Recreational Pony Bottles, completely unnecessary? Why or why not?

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So you wouldn't end the dive if a 1st stage broke, returning to the exit/surface with the surviving independent cylinder?
I never said anything of the sort. It was asked why a manifold is ever a plus. I answered that. I was not pushing the use of a manifold, nor telling you when to surface, or how to dive.
 
I think most DIR training also subscribes to the philosophy of being able to solve two problems at the same time, but even if that's not the case, consider the following (very unlikely, admittedly) problem:

Three DIR divers are swimming along at 90 feet doing a rec dive on AL80's. Their trim and buoyancy are perfect. They have a rock bottom gas plan. Suddenly one diver runs out of gas. Buddy 1 donates to Buddy 2 and then Buddy 3 runs out of gas. Without a redundant air source, someone has a serious problem that could result in death of injury to the whole team. If 3 has a pony bottle, everyone happily ascends to their safety stop and has a great story.
Great post (#614), not just the excerpt I quoted. As I understand it, the DIR philosophy is that you train to address one major failure at a time, perhaps in combination with minor failures, as the probability of two concurrent major failures is, as you said, very low. Part of the DIR philosophy is minimalism, and in that respect an equipment question is what is the least amount to carry on a particular type of dive to address all but the most improbable failures or combination of failures. Another part of the DIR philosophy is standardization. Some in this conversation may love carrying a pony on rec dives, but I doubt most divers in the real world would. Those who like standardization, whether they consider themselves DIR divers or not, may have a difficult time with the idea of bringing a pony on some dives and not others.

I didn't learn to carry redundant gas when I first started diving, but had it been part of the class, I'd have no problems doing it.
Me too. If the OW courses taught that a pony bottle is as basic an item of equipment for divers nowadays as a BC, an octo, etc., it would suit my standardization obsession.

The most effective risk mitigation you can do in regard to diving is to stay in bed every day, and then look for ways to mitigate the risk of bedsores. In all activities in life, we have to assume what level of risk we are willing to accept. Different people make different decisions.

I accept the fact that carrying a pony bottle mitigates risk--no question about it. As I said previously, for the overwhelming majority of my recreational dives, I do not use a pony, even though I accept that it mitigates risk. That is because I have decided that for me, the risk is not so great that I feel a need to carry one. That is my decision for the dives I do. Other people may make a different decision for the dives they do.
I wish I had the confidence, experience, or whatever it is, to know what to choose on a particular dive or, to put it another way, how to gauge the risk and choose the appropriate equipment configuration for that risk. If a dive seems more challenging than the overwhelming majority of my recreational dives, my first thought would be whether the dive is even for me. If I decided to do the dive, I would probably use doubles. Or if doubles were not available, stay in bed that day. I'm sure you have the experience to do this kind of picking-and-choosing of gear for the dive at hand. I'm not sure I do. How can one be sure they're not becoming complacent when they judge a particular dive not challenging enough to be worth taking a pony?

There is a concept of the correct tool for the job.

For many years I dived twin 12’s (litres) (doubles) prior to that I used twin 10’s.

Walking along the harbour I bumped into an some I new who was shocked to see me in a single and pony.

We had been diving from a RIB (Rigid Inflatable Boat), doing 20m wreck penetration dives. There was insufficient space for twins on the boat. But redundancy seemed sensible when doing single file limited penetration dives.
In fact we actually ran some out of air exercises as part of the weekend.

Similarly I once made the mistake of doing some shallow shore dives in twin 12’s. It almost killed me walking around the harbour and across the rocks getting in and out from the dive.
Never again. Now I would use a single and pony.(or twin 7’s).

One of the nicest OC rigs for shallow diving is a set of twin 7’s. Light, with redundancy and more gas than a single. But it is ‘another set’ to keep in test.

If you are teaching. A single with pony is perfect.
The benefits of a pony become questionable below 30/35m.
Then you really want to be on twins. They give you sufficient gas for the depth and any accrued decompression stops that need to be completed.
You make a compelling argument that there are some kinds of recreational/sport dives in which a pony is the right tool for the job. And these are in addition to those often mentioned as being use cases for a pony, such as solo diving and diving in very cold water. Having to pick the right gear configuration out of a number of options could be maddening for the standardization-obsessed. It's great if you can do it.
 
I wish I had the confidence, experience, or whatever it is, to know what to choose on a particular dive or, to put it another way, how to gauge the risk and choose the appropriate equipment configuration for that risk. If a dive seems more challenging than the overwhelming majority of my recreational dives, my first thought would be whether the dive is even for me. If I decided to do the dive, I would probably use doubles. Or if doubles were not available, stay in bed that day. I'm sure you have the experience to do this kind of picking-and-choosing of gear for the dive at hand. I'm not sure I do. How can one be sure they're not becoming complacent when they judge a particular dive not challenging enough to be worth taking a pony?
I am sorry, but I am having trouble understanding such mental paralysis. People make decisions like this all the time, day in and day out.

