Spare air

[Diveral]

If you are looking for a bail out system IMHO this is the best system H2Odyssey...Air Systems

6 cu ft is about the minimum size I would consider for a straight bail to the surface. 13 cu ft would be about the minimum adequate size for me for most of my dives which would allow me anything approaching a normal ascent with all stops.

Personally when I dive with a redundant air system I use either a 19 cu ft pony strapped to my tank or a 50 cu ft slung pony. Which one I use totally depends on my dive and my profile.

Hope this helps.

AL

 

[Shcubasteve]

Ill take the side of the Spare Air. I have one with me on every dive deeper then 50' and have yet to notice it is even there. I have it mounted on the cylinder behind me similar to how a pony tamer mounts a larger cylinder...I bought it used for $150, and had it rebuilt soon after. I have done controlled ascents with it no problem. True, there is not much air in it, but there is no excuse for running out of air on the bottom anyway, so you should never need it.. My concern would be a hose blowing underwater diving solo, but even then you will be able to start heading to the surface before you run out of air; the remaining ascent could be done with a spare air.... For reference, i get 10 breaths at 60'... This doesn't sound like much, but it lasted for about a minute and a half at a constant depth; the reduction in ambient pressure on your way up would give you more breaths... plenty of time to make it to the surface

Spare air is great for no-stop diving, because it will get you to the surface( albeit with no safety stop). Filling it yourself makes it free/ really cheap to fill with air or EANx to 40% from one of your main cylinders. No need to maintain a separate cylinder and regulator set up, so long term maintenance costs are less then that of a full pony rig. Also, it is so compact, that you wont even notice you have it with you. For recreational depths it is perfect. It is great to have enough air for a full safety stop, but within recreational limits that should not be necessary, just recommended... There is not a ton of air in it, but it would be enough to get you to your buddy 50' away whos not paying attention to you....

Steve W

 

[pescador775]

Diving with a pony could be compared to flying a small plane with parachute strapped on. If you roll that way go with it.

The chances of "running out of air" absent diver error probably about 1/100,000. In many such instances, the diver could make it to the surface by breathing in measured breaths from the regulator which releases air as the diver ascends per various physical laws. However, there varying degrees of risk, more hazardous situations like diving under ice or deco diving that require redundant air. This argues for twin cylinders and twin regulators. Spare air would not be considered suitable.

For no deco, reef diving the spare air should be near ideal. Dive computers are usually very conservative compared to the original Navy tables and deco meters available decades ago. Thus, the chance of needing a so called safety stop for anything other than mental reasons is questionable. When considering purchase look for the 3000 psi, 3 cf model. A diver ascending from 100 fsw should be able to get 10-20 breaths from the bottle, more than enough.

I got called away, hence the edit. I have to tell you it hard not to editorialize about pony bottles and the layering of so called safety devices on what should be trained and fit divers. However, this is a diverse community and one should expect a variety of opinions and interpretation of facts. Every day, there are thousands of free divers plunging to 60-80 fws and returning the way they came. To suggest that a SCUBA diver could not return safely from 100 fsw with 3 cf of air at his disposal is silly. This attitude is engendered in part by the Ralph Nader culture and the safety crazies working for insurance companies. There is no cure for it because it is based on emotion rather than science or experience.

If one feels the need for backup air, the SpareAir would be the less obtrusive than any kind of pony bottle per se. If you feel the need for a pony, swallow hard and purchase twin tanks.

 

[Graeme Tolton]

You can keep it beside your bed. If your house catches on fire, you can make it out the front door, avoiding smoke inhalation. But seriously, I have a 6cf bottle that i can sit still and breathe out of for 8 minutes at the surface. That puts my Surface Air Consumption at .75 Cubic Feet per Minute. At 120 Feet that is 3 CFM... Add the stress of an OOA situation, coupled with fighting a current, you will double that. 6 CFM. You now have 120 feet to ascend. Can you ascent 120 FT on 3CF air at a safe ascent rate of 30 ft/min? I didn't think so. Can you swim over to an ignorant buddy who is 100 feet away to grab his/her octo? Probably. Do your research, do some calculations. Buy something bigger. I am thinking of turning my 6 cf bottle into an argon system for my drysuit.

