Couple questions on a pony bottle for bail out

[Basking Ridge Diver]

Hey Errol - you have a basic mistake or typo... should be (100/33)+1 = 4

Gas Consumption Rate
An average diver has a surface consumption rate (SAC) of .75 cubic feet per minute. This means that on the surface a diver would use ¾ a cubic foot of gas per minute. To determine how much they would use at depth, you have to multiply by the ATA. At 100’ the ATA is (100/3) + 1 = 4 so .75cft/min x 4ata = 3 cubic feet per minute consumed on the bottom. We presumed a 20 minute bottom time so we will use 3cft/min x 20 minutes = 60 cft.


And not everyone subscribes to this - most of us have an emergency issue we are heading up and not hanging around waiting to see if we can fix it... This one has been beaten to death just saying this is not how everyone is going to prepare for an emergency ascent. For my diving I chose to use a pony.

Should an emergency happen on the bottom, it is likely that it will take you and your buddy a minute to sort it out and prepare to ascend. As we saw above, it will take approximately 7 minutes to ascend so that is a total of 8 minutes. As we learned an average diver will consume 3 cubic feet per minute at 100 feet without being stressed. For practical purposes, a dive team with an out of gas emergency will probably have an increased SAC rate so to increase the rate from .75 to 1cft/min is reasonable. For the ascent portion you would take the SAC times the average depth (in this case the average depth between maximum depth and the surface which is 50’ or 2.5ATA) Therefore, to plan gas for this out of gas diver ascent you take 8 minutes ascent time x 2 divers x 2.5 SAC = 40 cubic feet which is referred to as ‘Minimum Gas”. Therefore, a diver must depart the bottom when they have 40 cubic feet remaining. Using an Aluminum 80 that means when the pressure gauge reads 1600 psi it is time to ascend!

 

[jadairiii]

....
The whole point with nitrox is that you can NOT get it topped off if the shop is doing partial pressure blending. it must be completely dumped and re-filled EVERY time. We went over this before, didn't we?

WHAT? OMG, I must being going to die since I routinely have my nitrox and trimix tanks topped off, even with shops that do PP blending. Although I must admit it requires the diver to have a solid grasp of 6th grade Algebra to do it properly.


If you go to a shop or an instructor with an scuba tank with any mix other than air and want it topped up with the same mix without the necessity of dumping it completely and they cannot figure out how to do that (assuming they have the equipment) pick up the tank and go some place else. They are idiots. PP fill shops may not have the pressures to do that regularly but they better have the IQ's.


As an example, couple of weeks ago I went into my LDS (that does PP fills) with an 80 that I had used as a stage, had 1800 of 32%, did not feel like dumping down so I asked if their O2 banks were full, they were, so I handed to tank to them and had them top it off, they knew exactly what to do. Walked out with exactly 32% and a full 80.

 

[mrdre]

Errol, there is theory, there is GUI, and there is real life. And real life is often very different. Having a good buddy, good viz, no currents, proper equipment, is always good. But then there is a real life. You are in Caribbean, you are handed leaky 80 cft aluminium tank. You are on the tiny boat and you buddy up with somebody who can't even speak the language you speak. You aren't gonna dive? You are going to say "nope, I'm gonna sit in the boat"? You dive and then that buddy sees a manta and swims away. And that's the end of all the theories. You need to start ascent with 1600 psi of air. Really? Who would do that? You are handed 80 cft old tank with 2400 under the sun. Once you are on the water you realize it's 2100. You aren't diving? Of course you may say "no, I'm not diving", but 90% of the dives in Caribbean (and in many other places in the world) are like that. You dive with old tanks with random people, who do stupid things. You may choose not to dive, but then you will miss a lot of cool dives, or you will have to charter a boat, bring your own equipment, come with people you know, but it will cost you arm and leg.. Most people can't really afford it. So? Not diving?

Yet a lot of these problems are solved by just carrying 19 cft pony. That's it. You ascend with 800 psi. You enjoy the dives, you don't worry about idiots. Why not have the pony in such situations?

If you mention GUE, then it has to be GUE - the equipment must be all configured according to GUE, all the divers must be GUE trained. Moreover they often dive doubles, which is already self sufficient. But you can't expect to have it all the time. Diving doubles is impossible with a lot of recreational dives. They are heavy, beach entries and exits are tiresome, not all boats will fill doubles. You need to have either drysuit or double bladder wings. All that stuff is expensive. Most people simply don't do that. So shouldn't they be diving? Why not just add a pony and get rid of a lot of potential problems?

