Back mount pony bottle

[GiraffeMarineSalvage]

I've noticed a similar phemomenon, and written about it before.

I don't disagree at all with a al13 on your person is better than an al40 left onshore, except if considering human factors in diving (such as assumptions/miscalculations/doing more than one otherwise would, of which none of us is immune...) there's a very real risk of overestimating the value of 13 cu ft...
Yes, this is true of any gas volume, but in my opinion (of course depending on the dive profile...) an al13 is leaning closer towards "spare air" false sense of security territory (honestly I mean no offense to "spare air," IF that's all the air you need to complete your dive that's just swell, but reasonable realities drawn from proper preparation and gas planning, including panicked SAC rates, in my opinion present a rather stark contrast to marketing at Spare Air - Why I Invented Spare Air, or of overestimating the increased safety margin of adding a 13 cu ft pony bottle). Super simple objective math in relation to a standard aluminum 80 you're talking about addition of a 15% margin of safety (yes, I'm rounding slightly down from 16.67%, but in my opinion increased SAC rate in emergency is likely to more than offset that..). Relative to a steel 120 that relative safety margin drops to just over 10% more air ignoring a panicked SAC rate.
So, yes 10 to 15% more is undeniably better, at least right up until a diver makes decisions based upon the confidence this extra redundancy may bring that might require 20% more gas...

(Please note, regardless of my own personal preferences that I'm not in any way opposed to a pony bottle of any size; but realistically I also admit there were some dives in my past during a window of time between my more basic diving and my deeper diving that I was "lucky" as opposed to properly "prepared" and during those dives a 13 wouldn't have made the difference if for example my single steel 120 first stage had the high pressure seat fail or I had blown a hose. I have properly responded to plenty of adverse issues throughout my diving but there is a memorable time I was moderately narced at ~135 feet that if anything had gone catastrophically wrong for me or my buddy we would not have had the gas to safely make it back; we both lived and learned but not everyone gets that opportunity and there's no getting around the fact 13 cu ft just isn't a lot of gas at depth unless you're CCR...)

 

[CuzzA]

I've seen a reg failure at 180 fsw and the 13 did the job for the guy. You're still likely to have access to some gas during the time your primary tank empties from a reg or hose failure.

Bottom line, you know when something bad just happened regarding your gas supply. And if you're solo you need to get your ass close to the surface promptly. 60 ft per minute promptly.

 

[Boarderguy]

Not everybody loses their **** when an incident occurs. Heavy breathing because you've had a fre flow, blown hose or failed o-ring is stupid unless your NEW. A 13 can and will get you to the surface. IMO increase your ascent rate to 45 ish fpm and take bigger slower breaths letting the gas expand while you exhale going up. Then suck your pony dry at your stop and surface. For decades 60 fpm was acceptable. Follow your slowest bubble worked great. You should be able to get at least 10 minutes from a 13 once you get to your stop especially if you're hanging on a shot or the bottom for a shore dive. A 19 would be better which the OP is going to use, but a 13 works well is you know how to use it.

 

[SlugLife]

there's a very real risk of overestimating the value of 13 cu ft...

It might have been worth looking at the post I linked. Because I actually briefly touch on concepts like sizes, depths, and limits, and .....

Sizes: Someone may give the run-down about how to calculate your redundant gas. I'm going to over-simplify to get people started

...because I ALWAYS get a reply about how you really need more air, etc.

an al13 is leaning closer towards "spare air" false sense of security territory

I agree the Spare Air's are so bad they're probably more dangerous than nothing at all due to a false sense of security (as stated in the post).

The 13cu is not dangerous, unless operated by an idiot. The important concept is limits and depths, and being aware of those limits. IF we take an average rec-diver at 100ft or less, the 13cu is probably adequate (even if I recommend 19) to save their life in an OOA if they react appropriately.

Personally, I switch from 19cu to 80cu redundant past 100ft, because it's easy to do with SideMount. However, I also have a 6cu (and no 13cu), and had to take the 6cu on vacation (versus nothing); and I'm always mindful to not go super-deep, and that if I have to bail out, I'll be skipping the safety stop.

