of why they try to avoid using quick connects in the water unless there is an emergency. Having it as SoP and required for any dive with more than 2 tanks makes that water ingress a very real thing you have to worry about.

Trust me, I want the z-system to make sense, I have wanted it to make sense since the original one came out a LONG time ago, but no matter how we look at it from a cave diving standpoint, it just doesn't.

 

[Dan_P]

@Dan_P you can't talk about how a low pressure manifold system is superior to a high pressure or lack of manifold while decked out in UTD gear, posting from an official UTD youtube channel and not have everyone go straight to the only low pressure manifold system on the market. It is about the Z-system, whether you think it is or it isn't, it is the only option out there and you happen to teach for the only agency that uses or promotes it.

The video isn't at all about superiority of any one approach, it's about manifolds in general, and it speaks about a vast number of things but it's certainly not centered around any specific configuration. I never even mentioned the Z-system in the video, and I'm particularly sensitive about mentioning that it's my personal choice and why.
I don't think this is a very fair point to criticize, to be honest.
Of the solutions mentioned in this thread (indies backmount, BCD with increasingly more massive tanks with whichever impact to bouyancy one might imagine), I think Z System is by far the less controversial, anyway.

Swapping tanks should never be a planned procedure with anything other than al80's, and those tanks are not practical for most true technical diving.

Al80's work very, very well for technical diving - heck, almost everyone uses them for deco- or stage tanks anyway?
I'm not sure I undertand what you mean correctly with this argument..?

Low pressure manifolds are a great system in theory, but the practical applications of them just don't really make sense because by your own logic, the probability vs consequence of failure doesn't balance out to warrant the extensive added expense of that system nor the annoyance of having to open and close valves on a regular basis.

You're weighing up pro´s and con´s against cost in dollars?
Fine, but you're then stuck with your sidemount rig, for your logic to hold true.
You then have to use that same rig for open water-, tech-, team-, oceanic boat diving, ice diving, the works.
Okay, that's possible, but that's a heck of a cheapscape solution to tinker about with indies on an icy oceanic dive because of the cost of a manifold and a couple of gas connectors.
In the grand scheme of things, it would have been a heck of a lot cheaper for me, personally, to start out with Z-system from Day 1. That's not even taking into account all the jacket-style BCD, split-fins, computer and backup computer, etc. - purely looking at rig.

Use of others stage bottles is certainly not something you should ever do, however it does happen in rare circumstances, and there are individuals that would not be with us if those tanks did not have second stages on them. The KUR has second stages on all of their stage bottles despite having what is essentially a LP manifold attached to their rebreather because if they hadn't, at least one of their team members would have been dead because of it...

We could go into a lengthy discussion about rebreathers, but I'll keep it to being able to use the rebreather "base" as an open cirquit bailout platform, hence not requiring to add an extra LP hose with an extra reg, to it.
Those individuals you speak of, if they did get saved because someone had a spare reg on their staged tanks and everything worked out well, bene - but the QC was hardly the cause of their problems to begin with, and so the QC/reg shouldn't be the solution to them.

What if the "snatching" of those staged tanks actually ended up getting someone (else) killed?

The problem couldn't have been whether or not there was an extra reg on those tanks. It'll have been why the diver(s) who nicked them, weren't self-sufficient within their team.
I acknowledge that it'll might come off insensitive to say so, but all the same.

Surprised that one thing you hadn't mentioned as a con of that system is salt water ingress into the system. QC6 does not have a lot of water come in when you plug it in, but it does have some, and when diving in salt or any sort of contaminated water, you are blowing that all through the hoses/manifold/adapters/regulators and it does have a very real impact on how frequently you have to service regulators. I have seen the inside of some second stages from a guy that uses the z-system in salt water and it was UGLY. This was after the manufacturers recommended interval not an extended service interval. It is a concern that all CCR divers have and is part of why they try to avoid using quick connects in the water unless there is an emergency. Having it as SoP and required for any dive with more than 2 tanks makes that water ingress a very real thing you have to worry about.

