1At a glance
- Primary Function
- Redundant Emergency Air Supply
- Typical Volume Range
- 1.0–3.0 litres (10–30 cubic feet)
- Pressure Rating
- Typically 200–232 bar (3000–3500 psi)
- Mounting Location
- Attached to BCD, beside primary tank, or sidemounted
- Required Components
- Cylinder, dedicated regulator (first and second stage), SPG
- Recommended Use
- All dives, especially deep or technical profiles
- Alternative Names
- Spare air, bailout bottle (though 'Spare Air' is a brand)
2How a pony bottle works
A pony bottle functions as a completely independent breathing system. It consists of a small, high-pressure cylinder, a dedicated first-stage regulator that attaches directly to the cylinder valve, a second-stage regulator for breathing, and a submersible pressure gauge (SPG) to monitor the air remaining in the pony bottle. This entire system operates separately from the diver's primary scuba unit.
In the event of an emergency, such as a primary tank valve failure, a burst hose, or running out of air, the diver can switch to the pony bottle. The independent regulator system ensures that a failure in the primary system does not affect the emergency air supply. Divers practice deploying and breathing from their pony bottle during training to ensure a smooth transition under stress.
Proper sizing and gas management are crucial. The volume of the pony bottle should be sufficient to allow the diver to reach the surface safely, including performing any required safety stops, given their individual air consumption rate and the planned dive depth. For example, a 1.0-litre (10 cubic feet) cylinder might provide enough air for a shallow ascent, while deeper dives or those with decompression obligations would necessitate a larger pony bottle or a stage cylinder.
3Pony Bottle vs. Stage Tank vs. Spare Air
| Feature | Pony Bottle | Stage Tank | Spare Air (brand) |
|---|---|---|---|
| Primary Use | Emergency bailout (independent) | Decompression gas / travel gas / bailout (larger volume) | Emergency bailout (minimal volume) |
| Typical Size (volume) | 1.0–3.0 L (10–30 cu ft) | 5.5–11.0 L (40–80 cu ft) | 0.17–0.8 L (1.7–3.0 cu ft) |
| Mounting | Attached to BCD, cam-banded to primary, or sidemount | Clipped to side D-rings (sidemount style) | Attached to BCD shoulder strap or clipped on |
| Regulator | Full independent regulator system (1st & 2nd stage, SPG) | Full independent regulator system (1st & 2nd stage, SPG) | Integrated 1st and 2nd stage, small gauge |
| Gas Options | Air or Nitrox (if primary is Nitrox) | Air, Nitrox, or Trimix (specific for dive plan) | Air |
4What a pony bottle means for your liveaboard trip
Bringing or renting a pony bottle on a liveaboard trip can significantly enhance your diving safety, particularly for more advanced or remote dive sites often visited by liveaboards. While not always mandatory, the self-sufficiency it offers is a valuable asset, reducing reliance on buddy breathing and allowing for a more controlled response to an air emergency.
Before your trip, it is advisable to check with your liveaboard operator regarding their policies on redundant air sources. Some operators may recommend or require them for specific itineraries, especially those involving deeper wreck dives, strong currents, or distant reefs. Discussing this in advance can help you prepare whether to bring your own or if rental options are available on board.
While a pony bottle adds a small amount of extra equipment, the peace of mind it provides can be substantial. Proper training in its use, including practicing deployment and breathing from it, is essential. For divers who prioritise self-reliance and enhanced safety, a pony bottle is a worthwhile consideration for any liveaboard adventure.
5Pony bottle considerations by dive type
| Dive Type | Recommended Volume (approx.) | Mounting Option | Key Benefit |
|---|---|---|---|
| Recreational (Shallow/No-Decompression) | 1.0–1.7 litres (10–17 cu ft) | BC-mounted, integrated | Self-rescue from out-of-air |
| Deep Recreational (30+ metres) | 1.7–3.0 litres (17–30 cu ft) | Cam-banded to primary, BC-mounted | Sufficient air for deep safety stop & ascent |
| Wreck Penetration | 3.0+ litres (30+ cu ft) or small stage | Side-mounted, clipped | Redundant air for complex, overhead environment |
| Drift Dives (Strong Current) | 1.7–3.0 litres (17–30 cu ft) | BC-mounted, cam-banded | Extra time to signal, manage current, or for buddy |
| Technical / Decompression Dives | Large stage cylinder (5.5L+ / 40+ cu ft) | Side-mounted (full stage setup) | Specific decompression gas / extended bailout |
6Common misconceptions
Myth: A pony bottle is only for technical divers. Fact: While essential in technical diving, a pony bottle is highly beneficial for recreational divers too. It provides a vital independent air source for self-rescue during any dive, regardless of depth or complexity, significantly increasing safety margins for all experience levels.
Myth: A pony bottle means I don't need a buddy. Fact: A pony bottle enhances self-sufficiency but does not eliminate the need for a buddy. The buddy system provides multiple layers of safety, including mutual observation, emergency assistance, and shared responsibility. A pony bottle is an additional safety tool, not a replacement for a buddy.
Myth: Pony bottles are too heavy and cumbersome. Fact: While adding some weight and bulk, modern pony bottles are designed to be compact and can be mounted in various ways to minimise impact on trim and buoyancy. The added safety benefit often outweighs the minor inconvenience, especially considering the small sizes typically used for recreational diving.
Myth: My buddy's octopus is enough for an emergency. Fact: While a buddy's alternative air source is a critical component of dive safety, relying solely on it has limitations. It requires a functioning buddy and can be challenging to deploy under stress or in low visibility. A pony bottle offers immediate, independent access to air, removing the buddy-dependency in an out-of-air situation.
FAQ
What is the primary purpose of a pony bottle?
The primary purpose of a pony bottle is to serve as an independent, redundant air source. It provides a diver with emergency breathing gas to safely ascend to the surface, including any necessary safety stops, in case of a primary air system failure or an out-of-air situation.
How much air does a typical pony bottle hold?
A typical pony bottle for recreational diving usually holds between 1.0 to 3.0 litres (10 to 30 cubic feet) of air. The exact volume needed depends on the diver's air consumption, dive depth, and planned ascent profile.
Do I need a separate regulator for a pony bottle?
Yes, a pony bottle requires its own complete, independent regulator system. This includes a first-stage regulator that connects to the bottle's valve, a second-stage regulator for breathing, and a submersible pressure gauge (SPG) to monitor the air supply within the pony bottle.
Is a pony bottle required for liveaboard diving?
A pony bottle is not universally required for all liveaboard diving trips, but it is highly recommended for enhanced safety. Some liveaboard operators or dive professionals may specifically require or recommend them for certain dive itineraries, especially those involving deeper or more challenging dives.
How do I attach a pony bottle to my gear?
Pony bottles can be attached to your dive gear in several ways. Common methods include using cam-bands to secure it alongside your primary cylinder, attaching it to your BCD with quick-release clips, or using dedicated side-mount harness systems for larger bottles.
What is the difference between a pony bottle and a stage tank?
While both are redundant cylinders, a pony bottle is typically smaller (1.0-3.0 litres / 10-30 cubic feet) and primarily for emergency bailout during recreational dives. A stage tank is generally larger (5.5+ litres / 40+ cubic feet) and used in technical diving for specific decompression gases, extended bailout, or carrying extra gas for long duration dives.