Octo bungee logic?

[sea_ledford]

Another thing to consider in your LHOP (thanks for that TSandM) scenario is that if your primary fails at the same time your buddy is out of gas, you are now in a buddy breathing situation, which will likely not end well for either of you unless BOTH of you have practiced it regularly. And they don't even bother to teach buddy breathing in most OW classes (or ever) anymore. So you are proposing to solve a minuscule probability problem with a kludged up gear configuration necessitating the use of a skill you won't have.

A much easier solution is to use your back up second stage for every safety stop. That way you know it works when you need it, you know when it develops pin-holes in the side of the mouthpiece (it will) so you can replace it, and switching regulators is a non-issue.

-Chris

 

[Dhboner]

Of course if you were sidmounting you could always feather the tank valve on the free flowing regulator and continue to breath ;-)

 

[stuartv]

I use my octo(on a longer hose vs my primary) bungeed below my neck------IF a buddy 'needs my octo', I just pop it off the bungee loop & donate it, to him/her buddy(OR as wookie just described, if he/she 'steals' "MY" regulator--I know right where my 'other one' is, all nice & clean)......ie------I use my 'neck bungee' to simply 'hold' my octo in place below my chin, basically centered in my upper chest area....................

if your octo is bungeed to your neck, you know where it is, you don't really need a hand to get it to your mouth, or at least I don't, tuck your chin, nudge the octo, and slip it in.

Right. My question wasn't really about the reason for where you carry the octo or backup. It's about the logic of having it on a short hose that would make it very inconvenient to share it.

I had just read another post on here that recommended to a new diver who was shopping for gear to look at Dive Gear Express. The post specifically recommended a BP/W setup and the regulator sets that were also suggested all had the long primary hose, short secondary hose, and necklace bungee setup. Seeing this recommendation and the short hose for the secondary is what got me to wondering.

The additional hose length and potential for entanglement is the greater risk than the "simultaneous buddy out of air/primary regulator failure" scenario. Additionally, most divers who practice the DIR philosophy will never encounter an out of air situation...there is simply no excuse. Finally, your scenario also underscores why diving in a three man team is safer than the traditional buddy system.

The ones I saw on DGX were setup with a 90 degree swivel on the primary, so the hose could be run under the diver's arm. Why wouldn't you just use the same length hose and swivel arrangement for the one on the necklace bungee? Wouldn't this address the concern about entanglement?

Just BTW, but along the lines of terminology, I believe most people who dive with this configuration refer to the bungeed reg on the short hose as their "secondary" or "backup" rather than an "octopus" or "octo." The diver considers both of his regs to be equally functional.

Thanks for the correction!

Trying to build an equipment configuration that can handle anything can result in a setup of such complexity that the likelihood of a problem has actually been INCREASED.

I thoroughly understand that concept - from my daily job writing software and my former life racing motorcycles. So, do you feel like risk would be increased if the backup was on the same length hose, etc. (same hose routing, same swivel) as the primary?

You're overthinking it. The odds of a simultaneous OOA and primary reg failure are so miniscule as to not be worth bothering yourself with.

I think most OW student are still taught to donate the backup reg, and if that is your training, then it's probably not a good idea to have it on a necklace. On the other hand, the hose on most necklaced backup regs isn't really any shorter than the inflator hose, which is where you will find the backup reg for those who use Air II-type backup regs. If I absolutely needed to share my necklaced backup reg, I could. A good yank and I could pull it out of the necklace. Or I could slip it over my head. Or I could cut the bungee.

You're going to find that most people who have their backup reg on a necklace are using some variant of tech configuration. For example, their primary reg will likely be on a long hose, anywhere from 5-7' long. And they will be donating IT, not their backup. The idea here is to give the OOA (an stressed) diver a reg that you bot know is both (1) working and (2) has air. You, as the less stressed diver, then pop in your backup. Air sharing in this manner is quite unlike air sharing on a short hose (by short I mean normal rec diving length) and requires different training.