I don't think it's a problem, no. I have serviced plenty gear from QC and non-QC systems, and don't really see much of a difference. Most of what I've heard from the RB80-sphere was that the salt ingress was never really a big issue there either.
I've seen plenty of ugly insides of regs within service interval without QCs and plenty with QCs that looked stellar.

I get that you'd like for the Z system to make sense but struggle to in light of your personal diving. That's fine, I don't have a problem with that.
From this side of the table, it's looking like a bang tidy solution, that's all.

 

[tbone1004]

@Dan_P you didn't mention the Z-sytem, but it is clear that you have a preference to a LP manifold to other configurations.

AL80's are not practical primary tanks because they do not have enough gas. A dive that I can do with a pair of lp121's would have to be done with 4x al80's to carry the same amount of gas. That actually limits by penetration distance because of the time to don and doff, but also the extra drag created by carrying extra tanks around for cave diving. In the ocean, it means I have to wear lead so I have a less efficient system of weight:gas capacity than I would with steel cylinders, and still don't have sufficient bottom time which means I have to own more tanks.

I have 3 rigs. Deep Sea Supply backmount and Hollis Katana Sidemount
Single tank-$500
Double tank *which can also carry my rebreather*-$500
Sidemount-$500
Set of Deep6 regs that can do sidemount/backmount doubles/backmount singles is $900
Total cost, if new for all three is 2400

Sidemount Z-system is $1250 which includes the Z system, and the sidemount rig which can't do backmount
Alpha Delta system is sidemount or single tank but can't do doubles and is $700
Still need something to carry a set of doubles and/or rebreather, so add $600 to that from UTD.
Total is $2550, but I still need a pair of first stages, so that's another $600

So from UTD, I'm at $3150 for the exact same functionality that I get from my other rigs with the only difference being I have to take an adjustable wrench out for a couple of hoses if I go between the three which takes all of 2 minutes. Tanks are tanks are tanks, so there is no benefit to either system for the tanks themselves, so that's a wash. You may have spent needless amounts of money on other systems, but if you buy the right equipment the first time around, it is not possible that the UTD system is less expensive

When we go into additional bottles, the QC6 with OPV and hose costs the same as a second stage, so we will call all additional regulators a wash. Based on that, you are in for an extra $700.
Benefits
In backmount, with singles or a manifolded set of doubles, there is no benefit.
In sidemount or independent doubles *which basically no one ever dives in a technical environment*, you can donate the primary all the time. In reality, in technical diving you should never be "surprised" by an OOA situation and having been in several real ones while on my short hose, it does not take any time at all to get the long hose into their mouth.
In technical diving with multiple bottles it does allow you to share deco gas which saves the annoying double deco. Personally though, the double deco isn't that annoying and if the deco obligation is more than say 20, just bring a spare deco bottle with you, especially in a cave where you can drop them

 

[Dan_P]

I have 3 rigs. Deep Sea Supply backmount and Hollis Katana Sidemount
Single tank-$500
Double tank *which can also carry my rebreather*-$500
Sidemount-$500
Set of Deep6 regs that can do sidemount/backmount doubles/backmount singles is $900
Total cost, if new for all three is 2400

Sidemount Z-system is $1250 which includes the Z system, and the sidemount rig which can't do backmount
Alpha Delta system is sidemount or single tank but can't do doubles and is $700
Still need something to carry a set of doubles and/or rebreather, so add $600 to that from UTD.
Total is $2550, but I still need a pair of first stages, so that's another $600

Tanks are tanks are tanks, so there is no benefit to either system for the tanks themselves, so that's a wash. You may have spent needless amounts of money on other systems, but if you buy the right equipment the first time around, it is not possible that the UTD system is less expensive

You don't need anything to carry double backmount and rebreather, see?
You can use the alpha/delta hybrid for both sidemount and rebreather configurations, so there's no need to purchase anything more than that single wing/config, it will take you all the way from Day 1 to Day 1000.
Or, you can use other solutions, which cost more, if you have such a preference.

Taking regs and tanks out of the equation (where I'm at, counting in the tanks is in favor of Z system, but it may not be the same where you're at, so I'll disregard it - regs are brand neutral in either case);
The difference is you need to have three rigs, where I only need one. By your numbers, your model is more expensive - even if we do assume that you can recycle your tanks all the way from Day 1.

