Pony Bottle / Spare Air

[Reg Braithwaite]

I have yet a 3rd method for my 13cu ft pony. I mount in on my tank right side, valve down so I have easy access to the valve. The 2nd stage is right next to the pony valve with the hose held along the length of the pony with shock cord.

The 2nd for the pony is thus in a place that is not accessible by others, nor a cause of confusion, but easy for me to grab, always in exactly the place I left it. One quick tug and I have air. I still have my safe second on my primary because a 13cu ft pony by itself seems to be a little small to replace my normal safe second. Also, I can dive without the pony with my normal buddies and not change my regulator setup.

I consider a moderate sized pony a practical solution to the need for redundant air for solo or instant buddy situations. It is not ideal, but it is certainly much more practical for a diver that travels than going for doubles and an isolated manifold.

Three questions:

1. Can you check a pressure guage for the pony during the dive?
2. If you plan your dive and dive your plan in such a way that your main tank has enough air for you and your buddy should he go OOG, is your pony strictly for the case where you have an equipment failure?
3. When you fly, are you required to remove the valve of your pony tank?

 

[paddler3d]

[*]When you fly, are you required to remove the valve of your pony tank?
[/LIST]

There was another recent thread on this topic...I believe that the consensus was to remove the valve, cover the opening with clear tape and put it in your checked luggage.

 

[Dr Wu]

Please provide documented incidents to substanciate your statements. Otherwise I do not agree with or even believe most of your points.

From randomly selected DAN Annual Diving Reports. It took about 5 minutes and I only looked at two years.

For the sake of space I limited the cites to cases where the diver mistakes the pony for the main tank. (which was the "con" that seemed the most confusing to some)

There are lots more. BSAC has a bunch too.


DAN RECORD NO: 7294

A 35-year-old male went down to set the anchor prior to a group dive on a wreck in cold water. Visibility was poor, amd when he did not return the other divers assumed he had continued along the wreck. The descendant’s body was found seven hours later with his pony bottle empty and his main tank full.

DAN RECORD NO:5594

The descendent was a 58-year-old male who was an experienced underwater photographer. The sea conditions were calm and the weather was warm and sunny. The diver was found dead with an empty pony bottle and 2950psi in his main tank.

00-18 Out of air, breathing off wrong
regulator
This 53-year-old male had been certified for
two years and had advanced open-water qualifications.
He was making a dive to 50 fsw / 15
msw but first began to descend without his
regulator in his mouth. After returning to the
surface, the decedent again descended. This
time he made the ascent with the regulator
from his pony bottle in his mouth After 10 minutes, the
decedent was low on air and panicked. He
made a rapid ascent and became unconscious
shortly after reaching the surface.
Resuscitation procedures were unsuccessful.
The scuba tank that was connected
to his primary regulator was full.

 

[Reg Braithwaite]

Since this thread is heading towards "Best of Scubaboard clichés" status on its own... Here's an oft quoted maxim to debate:

Equipment cannot be used to solve a skills problem

 

[muddiver]

Three questions:

1. Can you check a pressure guage for the pony during the dive?
2. If you plan your dive and dive your plan in such a way that your main tank has enough air for you and your buddy should he go OOG, is your pony strictly for the case where you have an equipment failure?
3. When you fly, are you required to remove the valve of your pony tank?

1. Why? I check guage before dive and since the regulator is in front of me, I would know if it starts to free flow.
2. Yes, gas management should be done for the dive only using the main gas supply. The pony is only for emergency use and is never factored into the dive plan/gas management plan.
3. Yes, I put a peice of clear 2-inch wide tape over the cylinder opening.

By the way, the list function in HTML is pretty cool. Thanks for the new trick.

 

[awakefie]

Booth's rule #2, coined by skydiving pioneer Bill Booth, from Wikipedia's article on Risk Compensation.

I used to be a skydiver and I can say this is very true. Most skydiving fatalities these days are related to canopy piloting error (swooping etc.) rather than gear malfunctions.

 

[paddler3d]

From randomly selected DAN Annual Diving Reports. It took about 5 minutes and I only looked at two years.

