Use pony for additional air supply

[CIBDiving]

I've used my bailout ( I refuse to call it a pony ) on an occasionn or two to extend a dive, although for a safety factor more than just time. Once was on a destroyer out of Victoria BC (the mackensy ?). A rippin cuttent made the swim back to the up line a little longer than I'd planned for. Then once I got there and had started my ascent ( I was ~40 ft ) I could see there was no boat on the mooring ball! I realized I had gone up the wrong darn line. well gas wasn't critical, Yet, but a descent back to the deck and forward to the correct line was going to take me farther into deco. I switched to the bailout for the transit and back to the main for the deco stops ( air in both bottles). I came out of the water with 300 in the main and half a bottle of bailout left. I'm sure you can see my reasoning - I never was without a backup with enough gas for the job.

 

[Rec Diver]

A buddy of mine went on a charter that did exactly this. The charter gave everybody nitrox ponies. The dive was to 134', and at 90' they switched to their ponies. From what he told me, using the backgas, then switching to the pony, was part of the gas plan.

On dives over 100 feet this is exactly how I dive. On dives less than 100 feet I use air in my pony tank for emergency only. At my age, late 40's, breathing 40% oxygen during my ascent has virtually eliminated the fatigue I had experienced in the past from breathing air.

 

[ianr33]

So what is the difference between between using a nitrox "pony" that is switched to at 90 feet or whatever and a Staged Deco Dive ? Especially as dives below 100 feet come into the "all dives are deco dives" category

 

[teknitroxdiver]

There is no difference. All dives are deco dives, however, depth regardless. But switching gasses is a deco procedure.

 

[budgy]

I've used my pony as a redundant air source, I've keep it with 100% as a cheap O2 kit and I've used it at 5m as an accelerated deco cylinder. Maybe I should have 2 or 3.

 

[teknitroxdiver]

I've used my pony as a redundant air source, I've keep it with 100% as a cheap O2 kit and I've used it at 5m as an accelerated deco cylinder. Maybe I should have 2 or 3.

If you've got pure O2 in your pony, how can you use it as a redundant air source? Below 20 feet it's as useless as if it were empty.

 

[CIBDiving]

If you've got pure O2 in your pony, how can you use it as a redundant air source? Below 20 feet it's as useless as if it were empty.

It's More useless than if it WAS empty, at least if it's empty you wouldn't be sucking down pure O2 at 140 ft :11:

 

[teknitroxdiver]

It's More useless than if it WAS empty, at least if it's empty you wouldn't be sucking down pure O2 at 140 ft :11:

I've heard that can be slightly hazardous to your health..... :banana:

 

[HydroAuto]

If you read the last part of his post he states "...and I've used it at 5m as an accelerated deco cylinder". Hopefully that is all it use that it sees.

 

[Bwanar]

Well...obviously a pony with 100% O2 in it cannot be considered a redundant air source, but the person's examples were a little differant than the original question. In one case he said he wanted to use it to extend his safety stop and in that instance I think it would be perfectly acceptable. If he plans on using it to extend bottom times then I would recommend (at depths 90' or less and no chance of obligatory deco) that he could breath his main tank down to @500-600#'s and switch to his 30cu. pony down to @ 1000#'s and start his assent. That way there is adequate air to surface with a safety stop with either tank in the event of a failure. Still much safer than diving a single (the norm for Rec.'s at that depth)!

If you read the last part of his post he states "...and I've used it at 5m as an accelerated deco cylinder". Hopefully that is all it use that it sees.