I am one of those anal-retentive who done like to leave things to chance. I have 40cuft pony, and once in the water I hardly realize it is there ( I took off about 3lbs on that pony side ) I keep my SPG clipped in such a way so that all I have to do is look down to see it. Nice and clean. I use a super pony tamer and it comes off in a snap. I have yellow hose wrap on the reg which is a aqua-lung titan and I painted the req yellow too. I explain to my buddies how to unclip it. I feel much safer knowing I have a completely redundant system. Plus while I am having my primary reg serviced, I can still go diving!!! Ye ha!
Pony bottle setup/config
- Thread starter jepuskar
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H2OHead
Guest
at birthday parties. The kids absolutely love 'em.
Some guy once referred to gear selection like this as buying gear to correct a problem that you created in the first place (paraphrased because Im not about to look up the actual quote as the guy makes me nauseous). The problem created here is planning, the snowball effect is now, what reg, placement, hose routing, etc. Now youre back to the constant battle with solving problems that didnt exist prior to the decision to carry another useless bottle.
Some guy once referred to gear selection like this as buying gear to correct a problem that you created in the first place (paraphrased because Im not about to look up the actual quote as the guy makes me nauseous). The problem created here is planning, the snowball effect is now, what reg, placement, hose routing, etc. Now youre back to the constant battle with solving problems that didnt exist prior to the decision to carry another useless bottle.
No, a "truly redundant" system has gas supply equality as a requirement too. To understand why we say this, think "overhead environment" - where aborting requires as much gas to get back to the surface as it took you to get where you are, and sometimes considerably more if deco is involved. For the sake of consistancy across the board, what you're describing is a "bailout bottle," or an "independent air supply," as opposed to a redundant gas supply. That's not picking a nit to say "don't do it" - bailout bottles are fine and a good idea in many cases, but they are only partially redundant.
Rick
A more accurate term is "completely independent system." See my post above for why.
Rick
Whirling Girl
Contributor
Does a pony bottle give you enough gas to get you safely to the surface at a safe rate, including all your planned deco stops?
Just curious. I've never done the math before. I've figured out my rock bottom pressure on all my tanks, but never applied the same to a pony.
And I think at least some of the posters are making the point that diving without a pony is not diving without redundancy. Your buddy is your redundancy. Rock bottom is the amount of gas you need to get you AND your buddy safely to the surface and include all your deco stops.
Though I can also understand, and appreciate, the comments by some of the posters about not having the luxury of regular or trustworthy dive buddies, or being required to dive doubles or with ponies off certain boats.
It's an entirely different orientation to diving to rely on your own skills, awareness and responsibility, and yet still train yourself to put your trust in your buddy to do the same, so that in the event of a problem your first instinctive reaction is to go to him/her for help, rather than deploy a pony and go to the surface alone...
Just some thoughts.
Margaret
OP
In the type of diving I do, which is purely no deco diving, a pony bottle can provide enough air to safely ascend and make a safety stop around 15 feet. Ofcourse this is all depending on the size of the bottle you choose.
When you start talking about 'all your planned deco stops' then of course it sounds like your pony just became a couple horses.
When you start talking about 'all your planned deco stops' then of course it sounds like your pony just became a couple horses.
Whirling Girl
Contributor
"Ambiguity, the Devil's volleyball."
Sorry, my bad. I call safety stops, 'deco' stops. I often hear the phrase from my instructors and dive buddies that all diving is decompression diving and I guess it finally stuck.
So, a pony bottle has enough gas in it to slowly ascend from, let's say, 80 ft. to 15 ft., hover for 3 minutes, and then maybe even take another minute to ascend to the surface. What's that calculation look like?
Margaret
Sorry, my bad. I call safety stops, 'deco' stops. I often hear the phrase from my instructors and dive buddies that all diving is decompression diving and I guess it finally stuck.
So, a pony bottle has enough gas in it to slowly ascend from, let's say, 80 ft. to 15 ft., hover for 3 minutes, and then maybe even take another minute to ascend to the surface. What's that calculation look like?
Margaret
Say your surface air consumption(SAC) rate while being stressed out is 1cfm. (This is me, YMMV.)
Then, if you're at 90ft, your consumption is ~4cfm.
Now to ascend from this depth at a safe rate of 30ft/m, it will take you about 3 minutes to the surface.
If you are very conservative and say that your air consumption will be the same as when you were at depth, this will take 4*3 = 12 cubic feet of air to ascend directly to the surface. For the safety stop, you are at 1.5atm, so your air consumption is 1.5 times your SAC rate. Thus, a 3 minute safety stop will take 4.5 cubic feet of air.
These add up to 16.5 cubic feet. Now if we are more precise and take into account that the air consumption decreases as we ascend from depth, we can take off 4.5 cubic feet off the calculation, but you need some (very simple) integral calculus to do this, so I won't get into it.
