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

[boulderjohn]

Thanks John, it would take 9 minutes once the OOG situation was mitigated and both divers were on their way up sharing gas. E.g. I let my buddy know I was OOG, we do an s-drill, stop, stabilize and then head up. A direct ascent would take ~ 3 minutes and I would only recommend this if you could not reach you buddy. or the buddy had no idea.

Why would it take 9 minutes to ascend from 80 feet? How is that valuable?

Mod Edit I'll meet you half way—prove to me how a pony bottle is better than a minimum gas plan?

Prove to me that a minimum gas plan is necessary in an OOA situation.

Several years ago, I asked in a thread for GUE divers to explain the theory behind min deco. I got a lot of contradictory answers. One of the most frequently mentioned was that stopping every 10 feet was the way things are done in tech diving deco stops, so it was good practice.

Unsatisfied, I contacted GUE headquarters and got a very thorough and very official explanation. Here is a quick summary of the 3 main points.

1. The theoretical basis in terms of physiology is a belief that the ascent should slow down during the shallower segment. (BTW, no one in that SB thread mentioned this.)
2. The halfway point of the ascent was chosen as the time to begin stops because any idiot can calculate half the maximum depth.
3. Stopping every 10 feet was indeed selected because that is the way it is done in their deco dive training, so, yes, it is good practice.

So, to repeat my question, why is it necessary to take that much time using that methodology to take a probably panicked OW diver on an NDL dive to the surface? Do you believe that is the ideal time to begin technical dive training?

 

[barth]

A stage is part of your plan, a pony isn't.

If it gets you to the surface how can it be inadequate if that is it's purpose. .

How can a beginner know that his pony is large enough to get safe to the surface ?

Would a spare air or 2 liter be enough or is a larger pony required?

How does a beginner get this knowledge when it is not in his training?

 

[loosenit2]

two points;

1. I agree with those that say you do not add a pony bottle to dive planning gas calculations. The rule is that it is there for emergency only. You should carry a pony with sufficient gas to get you to the surface from the deepest part of your dive. Beyond that you should still plan the dive using your primary/back gas. Yes that requires some gas planning to ensure that your pony will get you there but it is not part of primary dive gas plan.

2. Doubles are not inherently technical or more complicated, but they can be. Learning to use all of the available option with doubles (all the valves etc) requires additional practice and skills drills, and requires more task loading. If you don't use any of the valves, just keep them all open, it is no more complicated than a single 80; with the exception of being heavier and a little more work to learn to balance correctly.

 

[KenGordon]

My argument is why? Why add a dead raccoon to your rig when that gas can be calculated in your back gas

The purpose of the pony is not more gas, it is for when there is absolutely no back gas due to a failure.

Whether I have a 15l (120ish) or a 10l (80) does not matter if my regulator is broken.

 

[boulderjohn]

A stage is part of your plan, a pony isn't.

I thought you might be interested in a planning sequence for the coming movie Harry Potter and the 100-foot wreck.

First scene: Harry is on the boat,assembling his gear. He is diving air in a single cylinder. Not sure that he has enough gas to do the dive he plans, he clips on an AL 40 clearly marked as having 32% nitrox. He removes his magic wand from his pocket shorts, waves it over the cylinder, and says, "Presto! You are a stage bottle!" He puts the stage bottle regulator in his mouth and jumps in.

Second scene: Harry is visiting the wreck at 100 feet. He has used 600 PSI of his stage bottle (16 cubic feet). He switches to the cylinder on his back. He pulls the magic wand from his pocket shorts, waves it over the stage bottle, and says, "Presto! You are a pony bottle!" He continues the dive until he reaches a pre-planned pressure on his back gas, a pressure that does not include his pony bottle in ascent calculations.

Third scene: Having nearly completed the NDL dive ascent, Harry begins a safety stop. He produces the magic wand from his pocket shorts, waves it over the pony bottle, and says, "Presto! You are a deco bottle!" He then breathes off the deco bottle throughout the safety stop as an added measure of safety.
​

It's good to be a magician.

 

[KenGordon]

How can a beginner know that his pony is large enough to get safe to the surface ?

Would a spare air or 2 liter be enough or is a larger pony required?

How does a beginner get this knowledge when it is not in his training?

They cannot. Ponies are not appropriate for beginners. They need to have been taught proper gas planning and understand how to work out how much gas they need to manage an ascent.

There are other physical and process reasons too.

 

[Hartattack]

Why would it take 9 minutes to ascend from 80 feet? How is that valuable?

Prove to me that a minimum gas plan is necessary in an OOA situation.

Several years ago, I asked in a thread for GUE divers to explain the theory behind min deco. I got a lot of contradictory answers. One of the most frequently mentioned was that stopping every 10 feet was the way things are done in tech diving deco stops, so it was good practice.

