Early Pony/bailout bottle use

[John C. Ratliff]

I have a lot of publications from the 1970s, and one is the Proceedings of the Sixth International Conference on Underwater Education (IQ6), "Sponsored by National Association of Underwater Instructors," Copyright NAUI 1975. In it there is a paper titled "An Introduction to East Coast Wreck Diving," by Ken Heist. Ken writes about the equipment for wreck divers:

...The divers can now get ready to dive. Their equipment over and above the "normal" diving equipment may include:

Double Tanks - Because of the depths involved in diving the "better" wrecks which are generally deeper than 100 feet an increased air supply is desirable. These wrecks are generally the more intact ones that have not been blown up by the Coast Guard or Navy as hazards to navigation.

Pony Bottles - Used as a totally independent source of air with a 10 to 13 cu. ft. capacity. Figure 2 shows a set of double tanks with a pony bottle. Note the pony regulator has no exhaust tee; this prevents confusion as to which regulator is the main regulator. This also helps to prevent the normally hanging pony regulator from getting caught on anything...

Proceedings of the Ninth International Conference on Underwater Education, Addendum (IQ9), Sponsored by The National Association of Underwater Instructors, Copyright NAUI 1977. Lee H. Somers, PhD, published an article in this publication titled "Profile of a Great Lakes Diver." In it Dr. Somers wrote:

Sixty percent of the divers now have submersible pressure gauges; this is slightly below the Skin Diver Reader Survey figures of 63.9%. It is encouraging to note that 23.2% now use an auxiliary second stage (octopus) or pony emergency unit.

In his Table 4, on diving equipment, he noted the following:

REGULATORS
Single Hose 77.4%
Double Hose 15%
Submersible Pressure Gauge 60%
Auxiliary Second Stage 19.2%
Reserve on regulator 10.8%
Pony Cylinder 4%

I just checked my book, the NOAA Diving Manual, Diving for Science and Technology, 1975 and it made no mention of either octopus or pony bottles. It did show a pony bottle in use, but it was mounted on top of a closed-circuit mixed-gas rebreather. This is in keeping with my recollections that pony bottles were used only in wreck, ice and cave diving at that time.

SeaRat

 

[DaleC]

Thanks John. One of my winter projects is to put together double AL40's with a USD centerpost manifold and have an Al19 nested between them just like that photo. I also want to encase them in an ABS clamshell but we'll have to see about that.
Akimbo, I do the same sort of thing with my single hose reg set. My back gas has black plastic SP second stages and my pony has a chrome SP 109. Very easy to tell apart.

 

[dumpsterDiver]

Thanks Akimbo and Captain, Luis those are the images that I have seen too.

This is what I have written so far. I just want to make sure the spirit of my text is correct.

A pony bottle is a secondary air source (usually a smaller cylinder equipped with a first/second stage regulator and SPG) that a diver carries along as a source of emergency air supply. When the first dedicated pony bottles began appearing on the diving scene is a good question but it was not uncommon early on to bring extra cylinders underwater when deeper dives, or those requiring possible decompression were done. These tanks were often hung on the anchor/buoy line for retrieval later in the dive. Books and images reflecting the early North Atlantic wreck diving era (such as Andrea Doria exploration) begin to depict bailout specific bottles as part of the divers personal rig. These were later largely replaced in technical diving as doubles with isolation manifolds became more popular.

The early tanks had no SPG, and when they were introduced, I doubt many people put an spg on a pony bottle. Also, you comment about hanging bottles seems to be in reference to pony bottles. Nobody is going to hand a pony bottle; too small. The standard 71.2 steel tank is a very nice hang bottle becuase it is not too heavy and is negatively buoyant.

I always find it funny to look at the old pics of the early first stages with the neck lanyards on the second stages. The had a decent rubber strap and then often a nice plastic snap. Then they went out of fashion for 30 years and now are stnadard for tec divers...

 

[AfterDark]

I had a 1800 psi converted fire extinguisher tank for many years strapped between my tanks. One of the problems with all the tanks on your back is that you would have 3 2nd stages to manage and tell apart. What many in the late 70's had settled on were Poseidon's on the mains and a standard conshelf/sherwood 2nd on the pony. For the Poseidons, we would have one Jetstream/Oden/Shower head and one Cyklon/Thor/Hockey Puck. As the three 2nd stages were radically different in shape you didn't get them confused. This is very important with indipendent mains so you can tell which tank you are breathing off of. We also had different SPG's with one tank's gauge being in a counsel and the other just a SPG taped to that counsel. Unfortunately, more than one diver was found dead on the bottom with an empty pony and full back tanks. They would jump in on the pony by accident, get to the bottom, run the pony dry, panic, etc.................

This is the concept I use still on my IDs. I can tell by feeling my 2nds which tank I'm on. I don't use a pony with the ID's but it would follow the same concept. What works, works. I recall talking about seeing "bailout bottle" back in the early 70's. Nobody I dived with back then had or used one. I remember talk of the Fenzy vest tanks being used for bailouts also.

 

[John C. Ratliff]

There are several reasons the pony bottle never "caught on" with divers. They were relatively expensive, they provided more bulk on the scuba tank, and they really did not add much to the safety of the diver from an amount of air available point of view. There is a means of determining the amount of air required at depth, which was published by Jim Foley in How to Find Your Way, A Complete Guide to Underwater Navigation, Dacor Corporation, 1979, page 82.

First you need to know your surface air consumption rate. Many of the dive computers will provide that for you, and on my last dive I had about a 0.5 cubic feet per minute (CFM) rate on a river drift dive. Usually, without knowing we use either a 1 CFM or a 2 CFM rate, depending upon the work load. If there is a high rate from anxiety or heavy work, then 3 CFM is a possibility. The formula Jim Foley published is:

Depth/33 + ATM of air x CFM consumption rate = CFM at depth

Example: 66/33 + 1 x 1 = 3 CFM at 66 feet

This tells the diver he requires 3 cubic feet per minute at a depth of 66 feet.

If we look at a 133 cubic foot capacity pony bottle, and a 100 foot depth, we can make the calculation for a panicked diver (using 3 CFM):

(100/33 + 1) x 3 CFM = 12 CFM consumed by the panicked diver. (The "+ 1 AMT" is to make the calculation using absolute pressure, which includes the pressure of the atmosphere above the water.) If that diver is given a 13.2 CF tank, then

13.2 ft3 / 12 ft3/min = 1.1 minutes of air

If that diver had been extremely calm, and used only 0.5 CFM Surface Air Consumption Rate, the calculation would be:

(100/33 + 1) x 0.5 CFM = 2 CFM consumed by the extremely calm diver at 100 feet depth (sea water). If that diver is given a 13.2 CF tank, then

13.2 ft3 / 2 ft3/min = 6.6 minutes of air under the best of circumstances. That's not much time either, but it is enough to get to the surface IF there was no decompression obligation.

SeaRat

 

[Bob3]

For ice diving back in the mid-'60s we would use the steel 20 cubic foot size "E" oxygen bottles rigged with a 1/2" NGT K valve.
I still have a couple of those yet.

 

[DaleC]

Thanks Bob.