So, with a SAC rate of 1cf/m, you need 12cft if everything goes without a hitch. However, if you are having problems then you may have to stay down until you fix things. If we allow a minute for this, it adds 4 cubic feet, for a total of 16.
As you can see, in order to do a safe ascent from 90ft and a 3 minute safety stop, 19 cubic feet is the least you need. Of course, if you are a Zen buddhist monk and can keep your air consumption rate the same when you are under stress, then 13cf pony will suffice.
It's quite possible that there will be situations where you will breath much faster. In which case you will have to multiply the above number with the maximum SAC rate that you think you need to guard against. And you can also decide to omit a safety stop when you are in a OOA situation, and decide to go for a smaller pony instead. It's a choice of how much inconvenience you are willing to go through for the additional safety factor. As for me, I use a 19cf pony because it's not much bigger than a 13cf but is way smaller/lighter than the 30cf pony.
Then, if you're at 90ft, your consumption is ~4cfm.
Now to ascend from this depth at a safe rate of 30ft/m, it will take you about 3 minutes to the surface.
If you are very conservative and say that your air consumption will be the same as when you were at depth, this will take 4*3 = 12 cubic feet of air to ascend directly to the surface. For the safety stop, you are at 1.5atm, so your air consumption is 1.5 times your SAC rate. Thus, a 3 minute safety stop will take 4.5 cubic feet of air.
These add up to 16.5 cubic feet. Now if we are more precise and take into account that the air consumption decreases as we ascend from depth, we can take off 4.5 cubic feet off the calculation, but you need some (very simple) integral calculus to do this, so I won't get into it.
So, with a SAC rate of 1cf/m, you need 12cft if everything goes without a hitch. However, if you are having problems then you may have to stay down until you fix things. If we allow a minute for this, it adds 4 cubic feet, for a total of 16.
As you can see, in order to do a safe ascent from 90ft and a 3 minute safety stop, 19 cubic feet is the least you need. Of course, if you are a Zen buddhist monk and can keep your air consumption rate the same when you are under stress, then 13cf pony will suffice.
It's quite possible that there will be situations where you will breath much faster. In which case you will have to multiply the above number with the maximum SAC rate that you think you need to guard against. And you can also decide to omit a safety stop when you are in a OOA situation, and decide to go for a smaller pony instead. It's a choice of how much inconvenience you are willing to go through for the additional safety factor. As for me, I use a 19cf pony because it's not much bigger than a 13cf but is way smaller/lighter than the 30cf pony.
nearly got himself seriously hurt or even possibly killed a couple of weeks ago by underestimating what he really needed for reundant air.
He was quite deep and went to unstick the anchor (last guy in the water.) Unfortunately, he hoovers gas to start with, was a bit low, and mistakenly thought he had enough gas to complete the job and his ascent. Dropping to the bottom upped his SAC, as did the work of huffing to unstick the anchor. He discovered that his original computation was bad when he ran out of air at 100' while unsticking the anchor.
Pony to the rescue, right? Uh, not quite. Still huffing, the small pony (I believe its a 9cf) went "poof" very, very quickly at 100'. He found himself out again, this time for real with no more backups at hand, at ~50 fsw.
Fortunately his buddy was at his safety stop and he found HIM at roughly 15', was able to secure gas, and at least stop to blow down some nitrogen before surfacing.
An ESA from 100' after being down for very close to the NDLs worth of time is a recipe for an immediate chamber ride at best.
Even worse, he was a good 40 miles offshore - at least an hour out from any meaningful emergency assistance on his boat at WOT.
All ended ok, but he has much more respect for the reading on his SPG after this incident, and no longer attempts to get the last few breaths out of his backgas.....
He was quite deep and went to unstick the anchor (last guy in the water.) Unfortunately, he hoovers gas to start with, was a bit low, and mistakenly thought he had enough gas to complete the job and his ascent. Dropping to the bottom upped his SAC, as did the work of huffing to unstick the anchor. He discovered that his original computation was bad when he ran out of air at 100' while unsticking the anchor.
Pony to the rescue, right? Uh, not quite. Still huffing, the small pony (I believe its a 9cf) went "poof" very, very quickly at 100'. He found himself out again, this time for real with no more backups at hand, at ~50 fsw.
Fortunately his buddy was at his safety stop and he found HIM at roughly 15', was able to secure gas, and at least stop to blow down some nitrogen before surfacing.
An ESA from 100' after being down for very close to the NDLs worth of time is a recipe for an immediate chamber ride at best.
Even worse, he was a good 40 miles offshore - at least an hour out from any meaningful emergency assistance on his boat at WOT.
All ended ok, but he has much more respect for the reading on his SPG after this incident, and no longer attempts to get the last few breaths out of his backgas.....
Sounds like I am glad I go the forty, The super pony tamer keeps it very secure. But I see a trend here on people who get themselves in trouble. Everytime I read a horror story, they started off by doing something really stupid. Rodale's mag seems to be famous for this. You read it and say to yourself, "boy that was really stupid" Darwin seems to love scuba divers.
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