Is a Pony Bottle too complicated for a beginner?

[wetb4igetinthewater]

How about this, since @CT-Rich , @grf88, @tursiops, and @Marie13 have all attacked my advice, opinions, and thoughts on this thread—why not you come up to the Midwest (Marie you are already here and dropped into two of my classes unannounced and with zero awareness at Haigh Quarry) come over and dive with me and show me why all of your solutions are superior. Let's put our money where our mouth is, I'd be happy to dive with all of you and see your point of view.

Hey you forgot about me! What a I? Chopped liver?

 

[lexvil]

Dogma divers can be tedious, not in their steadfast beliefs but more in their inability to believe that there are many many ways to dive.

meticulous planing is great as are doubles, which on the planet I live are not easier to carry, but they alone don’t solve every issue like dealing with a blown lp seat (happened to me) and let’s just say this is deep into the dive, first tank low (if not low because of the plan why?) and second tank in a freeflow does the plan help?

I carry a pony sometimes but mostly to test regulators, if all goes well my main tank will have extra air at the end of the dive but if something fails no big deal, a new diver who wants a pony for the psychological peace of mind harms no one, why care?

 

[Hartattack]

Hey you forgot about me! What a I? Chopped liver?

Haha I’d always dive with ya.

 

[CT-Rich]

How about this, since @CT-Rich , @grf88, @tursiops, and @Marie13 have all attacked my advice, opinions, and thoughts on this thread—why not you come up to the Midwest (Marie you are already here and dropped into two of my classes unannounced and with zero awareness at Haigh Quarry) come over and dive with me and show me why all of your solutions are superior. Let's put our money where our mouth is, I'd be happy to dive with all of you and see your point of view.

This is a *discussion* forum. That several people disagree is not surprising. You did call into question MY Credentials, even though I am only one of the half dozen people arguing against you POV. I am not a huge fan of quarry diving and I am not here to best anyone as a diver. I do have a degree in education and a few dives under my belt. I do realize that those who are interested in diving as a sport may get spooked away by making it seem too cost prohibitive or complex. Basic recreational diving is fun and easy. A deep understanding of the underlying physics and physiology are nice (I got the old school 12 week training). Expecting a novice diver to understand, much less calculate their SAC is unnecessary and intimidating. Would be divers that think math skills are essential to diving may get put off before they even learn.

The same could be said of gear, twinset tanks are heavy and expensive. Your average new diver may not be physically up to handling that much weight on land or in the water. A pony is not a stage bottle, the OP should learn the difference, apparently the difference hasn’t been entirely clear to some others in the forum .

If the OP wants to extend bottom time, a larger tank is the simplest solution. If they want a redundant air source in an emergency, a pony is a solution (as opposed to sharing air off a buddy’s safe second stage). These two solutions are not mutually exclusive, they could do both or neither. They could go to doubles, either together or as independent doubles. Independent doubles would require more skills training and more expense, which he is probably not ready for.

 

[grf88]

I should add that I will always challenge anybody who tries to discourage the use of pony tanks for recreational divers. I spell it PONEE for Piece of Necessary Emergency Equipment.

 

[Hartattack]

Let's you and I do a virtual dive to 80ft on single AL '80s, shall we? And in that dive, you have a seat failure where you start to lose your gas supply.

Dive Plan:

A critical goal in planning a dive in open water is determining how much gas is necessary for an emergency scenario, as you have listed above.
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.

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

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

Time: 11 minutes (10ft/min ascent rate plus one minute at depth to resolve the problem and initiate an ascent.

1.5 x 2.2 x 11 = 36.3 cuft of gas or (36.3 / Tank Factor 2.5 x 100 = 1,452 PSI or to make it easier on the SPG 1450 or 1500 Psi to be conservitive.

• Our plan states that if we share gas from the deepest point of the dive, we require at least 1500 psi in our AL80 to reach the surface while safely transferring from one cylinder.
So, @lexvil, at what point during the dive will we need to call it and head to the surface if all goes according to plan?

 

[grf88]

Let's you and I do a virtual dive to 80ft on single AL '80s, shall we? And in that dive, you have a seat failure where you start to lose your gas supply.

Dive Plan:

A critical goal in planning a dive in open water is determining how much gas is necessary for an emergency scenario, as you have listed above.
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.

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

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

Time: 11 minutes (10ft/min ascent rate plus one minute at depth to resolve the problem and initiate an ascent.

1.5 x 2.2 x 11 = 36.3 cuft of gas or (36.3 / Tank Factor 2.5 x 100 = 1,452 PSI or to make it easier on the SPG 1450 or 1500 Psi to be conservitive.

• Our plan states that if we share gas from the deepest point of the dive, we require at least 1500 psi in our AL80 to reach the surface while safely transferring from one cylinder.
So, @lexvil, at what point during the dive will we need to call it and head to the surface if all goes according to plan?

If each diver carries a pony sized to reach the surface from the planned depth at a safe speed including a safety stop these plans become redundant and the divers can enjoy a decent dive time. You failed to include the significantly increased SAC rate for the panicked diver, a panic that would be greatly mitigated if they knew they were self sufficient.

 

[Hartattack]

If each diver carries a pony sized to reach the surface from the planned depth at a safe speed including a safety stop these plans become redundant and the divers can enjoy a decent dive time. You failed to include the significantly increased SAC rate for the panicked diver, a panic that would be greatly mitigated if they new they were self sufficient.

Did I ask or state anything about a pony bottle or increased SCR yet? I think it would be nice to have @lexvil answer the question and we continue our virtual dive before being interrupted, no?

 

[grf88]

Nope, but you all wanted my answer and thought process, so now I am doing a virtual dive with @lexvil. What you are doing by interrupting is rude. Nevertheless, if you want to answer the question, by all means please do. I will get to your questions in a moment. But I want to keep this thread on topic for just a few minutes to give a solid and fluid explanation.

The topic is pony bottles not gas management. Please keep on topic.

 

[Hartattack]

The topic is pony bottles not gas management. Please keep on topic.

I am by showing that a new diver does not need one with an example that all of you asked me for or criticized. So with my example, what is our minimum gas for our planned dive and at what psi should we call it?