Weight/buoyancy of tank valve

[Zef]

I don't understand the approach of "handing off" the pony bottle.

The pony bottle is a redundant air source for the diver carrying it. One does hand off the gas they carry on their back. If there is a diver out of air the protocol is to donate and air source via a 2nd stage and then ascend with that person to the surface. If that person is not your dive buddy and their dive buddy is not in the immediate vicinity then you by nature of donating an air source are now the defacto buddy and should be ending your dive by heading to the surface with the ooa diver and your original dive buddy along side. With regards to a pony bottle I can't fathom an appropriate time that I should be handing over the bottle to someone underwater.

Also, the pony bottle if slung is typically clipped off by two bolt snaps....one to a shoulder/chest d-ring and the other on the hip or rear of the diver. There should not be a time when these are both unclipped at the same time...this not deco bottle that one might clip to a down line and such...it is a redundant air source so it should stay with the diver otherwise there is little to no reason to be diving with it, and as such there should be, relatively speaking, no chance of it being dropped into the abyss.

If one is adjusting the amount of lead they are going to carry due to the addition of a pony bottle, the adjustment should be based on the near empty weight/buoyancy characteristics of the bottle not when the bottle is full. The issue of being overweight at the beginning of a dive can be overcome with air in the BCD/wing/drysuit (if used), but not having enough weight at the end of the dive can turn into a very real problem.

-Z

 

[Zef]

Just a follow up thought...

In my mind, the prime reason a diver would choose to carry a pony bottle is to have a redundant air source for themself in case of an emergency situation. IF someone in my partner or someone in the vicinity is OOA and needs an alternate air source they get my octo/long hose. We both continue breathing off my back gas as we head to the surface. If they are breathing so much that the air source is being depleted then I will switch to the pony bottle, and they can continue with my back gas. If the bottle on my back can not supply a sufficient quantity of gas for them to safely reach the surface then they are SOL....at no time should one risk their own life in an attempt to save another.

I highly recommend one becomes familiar with the "Rock Bottom" paradigm and dive according to it....it takes into account that one might find themself in this type of emergency and pre-plans for it so that one moves up in the water column before one has a "critical" amount of air/gas available should the SHF.

Having a redundant air source does not diminish the responsibility we have to ourselves and our loved ones to come back from a dive safely, it does not increase our obligation to those around us, and it does not decrease our responsibility to plan our dive and dive our plan appropriately.

There is no substitute for knowledge and planning.

-Z

 

[Divectionist]

I like all of what you are saying there Zef.

I kept my mind open to the option of handing off a pony to an OOA diver that one would rather not be tethered to for an entire ascend, i.e., an erratic diver with unpredictable buoyancy. The idea would be to approach them for an initial air assist, then clip the pony onto their gear and maintain a watchful distance whilst seeing them up. I suppose this would be an option if handing the pony over is safer than staying attached to the OOA diver all the way up. At that point the dive is called anyway, and with my own intact primary system in place for my own immediate ascend, I would be okay handing off the pony for someone else's benefit, weighting myself accordingly.

 

[Zef]

I imagine that most experienced divers do not find themselves in an unexpected OOA situation. I imagine the most likely OOA situation to be an inexperienced diver who is not properly monitoring his air and/or is diving past their limits or comfort and either do not feel secure enough to indicate they should be higher in the water column or are just plain oblivious.

That said, I also imagine this type of diver does not have the experience to properly manage their buoyancy well either. Handing them or clipping a pony bottle onto them will probably result in more problems than it fixes and is outside the scope of training for most agencies. If the person sinks and dies with your pony bottle attached to them then you are in for one hell of a lawsuit.

To protect yourself and best aid a diver in this situation one should donate a regulator and stay in contact or close proximity with the diver and ascend with them. If they are panicking then you can wait until they pass out and conduct a full on rescue or let them bolt to the surface if that is their intent.....at no time should you accept an unnecessary increase risk to your life to save a diver that is out of control.

Even in rescue class (PADI) they do not teach to prevent a diver from bolting to the surface they teach to attempt to slow the diver's ascent to the surface by grabbing their BCD, leg, fin, etc, but if they are insistent on heading up lightning fast then let them go. It is always "best" to have zero victims, but if there are going to be victims it is better to keep that number to 1 if at all possible.

-Z

 

[Bob DBF]

I don't consider handing off my pony for the simple reason that it's not that big (19 cuft) and I have no idea how much gas the victim needs to surface, regardless of whether the time wasting transfer could take place. The training I have received, focuses on the donor supplying air and controlling the immediate ascent to the surface.

My go to rig consists of a second stage and bungeed alternate, I add the pony as necessary. Assisting an OOA diver, I would donate the primary use my alternate, and switch to the pony (if attached for the dive) dependent on gas usage.

As far a weighting, overall I don't change my normal weighting as the pony rig makes me only a pound or so heavy when empty. Sometimes I notice a roll to the pony side and shift weight to compensate, which can be done in the water.


Bob