Switching gasses at depth?

[JeffG]

So you guys really think the 3.0cf Spare Air is absolutely useless at depths shallower than 100ft?

Yep..

 

[Sonic04GT]

I think I'm gonna go ahead and return it then. It's probably still in the box. I'm in Iraq so I had it mailed home. Been gettin kinda carried away completing my kit while I've been over here. Just need a tank now, which I've already decided on, just waiting on a good price since I won't be home till later this year.

Later on I may look into like a 30cf pony and something cheap but reliable like one of the Oceanic regs.

Did one of you guys mention an octo also for the pony tank, or were you referring to the primary rig?

 

[rstofer]

So you guys really think the 3.0cf (50 breaths at surface) Spare Air is absolutely useless at depths shallower than 100ft and to just trust your buddy solely? Call me a rookie and maybe I don't know what I'm talking about but when I dive I like to relax and move freely, not pull along a 40cf pony tank. Sure it's pretty much weightless and can be mounted to your primary tank but do you have to buy another 1st/2nd stage for it also don't you? Sounds like it could get pretty expensive.

Got it for like $190 shipped from ScubaToys and I could probably still return it for a full refund at the cost of shipping it back.

It could be that a 19 cf pony would be adequate. They are a good deal lighter and are often slung from the D rings (hip and left chest) of a harness (think BP/W). Mounting it to the main tank in a non-removable manner would seem risky. Besides, it enhances the probability of entanglement).

I think I have stated (and been criticized for stating) that you should have a backup plan that doesn't involve your buddy. A completely separate pony bottle seems like a very good start.

Consider just a moment the OOA (Out Of Air) possibility. If you are low on air, so is your buddy. At least YOU would have a backup plan if you slung a pony bottle. Now, I know there is no excuse in the world for running out of air but I'm just saying... Have a plan! You could be OOA because you have used up your air solving some other problem (entrapment, entanglement, gear failure, blown o-ring, regulator free flow, regulator freezing, etc.).

BTW, if 19 cf is good for you and you have any concern for your buddy, maybe something a little larger would be good. Better still: both of you should have a pony.

Of course, this whole issue goes away if you are just diving to 30'. Anybody can do a screaming ascent from 30'. It's when you go below around 60' that you might want to think about this stuff and it gets real important around 100' or below. It's amazing how fast that pressure gauge drops at 100'.

Richard

 

[Reg Braithwaite]

I think I have stated (and been criticized for stating) that you should have a backup plan that doesn't involve your buddy. A completely separate pony bottle seems like a very good start.

To make my feelings perfectly plain, I agree with the statement there are a large number of circumstances under which a prudent diver should dive with a self-rescue plan. I also agree with the statement given the correct training, mind set, and buddy selection, there are a large number of circumstances under which a diver can safely rely on the team for rescue.

I think it is possible for reasonable people to believe both statements at once.

 

[Sonic04GT]

ScubaToys.com said they would take it back and issue a full refund.

Ironically I was just browsing through the Dec 2008 issue of Scuba Diving Magazine and the Spare Air is actually under "The Best of 2008" and listed as "Prior Year Favorite."

 

[String]

Just shows not to believe a thing you read in magazines. Especially as all of them rely on advertising revenue to survive.

 

[String]

So you guys really think the 3.0cf (50 breaths at surface) Spare Air is absolutely useless at depths shallower than 100ft

Yes. Its handy if your helicopter crashes and overturns in 5ft of water (which is what it was designed for) but thats it.

and to just trust your buddy solely?

Completely the opposite. Take redundant gas for the dive but make sure you take the RIGHT AMOUNT to get you out of trouble. Spare air is the worst of both worlds - it makes the diver think they're redundant when in reality they arent.

Got it for like $190 shipped from ScubaToys and I could probably still return it for a full refund at the cost of shipping it back.

Can get a proper sized pony and regs for that.

Edit:- Probably worth adding this bit here:

Remember these figures are based on 25slm air comsumption - in a stressed situation such as running out of gas it can hit 2-3x that so those times can be halved or more.

 

[tna9001]

Spare Air 3.0 at full charge = 80 cf tank at 113psi :shocked2:

 

[Sonic04GT]

Haha I could get to the surface in a minute, maybe not exactly safely.

Arranging to have it returned. Should be in the mail in a couple days.

 

[ZenDiver.3D]

redundancy.... nevermind