Unsatisfied, I contacted GUE headquarters and got a very thorough and very official explanation. Here is a quick summary of the 3 main points.

1. The theoretical basis in terms of physiology is a belief that the ascent should slow down during the shallower segment. (BTW, no one in that SB thread mentioned this.)
2. The halfway point of the ascent was chosen as the time to begin stops because any idiot can calculate half the maximum depth.
3. Stopping every 10 feet was indeed selected because that is the way it is done in their deco dive training, so, yes, it is good practice.

So, to repeat my question, why is it necessary to take that much time using that methodology to take a probably panicked OW diver on an NDL dive to the surface? Do you believe that is the ideal time to begin technical dive training?

John, the best way I can answer these questions without typing out four pages would be to send you here: The Fundamentals of Better Diving This is their new fundies book and has some great info.

 

[grf88]

I thought you might be interested in a planning sequence for the coming movie Harry Potter and the 100-foot wreck.

First scene: Harry is on the boat,assembling his gear. He is diving air in a single cylinder. Not sure that he has enough gas to do the dive he plans, he clips on an AL 40 clearly marked as having 32% nitrox. He removes his magic wand from his pocket shorts, waves it over the cylinder, and says, "Presto! You are a stage bottle!" He puts the stage bottle regulator in his mouth and jumps in.

Second scene: Harry is visiting the wreck at 100 feet. He has used 600 PSI of his stage bottle (16 cubic feet). He switches to the cylinder on his back. He pulls the magic wand from his pocket shorts, waves it over the stage bottle, and says, "Presto! You are a pony bottle!" He continues the dive until he reaches a pre-planned pressure on his back gas, a pressure that does not include his pony bottle in ascent calculations.

Third scene: Having nearly completed the NDL dive ascent, Harry begins a safety stop. He produces the magic wand from his pocket shorts, waves it over the pony bottle, and says, "Presto! You are a deco bottle!" He then breathes off the deco bottle throughout the safety stop as an added measure of safety.
​

It's good to be a magician.

A pony is a pony and a stage is a stage, no magic wands required. They look the same and can be use interchangeably but not on the same dive. If it is a pony it is charged and left on and is not part of the gas plan for the dive. if it is a stage it is charged and turned off, until required, and is part of the dive gas plan. Not really that hard of a concept but for some reason many have a problem understanding it.

 

[CT-Rich]

A doubles course can be taught in one day. Some folks don’t even take a traditional course, they learn from friends and mentors. Its not advanced diving or technical. Moreover, my argument is not a logical fallacy, it’s fact.

My god this horse is getting bloated and purple.
But slogging on… there is almost nothing you can’t learn from a friend or mentor in diving. There are no scuba cops (unless you are French). There are regional differences in training, a diver learning in Coz will not be training in a drysuit or even a 7mm wetsuit. They just don’t need them at the OW level. Divers in the Great Lakes region or Norway are likely to start out in drysuits from the get-go, because it is the only way to do any significant local diving. There are specialty classes for diving dry, those that don’t need them from the start.

Few new divers are going to be handed twins or a pony to start. You *could* train them that way, but that would not be the norm. A lot of people look at everything up to AOW as a license to learn. Dragging more gear into the water adds task loading. When I dive with totally new divers, I won’t even make them tow the flag. I want them to stick with me, not churn up the bottom, not kick me in the face and read their gauges. That is plenty.

To give them more to carry, or to do, or to think about needs to have a compelling reason. More junk is useless, because, unless they know how to use it, it’s more junk. If you do not know how to stay horizontal in the water and add and dump air to correctly trim, twins are just big heavy things to move around the water column. They also have valves and gauges hoses and they need to learn how to set them up and move around safely. Is there a compelling reason and benefit?

A new diver could master use of a pony, it’s not brain surgery. There are situation where having one makes sense, I’ve been on a charter boat that required them, low visibility, etc. I would recommend a pony before doubles. Why? Simplicity, a pony gives a diver a independent redundant air supply where they can see and reach it. Back mounted doubles have a LOT more opportunities for snagging an entanglement hazard. Second, do you need it? Does a new diver need that much gas? If they are not deco certified, why take twin eighties to a depth where you could have plenty of gas, but find yourself with unintended deco obligations?

New divers should learn to dive with the minimum amount of equipment to dive safely in the the underwater environment they are using. A pony is not an unreasonable thing to have because they are likely to be diving with equally unskilled and unreliable buddies. Would I suggest it as an early purchase? No.

 

[boulderjohn]

A pony is a pony and a stage is a stage, no magic wands required. They look the same and can be use interchangeably but not on the same dive. If it is a pony it is charged and left on and is not part of the gas plan for the dive. if it is a stage it is charged and turned off, until required, and is part of the dive gas plan. Not really that hard of a concept but for some reason many have a problem understanding it.

...or maybe they disagree.