How deep until you need to bring along a pony bottle?

[Diver0001]

neil once bubbled...
Does anyone here use a small set of doubles, like twin 50's or even 40's for shallowish OW diving. It seem that might be an answer for those who don't need all the gas of 80's or 100's. And it would be more balanced and out of the way than a pony. I have an OMS catalog that shows twin 46's. Looks like a sweet little setup.

When a reg on a set of doubles fails, or an o-ring goes, how long does it really take to shut it down and switch to the other?
Neil

I've never seen one with an isolator on it. I think the distance between the cylinders is probably too short. A buddy of mine has one of these things. It's got a volume of 14 litres but he says that it's more stable and lighter than a 15 litre tank.

R..

 

[humpback]

I am curious. Once I decide on a plan for when to use a pony, where do I get one. Transporting one outside the US brings with it several logistical problems - the most important one being the inability to bring a pony in and out of the country without disassembling it. At least that is my understanding. Is this correct? If so, do you rent a pony for the dive shop you are diving with?

 

[Diver0001]

MHK once bubbled...

CESA's aren't the issue,

That's right, but that's also not what I said. I said the issue for a puddlestomper (and I use the term affectionately) is bridging a 60 second gap in the highly unlikely event that some sort of problem leaves him OOA at a depth deeper than he can execute a CESA. The "issue" (if there is one) is self rescue at these depths.

Try to think like a puddlestomper. It's a different paradigm. This is what I mean by out of the box. Out of the DIR box.

<snip>

A very real consideration is gas management and available BT's..
If you approach gas management with a view's towards reserving sufficent gas to provide for both you and your buddy to surface in the event of a failure at depth, and also provide for gas management protocols that allow for slow, safe ascent rates even during an emergency, then you'll see that pony's and CESA's are the wrong approach to solving a potential problem..

Wrong? Since when is bailing out when it goes pear-shaped wrong? Puddlestompers don't have overheads and they don't have deco obligations. They have free access to the surface and fleeing to the surface is a viable option and one they're trained for. Puddlestompers are not honour bound to solving every problem under water. The thing about ascent rates is valid but don't forget we're talking about a once in a lifetime problem here (maybe). And also don't forget that a CESA *is* a controlled ascent.

When you dive in the 100'+ range gas management and contingency reserve are very real considerations that should be planned for in advance..

Gas management? Contingency reserve? You're off on a tangent. Puddlestompers are not taught gas management and contingency for a free-flow is limited to breathing off the freeflowing reg while aquiring the buddy's octopus and/or fleeing to the surface. Putting someone who doesn't have enough experience/training to stay calm when the reg is free-flowing into a heavy twin-set so they will have a huge gas reserve for contingency isn't going to change his emotional reaction. What will happen if you don't change the training is you'll end up with someone in 50kg of gear trying to hump it all upwards in a CESA when their reg malfunctions. If this sounds absurd to you then I would suggest teaching a few <pick your favorite rec-agency> classes to get your feet back on the ground. You're out of touch.

And a shutdown takes, what, 15-20 seconds? I say no way! Puddlestompers will buy fancy twinset because it makes them feel invulnerable (this was one of your objections to a pony, right) but they will not (most of them) practice shutdowns and so forth. I would submit that a typical recreational diver would be better off in light gear that he can hump to the surface in 60 seconds than in a twinset that will leave him at depth fumbing around (probably with a light on a lanyard whacking him in the face while the lanyard gets fouled in the valves) trying to do a shutdown, realising too late that it's gone snafu and then failing to hump it all to the surface anyway.

In other words I would conclude that your solution (putting the whole world into a twin set) has a very real potential to make problems worse for a lot of divers, not better. I say keep the gear light. Keep it simple and deal with the issue from the perspective of self-rescue/bailout in emergencies. Redundancy and contingency reserves are all well and good but you have to be committed to practice practice practice, which is asking a lot from the masses of people who only want to bimble around and have fun.

And yes, like it or not they will dive deep. They will go where ever the DM takes them and they will jump off the back of the boat with a buddy they've never even met before. Hoards of them. Every day. This is reality. Twinning all these people up is a wet-dream. We're much better off giving them realistic options (like a pony <gasp>) that fits in their paradigm.

And no, I don't see this paradigm shifting a long as there is money to be made from underwater tourism.

Approaching these types of dives, and acknowledging that if you use the proper gas,

The proper gas? There is only one gas. Air. Think like a puddlestomper, Michael.

the proper volume and do the proper planning you can do nearly 40 minutes at 100'

I know exactly what you're saying but you're not thinking like a puddlestomper. To a puddlestomper the proper volume is "full tank at begining of dive" the proper gas is AIR because there is no other and the proper bottom time at 100' off the top of my head is 20 min not 40.

<snip>

That is how we think outside the box, we try to think the whole problem through and consider that using a pony to do a CESA is only looking at part of the problem, not really looking at how to approach a dive of that magnitude..

Dive of that magnitude? It's a 100 feet, not a 100 meters. I almost get the impression that you're afraid in the dark. (just kidding).

R..

 

[Diver0001]

Genesis once bubbled...
<snip>

The arrogance of this point of view goes beyond self-serving to the point that one has to wonder if they WANT to see people die due to problems underwater that are ultimately "human."

Funny you should say this. I once heard a DIR sock-puppet (an acquaintance of MHK) say something to the effect that it's not always bad to see divers die. When I told him I thought he was a pr*ck for putting " being right " in front of " someones life " he could only respond to the effect that " it depends on whose life ".

I suspect (and given some of the writings I've seen from the Grand-Poobah himself) that this attitude comes from the top and permeates the hardcore following.


R..

 

[Diver0001]

humpback once bubbled...
I am curious. Once I decide on a plan for when to use a pony, where do I get one. Transporting one outside the US brings with it several logistical problems - the most important one being the inability to bring a pony in and out of the country without disassembling it. At least that is my understanding. Is this correct? If so, do you rent a pony for the dive shop you are diving with?

As I understand it, and these rules vary from country to country, it has to be empty and the valve has to be open to transport it on an airplane.

R..

 

[drbill]

MHK's post suggests he does not bellieve in solo diving at all. Since the majority of my 200+ dives per year are solo, I do not have the backup of a good buddy most of the time.

For that reason I dive with my pony bottle on most dives unless I know I will be above 40 feet the entire dive (often the case on my last dive of the day). I would never use my pony to extend bottom time since I already dive with a steel 120 HP tank and get all the bottom time I need (usually two 50-60 min. dives per fill).

Dr. Bill

 

[sheck33]

ElectricZombie once bubbled...
You would not have access to the gas in both cylinders though...just whichever one had not failed. That's why I said they were not "fully" redundant.

You DO have access to the air in both cylinders UNLESS you have a failure of the tankneck O-ring or worse if you have a catastrophic manifold failure....in the latter case you are just out of luck.

So, if you have a 2nd stage or 1st stage failure you simply turn off that reg and still have access to both cylinders.