Stage bottles

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Scuba446

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Can someone give me an instance in where and how STAGE bottles are used?

I am a new OW diver and am interested (eventually) in deeper wreck diving.

At what depth(s) and conditions would one need to warrant a 40 cu in stage bottle?
 
A 40 cu inch stage bottle? :) Spare Air isn't a stage bottle! :D (I know, it was a typo).

Stage cylinders are for extended diving - 80cf aluminum tanks are a popular choice. A diver would use stage cylinders in conjunction with back mounted double tanks, often breathing the gas in the stages before breathing the gas on their back. Think long cave penetrations with scooters, or deep extended dives.

40 cubic foot cylinders (which I guess is what you mean :) ) are more commonly used as deco bottles, holding generally nitrox, or two, holding nitrox and oxygen. EAN50 is a common deco mix, EAN80 has also been used extensively. And of course some people use them as bailout or pony bottles.
 
Yes,
My LDS that has a GUE/DIR Instructor said to get a 40 cu in bottle instead of any pony's..
 
The terms stage bottle and deco bottle are often, although technically incorrectly, used interchangably. I call my deco bottles stages as do most folks I know. Ben is right about the terms though, his description of a "stage" is the most proper.

40 cf is the correct size for most uses. If carrying only one it should be 100% O2, if carrying 2, they should be 100% and 50%.

I personally carry at least one on any deco dive, 2 on serious dives although carrying 2 is a PITA.

With all that said the use of stages and/or of O2/50% require additional training beyond recreational training. There's a distinct possiblity of killing yourself if you breath O2 or 50% at too great a depth.

If you feel you need a "pony bottle" I still recommend the aluminum 40 (Luxfer version) , stage rigged, not attached to your back, but filled with the same gas as your main tank(s).

Tom
 
Originally posted by WreckWriter
If you feel you need a "pony bottle" I still recommend the aluminum 40 (Luxfer version) , stage rigged, not attached to your back, but filled with the same gas as your main tank(s).

Tom

Tom,

What is the reasoning behind a 40 cf pony? Is such a pony to be used as additional air or a bailout? Keeping in mind that additional mass requires more effort to move, isn't 40 cf excessive for a bailout?

Here is the calculation that I came up with base on no overhead dives to no greater than 100 fsw..

Problem occurs:

2 minutes at 99 fsw to sort out problem with surface rate of 1.2 cfm = 9.6 cubic feet
Ascent from 99 fsw to 15 fsw at 30 ft/min with surface rate of 1 cfm = 7.6 cubic feet
3 min Safety stop 15 fsw with surface rate of 1 cfm = 4.4 cubic feet
Ascent to surface from 15 fsw at 30 ft/min with surface rate of 1 cfm = 22.2 cubic feet

The surface air consumption rates are probably conservative since my dives have been averaging a surface equivalent rate of 0.6 cfm, but there is potentially a high level of stress based on the fact that a problem exists resulting in the need for a bailout bottle.

The one thing that the calculation clearly shows is that a 3.0 cf Spare Air is a waste of money and potentially dangerous in that it promotes a false sense of security.

Any insight would be appreciated.

Mike
 
Originally posted by MikeS

Tom,
What is the reasoning behind a 40 cf pony? Is such a pony to be used as additional air or a bailout? Keeping in mind that additional mass requires more effort to move, isn't 40 cf excessive for a bailout?

A pony is for bailout. I don't personally like them, I prefer doubles with an isolation manifold but IF one must use a pony....

My primary reasoning is to get a bottle which will continue to be useful when/if the diver progresses to technical diving. Also, that extra gas might save your buddy's life.

Actually, when rigged correctly, a 40 cf stage produces very little drag, much less than a smaller pony tank mounted would produce.

Yes, spare air is useless.

Tom
 
Originally posted by MikeS
What is the reasoning behind a 40 cf pony? Is such a pony to be used as additional air or a bailout? Keeping in mind that additional mass requires more effort to move, isn't 40 cf excessive for a bailout?
Neither, let me restate what bengiddins and WW have said.

We have a tendency to use term “stage” incorrectly so let me be formal for the rest of this note...

A 40cf makes an excellent DECO bottle. For either pure O2 or in some cases (read: ocean) even for 50/50 because your gas consumption is low given the shallow depth.

A STAGE bottle is used for extending your dive, so I can’t think of any reason that you’d want a stage smaller than an AL80, why bother? Traditionally in caving you’d breathe a stage to 1/2 - 500, drop it, breathe the next stage to the same point, drop it, go to your back gas, breathe 1/3, turn the dive. On the way out you’d pick up the second stage you dropped and start breathing that, then the first stage and then you’re out.

Nowadays it sounds like the WKPP is starting to dive stages only and saving their back gas for emergencies.

You’re right, a 40 may be too big for a pony, but if you think that someday you might see the light :) go with a 40 cf pony and later you can turn it into your O2 or 50/50 bottle without further investment.

Roak
 
1/2 - 500?
 
I was thinking of going with a 40 and using it as a pony for now, sicne non of us dive twins or H-valves - and it might be good medicine for shipwrecks deeper than 60 ft, but not more than 100 ft.
 
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