 

[Errol Kalayci]

If you have the gas available through planning like I describe (typo noted I pulled a draft I found and did not check or post final article) and someone needs gas, there is no emergency since you the donor has enough gas for two people to make it to the surface following prescribed ascent rate. For properly trained divers, out of air emergency is solved and becomes a total non-emergency by donation of a functioning regulator (basically an S drill), then taking time to make sure they do not create a further problem.
Divers need not be technical divers to have great control in the water, be able to donate a regulator, remain horizontal and even backwards kick to maintain position if needed.
I understand that additional training is needed for many divers who do not have the control of buoyancy needed to stay together with a buddy or knowledge of how to properly plan. Fortunately, there is training available, a 4 day Fundamentals course through GUE will resolve these issues for divers at any level of training. I have conducted Fundamental courses for Technical Instructor Trainers from various agencies when they discovered their skills and knowledge were not what they COULD be and wanted to have said skills and knowledge after seeing a woman dive who had just taken open water in my class (we call it Rec 1) and were shocked thinking she was taking Instructor Trainer class. My personal goal is to be the best that I can be in whatever I do and to seek out the best informed and skilled instructor possible to learn anything I need to learn in life. I am not saying that I am the best instructor or that GUE is the best agency, I am saying that the ability to handle the situation proposed in the manner I describe should be held by divers of every level, from day 1 and training exists to make sure that happens. One caveat, I am not giving instruction on this site nor do I suggest anyone take advice from something they read on a forum. There are much better ways to dive where you will have more fun and increased safety, diving a pony is not one of them, suggest an open mind and seek out the information.

 

[uncfnp]

This is getting ridiculous. As to air vs nitrox, I propose a new dive formula...

Average diver on routine dives not pushing NDL's and wanting no hassles with fills or MOD = air

Diver pushes the envelope or has medical issue with higher risk, and dive profiles allow = generic 32

Obsessive diver that likes to pay for fills = same as back gas

If you are Greg Vic Diver, etc = band your pony to your main and install a manifold to = doubles!



To Errol and others. I respect your viewpoint and will not argue logic to your mantra. I resist the obvious insult to others like myself that choose to dive differently then you and your erroneous assumption that this is done in ignorance or lack of skill.

 

[DaleC]

Yup,
I think it is a basic error of philosophy to put your survival in the hands of anybody (stranger or well trained partner) if the means for self sufficiency is easy, practical and available. It's like trusting to blind jumps in caves. You've allowed the means of survival to leave your person. I don't trust someone to analyze my tanks, to turn my air on or to plan my dives. I also wouldn't let someone else carry my cutting tool, compass or SMB (if diving in conditions where surfacing required one) so why would I let them carry my redundant air source. Which is it? Am I too weak, lazy, unskilled or just plain trusting to do that myself.

The whole argument that it is too much equipment (a small pony) by some is ridiculous, especially when I see divers from that regime doing simple rec dives with doubles, canlights, argon bottles and scooters. To do all that and pretend a pony is extraneous is nothing less than comical.

If divers want to trust their life to a stranger or acquaintance more power to them. Personally, I call that sort of behavior foolish and I think it is equally foolish to promote "trust me" diving to others.

 

[Greg_Vic_Diver]

Whenever I am faced with a problem and I want to fix the root cause I use the 5 whys method (made famous by Toyota).


Here is my 5-Whys of using a pony bottle for diving (note I used 6 why’s here , but the technique is the same):


Q: Why are you using a pony bottle for diving?

A: For redundancy in case I run out of gas

Q: Why do you need redundancy?

A: Because buddies are not reliable

Q: Why are buddies not reliable?

A: Because they can’t share gas with me in an emergency

Q: Why can’t buddies share gas with you in an emergency?

A: Because they can’t give me the gas when I need it in an emergency and if they could it may not be enough for us both to get to the surface

Q: Why can’t they give gas and why is it not enough?

A: Because they haven’t reserved the amount of gas required for this and haven’t recently practiced this drill

Q: Why haven’t they reserved the required gas or practiced the gas sharing drill?

A: No training was provided on gas planning and lack of recent practice has degraded gas sharing skills

 

 

[DaleC]

Why do I carry a pony.
Because it's easy.
Because I refuse to offset my personal responsibility to others (yes taking care of myself is my responsibility).

But I get your way of thinking. It's like thinking BCD's and SPG's are crutches used by the weak and feeble and have come about as the result of skills degradation.

How about running that same Q and A on why people who don't use a piece of equipment feel the need to comment in a thread about it?

---------- Post added July 25th, 2014 at 05:16 PM ----------

Let's look at it this way

Use a pony

• Known volume
• Known mix
• Known equipment
• Known servicing of equipment
• Known location
• Known deployment

Buddy system:

• Unknown volume
• Unknown mix
• Unknown equipment
• Unknown servicing of equipment
• Unknown location
• Unknown deployment

Now, GUE can be commended for addressing many of those points by standardization and training but those members represent a whopping 1% of divers, and probably less than that in the purely recreational setting. Someone from that regime, suggesting practices to someone outside that regime, and expecting similar results, lacks basic situational awareness. I belong to the vintage diving equipment community but would never suggest some of our practices to a modern trained diver. It would be dangerous.