I've seen a reg failure at 180 fsw and the 13 did the job for the guy.

I believe I've seen the same video. The guy even did a safety stop. Obviously, the fact that this diver managed to do it says more about the diver than the pony-bottle. One would have to have a very low sac rate, start surfacing immediately, etc.

 

[SlugLife]

Not everybody loses their **** when an incident occurs. Heavy breathing because you've had a fre flow, blown hose or failed o-ring is stupid unless your NEW. A 13 can and will get you to the surface. IMO increase your ascent rate to 45 ish fpm and take bigger slower breaths letting the gas expand while you exhale going up. Then suck your pony dry at your stop and surface. For decades 60 fpm was acceptable. Follow your slowest bubble worked great. You should be able to get at least 10 minutes from a 13 once you get to your stop especially if you're hanging on a shot or the bottom for a shore dive. A 19 would be better which the OP is going to use, but a 13 works well is you know how to use it.

Agreed. I'd also add, having redundant air on you may also help significant reduce or prevent panic.

1. "Something is leaking bad! Well, that sucks. Guess I better shut off the tank, switch over to the pony, and surface."
2. Versus, "Where are these bubbles coming from! I'm at 100ft! I'm about to die! I better quickly drop weights, hammer the BCD-elevator-button and rocket to the surface now!"

 

[Ross19966]

Might be good idea to borrow the gear from the LDS and try it back mounted or slung.

So you are saying that a diver should not be surprised by a first stage failure or a hose pops? I don't understand how your comment relates to the OP's question?

I took his comment to mean that there should be no excuse for sucking a tank dry, not so much an equipment failure. I agree with that. Basic air management should prevent anyone from sucking a tank dry, but equipment failures do happen.

 

[Ross19966]

I agree the Spare Air's are so bad they're probably more dangerous than nothing at all due to a false sense of security (as stated in the post).

I have a spare air that I use for cleaning the pool drain. I would never use it for a dive.

 

[SlugLife]

I have a spare air that I use for cleaning the pool drain. I would never use it for a dive.

Anyone have some pool-drains or boat-hulls they need to clean? (I'm a terrible salesman)

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I have 2 Spare Airs & 1 Fill Adapter. I'm selling everything as a package. $200 for everything including (non-expedient) shipping in the US, pay with paypal F&F. Local pickup available around Cedar Park, TX (with discount) #1 Spare Air 3cu (yellow) 3 cu in size 2004 Birthdate Comes with...

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[johndiver999]

• 
  
• I'm a big fan of using necklaces, clips, or regulator-retainers of some sort. Your regulator should ideally always be where you can find it quickly and easily by feel alone.

There is an aspect of this which I think is worth emphasizing. If you have a back mounted pony and no ability to monitor the pressure during a dive, then it is very advantageous to wear the second stage where you can FEEL a free flow or leak. If you wear it as a normal octopus, it can blow bubbles especially on a rigorous descent down an anchor line in a current. It is easy to not notice a freeflow , for example when wearing a thick suit, hood etc. and swimming hard against a current and fighting waves etc.,

If the second stage is around your neck then you should be able to detect a freeflow.

If your normal octopus freeflows, you always have the ability to notice this when you check your air pressure.

 

[Boarderguy]

There is an aspect of this which I think is worth emphasizing. If you have a back mounted pony and no ability to monitor the pressure during a dive, then it is very advantageous to wear the second stage where you can FEEL a free flow or leak. If you wear it as a normal octopus, it can blow bubbles especially on a rigorous descent down an anchor line in a current. It is easy to not notice a freeflow , for example when wearing a thick suit, hood etc. and swimming hard against a current and fighting waves etc.,

If the second stage is around your neck then you should be able to detect a freeflow.

If you normal octopus freeflows, you always have the ability to notice this when you check your air pressure.

That is why you dive with it charged and turned off. Feather the valve as you descend to keep the hose pressurized OR charged and turned ever so slightly on so that it will keep the line charged but you won't lose more than a breath or two over the dive if it does get hit. Back mount should be upside down so you can reach the valve IMO.