I own an old cargo van that I use 90% of the time for scuba trips. I sometimes use it for errands requiring a large cargo area. It has different features than the car I regularly drive. This will no doubt shock you, but I regularly drive one vehicle or the other without shaking in fear that I will make a mistake in that driving choice. I am able to use the different features in the different vehicles even though they are not standardized.

I trained for years with an agency that was obsessed with standardization. I left it and discovered that making my own decisions about my own dives did not lead to certain death. Once you allow yourself the freedom to think for yourself, you get a wonderful sense of liberation.
 
I am sorry, but I am having trouble understanding such mental paralysis. People make decisions like this all the time, day in and day out.
People make decisions day in and day out about what equipment to take to avoid something as serious as not having air to breathe?

I own an old cargo van that I use 90% of the time for scuba trips. I sometimes use it for errands requiring a large cargo area. It has different features than the car I regularly drive. This will no doubt shock you, but I regularly drive one vehicle or the other without shaking in fear that I will make a mistake in that driving choice. I am able to use the different features in the different vehicles even though they are not standardized.

I trained for years with an agency that was obsessed with standardization. I left it and discovered that making my own decisions about my own dives did not lead to certain death. Once you allow yourself the freedom to think for yourself, you get a wonderful sense of liberation.
I think comparing choosing which vehicle to drive for the errand at hand to which scuba configuration to take to avoid not having air to breathe is a poor analogy.

Putting analogies aside, would you mind sharing how many years you spent with the standardization philosophy before you left it in favor of making gear decisions that the agency didn't provide for? Got a particular anecdote about when the light bulb went off?

I allow myself more freedom to make decisions about things that are unlikely to harm me and about which I know a lot. The cars I might choose for errands aren't dangerous, and I have decades of knowledge and experience choosing and driving cars. I'd be fooling myself to believe that about scuba and a number of other things in my life. There are agencies or schools of thought that state the alternatives to a pony and why they work, and there are agencies that hardly take any positions at all or give only vague answers. That difference is what drove me to the former.
 
I never said anything of the sort. It was asked why a manifold is ever a plus. I answered that. I was not pushing the use of a manifold, nor telling you when to surface, or how to dive.
Manifolds have their benefits. With two 1st & 2nd stages and hoses (necklaced? longhose?) they are great. There's the additional manifold valve and O-rings as a common failure point, but few (any?) have ever broken.

Comparing manifolded twinsets/doubles to independent backmount doubles is a change of philosophy.

Should a manifolded twinset go "phut" with a stream of bubbles, you go through your well-rehearsed shutdown drills, frequently shutting down the manifold first to save 'half' of your gas, then working out which regulator or hose has broken.

With independent twins/doubles, or sidemount for that matter, you don't have to do anything about it as you've a fully independent second source of gas to breathe off as you exit and swim to the surface. Obviously you may do something about it, but it largely depends upon the type of cylinders you're diving with. The reason being that most cylinders are rigged as "right hand" cylinders (i.e. looking from the back forwards, both cylinders have valve knobs pointing to the right). This means one of the cylinders cannot be shut down in the water by the diver; needs a buddy. To point one left, one right means the cylinder needs to be turned around, so the 1st stage is on the RHS.

Bottom line; they're completely independent so it doesn't "matter" that much if you can't sort it in the water. As it's independent, if you've shut it down, the only way of getting to the gas is feathering the valve, but you don't need to as you've enough in the other tank.

One *massive* caveat. You should breathe them down together, swapping between them. Although it depends on the dive; you might be breathing one cylinder down as a single with the other in reserve, then swap out the empty one back on the boat for the second dive.

Sidemount tends to breathe from both sides, breathe down by 30 bar / ??psi then switch to the other side. Tend to leave the longhose side higher than the shorthose side just in case a donation needs to be made.


There's more to independent doubles than first meets the eye.
 
People make decisions day in and day out about what equipment to take to avoid something as serious as not having air to breathe?
You are much more likely to die in a motor vehicle accident than from running out of air on scuba. On the surface, that makes choosing which car to drive a much more serious situation.

