Why extra air when solo?

[rhwestfall]

The right one for the job

One is none and two is one.

I hope you both understand it was a rhetorical question...

 

[dead dog]

Diving solo means no buddy who has an independent gas supply. So you bring your own. Separate tank, first stage and second stage. Which you will not need in your planning. Just in case the sh#t hits the fan.

I agree and a pony tank is your buddy.

 

[Bob DBF]

It depends on if, and to what depth, you consider the surface a redundant air source.


Bob

 

[johndiver999]

I would NOT use a pony bottle for that kind of diving. You are much more likely to get hurt by the weight of the pony than helped by the redundant air.

I honestly think the most dangerous part of diving off slippery rocks from shore (especially when you are alone) is due to falling on the descent or getting hurt while trying to get into the water or even out of the water when you are cold and tired. In those conditions, the weight of a pony bottle - even a small one is a detriment to your safety.

Getting from 30 feet to the surface in the unlikely event of a problem should not be too challenging.

 

[tursiops]

I gather that for people taking a solo course, the official equipment standard is to have a pony bottle or some such thing. My question is: why? And it's a serious question, I really don't get it.

My own experience a long time ago when I first certified inland and then went home to the NW coast on break from school and wanted to see the subtidal instead of just the intertidal was that if I wanted to see it, I'd best go when the going was good and that meant going on my own. Off a nice sloping rock shelf into nearly flat water on an unusually clear day, one of the days that are very few and far between there. I don't know where I'd have found a buddy. Since I was around 10 to 20 feet, maybe 30 feet deep tops, I figured that if I got into trouble at 10 to 20 feet, I could blow and go quicker than I could either try to find and get to a buddy if I had one, or fix the problem where I was. Now that I'm getting back into diving regularly, and my favorite place to travel to will be those same remote rocky shores, I thought about formally training in solo, but I'm not enthused about having to buy more big and heavy gear. So, why do I need a pony bottle when diving at 10-30 feet? Specifically, if my regulator fails, I have a second. If that fails too, then that would be sad. But how likely is that in real life? If both of them weren't getting air, that would probably mean my first stage had to have failed (unless, I suppose, I was stupid enough to run out of air). Are first stages prone to failure?

Is the whole logic behind the extra air source that someone might run out of air in their cylinder, or is there some other reason?

You really DO need a good Solo course so you can avoid assuming that you already know everything and have thought everything through.

 

[2airishuman]

You ask several questions.

I So, why do I need a pony bottle when diving at 10-30 feet?

It is my understanding that all solo diving classes teach that you must have redundant air of some kind when diving solo, regardless of depth.

Actual practice varies among divers. I typically do not carry redundant air unless I am diving below 30 feet, or there are other risk factors, such as entanglement potential or boat traffic. That doesn't mean that I recommend it for anyone else. As with all things in solo diving, you have to decide for yourself.

I do carry redundant gas at greater depths. Typically I use a twinset, but I have a pony bottle also.

Specifically, if my regulator fails, I have a second. If that fails too, then that would be sad. But how likely is that in real life? If both of them weren't getting air, that would probably mean my first stage had to have failed (unless, I suppose, I was stupid enough to run out of air). Are first stages prone to failure?

Cylinder, valve, and first stage failures are rare on shallow dives in warmer water (60F up, where freezeup isn't a factor). Nonetheless, they do happen, There have been several reports discussed on SB over the last few years:

1. One individual had a clogged dip tube in his cylinder valve.
2. There have been reports of burst discs failing during a dive.
3. There have been reports of o-rings extruding during a dive, though as far as I know these all involved yoke valve-to-regulator connections.
4. There have been 1st stage diaphragms that have pulled out from their retaining ring leading to a rapid loss of gas
   
5. There have been 1st stage seat delaminations leading to an abrupt loss of air delivery with no advance warning
   
6. There have been examples of SPGs sticking and indicating a sufficient amount of air to continue the dive, when the cylinder was in fact empty.
7. There have been hoses that have clogged due to internal deterioration.

