Pony Bottle / Spare Air

[SkimFisher]

Spare Air: Diver's Salvation

 

[Aaron528]

Regarding Spare Air and pony tanks... I wrote a little computer program to calculate the depth from which one could theoretically reach the surface breathing from a pony tank of a given size, assuming that (1) you are not in an overhead environment or on a decompression dive, (2) you ascend at 60 fpm until you reach 60 feet, then ascend at 30 fpm, (3) you plan to make a 3 minute safety stop at 15 feet, and (4) your SAC rate is 0.88 cfm (average). Your mileage may vary.

Here are the results:
1.8 cu. ft. -> does not even give enough for the safety stop! (Need 3.838 cu. ft.)
3 cu. ft. -> does not even give enough for the safety stop! (Need 3.838 cu. ft.)
6 cu. ft. -> 44 fsw
13 cu. ft. -> 154 fsw
19 cu. ft. -> 216 fsw
30 cu. ft. -> 301 fsw

This shows why SpareAir is not adequate. It just isn't enough air to surface safely from any depth where you would need it. Even 6 cu. ft. is pretty much useless, since most people can figure out how to swim to the surface from 44 feet without an air supply. Either 13 or 19 cu. ft. would be a good choice for a practical redundant air supply for recreational diving, if you are not in an overhead environment or a decompression dive. In those situations, you need to consider how much air you might need to get out of the overhead environment (Rule of Thirds, etc.), and how much you would need for stage decompression. The results tabulated above are NOT valid for those situations.

I've been lurking on this site for 6 months and haven't posted before. I went looking for a discussion about pony tanks and I'm enjoying this thread. I read someone elsewhere wrote of a "center drop" style reg to keep the setup streamlined, other than the Zeagle/H2Odyssey I haven't been able to find anyone that sells regulators with that title, and nothing comes up searching for pony regulators. I've seen others write about using a "bottom of the line" scubapro MK2 and related 1st stage/octo combos, but it seems this kind of arrangement would be heavy and not the best for travel. I have a follow up question to the general debate over size of tank: For those of you looking at this with experience, what kind of regulator have you got attached to your pony tank?

 

[travis99]

I am pretty new to diving, but I think a spare air would be just enough to get you to your buddy who was a few feet away so that you could do an emergency out of air accent. How about a spare air on your leg and a pony bottle on your side. I'm a big fan of backing up my backups.

Travis

 

[elmer fudd]

I've been diving for awhile now and I'd like to have a SpareAir.

I currently use a 19cf pony for all dives over 45' or so and most of the time on shallower dives too, but on a shallow dive where I anticipate doing a lot of finning, I'll sometimes ditch it in order to reduce drag.

For those shallow dives I think a SpareAir would be great. An extra thirty breaths of air would beat the hell out of a CESA where you'd likely first be just hoping you'd make it to the surface and then, if you made it, you'd be wondering whether you took a hit in the process.

What I'd really like to hear more about are the stories of people who actually have performed CESA's, and not training CESA's either, but actual emergencies.

The way I envision it happening is that I have just exhaled, my lungs are nearly empty and I go to take a breath. WTF? Nothing's there. No problem, I reach under my chin and grab my octopus. Oh, S%*#!!!! I look for my buddy and he's 10' away and moving in the other direction, (not all buddies are perfect). Now, it's been a few seconds, I'm probably really beginning to notice that my lungs are empty and I need to decide whether to break for the surface or to try to chase down my buddy.

I hope to never be in that situation and I take active steps to avoid it, (including gas management and the rest), but I also think you have to put things in perspective. For relatively shallow dives there's no need for doubles. In fact I'd probably be putting myself at greater risk by using them for that purpose. Shore entries can be difficult enough without an unnecessary, extra 40 lbs on your back.

For boat dives past 100' though, I can see where doubles are probably the best possible choice and somewhere in between 30 and 100 feet I think the pony bottle is probably the best choice.

 

[vladimir]

I wrote a little computer program to calculate the depth from which one could theoretically reach the surface breathing from a pony tank of a given size, assuming that (1) you are not in an overhead environment or on a decompression dive, (2) you ascend at 60 fpm until you reach 60 feet, then ascend at 30 fpm, (3) you plan to make a 3 minute safety stop at 15 feet, and (4) your SAC rate is 0.88 cfm (average). Your mileage may vary.

Here are the results:
1.8 cu. ft. -> does not even give enough for the safety stop! (Need 3.838 cu. ft.)
3 cu. ft. -> does not even give enough for the safety stop! (Need 3.838 cu. ft.)
6 cu. ft. -> 44 fsw
13 cu. ft. -> 154 fsw
19 cu. ft. -> 216 fsw
30 cu. ft. -> 301 fsw

This shows why SpareAir is not adequate. It just isn't enough air to surface safely from any depth where you would need it.