You're confusing a pony bottle and a deco bottle. Deco gas might have any concentration of O2, up to 100%, depending on the depth at which the plan calls for switching to that tank. A pony bottle for a solo dive will likely be filled with good old air. Also, keep in mind that a pony bottle is not used to extend the dive. It's a bailout bottle in case your primary system fails. That's why they're used by solo divers. They provide a redundant reg AND a redundant gas supply.

One last thing. Second stage regulators are designed to fail in the open position. This means that the vast majority of failures will result in a free flow. You can breath from a free flowing regulator just fine.

Me? Overthinking things?!!? LOL Yeah, I know...

The answer "that's so unlikely that it's not worth preparing for" seems like the succinct answer that I was essentially expecting. And I can accept that.

I imagine you are correct about what we'll be taught. But, after reading all I have on here about BP/W versus jacket BCDs, I (in the future, when I actually buy a BCD and regulators) have gotten pretty swayed towards the idea of going BP/W and also following the suggestion I read about the DGX regulator setup. IOW, when I do eventually buy gear (not any time real soon), I could see myself ending up with a regulator setup with the backup on a bungee necklace. In which case, having been trained differently won't mean much except that I need to do some practicing with my own rig after I get it, and be sure to have the appropriate conversation with my buddy, before we get in the water, including how we'll handle it if an OOA situation occurs.

Thank you as well for straightening me out on the various bottle terms.

---------- Post added September 24th, 2014 at 02:33 PM ----------

Also, when I started the thread, I realized that the likely answer to a primary failure would be that the OVERWHELMINGLY common failure mode would be free flowing - in which case someone could still breathe from it.

But, what about a failure where you can't breathe from it? For example, a LP hose failure? I talked to a tech at a LDS who said that hose failures aren't that common, but that he does see them more often than he sees some other types of failures that people seem to feel like are an actual thing to be concerned with.

In addition, I read another post here today from a guy who happened to discover a crack in his LP hose that was hidden by a slide-on strain relief. When I think about that, I imagine that crack lurking there undetected for some time. And then one day, the diver has to pass their regulator to a buddy who is OOA. The buddy extends the hose further then it normally gets extended and maybe even pulls on it a little bit. And suddenly, the hidden crack in the hose for the primary regulator ruptures and you have the exact scenario I postulated to begin with.

Now, obviously, that particular scenario is one that could be considered to be diver error - because the diver didn't properly inspect his equipment before he got in the water. But, isn't risk mitigation all about recognizing that things like that happen, and then designing a solution that mitigates the risk - hopefully without adding any new risk?

 

[Wookie]

Even in the nuclear industry, you could only plan for 2 cascading problems, one equipment problem and one operator problem. Sure, we've all seen Yakisoba and TMI and a few Russian Navy Oopsies, but in nuclear, you just can't plan for too many cascading failures, so you train your operators to take care of one problem at a time. Same with scuba. You train your divers to respond appropriately to a failure so it doesn't turn into 2 failures that they have to deal with at the same time. Run out of air? Use your backup or a buddy's backup. Didn't set your dive computer properly? Surface, set the computer, continue the dive.

In thousands of dives and being a dive operator for thousands of years, I have never seen a LP hose fail so dramatically the diver can't breath from it. I've never seen a HP hose do that either. What I HAVE seen is dive shops improperly assemble second stages so that it fails to deliver air, and I have seen main springs corrode through so that the regulator fails to deliver air. I've seen each happen once. The diver with the poorly assembled reg aborted the dive, came up on his octo, and we fixed his reg. The broken main spring belonged to my wife, and we now service the regulators every year, just like you are supposed to.

 

[stuartv]

Thanks, Wookie. I'm clear on most of that except - are you saying that you would only train divers to deal with one problem? Or you would only train them to deal with, at most, two problems at once? It it's two, then I would have thought OOA would be one and primary reg failure would be a second.

