Zeagle question for Scott and others

[MrConclusion]

Jettyrat, ask your instructor to prove his/her math. I know that the spare air is hated by some, but the point is that it's SPARE air. As in, "a lot better than nothing."

If you could only get 2-3 breaths off a spare air at 80 feet, then that means you'd only be getting 53-80 breaths off of a full-sized 3000psi aluminum 80 tank, and this demonstrably isn't the case!

At 80 feet (from which, for some insane reason, you aren't immediately ascending) the Spare Air (3 cu/ft @ 3000 psi) will supply about 1.2 cubic feet (about 39 liters) of air. The "Average Person" has a lung capacity of about 4 liters. So... they'd get almost 10 breaths. Even with 6 liter lung capacity you get more than 6 breaths.

The real point to remember is that your first breath or two may be taken at 80 feet, but then you're immediately ascending - and using less air each breath. Sure, you're going to blow off the recommended safety stop, but you aren't using a Spare Air for dives requiring deco or in overhead environments.

 

[lackingcreativity]

Can we avoid starting this again. If you like it fine, if you don't fine. In the end you, and only you, decides what to use.

 

[jettyrat21]

Mr C, even ten breaths at 80 ft. is alot less than the 50 advertised. A gallon milkjug on a cindrblock will give you more air than a spare air at depth. It's better than nothing, right? As a newbies my wife and I were taken in by the spare air ad that is at best missleading. I was just trying to help some other newbies avoid my mistakes. Also, I am new to this forum and was not aware of any debate on this issue. This is just my opinion and should be taken for what it's worth.
Back to lurk mode.

 

[m7scuba]

Mr C, even ten breaths at 80 ft. is alot less than the 50 advertised.

Just a clarification... the Spare Air 300 (3.0 cf) is advertised to provide 57 breaths at the surface.

 

[scubatoys]

Hate to come out and correct when you are relatively new here.... but this line is again, not true if you do the math.

Mr C, even ten breaths at 80 ft. is alot less than the 50 advertised. A gallon milkjug on a cindrblock will give you more air than a spare air at depth.

A Gallon is approx 1/8 of a cubic foot. If you refill the gallon milk jug at 80 feet, that would then be 3.42 atm of pressure, so you would have a volume of .427 cubic feet of surface air, or .125 of air at depth. A 3 cubic foot spare air would have 3 cubic feet of surface air, or slighly less than 1 cubic foot at 80 feet. So approx 6 times the air supply of a milk jug. Based on average breathing, that is going to be approx 1 minute of air at that depth, or if ascending while using it, approx 3 minutes.

I've taken a 1.7 cubic ft from 130 to the surface... in a non emergency testing situation. Is carrying 6 cubic foot better..., 13, 19, maybe a 30, 40, 50, how about another 80, a spare steel 130? Why not 3 or 4 of them?!

Sure... More is probably better, but if it's too much hassle, and folks don't carry it... the most useless safety equipment is the stuff that stays in the closet because it's too bulky to wear. If given the choice of 3 extra cubic feet or nothing... I'll take 3.

Besides... his original question was where to mount it on the BC... not should he get one.

 

[jettyrat21]

Larry, your right and I appologize for hijacking the thread. I guess the answer to the question is that he should mount it on his mask instead of a snorkle as you get 57 breaths at the surface.
Seriously Larry, do you carry a spare air?

 

[scubatoys]

Larry, your right and I appologize for hijacking the thread. I guess the answer to the question is that he should mount it on his mask instead of a snorkle as you get 57 breaths at the surface.
Seriously Larry, do you carry a spare air?

Seriously yes... In most the traveling I do, carrying a pony setup would be virtually impossible. A spare air will give me my 10 - 20 breaths... and that can get me up from any depth. So I know I'll get tossed off the board, but I use split fins... Have a bio filter on my reg, and yes... carry a spare air. Go figure eh?