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

[James79]

I'm trying to discuss in good faith, but I can't ignore moving goalposts. The OP presented the risk of wrong mix in a pony tank. On further discussion he says he teaches all students to analyze every tank, and some agencies teach on EAN to start (so now we are making Nitrox the minimum entry point). But analyzing every tank (as he said he teaches NEW students to do) obviates the original point of wrong mix.
The first post raised the question of if ponies are always unnecessary.... and the OP has devolved into why his way is always better.
Hartattack, I will debate in good faith... but I ask that you listen to the idea of options others present, instead of focusing on "one right way." And, for the record, you still haven't addressed why this keeps being discussed as "planning or a pony" with no allowance for "planning, with a pony for when things go sideways."
And if it is "agree to disagree," I can leave it there to.

Respectfully,

James

 

[Hartattack]

You need to stop making wild assumptions. Some of my best friends are GUE, and GUE instructors.
They don't run around making uninformed statements about the way people dive and asserting that their way is the only way.
You don't use a pony bottle; you don't even know how to use one. We got it.

I gave my reasons why you don't need a pony; these are not uniformed. Moreover, dive how you like. Nevertheless, you didn't like that, so I debated that, and you have yet to present why your way is better. Which is ironic since you think I'm asserting my way is the only way. (I have stated many times it depends on the advanced divers situation, but, I still like my way)

I do not use a pony bottle. That is correct because they are not helpful, IMHO.

I do, however, use a decompression bottle.

With all of this said, let's get together for a dive sometime. I'd be happy to, and I think we could clear the air a bit here. I'm on the east coast all the time.

 

[Wibble]

I do not use a pony bottle. That is correct because they are not helpful.

I do, however, use a decompression bottle.

Do you dive a twinset/doubles perchance? Were you trained in valve drills? Do you regularly practice shutdowns and valve checks?

Twinsets are commonly used due to their inherent redundancy (once the isolator valve's closed). Thus your redundancy is inherent and you don't need a redundant bailout cylinder (aka pony).

New divers dive on air and a single tank. At first they do not dive in challenging conditions and are always with more experienced divers. Only after are they able to work up to deeper dives where they will use a pony cylinder (certainly will have been introduced to one in the "deep" diving course, 40m/130')

 

[elan]

To clarify again:

I have a problem with folks on the scuba board recommending a new diver to use a pony. It is unnecessary and adds complexity to a new diver that is not needed.

When it comes to advanced/working divers, do what you like. However, I still think they are unnecessary because I use MG in my dive planning with my team. Moreover, we usually dive in doubles and practice OOG and valve drills and can do them without much movement in the water column. I'd be happy to show anyone here how we do this.

We reserve "pony bottles" for left sided slung Decompression Bottles or Stages e.g. AL 80 or AL 40. We also calculate this gas into our dive plans. However, this now goes into the Rec 3, Tech 1, Cave 2 levels.

Ponies fit nicely in between no redundancy (I am not considering my single tank buddy to be redundant supply in certain situation like cold water) single tank dives and doubles.

While doubles are a better tool they do have a steep learning curve including the buddies being trained in them. Reaching valves, balancing them fore-and-aft, manifold failures. Manifold failures management is taught at Tech 1 level, so until you get to that level strapping doubles to ones back does not mean you can effectively leverage their capabilities.

So many people do not want to transition into doubles for many reasons yet need redundancy. This is where the pony option fit nicely IMHO.

Managing failure of the main tank when you have a pony is nowhere close in complexity to managing failures with the doubles.

 

[Hartattack]

I'm trying to discuss in good faith, but I can't ignore moving goalposts. The OP presented the risk of wrong mix in a pony tank. On further discussion he says he teaches all students to analyze every tank, and some agencies teach on EAN to start (so now we are making Nitrox the minimum entry point). But analyzing every tank (as he said he teaches NEW students to do) obviates the original point of wrong mix.
The first post raised the question of if ponies are always unnecessary.... and the OP has devolved into why his way is always better.
Hartattack, I will debate in good faith... but I ask that you listen to the idea of options others present, instead of focusing on "one right way." And, for the record, you still haven't addressed why this keeps being discussed as "planning or a pony" with no allowance for "planning, with a pony for when things go sideways."
And if it is "agree to disagree," I can leave it there to.

Respectfully,

James

Hi James, like I said to another person asking this question:

That's fair, and some folks have given some wonderful examples of when they might be helpful, to which I acknowledged with a "great point" or "That's fair" and then asked more questions or referred back to the new diver debate in the original thread for clarification. I even went so far as to add a dive plan as an example of my thought process and why I wouldn't recommend one to a new diver or anyone, honestly. I still think they are a marketing gimmick, especially something like a share air or 19cuft.