Though, really, I don't think I was asking about training. I was asking about the preparation that you might do, for in case you have those two particular problems at once. I realize you might not train divers on specifically what to do if one runs OOA and the buddy's primary fails when they start sharing it. But, even though you don't train people specifically on that, that doesn't mean you would not account for the possibility in the prep of your gear.

That said, I think I understood the rest of your post - i.e. that this particular scenario is SO unlikely that you would not bother to even prepare your gear to accommodate it.

 

[Dirty-Dog]

Of course if you were sidmounting you could always feather the tank valve on the free flowing regulator and continue to breath ;-)

You're not confusedly thinking that you can't do this on backmount, are you?

 

[Wookie]

Thanks, Wookie. I'm clear on most of that except - are you saying that you would only train divers to deal with one problem? Or you would only train them to deal with, at most, two problems at once? It it's two, then I would have thought OOA would be one and primary reg failure would be a second.

Though, really, I don't think I was asking about training. I was asking about the preparation that you might do, for in case you have those two particular problems at once. I realize you might not train divers on specifically what to do if one runs OOA and the buddy's primary fails when they start sharing it. But, even though you don't train people specifically on that, that doesn't mean you would not account for the possibility in the prep of your gear.

That said, I think I understood the rest of your post - i.e. that this particular scenario is SO unlikely that you would not bother to even prepare your gear to accommodate it.

The problem with planning for 2 equipment failures is which 2 do you plan for? The dog would chase his tail forever analyzing and analyzing and analyzing. What the nuclear industry plans for is a single equipment failure and failure of the operator to take appropriate action. That's the training part. That's why we say that "some gear" is an equipment solution to a training problem. So, in your scenario, a diver running OOA is a training problem. The buddy's primary reg failing is the equipment problem, and there is training to cover that, namely buddy breathing. Granted, buddy breathing isn't taught much any more, but there are procedures and any instructor who has been around longer than a few years will remember how to do it. It isn't taught because the reliability of equipment is so good, a spontaneous failure of a working regulator is hardly calculable. In the event that both buddies are out of air, the Controlled Emergency Swimming Ascent is taught, so indeed, the training failure and the equipment failure are covered procedurally.

Eventually you will encounter diving that cannot be accounted for with simple procedures, like running OOA in a wreck, cave, or in deco. In that case, we devise equipment solutions to cover a single failure of equipment with a single operator error. Remember, the operator error is almost always devised to be the failure to follow proper procedure for the equipment failure.

 

[stuartv]

Gotcha! Thanks!

 

[Dhboner]

You're not confusedly thinking that you can't do this on backmount, are you?

I can't (with my 56 year old shoulders...half dead from dozens of mountain bike crashes) but I do know that lots of backmounters can do it ;-)

 

[victorzamora]

In addition, I read another post here today from a guy who happened to discover a crack in his LP hose that was hidden by a slide-on strain relief. When I think about that, I imagine that crack lurking there undetected for some time. And then one day, the diver has to pass their regulator to a buddy who is OOA. The buddy extends the hose further then it normally gets extended and maybe even pulls on it a little bit. And suddenly, the hidden crack in the hose for the primary regulator ruptures and you have the exact scenario I postulated to begin with.

The hose will begin to dry rot long before it explodes. However, I can guarantee you that there will be no crack "lurking" beneath a strain-relief. Dry rot and water lurks under strain-reliefs (why I don't dive any on any of my regs). However, when a hose blows, it BLOWS. I've been diving for over a decade and have seen two blow. One was practically on purpose. The other was a rental in salt water with a crew that didn't take too much care of gear, and was then kinked between the tank and the boat. 5min later (after I said something), a gun went off....or at least I thought it had. Long story short, this is certainly not something you plan for as "possible" and certainly not a compounding failure.

One thing new divers tend to either ignore, misunderstand, or simply not give enough credit to is the fact that when something goes wrong, thumbs come up. I've never decided to leisurely continue a dive when something went WRONG. I've continued dives when stuff has gone less than good, but never when something is WRONG.