For the sake of space I limited the cites to cases where the diver mistakes the pony for the main tank. (which was the "con" that seemed the most confusing to some)

There are lots more. BSAC has a bunch too.


DAN RECORD NO: 7294

A 35-year-old male went down to set the anchor prior to a group dive on a wreck in cold water. Visibility was poor, amd when he did not return the other divers assumed he had continued along the wreck. The descendant’s body was found seven hours later with his pony bottle empty and his main tank full.

DAN RECORD NO:5594

The descendent was a 58-year-old male who was an experienced underwater photographer. The sea conditions were calm and the weather was warm and sunny. The diver was found dead with an empty pony bottle and 2950psi in his main tank.

00-18 Out of air, breathing off wrong
regulator
This 53-year-old male had been certified for
two years and had advanced open-water qualifications.
He was making a dive to 50 fsw / 15
msw but first began to descend without his
regulator in his mouth. After returning to the
surface, the decedent again descended. This
time he made the ascent with the regulator
from his pony bottle in his mouth After 10 minutes, the
decedent was low on air and panicked. He
made a rapid ascent and became unconscious
shortly after reaching the surface.
Resuscitation procedures were unsuccessful.
The scuba tank that was connected
to his primary regulator was full.

So couldn't it be argued that these deaths, tragic as they are, may have occurred even if they were breathing off their back gas?

I have a working reg in my mouth. All of a sudden, it doesn't work. I'm going to grab one of my other regs. There is a 50% chance that one of the remain regs is going to work, assuming you have a primary, secondary and pony reg. I breath my pony reg down, logically one of the two other regs are going to work, and in this case both should work.

 

[Reg Braithwaite]

So couldn't it be argued that these deaths, tragic as they are, may have occurred even if they were breathing off their back gas?

Anything could be argued. What I argue is that additional equipment introduces additional modes of failure that introduce new risks. It also introduces a potentially false sense of security that modifies the behaviour of the diver. The objective is for the new equipment to address existing failure modes, eliminating existing risks. With training and skills practice, the likelihood of experiencing the new failure modes can be dramatically reduced, and the likelihood of eliminating the existing risks can be increased. With training, the sense of security can be brought in line with the actual improvement in the diver's ability to survive a failure.

I argue that discussing the equipment without considering all three factors (risks introduced v.s risks addressed, potentially false sense of security, and skills practice) is going to fall a little short of ideal. At the very least, we should agree on what type of diver is being debated. Are we talking about an experienced diver with Solo Diving training carrying a pony? Or someone like myself with 72 dives who rents a pony at the dive shop without considering how it fits in with my existing gear and dive habits?

 

[Dr Wu]

So couldn't it be argued that these deaths, tragic as they are, may have occurred even if they were breathing off their back gas?

I don't see how. Of course we don't really know what happened but it would appear they died because they thought they were on their back gas. They also thought they had full ponies "just in case".

One can infer the "full pony" gave them a great deal security in their dive plan.

When they unexpectedly went OOA their "plan" went south and they were unable to recover.

I have a working reg in my mouth. All of a sudden, it doesn't work. I'm going to grab one of my other regs. There is a 50% chance that one of the remain regs is going to work, assuming you have a primary, secondary and pony reg. I breath my pony reg down, logically one of the two other regs are going to work, and in this case both should work.

You could take the time to do all that and hope in the "chance" or you could follow proper procedure and either find your buddy or do a CESA.

 

[muddiver]

Odd, I have met some people that say the exact same thing about carrying a pony! Their argument is that as long as you are carrying a second tank, a two first stages, and two or more second stages, you might as well add a manifold with an isolator and dive doubles.

Now you have full redundancy over a large set of failures a simple setup with fewer opportunities to make mistakes, and access to all of your gas. So, the argument goes, if you choose to execute a dive where you do not rely on your buddy for redundant gas, using a pony suggests you don't have the training or haven't really thought about the possible failures and how to handle them

Sorry, but I am not following your logic.

My statement is that it one is going to dive with the standard recreational basic scuba setup of a regulator on a single cylinder that has a primary second stage and an alternate second stage off of it, why add one more mouth piece to the mix.