And then there's the inconsistency in terms of protocol.

Dan_P you didn't mention the Z-sytem, but it is clear that you have a preference to a LP manifold to other configurations.

Yet, the video is about anything from indies in backmount, to high-pressure connections in sidemount, and anything in between.
I'm happy to have a conversation about pro's and con's, but to say that because I have a position that differs from yours, I don't get to have a say, is incompatible with discussing pro's and con's.
I really think I've been very fair and balanced in my way to speak of the various approaches and their pro's/con's with this video. I don't think it's fair to say that because of my preference, I don't get to have a say in the matter.

Benefits
In backmount, with singles or a manifolded set of doubles, there is no benefit.
In sidemount or independent doubles *which basically no one ever dives in a technical environment*, you can donate the primary all the time. In reality, in technical diving you should never be "surprised" by an OOA situation and having been in several real ones while on my short hose, it does not take any time at all to get the long hose into their mouth.
In technical diving with multiple bottles it does allow you to share deco gas which saves the annoying double deco. Personally though, the double deco isn't that annoying and if the deco obligation is more than say 20, just bring a spare deco bottle with you, especially in a cave where you can drop them

I don't agree that there are no benefits with a Z-system, compared to single- and double backmount. The fact that you'd need both a single backmount rig and a doubles backmount rig, is a pretty good start.
Other than that, sure, there are pro's and con's. We're dealing with technical details here, but there are some - i don't know that those would tip the scales either way for anyone purely looking at single tank, but in doubles, it becomes a thing.
If you like being on a doubles rig, consider that on a 75m diive, you're only on it 25% of the time, compared to 100% on Z-system. I can't see how that doesn't matter.
And yes, I think it actually does make a big difference whether you have a Z system or double backmount, when someone loses a deco tank. Quite a bit, actually.

As for sidemount, with Z-system - it's the same rig. You don't need to differentiate between those two worlds anymore, because they're identical.
Further, I really don't agree that the gasshare protocol hasn't a significant impact.
Being able to always donate the same way (O/C) does have an impact. Particularly when we're looking at indies in sidemount for comparison;

You're more than welcome to explain any indies sidemount configuration you prefer. I'll bet you it's one I've considered and discarded because of an issue I can't accept somewhere, when scaled, most likely related to gasshare protocol.

 

[PfcAJ]

All this talk about “scalability” is laughable.

Normal backmount doubles “scales” just fine. Guys went TEN THOUSAND FEET on open circuit in a 280’ deep cave two decades ago with normal oc doubles and stage bottles. No QC6 and goofy lp manifolds required.

George Irvine got it right. “If you see something that is a complete mess, makes no sense, is less than optimal, or is designed to accommodate some phobia while ignoring all else, you are dealing with a stroke.”

 

[Dan_P]

All this talk about “scalability” is laughable.

Normal backmount doubles “scales” just fine. Guys went TEN THOUSAND FEET on open circuit in a 280’ deep cave two decades ago with normal oc doubles and stage bottles. No QC6 and goofy lp manifolds required.

George Irvine got it right. “If you see something that is a complete mess, makes no sense, is less than optimal, or is designed to accommodate some phobia while ignoring all else, you are dealing with a stroke.”

What kind of argumentation is that?
People probably flew around in the air with a rubber band engine and a tarp once upon a time. So what?

And that quote is nothing but frontrunning the art of internet bashing. Congratulations for picking up the beton, even though the context is obviously lost in the transition.

Besides, those doubles on your back, you'll be on them less than 25% of the dive if going to 280ft. - and those same guys that you mention, did go on to add and employ a different solution, which paradoxally also had a QC6 on it.

Even so, I'm not saying what you're diving is bad or lesser than, and my way or the high way, or anything to that effect. I'm posting a video explaining manifolds in general, which is actually advocating the traditional hogarthian setup to the same level, if any at all, as the Z-system.

I've been more than fair and balanced in explaining pro's and con's on an even field.
Just argue the matter at hand.