No such thing as a Pony Bottle

[KenGordon]

Dude, I'm sorry. I thought I was discussing with someone who was able to understand context, not just relate to the literal wording of an argument. So, let me rephrase my question:

What's the practical difference, considering diver safety?


And just FTR, I know that there's two 1st stages instead of one, that there's two - or three - valves instead of one, and that the tanks are fixed to the BP (or BCD) by steel tank bands and screws rather than by webbing and a buckle. I'm wondering what the practical, safety-related difference might be once someone has rigged his/her gear, briefed his/her buddy about the location of the alternate and ensured that the tank valve(s) is/are open.

It's a well-known fact that once you find yourself in a hole, it might be a good idea to stop digging. Or, like Jim said: Dude, get a ladder.

To gain advantage from a twinset the diver needs to be able to properly operate the valves. That isn't a trivial skill. If they think that having a twinset is a magic get out of jail card but cannot shut it down and proceed with dives which would be iffy on a single then they are probably taking on more risk than they realise.

So the danger is not direct, but consequential. Similarly, being prepared to go to 40m on a single and pony thinking "I am ok because I have a pony" may be more dangerous than the OP expects.

Sadly most of the replies jumped on the instructor rather than saying yes to the explicit question as to whether there was anything non obvious she might be missing.

 

[Storker]

To gain advantage from a twinset the diver needs to be able to properly operate the valves.

Not if the only "advantage" the diver expects is a center of mass closer to his/her back than what a single tank setup provides. Or if the expected "advantage" is to carry a little more gas in a more comfortable way than with a 15L 300bar single tank.

BTW, the question wasn't "what kind of esoteric 'advantage' can be gained from a twinset, provided this and that". The question was "what kind of safety-related problem does a twinset pose which a single tank setuo doesn't?" Quit your handwaving and answer the question, please.

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Typos are a feature, not a bug

 

[KenGordon]

Not if the only "advantage" the diver expects is a center of mass closer to his/her back than what a single tank setup provides. Or if the expected "advantage" is to carry a little more gas in a more comfortable way than with a 15L 300bar single tank.

BTW, the question wasn't "what kind of esoteric 'advantage' can be gained from a twinset, provided this and that". The question was "what kind of safety-related problem does a twinset pose which a single tank setuo doesn't?" Quit your handwaving and answer the question, please.

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Typos are a feature, not a bug

Being lulled into a false sense of security if not able to use it properly. Doing dives which require a redundant supply while unable to do a shutdown.

With a pony, doing dives which are too deep given the capacity and SAC.

If a person is competent then fine, both a pony and a twinset have safety advantages in certain circumstances. They also have disadvantages in some circumstances. Thus it all depends on the circumstances. Who is better placed to judge, the bloke running the course or people on SB?

 

[Akimbo]

To gain advantage from a twinset the diver needs to be able to properly operate the valves. That isn't a trivial skill...

It can be. In fact, it is so easy that I normally keep my isolation valve shut using Progressive Equalization… but that’s a separate discussion.

 

[KenGordon]

It can be. In fact, it is so easy that I normally keep my isolation valve shut using Progressive Equalization… but that’s a separate discussion.

That is cheating.

 

[Storker]

Doing dives which require a redundant supply while unable to do a shutdown

I never claimed that the doubles were supposed to ensure redundant gas. I see that you persist in avoiding to answer my question. Moving the goalposts fallacy this time.

Again, what is the problem with diving doubles per se?




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Typos are a feature, not a bug

 

[KenGordon]

I never claimed that the doubles were supposed to ensure redundant gas. I see that you persist in avoiding to answer my question. Moving the goalposts fallacy this time.

Again, what is the problem with diving doubles per se?




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Typos are a feature, not a bug

There is no problem with diving a twinset if you can work it.

You may not claim they are for redundant gas, but that is why I dive one, especially if diving with a buddy who thinks having a pony removes the need for two second stages on his main cylinder.

 

[Storker]

You may not claim they are for redundant gas, but that is why I dive one

Ah. I get it. "Everyone does things for the same reasons I do them". Sorry to bust your bubble, dude, but someone has to break it to you:

(prepare yourself)


It ain't so.



--
Sent from my Android phone
Typos are a feature, not a bug

 

[KenGordon]

Ah. I get it. "Everyone does things for the same reasons I do them". Sorry to bust your bubble, dude, but someone has to break it to you:

(prepare yourself)


It ain't so.



--
Sent from my Android phone
Typos are a feature, not a bug

Why two first stages then?

 

[mrdre]

You're right. I don't see a big need for a pony for myself, given the way I dive. However, if one of my buddys slung a pony, should I tell him that HE doesn't need it? No effing way. If he feels safer with a pony, that's his choice. As long as he's following the buddy procedures I expect from my buddy (1: carry an alternate I can use and be able to donate it if fit hits the shan, 2: stay in contact with me and don't swim off), I won't tell him how to rig his kit. His kit, his choice.

Well, again. We are talking about CLASS with instructor OP chose and pays to teach. It's not just a dive with some buddy. If you don't trust your instructor - find another one, if you do - do as he says. It's that simple.

Now. Learning how to feel comfortable WITHOUT pony, monitoring air, being aware of other divers, surroundings is BEST with the instructor. It's a class. This is where you learn how to deal with things without pony. As I said before - after the class, pony or no pony - nobody cares. Sling 2 ponies if you want to, but in the class it's the best time to learn how to deal with situations without pony. Why? Because in real life situation you have chances (although slim) ending up at 130 feet alone without pony; and if you have never done it before you have a very high chance of panicking and eventually getting into an accident. That's why when you are with the instructor you chose and paid you practice the worst scenario.

Later, during the "regular" dives - yeah, do whatever you want, but class is not a "dive", class is where you practice all sorts of possible scenarios that may happen in real life.


And I agree with the insutructor taking the student to 130 feet with 5 mm wetsuit on 50 degrees. Why? Because it can happen in real life. A person may get separated, be swept away by the current, get entangled, hit thermocline, end up in depth that wasn't planned. And if that person never done that, then there is a high chance of person starting panicking. So.. the class with an instructor is the best place to practice these extreme scenarios.

My friend had a class like that. The instructor took him to about 40F deep dive, everybody got narked, it was dark, few folks started panicking, but they handled the situation. The instructor had 2 more assistant divers. Well.. months later my friend ended up saving a panicky girl on a deep dive. He said "after that crazy dive we did, getting a girl from a 90 feet was piece of cake". My friend had about 30 dives back then, she had about 100. Eventually he appreciated that deep dive, he always said "at least I know how it feels being narced in dark murky freezing water, now I know I can handle it".