Ojai Diver:
I really don’t think the reaction is quite as extreme as mentioned, or the message that focused, although I agree that there is a strongly stated preference among a number of SB users for bottles larger than 13 cf – certainly larger than a 3cf Spare Air, or a 6 cf Jumbo Spare Air (not a brand, just a description
).One way of summarizing the different views might be to suggest it involves the perceived difference between an EMERGENCY air supply, and a redundant air supply. An emergency air supply provides some air, of whatever quantity, when you are OOA and have no hope of getting to the surface without something / anything. It allows you to (attempt to) make an emergency exit from a life-threatening situation. A redundant air supply is also an emergency air supply, but it is one which (temporarily) replaces your primary air supply if it ceases to function, and allows you to make an exit from that life-threatening situation without undue stress and with a minimum of confusion – i.e. you complete a dive in a orderly, safe manner – irrespective of depth, etc. It does that by providing you with (more) gas supply, which provides you with (more) time. Two approaches, on the same continuum.
If I am diving to 100 ft+, I know from calculating my gas requirements to get to the surface, that a 13 cf bottle will not allow me to make a safe, orderly ascent – I base my calculation on taking a full minute at depth to switch to my redundant air supply, and see if I can figure out what is wrong, then 3 minutes for an ascent to 15 feet, then 3 minutes for a safety stop (since I am ascending from deeper than 100 ft). Yes, I could ‘blow and go’ from 100+ft, using a 6 cf bottle, but I would not be doing so in a safe, orderly manner, without undue stress, and with a minimum of confusion. If I am diving to 50 ft, the amount of redundant gas needed changes. But, another factor that may be at play in these threads is the preference of some divers not to accumulate an assortment of pony bottles. I prefer a 30 cf or 40 cf for my redundant air supply – I have several of each. I am used to diving them, and can do so under a variety of conditions - I don't even notice they are there. But, I also have a 6cf, and a 13 cf – the former is my drysuit inflator bottle and never used as a pony, and the latter, bought before I understood the concept of redundancy, is used in my Gas Blender class to teach oxygen cleaning techniques. It is like a hanger queen airplane, and doesn’t dive any more. Other than that, my 30s and 40s are – for me – appropriate redundant air supplies (and appropriate deco bottles as well).
If a 13 works for you, fine. If a 3, or a 6, works for you, that is fine. It is your choice. If a larger bottle is inconvenient for your style of diving, that is also your choice. If the OP wants to spend $319 for the unit he asked about, that is entirely up to him. He asked, ‘What do you guys think?’, and quite a few users replied that they thought that a 6 cf bottle was not particularly useful (I was one of those).
As for rec divers who go in the water without either an emergency or a redundant air supply: I don’t think they are necessarily mad. The probability of a diver going OOA on any given dive is VERY (very, very, very) low. Yet, ‘gas supply problems’ continues to be the most frequently cited contributor to scuba-related fatalities, according to DAN, with ‘emergency ascents’ being the second leading contributor. I admit, I don’t carry a redundant gas supply when diving to 50 ft on Bonaire reefs. So, if that is the kind of diving you do, it is not altogether surprising that you don’t see others with a pony. AND, a 13 cf supply is probably appropriate. But, I think that divers who go to 100 ft+, with a single cylinder and no emergency or redundant air supply are presuming that a) an OOA situation won’t develop, and b) even if it does they will have their buddy’s air supply to help them make that emergency exit from that life-threatening, OOA situation (even though they may not have practiced an alternate air ascent since their initial OW training). I think that is possibly naïve, not mad. But, it is their choice. Personally, I prefer to be more self-reliant than that. I love buddy diving and group diving. I am more often than not in a situation where – if I do go OOA – I could swim to my buddy, or another diver, for assistance. I simply choose NOT to make that my primary option for exiting the life-threatening situation. I am not judging others who choose a different approach. I am merely stating what I think, and what I do and why.
I don’t think the thread is tedious at all. The OP asked a legitimate question. And, received answers that reflect the broad base of experience that characterizes the SB user community.
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