 

[John C. Ratliff]

Whenever I am faced with a problem and I want to fix the root cause I use the 5 whys method (made famous by Toyota).


Here is my 5-Whys of using a pony bottle for diving (note I used 6 why’s here , but the technique is the same):


Q: Why are you using a pony bottle for diving?

A: For redundancy in case I run out of gas

Q: Why do you need redundancy?

A: Because buddies are not reliable

Q: Why are buddies not reliable?

A: Because they can’t share gas with me in an emergency

Q: Why can’t buddies share gas with you in an emergency?

A: Because they can’t give me the gas when I need it in an emergency and if they could it may not be enough for us both to get to the surface

Q: Why can’t they give gas and why is it not enough?

A: Because they haven’t reserved the amount of gas required for this and haven’t recently practiced this drill

Q: Why haven’t they reserved the required gas or practiced the gas sharing drill?

A: No training was provided on gas planning and lack of recent practice has degraded gas sharing skills

I have used the Five Whys analysis technique for accident investigation when I was EHS Manager for a chemical manufacturing company for the semiconductor industry. It is one of many different techniques to get to root causes (plural) of an incident or accident. However, it is difficult to do until there is an actual incident, as each is unique. By the way, you need to count, as you have six questions here, not five. Concerning your questions, each one has multiple answers. For instance, you ask, "Why are you using a pony bottle for diving?" and answer that it's "For redundancy in case I run out of air." It could also be for your buddy running out of air, or feeling sick and needing to switch air sources because of contamination (CO poisoning comes to mind). But there is no accident/incident that this question is pointing toward. Wikipedia has an article on Five Whys, and also some critique:

While the 5 Whys is a powerful tool for engineers or technically savvy individuals to help get to the true causes of problems, it has been criticized by Teruyuki Minoura, former managing director of global purchasing for Toyota, as being too basic a tool to analyze root causes to the depth that is needed to ensure that they are fixed.^[6] Reasons for this criticism include:

• Tendency for investigators to stop at symptoms rather than going on to lower-level root causes.
• Inability to go beyond the investigator's current knowledge - cannot find causes that they do not already know.
• Lack of support to help the investigator ask the right "why" questions.
• Results are not repeatable - different people using 5 Whys come up with different causes for the same problem.
• Tendency to isolate a single root cause, whereas each question could elicit many different root causes.

These can be significant problems when the method is applied through deduction only. On-the-spot verification of the answer to the current "why" question before proceeding to the next is recommended to avoid these issues.

A pony bottle is only one of several methods of coping with or preventing out-of-air situations. The submersible pressure gauge (SPG) was touted as an answer to out-of-air in the 1970s. Each has advantages and disadvantages.

Today, on my dive in the Clackamas River, I used twin 42s (you cannot buy these--they are what I call PJ tanks, and are not available commercially). It has a J-valve on the twin manifold. I was using a dive computer, and surfaced with about 700 psig showing in the tanks, but also with the J-valve "Up," meaning that I had another 500 psig in one tank as reserve air. On a different vintage diving website, I coined the term, "internal pony bottle," to describe diving with both the SPG and the J-valve in the "Up" position throughout the dive. This gives an extra bit of air available if something happens.

A different way of thinking of the J-reserve is that it is actually an internal "pony bottle." A single "72" cylinder (which actually contains about 64.7 cubic feet of air at 2250 psig) has a reserve equivalent of a 8.6 cubic foot pony bottle, but it is integrated into the same cylinder, so there is no additional drag. My twin steel 45s, with a 1800 psig rating, contains the equivalent of a 12.5 cubic foot pony bottle (500 psi spring on the double J-reserve). For twin 72s, with a 500 psi spring, the "internal pony bottle" is about 14.4 cubic feet. All of this is within the same cylinder, so no added drag in current from a pony bottle.

I dive my SPG with the J-valve up, and use the tanks as if they were K-valves. Therefore, I will come out of the dive with my J-valve up, and will have that amount of air "in reserve" in case of an emergency. I have one set of doubles with both tanks equipped with J-valves, and a crossover manifold. These are steel 52 cubic foot tanks at 1800 psig. With both J-valves in the "Up" position, I have in reserve 17.3 cubic feet of air. This would be the same if I had used K-valves, and the J-valve on my Calypso regulator (which is center-mounted). All this is internal, without clutter of a pony bottle.

Read more: Respect for Vintage | Vintage Scuba Diving Community Forum

The photo below is of a diver in 1969 wearing the PJ tanks.

SeaRat

 

[Errol Kalayci]

The Hydro Atlantic dive July 18 2014 on Vimeo