Do you actually see people diving with pony bottles?

[Coztick]

The pony should only be used as an emergency. If you choose to use it during the dive that's your prerogative, but then you have no emergency bailout later.

I think that 500psi of backgas is dedicated to emergency and is not to be used as well.
At no time did I plan to use it during the dive otherwise it would be unavailable during an emergency at the end and you are obviously missing my point.
I do dive sm. and have taken 2 80s for deeper dives requiring more swimming in Coz.
I love the scale-ability and comfort. I've got 4 lp 72s for home.
I only carry the pony on the simple stuff as instabuddy backup.
400 psi is a good bit of time over a 2 week trip.

 

[Coztick]

My pony is redundancy for emergency purposes, not to extend the dive. I don't dip into it.

I never intended to dip.
Only to consider it's volume as available emergency gas ( which it is by definition)
at the END of a dive.

 

[Coztick]

Heck, I'm safer because my remaining gas is still redundant.

 

[Kharon]

If your primary and pony are back mounted and the hoses both come off the top then how are you supposed to tell?

You sling the pony (why the hell would you back mount?) and attach both regs in different places. For example, a necklace for my primary and a shoulder attachment for my pony reg - IF I am using a reg on a hose. When diving solo the reg is mounted directly on the H2Odyssey valve/1st stage. No way possible to mix them up with that configuration. You can't justifiably condemn equipment because of the way some people choose to configure it.

 

[uncfnp]

A question.
If, for example, while on a guided dive, the dive plan is to begin your accent with your buddy when one of you hits 1000psi.
Can I consider the contents of my 13cuft pony to be half of this accent pressure (assuming 80cuft main) and available for my buddy in emergency and therefor start my accent at 500 psi.?
Solo would work the same, 500psi in your main and a redundant supply of equal quantity in a pony?
Would this be acceptable gas planning?
I'm thinking it would depend on the when and where as to how conservative is prudent.
I'm specifically talking about Cozumel.
I'm thinking that if I don't suck a tank dry, and have to switch to the pony before re-boarding the boat, then I've returned with more than they requested.
OK, fire at will....

Hmmm. Good question. A pony bottle, used *by the book* is never part of your gas planning for a dive, even drift dives like Cozumel. So no. You can not count it as part of the gas plan. And a 13 cf for drift diving Coz would be a poor choice to use to extend dives, just not enough gas. You would have to refill it before each dive and that’s just not pratical. Otherwise you have lost the use of the pony bottle for any purpose.

Drift diving I use 750 as my minimun for ascent. This gets me back on the boat with around 500.

BTW. I have never had a DM check my gauge.

 

[Coztick]

Where in my plan, did I use any gas from the pony?
No emergency?
No need to refill.
Guess the problem is I called it a pony instead of my right side cylinder...

 

[MaxBottomtime]

I think that 500psi of backgas is dedicated to emergency and is not to be used as well.
At no time did I plan to use it during the dive otherwise it would be unavailable during an emergency at the end and you are obviously missing my point.
I do dive sm. and have taken 2 80s for deeper dives requiring more swimming in Coz.
I love the scale-ability and comfort. I've got 4 lp 72s for home.
I only carry the pony on the simple stuff as instabuddy backup.
400 psi is a good bit of time over a 2 week trip.

I understand your point, but the pony should not be taken into account as part of your reserve. The DM will only be looking at your spg from your 80. Would I begin my ascent from a shallow dive with 1000 psi at home? Not likely but when you are diving on a commercial boat you play by their rules. They probably would not be happy if your spg read 250 psi.

 

[uncfnp]

Where in my plan, did I use any gas from the pony?
No emergency?
No need to refill.
Guess the problem is I called it a pony instead of my right side cylinder...

"Can I consider the contents of my 13cuft pony to be half of this accent pressure (assuming 80cuft main) and available for my buddy in emergency and therefor start my accent at 500 psi.?
Solo would work the same, 500psi in your main and a redundant supply of equal quantity in a pony?
Would this be acceptable gas planning?"

Can you “start my ascent at 500 psi” in the main tank and still get back on the boat with a minimal amount of gas in the main tank without using the pony?

No need to get defensive. You asked a question and I gave my opinion.
And I also answered the second part, in my opinion a 13 cf makes a poor "right side" (or left) cylinder.

 

[2airishuman]

You sling the pony (why the hell would you back mount?) ... You can't justifiably condemn equipment because of the way some people choose to configure it.

The point I've been trying to make is that there is no formal guidance on this. There are reputable suppliers that will sell you gear for back mounting a pony cylinder. There are accomplished divers (like @CuzzA and @Wookie) who dive this way. Usually the reasoning has to do with keeping the sides and chest clear so that other equipment can be placed there. I don't second-guess their reasons. There are ways to back-mount a pony cylinder safely. Perhaps the most common setup is to necklace the pony reg and use an Air2 or similar as the secondary regular for the main cylinder. There are also some people who configure the pony valve-down so that hose routing is different enough to be obvious.

The evidence is out there and we know from experience which configurations are safe and which are not.

Hmmm. Good question. A pony bottle, used *by the book* is never part of your gas planning for a dive

Which book? I don't think there's a thorough treatment of recreational gas planning anywhere that addresses the use of pony cylinders in a thorough way. I don't think there's a consensus on terminology or on what is and is not a safe gas planning approach for recreational dives.

And I would not agree that pretending the pony doesn't exist is the only reasonable gas planning strategy.

 

[uncfnp]

The point I've been trying to make is that there is no formal guidance on this. There are reputable suppliers that will sell you gear for back mounting a pony cylinder. There are accomplished divers (like @CuzzA and @Wookie) who dive this way. Usually the reasoning has to do with keeping the sides and chest clear so that other equipment can be placed there. I don't second-guess their reasons. There are ways to back-mount a pony cylinder safely. Perhaps the most common setup is to necklace the pony reg and use an Air2 or similar as the secondary regular for the main cylinder. There are also some people who configure the pony valve-down so that hose routing is different enough to be obvious.

The evidence is out there and we know from experience which configurations are safe and which are not.



Which book? I don't think there's a thorough treatment of recreational gas planning anywhere that addresses the use of pony cylinders in a thorough way. I don't think there's a consensus on terminology or on what is and is not a safe gas planning approach for recreational dives.

And I would not agree that pretending the pony doesn't exist is the only reasonable gas planning strategy.

I meant it a bit tongue in cheek, hence the asterisks. There are several schools of thought regarding ponies but a common one is that the pony is only for redundancy and as such should not be used as part of gas planning.

Another school of thought is the other use also mentioned here and that is as a dual cylinder, to extend the dive and as redundancy. And this does require thoughtful gas planning and management.

But IMHO a 13 cf is only large enough to serve as emergency redundancy.