Why can't scuba tanks be set up like a firefighter's scba?

[Blue Sparkle]

This is a slight tangent, but I was just wondering, as I read along, if perhaps one reason the "valve up" orientation became standard is that with double-hose regs, the regulator "can" needs to be close to your lungs. With it mounted on the tank valve, it seems like that would be hard to achieve if the tank were valve down.

 

[DevonDiver]

I find it harder in thick neoprene gloves, but without the gloves I might agree with you.

Agreed - I have vague recollections of wearing thick neoprene gloves from my first decade diving in the UK.

That said, surely the issue is better dealt with by temporarily removing the glove and gaining dexterity, rather than temporarily removing the air to ease the pressure?!?

If skills are harder in gloves, or due to other critical equipment/exposure protection, then training and familiarity is the solution.

I still don't see any of this as a persuasive arguement towards a need for inverted tanks.

I've always considered the disconnect the critical skill; you can take your time with the reconnect, or abort the dive.

Like most 'critical' skills that form the foundation of diving, it falls into disuse and neglect until the situation arises where it needs to be performed to resolve/prevent an incident. If core skills were maintained/improved by divers, then there'd be less need for improvised 'air-off' procedures or discussion about why inverted tanks could be a benefit

 

[jh_MacLeod]

Well thanks DevonDiver for the detailed analysis; you make some valid points. I’m not going to take the time to address all of your comments but I will respond to a few.

As you said, the need may be rare or easily rectifiable through other methods; but as I said, I like to be able to turn my valve on and off. It’s not a need, simply my preference. And I have practiced and mastered the ‘reach back’ manipulation of my valve. I do it at least twice on every dive. But, if I did have limitations in my arm and shoulder mobility, I wouldn’t mind spending the money on a upside-down tank system, even if it is an equipment solution to a skills problem. Convenience of access, in my opinion, is a valid reason for liking a particular equipment configuration.

I had never had a problem with the inflator connector before that dive, and have not had a problem since. I do take extra precautions now, just to make sure that it is securely attached while still on the surface. I had previously disconnected it, and reconnected it, while under water and under pressure several times before, but never at that depth. Both my buddy and I are familiar with the valve and how it works. All I can say is that on that particular dive, neither of us could reattach it while the tank was turned on. We didn’t understand the cause either, but it seemed at the time as if we could not exert enough pressure to press the connector down far enough for it to latch. Once the pressure from the tank was off, it easily reattached and latched. I was wearing tropical gloves; my buddy had no gloves. The wing inflator is a DSS, more than two years old, but as far as I can tell still in perfect condition. It is a precision fit, however; not at all ‘sloppy’ or loose.

I didn’t have a reluctance to utilize my buddy. When my attempts to reattach the connector failed, that is who I turned to. But given the opportunity to safely attempt to do something myself without outside assistance, that is the choice I made. Call it a character flaw if you want, but the feeling of self-reliance, not buddies, is one of the aspects of diving that I most enjoy. That said however, I would not have attempted it without a redundant air supply available.

As for the two divers I know who returned to the surface in a similar situation, I will simply point out that both of them were PADI trained (as I recall, one OW & one AOW, but both vacation divers with less than 50 dives each), and each one was diving with a PADI dive master as a guide :-^). So perhaps that criticism should be taken up with your fellow dive professionals. I wasn’t in the water with them either time, but my guess is that the relatively inexperienced dive masters looked into the eyes of these inexperienced divers and made the safe choice, for everyone concerned.

 

[DevonDiver]

As you said, the need may be rare or easily rectifiable through other methods; but as I said, I like to be able to turn my valve on and off. It’s not a need, simply my preference. ...I wouldn’t mind spending the money on a upside-down tank system, even if it is an equipment solution to a skills problem. Convenience of access, in my opinion, is a valid reason for liking a particular equipment configuration.

(back on topic )

Of course, that's personal preference. In general though, I tend to measure the pros and cons of issues; in this case, convenience of (non-essential) access versus the inconvenience of all-round equipment use and logistics.

When I started using doubles, I opted for a 'cage' to protect the valves when doing wreck penetration. The same type of cage (Custom Divers) that can be used to 'stand' the tanks if inverted. I abandoned the cages in the end, because they caused more problems (entanglement/obstruction) than they solved. If used to invert tanks, then you'd not have an easy job changing them from dive to dive when using rental cylinders. They simply aren't designed for that - and would probably wear out. They're a possible solution if you only dove with your own tanks however.



Then comes the problem of hose routing. Your primary and secondary air-sources would need to route up your back and into a convenient (not-snagging) position for use. You'd need to purchase custom-length hoses for that task and establish a safe and low-profile method of routing them to the desired position - that would probably mean getting some sort of retainer sewn into the back of your BCD... or elastic bungees/clips if using a BP&W. Likewise, the LPI would need to be very long to reach up - I'm not even sure if you can buy LPI hoses of sufficient length to accomplish that?

