Is there a valid reason for a pony bottle

[grf88]

As a matter of interest who participating on this thread has had to share air in a full-blown emergency. I am not talking about practising air shares, they are easy, but having to help a diver in full blown panic who was clawing for the surface. This doesn't have to be your buddy but could be another diver in a group who picks you to mug as has happened to me. He was not even a member of the group I was with. Maybe if he had a pony he would not have put me at risk.

 

[markmud]

You care about DCS ?



From 90 ft / 27 meter to the surface in 2.5 minute? You go to the surface with a speed of more than 30 feet/minute. And you skip your safety stop. I thought you did care about DCS.



I wouldn't agree with that. I would like to have a minimum gas of 1200 liter for 2 divers for 100 feet / 30 m. I never dive with a pony, but if I would dive solo to 30 meter / 100 feet I want at least 600 liter in a pony I wouldn't accept 368 liter / 13 cuft.

(But I never do solodiving, and I never use a pony. Single tank and buddy is enough for me. If that is not enough I will use doubles.)

Hi Barth,

Please school me. I thought that an accepted ascent rate from depth to 60 feet was 60 feet per minute. I thought an accepted ascent rate from 60 feet to the surface is 30 feet per minute. If that is true, 2.5 minutes is the correct answer.

I was scolded for doing a safety stop while doing my solo diver cert dives. Safety stops are voluntary (but a really good idea). In a SHTF situation, go for the surface and skip the safety stop (I agree with that protocol).

I am glad that you have thought about this issue and concluded for yourself that a pony is not needed. You are probably a really good buddy diver and one that I would enjoy diving with.

cheers,
markm

 

[KenGordon]

My reading of this thread is that there are two sides. One side that feels that there are valid reasons for taking a pony on some dives (the answer to the OP). The other side feels that good buddy skills and gear maintenance results in the same risk reduction that a pony does, so they don't want to deal with the expense (upfront and maintenance), drag, entanglement issues and balance issues that they see as downsides to a pony. I'm "pro-pony", but I do understand the point of the other side, and they may be right (it's a hard thing to calculate precisely).

My problem is not the drag, entanglement, balance, expense and risk of breathing off the wrong gas issues, it is that for the dives where redundancy is really required (ie the ones which are fairly deep) a pony is inadequate.

Size matters. Assuming, as has been pushed by a couple of post here, that the ascent is done at a full 10m/minute but that the rate of gas use is low (doubling an already low value was used as an example) leads to underestimating actual gas requirements.

Someone objected that a twinset is not a proper isolated redundant system. That is a fair point, if you are relying on it being redundant you need to be able to do a shutdown. Or you could take a 12l back mounted pony.

If I am at 30m on a single my plan is not to be so far from my buddy that it can be a terminal problem to have a failure. We will have planned enough gas for the ascent.

Solo diving is different, redundancy is required and if the dive is shallow a pony will do.

My personal experience was that a 3l steel side slung pony was a pain, so I used independent twins and then a proper manifolded twinset. I will be using that tomorrow when I take in a diver for her first dive in a 10m lake. I am essentially solo Freeflow is a slight risk, but having plenty of gas is a nice bonus. I like having plenty of gas. It is relaxing.

 

[lexvil]

I would have never imagined that this subject would lead to the scuba swat team being activated.

 

[Joneill]

What's the difference between a stage bottle and a pony bottle?

The dive plan. Otherwise, they are identical pieces of gear.

That is true - but we were more focused on the use here and, in that sense, the term pony is more appropriate, right?

 

[markmud]

Yeah, good luck with that.

What happens if you have a failure mid water?

When SHTF, you don’t “rise to the occasion” you sink to the level of your training. Are you 100% sure you could perform all that under real pressure?

Hi ryan,

No I think you should ask yourself that question. Why are you focused on this. I am starting to believe you are projecting your reactions on others.

I have been in lots of scrapes, and I react the opposite way. I slow down and focus on the most important task at hand. I don't melt like a snowflake. I have learned to do a "gut check" and to follow my training. Slow is fast. My dad was a fighter pilot and scuba diver. He taught me these things when I was a kid. Sports teaches you these things.

You claim to be a cave diver and tech diver. I don't know about that man?

It's OK if you don't want to use a pony. That's your decision. Pushing your fears on others who are capable of handling minor situations is not rational.

cheers,
markm
PS: It is a minor situation when you have redundant gear and know how to use it.

 

[doctormike]

That is true - but we were more focused on the use here and, in that sense, the term pony is more appropriate, right?

Absolutely. But I guess you could ask the OP. Maybe they really meant to say "is there a valid reason for a second scuba tank and regulator that might or might not be smaller than your primary back gas tank?"

 

[markmud]

I use a slightly different method to calculate pony size. It works for me.

AL80= 80 cf.
13cf pony/80cf AL80 = 0.1625

In Bar 0.1625 x 200 bar = 32.5 bar. A 13cf pony contains the equivalent of 32.5 bar in an AL80. That is a lot of gas.

Hi CWK,

Minor point here: An AL80 has 77cf not 80cf.

I know that is a picayune difference, but that is what I based my numbers on.

Your point is very well recieved.

markm

 

[northernone]

As a matter of interest who participating on this thread has had to share air in a full-blown emergency. I am not talking about practising air shares, they are easy, but having to help a diver in full blown panic who was clawing for the surface. This doesn't have to be your buddy but could be another diver in a group who picks you to mug as has happened to me. He was not even a member of the group I was with. Maybe if he had a pony he would not have put me at risk.

I've had that a couple times too. Never my buddy, but random strangers in the water and I'm nearby and the first to respond.

Panic kills. If they aren't calm enough to reach a buddy or the surface, quite likely they aren't calm enough to successfully deploy a pony reg either.

People drown with air in their tanks and weight systems in place after panicking at the surface. If someone can't think to ditch weights I can't expect them to safety deploy a pony reg either appropriately when it really counts.

We can't always fix a diver problem with a equipment solution.

Bit of a devil's advocate on this one... I love a second tank attached to me. But if they become standard equipment I doubt it will reduce the number of dead divers. (only based on poor data and conjecture)

Cameron

 

[markmud]

I've had that a couple times too. Never my buddy, but random strangers in the water and I'm nearby and the first to respond.

Panic kills. If they aren't calm enough to reach a buddy or the surface, quite likely they aren't calm enough to successfully deploy a pony reg either.

People drown with air in their tanks and weight systems in place after panicking at the surface. If someone can't think to ditch weights I can't expect them to safety deploy a pony reg either appropriately when it really counts.

We can't always fix a diver problem with a equipment solution.

Bit of a devil's advocate on this one... I love a second tank attached to me. But if they become standard equipment I doubt it will reduce the number of dead divers. (only based on poor data and conjecture)

Cameron

Hi Cameron,

Do you believe it is a good idea for PADI, SDI, and SSI to require 100 logged dives as a prerequisite to train for a solo/self-reliant/independent cert?

I do.

thanks,
markm