None of these are common, and careful maintenance can reduce the odds.

Second stage failures are more common. Freeflows happen, diaphragms rip, mouthpieces come off, levers break.

Is the whole logic behind the extra air source that someone might run out of air in their cylinder, or is there some other reason?

The rationale for bringing redundant air covers all possible failures, including gas planning/SPG monitoring failures as well as mechanical failures of the air delivery system.

 

[NAUI Wowie]

I would NOT use a pony bottle for that kind of diving. You are much more likely to get hurt by the weight of the pony than helped by the redundant air.

I honestly think the most dangerous part of diving off slippery rocks from shore (especially when you are alone) is due to falling on the descent or getting hurt while trying to get into the water or even out of the water when you are cold and tired. In those conditions, the weight of a pony bottle - even a small one is a detriment to your safety.

Getting from 30 feet to the surface in the unlikely event of a problem should not be too challenging.

weight of the pony bottle will hurt you? I carry a 19cf but you can carry a 13 or even a 6cf. For the o.p. You say you go to 30 ft but maybe you go to 50 now and then. Maybe not.

All in all maybe a pony isnt for you o.p. but for most of us that travel and always dive with strangers and in strange foreign lands and do wrecks in these places a pony is pure awesomeness.

For me personally if I were you and i have been underwater at 30ish feet for an hour or more id not want to cesa when carrying a small pony will get me to the surface just fine.

whats it gonna hurt to carry insurance on your life? What if you get entangled in something and try to rip free and lose your air and are still entangled? for northern east coast divers in the usa that can be a huge issue. a couple seconds of no air and brain panic haze descends on you bad things can happen even at 30 ft. A pony prevents immediate panic.

at 30 ft is it needed? well that also depends on your age and health. are you over 60? over 70? overweight? , didnt sleep the night before?, dehydrated forgot to drink water before dive? heck combine all the above on a one hour long dive and cesa from 30 maybe just maybe you get some amount of dcs. Id rather get no dcs at all than have to deal with skin bends etc

I dont know but what I do know is that I always no matter what carry my 19cf pony even on a cake walk 50ft deep tame reef drift dive.

at least i wont have to cesa. Let someone else take that risk.

 

[AfterDark]

It's not extra air... it's insurance, a fire extinguisher, a spare tire, a parachute, a carry gun. All things we have that we hope never to use, but are better to have and not need them than to need and not have.

 

[doctormike]

I think that you should ALWAYS be able to do a safe, normal ascent as plan B. Which means that if you use the surface as your alternative gas supply (i.e. CESA), you are ruling that out in case of catastrophic gas loss (e.g. blown LP hose or unstoppable free flow, late in the dive). To answer one of the OP's questions - those are probably more likely than a first stage failure. CESA involves unnecessary decompression stress. Why rely on it if you don't have to?

Now you can reduce this argument to trivialities ("what about 20 feet, what about 10 feet, what about two feet?"), but for the purposes of a general answer, if you are solo diving you should have an alternate gas source.

Note that if you are diving solo and have a pony bottle, you don't need two second stages on your back gas regulator. You should get rid of that potential failure point.

 

[Ana]

I gather that for people taking a solo course, the official equipment standard is to have a pony bottle or some such thing. My question is: why? And it's a serious question, I really don't get it.

If you're going to take a solo course you have to follow their rules, having redundancy for air supply has no room for discussion.
Most likely no one will actually listen to your reasoning for not having it. Polite people will wait until your lips stop moving and then present you a list of what ifs. Less polite people will roll their eyes and post here on a different thread about this idiot that wants to dive solo without redundancy.

So you can do many things: Maybe take the course and learn with rental redundancy and afterwards if you think what they say has merit go buy your redundant gear.
Or you could figure other way to learn without hard requirements for particular gear. Or maybe throw caution in the wind and just figure things out as you go.

Whatever you decide make sure you accept your responsibility for your own actions, even if you do what you're told you are responsible for yourself.