If when diving, especially away from home and/or in a remote location, you have a hose failure... you're gonna be screwed to get a convenient replacement hose to make your configuration 'work'.

I'd also be very curious about the trim aspects of inverting the cylinder. The tank would have to be lower - meaning the normal buoyancy/weight distribution was reversed. This means you'd get 'head buoyant' during the dive (esp with Ali cylinders) and that the reg valve would be situated somewhere close to your coccyx... which'd be a painful place if it made even infrequent contact with you. Reg valves would route towards your body - projecting where the cylinder base normally wouldn't. The tank would have to be lower, because whilst the valves (upright) can sit behind the arch of your neck, the (inverted) cylinder base couldn't... so down slides the tank and you get a chrome-and-brass enema if you ever manoeuvre badly wearing the kit

 

[DaleC]

You will encounter just as many problems and objections diving an inverted cylinder as you will diving side mount in OW. If you can do one; you can do the other. The problem with imagining all the pitfalls, without actually trying it, is that they mostly, turn out to be bogeymen.

I have dived an inverted single rig and it was simple to set up and use. This talk of "needs" and "what problems does it solve" is unnecessary and stifling; I thought diving was supposed to be fun! If one wants to dive this configuration just do so for it's own sake - because one wants to, then the little issues that arise and fall away will be not be troublesome. There may be problems with rentals and charters but most of these have to do with convenience for the operator, not the client, which is a whole other can of worms I leave aside so my comments will be directed towards equipment owners.

Standard hoses (longhose & bungiied B/U, SPG, DS whip) connect all with the exception of the BC inflator. One can buy LP hoses online in any length for the same price as standard hoses though. Travel issues with that one hose would be the same as for anyone who uses a prescription lens - you plan ahead.

Hose routing isn't really a problem. In fact, lost regulator recovery is easier because one simply reaches back to the first stage and traces the hose forward from there. No more giant sweeps with the arm.

Trim issues are what they are. The first time someone dives any BC they may some adjustments.

Boat use is a non issue (at least around here). The tank simply rides upside down until use when it is flipped and donned.

The ability to turn the tank valve is a lot easier and those that minimize it probably haven't tried it. It's worth noting that RB users all have their valves down for a reason. I'll give you a valve up and a valve down rig and if you say the valve up is easier to turn I'll say you're full of beans.



Now, all of this precludes three characteristics that a diver should have if wanting to dive this route.

The courage to stand apart from the herd
The intelligence to think through issues for themselves
The work ethic to put in the effort needed

If one does not possess those attributes then they will have to wait. Soon, like sidemount in OW, the major agencies will figure out how to make money off inverting and then there will be gear and courses for all.

And Blue Sparkle, you are partially correct. Valve up and valve down both came into existence around the same time and early rigs employed both. The Aussies used single hoses quite early and were valve down. With double hoses they ran a stem up between the tanks so the cans sat between the shoulders. In Europe, up and down were mix and matched. Cousteau often rigged multi tanks with both but in those cases the off/on or reserve valve activator was usually down. With the mass production of doublehoses and single tank rigs in North America the valve up configuration won out.
For more info on this phenomenon google: VHS vs Beta ;0

 

[Leadking]

Reading the bulk of responses, the advantage to reg up is all top-side and the advantage to reg down is all underwater. It shouldn't take a rocket scientist to figure out which has more life threatening potential. The argument that we've always done it that way is Darwinism squared.

 

[DevonDiver]

The problem with imagining all the pitfalls, without actually trying it, is that they mostly, turn out to be bogeymen.

Unless someone visits the forum to rely personal experience (as you have done) then all we can do is speculate. However, we can do that from an informed and educated perspective.

It doesn't take specific 'experience' to work out that different length hoses are required, trim will be altered, or that inverted tanks won't fit into most cylinder racks on dive boats...

I have dived an inverted single rig and it was simple to set up and use.

Then please explain the basics of the configuration. It'd be more beneficial than just telling people they're wrong.

This talk of "needs" and "what problems does it solve" is unnecessary and stifling; I thought diving was supposed to be fun!

The thread was stared upon the premise of "why don't divers commonly use inverted tanks, like firemen?".

That question was answered; especially in respect of need and potential problems.

I think you're doing a knee-jerk 'rage against the machine' here... nobody's stating you cannot or should not use an inverted tank. Merely discussing the pros, cons and merits of such an approach. Relax Dale... nobody's personal freedom's are being curtailed.

If one wants to dive this configuration just do so for it's own sake - because one wants to,

The same could be said of wearing a 'My Little Mermaid' outfit, or paper-mache fins. Whilst you strike a laudable blow for divers' freedom... you aren't helping to educate any readers on the actual issues involved with that option.

Standard hoses (longhose & bungiied B/U, SPG, DS whip) connect all with the exception of the BC inflator. One can buy LP hoses online in any length for the same price as standard hoses though.