Safety stops are considered optional--that's what distinguishes them from deco stops. If I were calculating my minimum gas needs in an out-of-gas situation, I would not factor in any deep stops, 1 minute stops every 10 feet, or a 3 minute stop at 15 feet. I would assume an ascent at 60 feet per minute to 60 feet, and 30 feet per minute to the surface.

 

[Jonnyspecial]

As I posted in January, I had to do a CESA, and that event made me consider Spare Air or a pony. Also, I fly often when diving, and so needed the travel-friendly option of an easily removable valve like Spare Air offers.

That experience, combined with some other occurences (e.g., a hyperventilating, catatonic AOW student on his Deep Dive who I had to pull up from 32m to the anchor line at 10m [he wasn't swimming AT ALL] against a current so by the time we were even considering a safety stop his tank was empty and mine was at 40 BAR!) lead me to purchase the Spare Air recently. I will test it at rest and at work at various depths to test its efficacy, and practice handling it - both for myself and any other diver.

*ORIGINAL POST*

"Some of you seem to have forgotten that the OOA situation I experienced was an excellent example of why a SA _or_ a Pony is an excellent choice:

I ran OOA when my rental SPG read 55 Bar.
[As I wrote, I have never used rental equipment since...]
I was at 20~22m depth.
I was diving in Indonesia, between Bali and Lombok.
I had my OW/AOW/MFA at this point.
I was diving with a newbie OW.
The currents were strong [5 knots] and we were tumbling, rather than drifting, I'd say.

Once we were down, it was impossible to gather together, but I wasted air trying to stay with my buddy, that is for sure. So it was a heavy workload dive, and the usual "guesstimations"/'calculations' on air use wouldn't work.
The look of fear on the newbie when we first got down and the current starting carrying us off made me perversely chuckle, but I tried to stay close to him.
I imagine I had a similar look later when my OOA situation occurred.
Perhaps he perversely chuckled in return!

Needless to say, this OOA situation involved several co-factors:
faulty rental equipment,
very tough dive conditions,
a new diver as a dive buddy,
a [perhaps?] irresponsible divemaster for choosing that location and renting sh*** equipment! [although, to admit, until the OOA situation I was enjoying the tumbling...]

The question is, were these conditions SO rare that it is improbable that it will NEVER happen to anyone else [or, for that matter, me, again]?

Will any of you ever have a SPG problem?
Tough dive?
New or inexperienced buddy, not by your side?
Perhaps bad guiding/choice of location?

No?!?!? Lucky you.

I now am a 2Star Instructor, with CMAS, under which my rigorous training has prepared me for as much as I think is reasonably possible; I have been diving in many challenging situations, and I agree with the wisdom expressed herewithin about carrying dive insurance, having a dive plan and diving it with a well-briefed and suitable partner, with whom you've discussed all contingencies...

Nonetheless, as soon as my US$ 180 Spare Air kit arrives, I will fill'er up, strap'er on, and while not changing my dive behaviour for the worse, feel _slightly_ better that while monitoring my air usage and equipment maintenance and buddy diving methods, I will also have another backup should any of those factors come into play again for me, or for the first time for anyone with which I am diving.

Finally, I appreciated the explanation of the screw-off pony; I think in Japan, where I live and do 90% of my diving, that due to stringent [excessive?!?] safety requirements, pony valves are sealed except for inspection, and so one cannot remove the valve. Maybe a Zen Divers member can clarify this point..."

*ENDS ORIGINAL POST*

 

[vladimir]

I now am a 2Star Instructor, with CMAS, under which my rigorous training has prepared me for as much as I think is reasonably possible

I'm not familiar with CMAS training; when you say it is "rigorous," and has prepared you "as much as...is reasonably possible," are we talking Navy Seals, YMCA in the 1970s, or PADI Discover Scuba Diving, but one where you have to carry your own tank?

 

[Jonnyspecial]

Safety stops are considered optional--that's what distinguishes them from deco stops. If I were calculating my minimum gas needs in an out-of-gas situation, I would not factor in any deep stops, 1 minute stops every 10 feet, or a 3 minute stop at 15 feet. I would assume an ascent at 60 feet per minute to 60 feet, and 30 feet per minute to the surface.

I appreciate JohnB47's providing his calculations for pony tanks.
[Although I think in metric, and - lazily - would have appreciated the figures in both Imperial and Metric...]

I completely agree that it is better to have a 13 or 19 strapped on to allow for a SS, rather than do a CESA (with or without a SA) and risk the Bends. GIVEN A CHOICE, a larger volume pony beats the SA on many counts, but not all:

(I also agree with the logic of diving doubles or with a larger pony for deep dives.)

But I find a lot of the discussions on this forum make a lot of assumptions - such as that we _all_ throw our gear in a truck, head down the coast, and cast away, and so can easily deal with doubles, ponies, etc.

