Spare Air

[TheRedHead]

That's a great skill and such a mental thing. I had to swim 65 feet OOA to my buddy for a class and thought I would die, even though I can hold my breath for over 2 minutes.

 

[teknitroxdiver]

I'm not, all I'm suggesting is that a minute and a half would give you enough time to get your buddy's attention and begin an orderly, dependent, ascent. That's the same amount of time that a spare air would provide at 130. And I'd teach you for less that half of the $193.90 plus shipping that ScubaToys gets for the spare-air.<G>


Added on Edit: Now that I think about it, why not? For the sake of what we are discussing here (Spare-Air) it strikes me that a CESA is an equally viable alternative.

Really, if you choose the spare air, your ascent will become a CESA well before you reach the surface!

 

[Thalassamania]

Like everything else worthwhile it takes a little training, a lot of practice and continued drill.

But it's a double-edged sword. This ability means that prior to every dive I must spend five to ten minutes doing breathing exercises, but that puts my head in a good place for the dive anyway and gives me time to previsualize every little thing.

 

[TheRedHead]

Thal, you should offer a seminar on some of these skills. That's how the kool-aid gang started with rec divers. And keep it a seminar with no cards issued.

 

[Thalassamania]

That's because the spare-air is BS and why the "average diver" needs a better alternative. But, as usual there's more than one way to skin a cat.

 

[DivingDoc]

I have the 3 cu ft one, but have never tried to ascend from depth with one. The only time I used it was to extend my last dive of the week. I didn't time it, though, or count the breaths. It was an easy way to empty it for the trip home. It does breathe hard.

I also have a 13 cu ft pony, but I hate the extra set-up time and the extra weight of the pony plus regulator, so I try to reserve it for deeper dives. I always bring both with me for a week of diving. I just haven't decided where my cut-off point is for what depth to use the pony rather than the spare air. I'm thinking 80.

The owner of a local dive shop claims he succesfully made an ascent from 130 using only the Spare Air, but of course he didn't make a safety stop or ascent at 30 fps.

What's a SAC rate and how do you calculate it?

 

[Halthron]

That's because the spare-air is BS and why the "average diver" needs a better alternative. But, as usual there's more than one way to skin a cat.

But, the average diver wants instant gratification that fills all of their "needs". SpareAir gives them the comfort necessary not to think. Never mind that there are people using it who no doubt push their NDL to the limit. Add out of shape and hung over to no deco stops and it's a chamber ride waiting to happen.

 

[Thalassamania]

Tell him that's very nice but you'd rather not make your emergency ascents at +70FPM.

Surface Air Consumption rate. Go down to a known depth and breath for a known time (longer is better) and record your starting pressure and ending pressure. Now you can calculate how many cubic feet you use per unit time and you can adjust it to one ATM.

 

[redacted]

What's a SAC rate and how do you calculate it?

Surface Air Consumption expressed as a rate in cu ft per minute. Some AI computers calculate it. Otherwise, you can calculate the amount of air consumed during a dive base on tank capacity and start and end pressures; and divide that by your average depth in atmospheres and then by your dive time in minutes. The more square your profile, the more accurate your average depth estimate should be.

Next time you find yourself having to use your spare air to extend your dive, consider golf Although draining that spare air as part of your rest stop is reasonable

 

[DivingDoc]

Awww -- c'mon, there must be some out there who wish to argue FOR Spare Airs -- I want to hear both sides of the argument.

I have an Oceanic VT pro AI computer -- does anyone know if that one calculates SAC?

BTW, how does one upload photos to one's gallery?