Redundant Air: H Valves, Ponies, Doubles, And The Surface.

My single tank rig has one of those little 'Spare Air' things sewn right onto it. Never used, but it pulls its weight every single dive. Even with a vastly experienced guide shadowing my every move, I would use it first then calmly go ask to borrow some of his air. With a same-ocean instabuddy it makes me feel all the more relaxed.

 

I don't know of a Spare Air that has capacity to allow anything other than a few breaths on an otherwise immediate CESA. I'd test and confirm it's capability before assuming it gives you time to track down an inattentive, distant buddy and access their AAS. If something went wrong with that plan, you'd be left with nothing.

Very few people consider Spare Air as a true redundant gas source. It's an emergency ascent bottle only.

Sometimes confidence can be a false-confidence. I feel that Spare Air promotes false confidence.

 

I think the key word here was safest. Even in 10 ft of water if you have boat traffic you can not make a cesa to the surface with a guaranteed safe arrival. To suggest redundancy has no benefit says you are thinking specific conditions and not all conditions. The goal IMO while diving solo is to never cesa. If you have a problem you head up making all stop obligations mandatory or not.

 

It is very limited in what it can do, and one must be aware of those limits for sure! It can get me from 120' to 15' without overtaking my bubbles but cannot do a 3 min safety stop after, so it's like a CESA with more 'C' and less 'E'. If you are under a virtual or physical ceiling you are right about the false confidence. But it is plenty enough to hold off panic, think about what to do, and do it calmly and purposefully. Looking through the incident reports it seems this is where many folks run into trouble.

 

Like the .380 for CCL, the gun you have is better than the gun you do not have, for Spare Air, if that one breath or two is enough, then it is enough and if it is not, well, the board has a section for that.

These threads are always interesting to read. Spare air, pony, no redundancy, redundancy, my plan is to win the situation and avoid situations that I cannot.

I used to be of the mind that drowning me would be like trying to sink styrofoam. But, then I got older. I try to account for limitations without becoming a redundancy ninny. Redundancy is good, most of the time I simply do not need it. I know where the surface is and I am going there.

N

 

In dive planning, it is common to assume that a diver doing an OOA ascent will consume air at a SAC rate of 1.0 cubic feet per minute. Ascending from 120 feet to 15 feet at 60 FPM will take just under 2 minutes, and the average pressure/depth will be just over 3 ATA, so a decent approximation of the gas needed for that ascent is 2 * 3 = 6 cubic feet.

 

Standard size SpareAir is 85Liters/3Cuft, which practically useless in this instance. An arbitrary conservative safe & sane ascent from 36m/120' would require over 700 Liters/25 Cuft -an AL30 Pony Cylinder would do.

 

I do a lot of metal detecting at the beach in designated swim aread with no boat traffic. Most of the good stuff is found in about 5'-7' of water on a flat sand bottom with no obstructions or entanglements. Most people don't swim out much further than their toes can touch the sand. I used to use a 6' pony but I came to the conclusion that in the time it takes me to switch regs and turn the pony on I can either reach the surface or just stand up and wade to shore. To be honest for those dives I don't usually bother with an octopus either (I'm wearing asbestos underwear so flame away). Just one reg, a pressure gauge, depth gauge, a compass, a whistle, a mirror and a watch (so I don't forget how much time I have left on the parking meter). I'm considering going to a j valve to get rid of the pressure gauge.
For all other solo diving I use a 6' pony at the very least along with an octo and various other safety/rescue gear.

 

Although I believe in going through a routine or a checklist, I also consent that each dive should be analyzed and prepared for individually, acknowledging that each particular dive will have its own characteristics, requirements and needs for particular gear.

One of my favorite places in the world to dive is Frederiksted Pier in St. Croix. I'm very comfortable there and have done solo dives day/night to about 60 feet with a single tank. For me, they were always relaxing, comfortable and enjoyable. If an OOA situation occurred, I would go straight up. I was OK with that at 60 feet, but my average depth was usually 30ish. In tose warm waters, I was diving with 2 knives and a pair of EMS shears (tons of fishing line off that pier) and always with two masks, and two lights. In that environment, I was comfortable with that set up.

In another setting, high altitude cold water fresh lake diving, I was diving to 53 feet but never would have gotten in the water without my extra stage in tow in conjunction with other typical redundant gear. It's cold, and the physiological demands of higher altitude and colder water make an OOA ascent more dangerous in my mind. I'm uncomfortable NOT having that redundant air source. I imagine most places I dive or plan to dive will mandate a redundant air source - even when diving with buddies, I've begun using a slung staged bottle because I can. And I don't trust my buddies (or what I mean is, I don't depend on my buddies). No one should - I think that's the basic tenet of SOLO diving.

 

Respectfully, I don't think using Quero's case as a redundant air source error is any more valid than using Lynne's as a knock against the buddy system. Other factors involved.

Boulderjohn makes a good argument but one could ask why starting an ascent with so little reserve in the main tank, thus leaving no room for dealing with one failure (entanglement).

Gas supply is a holistic system that involves equipment, experience and planning. People in these discussions like to focus on the equipment (a redundant air source) as the catch all but I also see it as a false security if you don't have the other two figured out. I know people who go solo diving "always with their ponies" who really have no sense of conservative gas management, one I don't even buddy with because they always push the limits.

Sometimes I do use a redundant source, sometimes I don't. What I do though is think about the dive, when I will turn it and surface with enough gas, where the surface is and how I will access it throughout the dive etc... That's the agenda I follow.

To me entanglement is not a redundancy issue (except for a cutting tool - ever drop one when you're nervous?). That is a conservative main tank reserve issue. Another OOA diver? That's a donatable second stage issue. An AAS is a catastrophic failure of the main supply issue. Whether I carry one depends on how I think I want to deal with that failure on the dive and that depends on the parameters of the dive.

But that's just me. Solo diving is, by its nature, a solo pursuit. Anyone doing so has to "own" their actions and not put that responsibility on to what a course, forum or book says. You may agree with them and adopt something but in the end it will be your choice and no one else's.