But what I was waiting for and wanted to "hash out," as the mod said in the beginning, is the folks who attacked me in the original thread. Tursiops, grf88, and others who want to bash GUE because I am a part of that crowd, so anything I say is wrong to them, and they will find any ways to discredit that agency because someone hurt them in the past, I would assume, yet they have never taken a class.

To give more context into the EAN debate, yes, I teach all of my students how to do this because I find value in it, and I think it is a vital safety portion missed in open water training. This idea continues to back the idea that new divers should not be using pony bottles because this training is NOT included in most agencies' open watercourses. The "what if" of a pony bottle being filled with the incorrect gas is much more of a possibility than a reg failure or OOG situation, IMHO. Not saying those do not happen, but I have seen in my experience more incorrect gas fills than I have seen reg failures or folks OOG.

Nevertheless, I will stick to my guns on why I think pony bottles are not valuable for both novice and advanced diving applications; folks can agree or disagree with me. However, I provided a plan that gives a diver the reserve gas within their back gas. This way of diving eliminates the need for a pony bottle, reduces drag, extra equipment, and a need for a second first stage and regulator. If someone would like to provide a better plan for this, I am all ears.

 

[James79]

But what I was waiting for and wanted to "hash out," as the mod said in the beginning, is the folks who attacked me in the original thread. tursiops, grf88 and others who want to bash GUE because I am a part of that crowd, so anything I say is wrong to them, and they will find any ways to discredit that agency because someone hurt them in the past, I would assume, yet they have never taken a class.

This statement here, reads as that you didn't want to debate.... you wanted to hash out a disagreement with specific people. I think that would have been better handled in a private conversation. But, since you did invite conversation from all.... could you respond specifically to why you see it as an all or nothing, gas management or a pony, binary choice? Not to argue with you (you have your set position, and I have mine, and I can respect that), but to clarify your position for the sake of discussion.

Thanks,

James

 

[tursiops]

share air

It's Spare Air, and I agree completely. I do not allow them as the required redundant air source when teaching solo. Too small. I'll allow a 13cuft for the class, but recommend a 19 or 30 for actual use.

 

[KenGordon]

I am glad you brought this up, Ken. So with this example, @tursiops and @boulderjohn what should we do about my ascent rate in my plan? Is it still too long?

If she had taken 2 minutes to the surface how do you think her urge to breath would have been?

My point is a Bolt to the surface is a poor solution as much as macho divers might claim otherwise.

 

[Hartattack]

This statement here, reads as that you didn't want to debate.... you wanted to hash out a disagreement with specific people. I think that would have been better handled in a private conversation. But, since you did invite conversation from all.... could you respond specifically to why you see it as an all or nothing, gas management or a pony, binary choice? Not to argue with you (you have your set position, and I have mine, and I can respect that), but to clarify your position for the sake of discussion.

Thanks,

James

That's partly true, and after this conversation, I think you are right, and my apologies for making this thread ridiculous. The best way to state my position is with the dive plan, which I will list below. Of course, ascent rates can be changed and recalculated. But, the thought process is there. Why use a pony bottle, when the reserve gas is already there in the first place? If you cannot find your buddy during an OOG emergency, revert back to your open water training and head for the surface.

Dive Plan:

A critical goal in planning a dive in open water is determining how much gas is necessary for an emergency scenario; With that in mind, we want to plan for one diver to suffer an out-of-gas emergency during the deepest part of the dive, which provides sufficient reserves for any range of potential problems within the buddy group.


Let's make a few educated assumptions that leave us all with a bit of room for conservatism.

1. Let's assume that our average surface consumption rate is ~ 20 L/ 0.75 cuft per minute.

2. The assumed ascent speed will be on average 3m/10 ft per minute.

3. The average depth of the ascent is used for all calculations. Divers should attempt to maintain a controlled ascent of between 20 to 30 feet per minute and follow minimum deco (MDL/NDL) profiles. This is based on a slow but foreseeable ascent rate that provides some wiggle room for safety. Also, the 20 L/ 0.75 cuft per minute SCR is approximate based on the outcome of an average diver in most situations.

• MG should never be less than 40 bar/600psi to account for inaccuracy and/or readability in SPG's.

Let's determine our minimum gas for the dive.


Minimum Gas:

Consumption= 0.75 SCR x 2 divers= 1.5 cuft /min

ATA: (80ft / 2 = 40ft); (40 ft / 33 +1 = 2.2 ATA

Time: 9 minutes (10ft/min ascent rate plus one minute at depth to resolve the problem and initiate an ascent (8 + 1= 9).

