Spare Air on deep but no deco dives??

[doctormike]

Even if a diver does run a bit short, he or she can still safely make it to the surface on that last breath, which can easily last a minute or more. I know I can hold a breath and swim the complete length of a 40' inground pool underwater and back again- without surfacing. I can surely make it to the surface even if I deplete my air supply before I completely get there, I'm not just going to take a last breath in say, 20-30' and think "I'm a goner.. and I was sooooo close".

What do you mean by "make it safely to the surface"...? Do you think that the safety stop and a slow ascent is of no benefit? Not being facetious, but if there is no reason for doing it, then why do we do it?

And if there is a reason for doing a safety stop and a slow ascent, why would you put together a gear configuration and dive plan that wouldn't let you do that in an emergency?

Do you see my point? I can sort of see the argument for no redundancy on dives with no physical or virtual overhead - you basically have decided that you will just CESA if you have a catastrophic gas failure. Even though there is a risk of DCI, the chance of needing to do that is so remote that you decide not to bother with the expense and annual maintenance of a redundant gas supply of any kind.

On the other hand, buying a Spare Air means that you DO want to have more safety than just relying on CESA, and that you DO feel that the chance of being OOG is not insignificant. But now you have the worst of both worlds. You have the cost and yearly maintenance of an alternative gas supply, but you went out of your way to choose one that MIGHT be able to get you to the surface if you blow off the safety stop and just CESA for the last 20 feet anyway.

 

[doctormike]

One more thing. Those of you who precisely calculate how much gas you need for an emergency ascent and conclude that the 3 CUF of the Spare Air is adequate, read this article.

Any second stage can free flow, or the purge button can be hit inadvertently.

A free flowing reg at 99 feet will empty a full AL80 with 3000 PSI, in 155 seconds. 3 CUF will be gone in less than six seconds. I'm sure that the designers of the Spare Air made it relatively hard to free flow by detuning it a bit (at least according to reviews). But it's still got a second stage and a purge valve, from what I can tell.

Be careful.

 

[Steve_C]

1. I like to dive. I have some reliable buddies but at least 50% of my dives are with instabuddies. I try to be a big buddy but in fact the instabuddies are often not what I would most want in an emergency. If it is boat dive deeper than 40 ft I am usually in a solo configuration.

2. Tank hanging below the boat? That may be common in some places but I have 500 dives in Florida, NC, SC, Caymans, Greece, Hawaii, Vancouver, California and some other places. About half are boat dives. I have never seen a tank hanging below the boat.

 

[stevensamler]

Wow I looked away last night and went to dinner with my wife for our anniversary and came back to this amazing discussion!! OK, so thanks everyone very much for all the great input.

I have at least two major takeaways: First, I do agree and think that if I ran out of air at 120 feet or so and couldn't find my buddy or anyone else to grab their octo (I don't dive alone, always in a group), I would NOT be making a controlled ascent and I would NOT be doing a safety stop. I would drop my weights and shoot to the surface as fast as I could, recognizing that I'm likely to get bent. But better bent than DEAD, right? So, as more than a few in this discussion have noted, in that scenario, the Spare Air 3 would be worlds better than nothing, right?

But, second, I've got more than a 100 dives in 2.5 years, all over the Caribbean, and repeatedly in Cozumel and Grand and Little Cayman, and I've never seen anyone with a Spare Air or, for that matter, a pony bottle (as so many have suggested). Yes, I know, 100 plus dives is not that many, but, for example, in Little Cayman I've dived with people with many hundreds of dives (with Reef Divers (excellent excellent outfit, as you probably know)) and no one has ever had a pony or Spare Air.

The issue for me is that I love to go deep, and am usually the deepest one on most dives. My buddy is sometimes 20 feet above me and maybe 20 feet away horizontally, so if a hose burst or an O-ring blew out, etc., I might have to swim hard and fast to him (or another diver). Having said that, I'm in great shape and can swim very fast; I can hold my breath for a long time (yes, I know, I would not hold my breath while ascendiing); and I've invested a lot in very high quality equipment and think the chance of regulator or hose failure is quite remote. Still, I wonder....

I just don't get why I've never seen anyone with either a Spare Air or a pony??

If you love deep diving you should be team diving and diving doubles. If your teammate is 20' above you or 20' away you're out of gas anyway.

 

[wetb4igetinthewater]

One more thing. Those of you who precisely calculate how much gas you need for an emergency ascent and conclude that the 3 CUF of the Spare Air is adequate, read this article.

Any second stage can free flow, or the purge button can be hit inadvertently.

A free flowing reg at 99 feet will empty a full AL80 with 3000 PSI, in 155 seconds. 3 CUF will be gone in less than six seconds. I'm sure that the designers of the Spare Air made it relatively hard to free flow by detuning it a bit (at least according to reviews). But it's still got a second stage and a purge valve, from what I can tell.

Be careful.

My understanding is that SpareAir was intended for helicopter pilots who crash in the water. It is perfect for that. Then some marketing yahoo (my theory) decided to market it to scuba divers.

If you start calculating the ascent rate required based on different gas consumption rates at different depths, it gets pretty ridiculous pretty fast. Sure it can get you close to the surface. But the point is, it is just inadequate in my opinion to be taken seriously and not mocked.

 

[BDSC]

My understanding is that SpareAir was intended for helicopter pilots who crash in the water. It is perfect for that. Then some marketing yahoo (my theory) decided to market it to scuba divers.

You have it all wrong.

 

[Colliam7]

You have it all wrong.

Apparently so, based on the interview with the designer that Bob linked.

I am impressed that this idea has gained the traction that it has - I certainly was under that mis-impression, and have been for some time. Now, I wonder if such military uses have been adapted, or if there is simply no substance to the rumor at all.

 

[BDSC]

Now, I wonder if such military uses have been adapted, or if there is simply no substance to the rumor at all.

So I found this from an article back in 1987:

Late in 1986, Spare Air (which the military calls HEED II, for Helicopter Emergency Egress Device, Type Two) was approved, and Williamson got an initial order for 8,200 tanks, at $195 per canister. The prospect of a $1 million gross delights him, but Williamson says his best reward still comes from fellow scuba divers when they stop by to say, “You know, this is the greatest thing in the world. It saved my life.”

Have no idea if he still does business with the military but at one time he did.

 

[Marie13]

1. I like to dive. I have some reliable buddies but at least 50% of my dives are with instabuddies. I try to be a big buddy but in fact the instabuddies are often not what I would most want in an emergency. If it is boat dive deeper than 40 ft I am usually in a solo configuration.

When I hit Lake Michigan, it’s a toss up if I’ll be diving with someone I know. I’ll carry a pony on any dive deeper than 40ft myself.

 

[Bob DBF]

At one time, I believe Spare Air marketed along the lines of "if it good enough for the military", or something like that. With divers today that is not nessary.


Bob