Going below the surface, I simply don't see the different choices as being that big a deal, and it makes the automobile analogy apt. I am not so feeble minded that I cannot deal with configuration changes in my scuba gear, just as I am not so feeble minded that I can't deal with changes in different kinds of motor vehicles.
Putting analogies aside, would you mind sharing how many years you spent with the standardization philosophy before you left it in favor of making gear decisions that the agency didn't provide for? Got a particular anecdote about when the light bulb went off?
I began taking tech training through the shop where I was employed, and it was TDI in name only; the instructor's TDI instructor training had come from an employee of Extreme Exposure (home of GUE), and he told us we would be ignoring TDI standards and following GUE's in the program. (Interestingly enough, TDI was just fine with that when I asked them about it.)

When GUE exile Andrew Georgitsis formed UTD, our instructor was one of the first to cross over, and our TDI student group all became UTD students. There was very little different from our original TDI/GUE training, but we had to start over at UTD Intro to Tech. I frankly battled UTD leadership regularly over things that my own research had shown were at least questionable. I always lost. After a couple years, I was a UTD Tech 2 diver when I made the momentous decision to switch back to TDI, getting Advanced Trimix certified in Florida. That was a huge decision--I knew getting certified in a tech program outside of the shop where I was employed meant I could no longer work for that shop. I was very happy working for that shop, so that indicates how strongly I felt the need to change.

Before I did that, I had gotten cave certified through NSS-CDS, and when I asked about configurations, my instructor said I could do whatever I wanted within reason, provided I could explain why. In time, we discussed some of the things I had been taught, and he shook his head in bewilderment. Why do it that way? I honestly did not know. It was because I was told that I must do it that way. "Dogma!" he said in disgust. "Dogma!"

When I switched back to TDI, I ran into more of the same. I learned that I preferred doing some things differently from the way I had been absolutely, positively required to do it before. This included procedures when I became a TDI instructor. When I did my practice teaching, my Instructor trainers wondered why I taught some things the way I did. The only thing I could tell them was that was how I had been told things MUST be done.

As a tech instructor, I have made understanding why things are the way they are a key facet of instruction. For example, my students are required to read a variety of sources on decompression theory and come to a decision on what decompression algorithm they want to use, and they have to explain why they chose it over the others.

When I later became a PADI trimix instructor, I ran into an interesting problem. Several of my fellow students from our UTD group came to me and wanted me to certify them for trimix diving. (They had been at the same level as me years before when we were students together.) PADI has a chart that shows at what level divers from different agencies could crossover for PADI tech, but the chart did not include UTD. PADI had to research the agency to determine at what level the former UTD students could cross over. It turned out to be surprisingly low, and the primary reason that was explained to me was that former UTD students need to learn to make their own decisions on things.

While on a cave diving trip, I listened to a DIR diver telling another DIR diver about a disconcerting conversation he had had with someone once associated with DIR but who was now diving with a number of practices that did not conform to DIR standardization. He said that this now non-standardized diver said he had made the changes because he liked them better. But what about standardization? In describing the man's reply, he made a crude gesture, indicating that the man did not give a rat's ass about that. That man's name is Bill Hogarth Main. You may have heard of him.
 
FIFY

Nothing like having proper redundancy, simple access to the valves, everything in front/side of you, sublime trim and streamlining...

Sigh. The season's just ended :(

Must do some mine diving...
@Wibble

I don't understand your point.

With side mount you have a similar problem to that of Independent twins.
If you loose the first/second stage on one of the cylinders, you can no longer access the gas in that cylinder. Thats a huge black mark for me. Been caught once, have no interest in being caught a second time - I might not be so lucky a second time!

I tend not to dive tight squeezes, so I don't need to use side mount. In the past I've passed a twinset through a hole and followed it. But I haven't dived anything in recent years which would require that tight a squeeze. As a general rule, if it's that tight, I'm not going there.

90% of my dives this year have involved carrying at least one stage. It's a real pleasure when i can get rid of the cylinders from under my arms. I bloody hate carrying stages.
 
@Wibble

I don't understand your point.

With side mount you have a similar problem to that of Independent twins.
If you loose the first/second stage on one of the cylinders, you can no longer access the gas in that cylinder. Thats a huge black mark for me. Been caught once, have no interest in being caught a second time - I might not be so lucky a second time!

I tend not to dive tight squeezes, so I don't need to use side mount. In the past I've passed a twinset through a hole and followed it. But I haven't dived anything in recent years which would require that tight a squeeze. As a general rule, if it's that tight, I'm not going there.

90% of my dives this year have involved carrying at least one stage. It's a real pleasure when i can get rid of the cylinders from under my arms. I bloody hate carrying stages.
What's the problem with feathering? In extreme scenarios, while I am not a cave diver, I understand that first stages can be swapped. You are going to have to service your reg, but at least you get that cylinder's gas
 
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