1.5 x 2.2 x 9 = 29.7 cuft of gas or (29.7 / Tank Factor 2.5 ) x 100 = 1,188PSI or to make it easier on the SPG 1200 Psi Minimum Gas to be conservitive.


To keep this dive easy and fun, this will be an all-gas usable dive in the Caribbean of the Midwest, Haigh Quarry. Our plan states that if we share gas from the deepest point of the dive, we require at least 1200 psi in our AL80 to reach the surface while safely transferring from one cylinder. As soon as we get 1200 psi, we would have to call the dive and begin our ascent. With that said, let's determine our usable gas with our MG and SCR examples.


Usable Gas:

1200 MG subtracted from the fill pressure of an AL 80 3000 psi

1200 psi – 3000 psi = 1800 psi usable gas


Now, with that information, let's determine our bottom time:


Bottom Time:

80 cuft tank with 1800 psi = 45 cuft usable (1800 psi / 100) x 2.5 TF = 45 cuft

0.75 cuft/ min SCR x 2.2 ATA = 1.65 cuft / min @ 80ft

45 cuft / 1.65 cuft/ min = ~ 27-minute bottom time.


Now, we are ready to dive and have fun on a single tank without a need for a pony bottle.


However, this does give us some wiggle room if we want to go for a more extended dive, right? According to the MDL for Standard Gas 32% (My agency), we have up to 50 minutes at 80ft. So let's do this dive in the AL 80s.


Minimum Gas:

Consumption= 0.75 SCR x 2 divers= 1.5 cuft /min


ATA: (80ft / 2 = 40ft); (40 ft / 33 +1 = 2.2 ATA


Time: 9 minutes (10ft/min ascent rate plus one minute at depth to resolve the problem and initiate an ascent. 8 + 1= 9)


1.5 x 2.2 x 9 = 29.7 cuft of gas or (29.7 / Tank Factor 5 ) x 100 = 594 PSI or make it easier on the SPG 600 PSI Minimum Gas to be conservative.


Usable Gas:

600 MG subtracted from the fill pressure of an AL 80 3000 psi

600 psi – 3000 psi = 2400 psi usable gas


Bottom Time:

Double 80 cuft tank with 2400 psi = 120 cuft usable (2400 psi / 100) x 5 TF = 120 cuft


0.75 cuft/ min SCR x 2.2 ATA = 1.65 cuft / min @ 80ft


120 cuft / 1.65 cuft/ min = ~ 72-minute bottom time which goes over our 50 minute MDL time. So, as a buddy team, you would have to be watching your depth and time throughout the dive if you decided to use doubles.


let's go over our pre-dive check:


Goal: Have fun at Haigh Quarry and see some catfish.


Unified Team: Diver 1, Diver 2, etc.


Equipment Check: Does all of our equipment work properly, valves, regs, inflators, valve dumps, primary light, backup light, what's in our pockets? Computers on and working? Do we have a cutting device?

Modified S-drill to make sure the primary hose is free from obstructions.

Exposure: (depth and time) 80 ft for 27 minutes (Single Tank) 50 (Doubles)

Deco: Minimum Deco or MDL procedures. 50 Minutes on 32% EANX @ 80 ft.

Gas strategies:

AL 80: 3000 psi, MG 1200, 1800 UG.

AL 80 x 2 3000 PSI, 600 MG, 2400 UG.

Environment: Haigh Quarry, viz is about 30 ft, water temp 55 at depth.


So, before we "ok" each other as a buddy team to descend, after planning the dive and checking all of our gear, what do you think the likelihood of a catastrophic failure or the need for a pony bottle would be?

 

[DAJ]

I think the disconnect here is the assumption that the "back gas" will always be available while those supporting a pony take the position that no gas is available in your primary cylinder(s) so the contingency is to carry a pony. While the complete failure of the primary system may be extremely remote, that slim chance directs some to address the possibility. Could a tank valve fail...maybe, could your primary/secondary hoses have a failure due to getting caught on an obstacle on a wreck dive or an overzealous buddy cutting away a bunch of fishing line...maybe. Even though that "maybe" might represent a 1 in 100,000 chance, some folks like the redundancy for the unknowns. Don't rely on your buddy as your main rescue plan. While it's easy to say "just get help from your buddy", how many dive in areas where they have difficulty keeping visual contact. This type of response only applies if those involved are constantly aware of the location of their buddy/group at all times. If it goes sideways and you don't see a buddy nearby, you are going for the surface. How many dive accidents have been posted here this year with the same scenario where a group of folks go diving and they only notice when one of the group is missing when it's time to return to the boat or they don't see them on the surface after a dive. While we would all like to say that they stay within a few feet of their buddy at all times, this is not the reality of what is actually going on.