But I live in Japan, and fly domestically and internationally for a lot of my dive trips. So larger tanks are not going to be accepted since they are, for the most part, sealed and pressurized as well as too heavy for luggage weight limits. That leaves smaller tanks that can have the valves easily removed, be visually inspected, and meet luggage weight restrictions.

Like most divers/instructors, I try to do as much as possible to keep current on my training, maintain and upgrade my equipment, and keep the safety of myself, my buddy and my students utmost in my mind. Here, redundancies are key.

So I consider the minor investment required for a SA/Oddessy/small pony one that most should make as a minimum, and if situations support, strapping on a larger volume pony for self- and buddy-rescue _with which one has practiced and always brings on every dive_ .

 

[Jonnyspecial]

I'm not familiar with CMAS training; when you say it is "rigorous," and has prepared you "as much as...is reasonably possible," are we talking Navy Seals, YMCA in the 1970s, or PADI Discover Scuba Diving, but one where you have to carry your own tank?

I can appreciate the humour in your post.
I wonder, if after reading #1 for overview and #2 & #3 for fitness and the care we can extend to divers, my 2-Star Instructor training even comes close to the rigours of your OW and Nitrox courses?! :shocked2:

Anyone up to the challenge??? Then please read, and get certified up to Rescue Diver as a minimum to demonstrate your commitment to diving safety.
[I always like to promote CMAS's standards as THE standard.]

#1: CMAS America 2-Star Instructor Overview:
CMAS Americas Standards

Two Star Instructor - qualified to direct and certify all CMAS diver levels, all CMAS Snorkel Instructor levels and Instructor level programs for DAN Dive Rescue programs including Hazardous Marine Life and Diver Emergency Management Provider courses. They are an experienced one star instructor who has completed a two star Instructor course to gain the knowledge, skills, and experience required to teach groups of divers in the classroom, pool, and in open water, from One Snorkelers up to One Star Instructors. Two Star Instructors are Instructor Trainers for all CMAS Programs.


#2: ILSF's CMAS Divemaster [prior to 1-Star Instructor] Overview
Appendix 15: International Rescue Dive Master (CMAS ***) | International Life Saving Federation
Examination Conditions

In open water with mask, snorkel and fins:
Demonstrate competence in the use of mask, snorkel and fins, by swimming 1500 metres, followed by a 10 metres surface dive to recover an object.

Demonstrate fitness and ability to support self and/or victim following fast surface swim of 100 metres and 20 seconds surface dive, a surface period of 10 seconds maximum followed by a further snorkel dive to 3 metres to recover a manikin of 1.5 kg apparent weight, to be towed on the surface for 50 metres.

Wearing full equipment, swim on the surface 1000 metres using snorkel.

Testing the theoretical and practical experience of the candidate as a responsible team leader, especially in cases of large rescue (action) diving operations.


#3: ILSF's CMAS 1-Star Instructor Overview
Appendix 16: Rescue Dive Instructor 1 Star (CMAS * Instructor) | International Life Saving Federation

Learning Outcome 1: Using mask, snorkel and fins
Assessment Criteria
Breath holding dive to a depth of 12 metres.

Undertake a 45 metres breath holding under water swim.

Undertake a 60 seconds breath holding dive.

Learning Outcome 2: Equipped with scuba
Assessment Criteria
Two dives as a three divers group leader: Open Water Diver's exercises:

Demonstrate and respond to the international hand signals for divers.

Remove, clear and replace own mask.

Two minutes sharing a single regulator with a buddy.

Orientation exercices.

Rescue Exercice:
Dive fully equipped to a patient "casualty" at 10-12 metres depth who is also fully equipped. Recover the patient, complete with equipment, to the surface and then tow him for a minimum of about 200 metres to the shore. Recover him onto dry land and prepare for Cardio Pulmonary Resuscitation.

************

So, CMAS's fitness, extensive rescue and boat-handling requirements (this latter not listed here, but nonetheless, a component) are far superior to most agencies. We might not be armed like SEALs, but I'm think the training I had to successfully undergo can be acurately describe as rigorous.

PS. On beach dives, it's not just a few times I've had to carry the full BC/tank set up of 1 or 2 other 1st time divers doing "Experience Dives" who were too tired or lazy to walk the 250 metres back to the set-up area while wearing my own gear. That's 20kg of mine plus 20-40 kg of their gear in HOT, HUMID southern Japan summers, so don't even get me started on "one where you have to carry your own tank" as you wrote.

Frankly, most people couldn't do it, and all non-pro divers just don't qualify to make statements on the rigours of professional dive training.

Schooled!:mooner:

 

[JohnB47]

I'm curious where you got this as an average figure for SAC rate. Seems a bit on the high side to me.

UKDivers.net - Air calculations gives 24 - 25 liters per minute as an average value. I took 25 lpm and converted to cfm, and got 0.8829

As I said, your mileage may vary. Anyway, if the number I used is too high, that just makes the calculation a bit more conservative.