So.. BC inflator is a custom order from online. That's not convenient, especially for those who live outside the USA (there are a few people who do). If I took that option, I'd be paying international shipping and a 40% import tax. And I'd need at least 2 of them right? Planning ahead?

Long hose.. routed from inverted... becomes a very long hose. What do you do with the extra metre? Bungee it?
Short hose/Bungeed B/U... how long is that? To route from inverted? Where does it run? What stops if flopping? What stops it pulling against the neck when used?
SPG... what length? Routed to where? 22-24" would be long. What do you do with the extra? Run it up the body onto the chest?
DS LPI... again, what length? routed around the waist then 'up' to the drysuit valve? What if the valve doesn't rotate? Under/Over the weightbelt?

I'm really not trying to be facitious... there's a bunch of questions... and stuff that any potential 'inverted cylinder' diver would have to consider.

If you've done it, then please share the technical details... because 'standard hoses' just doesn't fit the bill, at least without some decent explanation.

Travel issues with that one hose would be the same as for anyone who uses a prescription lens - you plan ahead.

Again...an answer that isn't really an answer. What do you mean? Buy two of everything?

(again, let's not assume the diver concerned is in continental USA within 24 hours delivery range of their favoured online dive retailer).

Hose routing isn't really a problem.

Hoses have to travel an extra torso-length from valve to mouth etc. That seems like a problem to me.

In fact, lost regulator recovery is easier because one simply reaches back to the first stage and traces the hose forward from there. No more giant sweeps with the arm.

...and when the hose dangled down way below the diver.. that won't cause a problem? What about use inside wrecks? Or in current?... over coral?

...what if the hose gets trapped behind the diver? Is it easier to recover.. or harder? I've never had a problem recovering a hose from an 'upright' cylinder when it's been tangled behind. Given that my arms will only reach the very nearest end on an inverted set-up, doesn't that limit my options?

Trim issues are what they are. The first time someone dives any BC they may some adjustments.

Granted. But it is a consideration isn't it? Something that needs to be amended before use? Something divers should be aware of?

It won't be like simply 'moving the cylinder up or down' to change trim... certainly in the case of Ali cylinders, they float very differently at the top and bottom.

Boat use is a non issue (at least around here). The tank simply rides upside down until use when it is flipped and donned.

It'd be an issue in Asia... or in the UK for that matter. Unless you're suggesting that the tank would extend a good few inches above the top of the BCD... because that's the clearance required to seat the cylinder in most racks I've ever seen. I thought the inverted tanks weren't supposed to smash you in the head when you wore them?

It's worth noting that RB users all have their valves down for a reason.

It's also worth noting that tank shut-down is a critical life preserving skill for RB users. Not so for single-tank divers.

I'll give you a valve up and a valve down rig and if you say the valve up is easier to turn I'll say you're full of beans.

Valid point, but I don't think anyone has said that... all they said was "why?" and "at what cost/inconvenience?"

Now, all of this precludes three characteristics that a diver should have if wanting to dive this route.

The courage to stand apart from the herd
The intelligence to think through issues for themselves
The work ethic to put in the effort needed

Or... the intelligence to understand that work ethic should be balanced against the pros and cons gained...

Courage? I haven't seen a single post in this thread that illustrates any sort of 'herd thinking'... just rationale investigation of the option.

If one does not possess those attributes then they will have to wait. Soon, like sidemount in OW, the major agencies will figure out how to make money off inverting and then there will be gear and courses for all.

I doubt it... I really do. It serves no purpose...in doubles, yes. But in singles? What purpose?

Valve up and valve down both came into existence around the same time and early rigs employed both.....the off/on or reserve valve activator was usually down.
For more info on this phenomenon google: VHS vs Beta ;0

So... when the 'J' valve was used... tanks were inverted so that valve could be accessed. It was harder to access the valve with an 'upright' cylinder... then J-Valves went to join the dinosaurs and that consideration ceased to exist... so the inversion of tanks ceased to be necessary?

 

[fdog]

Meh. This thread is right on time, my estimate is 1.5 months before the next identical thread gets started.

I am intimately aware of the differences between the two. I wear an inverted cylinder a couple of hours a day when at work, so I pretty much have equal time between "valve up" & "valve down".

In my own personal opinion, there is no contest...valve down is superior in almost every way.



However, we have "valve up" in scuba diving because of industry inertia, and that is almost impossible to derail at this point.



All the best, James

 

[DevonDiver]

I am intimately aware of the differences between the two. I wear an inverted cylinder a couple of hours a day when at work, so I pretty much have equal time between "valve up" & "valve down".

In my own personal opinion, there is no contest...valve down is superior in almost every way.

James, again (with fear of being repetitive and demanding..and maybe sounding a bit like Halemano)...,why do you feel this?

Genuinely interested to know...

 

[VooDooGasMan]

Devon fdog must be a firefighter, I learned inverted from building a fire training tower and it really is a safe way to carry a cylinder.

An air2 will be useful if hose falls behind and can not be Obtained.