Pony tank
- Thread starter k954triniz
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broncobowsher
Contributor
Yes still a problem. Take a sidemount class and learn what proper gas planning using multiple tanks and gas switches during a dive is. So one tank is bigger and back mounted, still proper gas management.
You never see a sidemount diver come back and claim they sucked one tank down to 50 PSI but that is OK, the other one is still full. What they do is take some from one tank, then some from the other, back to the first, etc. Come back with roughly balanced pressure between both tanks.
In this case (guessing everything here is air) there should be some gas switches during the dive. It will be a bit ugly with mis-matched tank sizes. But that would be the more proper way to run a staged bottle setup.
That way you will always surface with air, even if one reg craps out and you are running a little late that day. Downfall, you are paying for 2 fills instead of 1. A more correct solution would be to run a larger primary tank and keep the pony. Or get a pair of tanks and run them down sidemount style.
Just because the gauge says you have pressure in your stage/pony/monkey butt cylinder doesn't mean it will be usable at the end of the dive.
I know several boats that if they saw you come up with that little air, you would not be allowed in for a second dive. If allowed on the boat ever again.
A stage, which is what you have when you plan to use your 19cf bottle for your accent because your main tank is empty, is different than a "pony" that you would only use in an emergency.
Stages are different practically, theoretically, and physically from a pony bottle, which is nothing more than an emergency accent bottle, providing a gas supply just to get you to the surface.
Stages are different practically, theoretically, and physically from a pony bottle, which is nothing more than an emergency accent bottle, providing a gas supply just to get you to the surface.
Stages are not reserve any more than the 1/3 or 1/4 that you plan to leave in your tank is. A pony bottle exists beyond that calculation. It is there when your stage gas has been lost and you need enough air to get to the surface. A pony is a supplement to your back gas, not an addition to your back gas.
At least as far as as I know.
Do you dive with a buddy?
The gas in a pony is only accessible to one diver. The same gas in a single with two second stages is available to both divers. If you have to donate when down at 100 psi you are essentially bolting to the surface as only one of you actually has any gas, so no improvement on the original OOA diver having no gas. Next, when you get to the surface you will have extra fun making sure you have buoyancy. Yes you could manually inflate or drop a weight belt but that is harder than pressing a button.
Sure plan to use the gas, but keep enough in each cylinder to deal with an emergency. That is the key principle of gas planning whatever combination of cylinders you use. Two divers? You need enough gas for two divers to get to the surface at all points in the dive.
The point of a pony is different, that is why there is a different word for it. The pony is to allow for self rescue.
Primary Gas = (back mounted cylinders, or side slung cylinder(s)) gas used during the dive. Part of the gas calculation.
Stage Cylinder = (generally side slung cylinder(s)) gas used to extend the range of the Primary gas. Part of the gas calculation.
Travel gas = (generally carried side slung), used as a transitioning gas to/from the bottom gas on descent and ascent. On ascent used prior to the decompression gas as part of the decompression phase of the dive. Part of the gas calculation.
Decompression gas = (generally carried side slung), used for the decompression phase of the dive. Part of the gas calculation.
Pony Cylinder = (back mounted or side slung), a small cylinder (3 litre typical), carried as an emergency bailout supply for the diver. NOT part of the gas calculation for the dive. (Although sensible to know how much/how long it will last). Generally carried for no deco or light deco dives due to minimal available gas.
Bailout Cylinder = (generally side slung). Carried primarily by CCR divers. Part of the emergency supply in the event of unit failure. Specifically part of the bailout gas calculations - may well be more than one cylinder of differing gas mixes to enable safe ascent and decompression.
Pony cylinders are NOT used as part of a normal dive plan / profile. They are an emergency self help supply of gas, with the specific intent that when in use the diver is aborting the dive.
Generally;
Primary Gas and Stage cylinder gas follows rule of thirds.
Decompression gas & travel gas, rule of half's.
A Pony cylinder should have sufficient gas to get THE diver from the bottom to the surface and cover any required decompression.
Bailout Cylinder(s), should ensure the CCR diver can safely get from the furthest extent of the dive to the surface, completing all decompression. On extreme dives this may well require shared bailout protocols - to be avoided if possible. Calculations may need to be adjusted if it also intended to support OC divers/buddies.
DO NOT use the pony to extend a normal dive.
Do practice, ensure you are proficient with your pony if you have one.
[1] Travel Gas statement amended as requested - see following posts (@beldridg
)
Stage Cylinder = (generally side slung cylinder(s)) gas used to extend the range of the Primary gas. Part of the gas calculation.
Travel gas = (generally carried side slung), used as a transitioning gas to/from the bottom gas on descent and ascent. On ascent used prior to the decompression gas as part of the decompression phase of the dive. Part of the gas calculation.
Decompression gas = (generally carried side slung), used for the decompression phase of the dive. Part of the gas calculation.
Pony Cylinder = (back mounted or side slung), a small cylinder (3 litre typical), carried as an emergency bailout supply for the diver. NOT part of the gas calculation for the dive. (Although sensible to know how much/how long it will last). Generally carried for no deco or light deco dives due to minimal available gas.
Bailout Cylinder = (generally side slung). Carried primarily by CCR divers. Part of the emergency supply in the event of unit failure. Specifically part of the bailout gas calculations - may well be more than one cylinder of differing gas mixes to enable safe ascent and decompression.
Pony cylinders are NOT used as part of a normal dive plan / profile. They are an emergency self help supply of gas, with the specific intent that when in use the diver is aborting the dive.
Generally;
Primary Gas and Stage cylinder gas follows rule of thirds.
Decompression gas & travel gas, rule of half's.
A Pony cylinder should have sufficient gas to get THE diver from the bottom to the surface and cover any required decompression.
Bailout Cylinder(s), should ensure the CCR diver can safely get from the furthest extent of the dive to the surface, completing all decompression. On extreme dives this may well require shared bailout protocols - to be avoided if possible. Calculations may need to be adjusted if it also intended to support OC divers/buddies.
DO NOT use the pony to extend a normal dive.
Do practice, ensure you are proficient with your pony if you have one.
[1] Travel Gas statement amended as requested - see following posts (@beldridg
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