 

[salth2owannabe]

My problem with the calculation aspect of the pony discussion is that every one I have read always throws in the "you can double that because of stress, or panic, in that situation". I may be a strange one, but why the panic factor? How is switching to a pony reg any different then switching to an octo reg or even clearing your primary reg? I wear a pony so that if something happens I can simply reach for my pony reg and breathe, no panic involved in that.
In my profession we train for issues that may pop up so that we are mentally prepared and have the muscle memory to act when the situation arises. We also train with our equipment so we know it's effectiveness and limitations. Get an appropriate size pony for the dive, practice with it, and know what it will do for you. No panic in that!

 

[Thalassamania]

Not panic, just stress, will double your SAC rate or more. The point is that a Spare Air is not much better than practicing free ascents, while a properly sized pony (I like 30s and 40s) turns what might have been an emergency causing stress into a normal backup procedure (as you observed).

 

[PerroneFord]

My problem with the calculation aspect of the pony discussion is that every one I have read always throws in the "you can double that because of stress, or panic, in that situation"...


...In my profession we train for issues that may pop up so that we are mentally prepared and have the muscle memory to act when the situation arises.

Question and answer. Most people do not have a profession that trains them this way, and most people don't practice it underwater either. So if you DON'T practice, and DON'T have the muscle memory, you can bet that running out of gas or having a catastrophic loss of gas will cause elevated breathing levels. This is repeatable over a wide variety of divers, under a wide variety of conditions, and over a long period of time.

 

[Graeme Tolton]

I am just saying that 3CF is insufficient for almost any diving situation. So, no panic involved, scfm is based on at rest, not while swimming. Still 3CFM at 120 feet with 3 CF to get to the surface doesn't seem like a good idea.

 

[PriusDrIVER]

The biggest problem with any of these "dedicated" pony systems it the cost of ownership. How many shops can (will) actually service the Spare Air? How much does it cost for each service? How much does it cost to replace the fill-adapter when you lose it...or forget to take it and it turns out your Spare Air leaked and is empty now, so you are without your "redundant" system. This goes for the H2Odyssey as well, anything that requires special adapters to fill is a PITA.

The big strength of a standard cylinder with a standard regulator set is that they serve more than 1 function. The first and second are also now part of your save-a-dive kit. Something wrong with your primary reg set, go without the pony, swap parts and do your buddy dive as normal. You cannot use any of these dedicated pony "systems" for any purpose beyond a pony.

Find a bargain on a good reliable primary (Mk2+) get a reasonable secondary, throw on a button gauge and OPV...dive. When you need a bigger "pony" just upgrade the cylinder. Start with a 13 today, get a 30 tomorrow. Its far more adaptable. They can grow into serving as staging or deco bottles if you go that route, however a dedicated "regulator/valve" is not as flexible.

Again, anything that requires a special part to get a fill is bad news. Forget it or lose it and your investment either becomes worthless or more expensive.

 

[salth2owannabe]

Don't get me wrong - I'm not a proponent of the spare-air for most any recreational diving depths. If I was going to only ever dive and use it to 50' it would probably work for me but then why buy it for that limitied use.
My concern is with those that discredit various size pony tanks and make the math fit their argument when they have never actually tried them in the water.
I'm not advocating taking a 6 cu ft pony down to 120' either, at least I'm not going to do it, but I know it will work for me down to 100' (with certain dive conditions) because I've practiced with it.
My whole point, to wrap my thoughts up, - get what is appropriate for the depth and practice with it so you know what works for you. When you know a bail out system will work for your dive plan going into the water you basically take the panic factor out of the equation.