I agree with you 110%. We've come a long way from the first dives, when he was 12. I used to turn away for 10 seconds, literally, and turn back and he would be 50 feet away. He would see a turtle and swim toward it like there was no tomorrow without signaling me whatsoever. Some serious scolding, reviewing and stressing that we depend entirely upon each other has solved most of that. But we are still developing. We will be taking rescue diving end of June, which I think should be a really good class for him, and me. Developing and developed are two different things.
So as we are DEVELOPING, is there something about pony bottles that we should stay away from, something I'm not understanding?
YES! Pony bottles have literally KILLED people. It is important that you understand how.
But first, i will tell you I always dive with a pony and so does my young son. It is an essential part of our configuration and there is absolutely no way i could enjoy my dive or turn my back on my son (who started diving with me at 9 yrs old) if he was not wearing a redundant system. I would just be way too nervous.
The pony you bought is over-kill for 80 ft depths.. my son uses a 6 cu-ft to depths of 90 feet or so.
But back to how a pony can kill you or your son... IF (and only if) you back mount the tank like I do.... there is a potential to confuse the two second stages - mixxing up the pony versus main tank... So this is how the accident can evolve..
The diver checks his air in both tanks, checks the regs for operation, turns both tanks on and gets ready to dive. Some silly distraction occurs, maybe the diver is sea sick and pukes and feels terrible and just wants to get below the waves..
So after the puke fest, the diver grabs the pony reg, and rolls over. Now 8.36 minutes later it gets a little hard to breath and then there is one more breath and nothing. The diver checks his has supply (from the primary tank) and the gage shows full, but he ain't getting no air from the regulator (when a pony goes empty, it is much faster than a big tank- you can't milk it slowly) ---
So the diver figures his main tank must have somehow failed and he is getting a little panicked and confused, so he spits the regulator out, maybe signals to his buddy who isn't watching at that precise moment and then... he tries to switch regs, but since he is absolutely sure he was breathing from the primary reg, he puts the empty pony bottle reg BACK in his mouth and gets nothing.
He is beyond panic, can't understand why BOTH tanks failed today and since he has been dicking around instead of heading for the surface during this whole ordeal, he may well die if he doesn't get air from his buddy. People HAVE died with empty ponies and full working tanks and I personally know an inexperienced diver who made this exact mistake on a solo dive and just barely figured out his mistake.
A pony bottle does add some complexity. It is safer to have it clipped off in the front like a stage bottle, but that is a PITA, particularly if you don't have BC's that provide good attachment locations. if the tank is clipped off in front of you like a stage bottle and you can SEE the tank and follow the hose and regulator, it is almost impossible to get confused. But, I use back mounted... less safe, more prone to entanglement and more confusing during a failure (still the benefits outweigh the drawbacks for me).
This video shows an actual scuba failure i had with my son while diving with a pony bottle. We (I) got my signals crossed and ended up with some confusion of where the failure was from my back mounted rig. We weren't close to a really dangerous situation, but it might give you some insight into some issues.
You can skip forward to about 1:45 minutes if you get bored. FYI. this video is authentic and not staged in any manner.
[video=youtube_share;Bap2PxetarQ]http://youtu.be/Bap2PxetarQ[/video]
---------- Post added May 19th, 2014 at 07:37 PM ----------
I see it this way; you've needlessly removed an important and common piece of gear for no reason. There is no reason not to carry an octo.
Here's a few scenarios that you may want to think about.
What if you're doing a simple, shallow reef dive? You don't need a pony, or the additional weight. Now, you have to change your gear around and add an octo back to your rig.
What if you're on a deep wreck; you're ready to ascend, but as you start up, you see a diver below, frantically signalling OOA. YOu meet, and hand them off your pony. They're panicked, breathing hard, and they have really drained that pony. At 90 feet, you're using air 4 times faster than at the surface. That pony can be gone in 2-3 minutes. And your son? He didn't see you go back for the diver, and continued to ascend. Now, you have a stressed diver breathing out the last dregs of air, and no way to get them more air without buddy breathing that one reg you have left- the one that is also your gas supply.
Or, as he comes back to look for you, he runs out and switchs to his pony. Now he's breathing his emergency supply, looking for Dad, and now you don't have that emergency backup.
It is very possible to breath out those ponies in an emergency. If that happens, that OOA diver has no backup except to buddy breath, a difficult and stressful task even in training. You could drain off those two ponies, and have plenty of gas in your main tank, but now no way to supply it to the diver without using a difficult and dangerous procedure.
You can have 6 air sources with the pony and Octos. You can supply the OOA diver with gas from four sources, and still increase your redundancy over your system. Think of the octo as a third backup. Don't most aircraft have at least triple redundant backup systems? The odds of your regulators failing in a position that closes them is almost zero. They're designed to fail open.
We're not saying don't take a pony, but not taking a simple device like the octo doesn't make sense to me. Can you explain why you don't want an octo, in addition to the pony and it's regulator?
The way it sounds, in my opinion, You've convinced yourself that this is the way to go. Nothing I, or anyone else here says will change your mind.
There are some very good reasons to NOT carry 3 second stages. Particularly if you back mount the pony. The potential for freeflow and failure goes up significantly. During a free flow event, it may be very confusing as to which reg is actually the problem.. a new rec diver is going to be stressed enough with a simple free flow, juggling three regs can add to the confusion. Also a second stage clipped off in the golden triangle is quite likely to freeflow and on a hard descent down an anchor line in a strong current when you are enveloped in the bubble stream from 2-3 divers (working hard) below you and it is EASY to fail to detect your own freeflow..
The diver needs to balance the increased complexity, potential for failure versus the added safety and/or convenience of each piece of gear. It is NOT a no-brainer to carry 3 second stages with a typical back mounnted pony configuration.
But without a Octo, he has to use that pony to breath.
