Why extra air when solo?

[johndiver999]

The topic has drifted quite a ways from "why do I need a pony when diving solo at an average depth of 5 meters" .

However the issue of a diver confusing the back mounted pony regulator with a primary regulator or octopus regulator is a serious consideration. As mentioned, it has killed people in the past - yet some seem to be skeptical or dismissive of the potential problem. It is a serious consideration - especially if a diver does not recognize the potential problem before the dive!

Carrying three second stages and the increased chance of freeflow, confusion and failure needs to be offset by enhanced utility or safety. Choose carefully.

 

[Zef]

The topic has drifted quite a ways from "why do I need a pony when diving solo at an average depth of 5 meters" .

However the issue of a diver confusing the back mounted pony regulator with a primary regulator or octopus regulator is a serious consideration. As mentioned, it has killed people in the past - yet some seem to be skeptical or dismissive of the potential problem. It is a serious consideration - especially if a diver does not recognize the potential problem before the dive!

Carrying three second stages and the increased chance of freeflow, confusion and failure needs to be offset by enhanced utility or safety. Choose carefully.

It should be noted that in all these cases it is not the configuration that is the problem it is the diver.

The first citation discussed a diver who died because he breathed his pony bottle down, yet his back gas valve was open, determined from the sentence indicating that the back gas tank was not full due to the diver inflating his drysuit. If the diver breathed his pony bottle dry without realizing he was using his pony bottle then the simple thing to do would be to just switch to a different 2nd stage. Even with 3 2nd stages hanging off oneself one should be able to cycle through them fairly quick to find the one that works to correct the mistake of not being on the one connected to the back gas supply in the first place.

If having too many 2nd stages with one on a dive is a concern then those diving with stage bottles and multiple sidemount cylinders are all in grave peril...how on earth will they be able to manage this...oh yeah thats right, they are expected to think about their configuration, be intimately familiar with it, and have a checklist to ensure things are setup properly. If one is solo diving that is just as or even more important.

Just because someone dies using a particular configuration does not mean that configuration in and of itself presents an inherent danger.

During a pre-dive check, a diver should be checking that each of his 2nd stages is operational, if the back gas is shut off it will be clear if the op-check is performed properly. And if this is a solo diver there is no dive buddy to mistakenly shut the valve off. This op-check will show the gas supply is off even if the hose was charged and the valve subsequently closed. 2-3 breaths while watching the spg, one will see the needle move if a gas supply is turned off.

Diving, like other general high risk activities such as rock climbing, sky diving, etc, are very punishing to those who engage without thinking. It is incumbent on the participant to ensure they do not fall victim to their cognitive bias, as the punishment for this is often injury or death.

Stay safe or stay in bed.

-Z

 

[caruso]

I've been diving solo off my own boat for the past 2 summers to depths of about 45'. There's an occasional boat here and there but for all practical purposes boat traffic can be considered nonexistant.

I've stopped bringing my 19cf bottle on dives. Just too much gear to carry and assemble on my 18 ft center console. I might dive a bit more conservatively, keep a bit more reserve in my tank, and although I'm diving wrecks they're not the type that I will be deep inside with no direct access to the surface.

For whatever that's worth.

 

[johndiver999]

It should be noted that in all these cases it is not the configuration that is the problem it is the diver.

The first citation discussed a diver who died because he breathed his pony bottle down, yet his back gas valve was open, determined from the sentence indicating that the back gas tank was not full due to the diver inflating his drysuit. If the diver breathed his pony bottle dry without realizing he was using his pony bottle then the simple thing to do would be to just switch to a different 2nd stage. Even with 3 2nd stages hanging off oneself one should be able to cycle through them fairly quick to find the one that works to correct the mistake of not being on the one connected to the back gas supply in the first place.

If having too many 2nd stages with one on a dive is a concern then those diving with stage bottles and multiple sidemount cylinders are all in grave peril...how on earth will they be able to manage this...oh yeah thats right, they are expected to think about their configuration, be intimately familiar with it, and have a checklist to ensure things are setup properly. If one is solo diving that is just as or even more important.

Just because someone dies using a particular configuration does not mean that configuration in and of itself presents an inherent danger.

During a pre-dive check, a diver should be checking that each of his 2nd stages is operational, if the back gas is shut off it will be clear if the op-check is performed properly. And if this is a solo diver there is no dive buddy to mistakenly shut the valve off. This op-check will show the gas supply is off even if the hose was charged and the valve subsequently closed. 2-3 breaths while watching the spg, one will see the needle move if a gas supply is turned off.

Diving, like other general high risk activities such as rock climbing, sky diving, etc, are very punishing to those who engage without thinking. It is incumbent on the participant to ensure they do not fall victim to their cognitive bias, as the punishment for this is often injury or death.

Stay safe or stay in bed.

-Z

The issues that were raised identifying the complexities of three second stages were to help inform people who might think that slapping a pony bottle onto the main tank is entirely trivial and will necessarily improve safety.

I'm sure most dive accidents can ultimately be attributed to diver error. Another big chunk is probably medical issues and another might be caused by problems that originate from a buddy, but of course diver error is a huge factor.

However, you seem to be dismissing the cautionary information as inconsequential because it is ultimately diver error. That (obvious) observation is true, however it may be easier to make that mistake than you realize. There are other cases of divers getting killed because of confusion and I personally know someone who made the same mistake - yet (luckily) realized the error and avoided an accident by very little margin (according to his personal account).

The idea that tech divers carry multiple bottles and side mount carries more than one is not really relevant. Perhaps the important point you are missing is that the caution is being directed specifically toward BACK MOUNTED pony bottles. A diver selecting this type of configuration can NOT visually and physically trace the second stage hose back to a specific tank and valve. This is a huge distinction.

A stage bottle and the valve can be seen by the diver and they can verify identity by tracing the hose back to the source and further verify by manipulating the valve. This sort of (nearly) idiot proof configuration is NOT available for a back mounted pony - although mounting the tank upside down might offset some of the weaknesses of this configuration.

This is why a previous poster commented that back mounting was not as safe as rigging the pony bottle on the side as a stage bottle. Side rigging also has other significant advantages as well (over back mount), which probably don't need to be discussed.

 

[drbill]

Didn't you originally post that the dip tube had come loose and was clanging around inside your tank?

No, it wasn't loose

 

[Storker]

I've stopped bringing my 19cf bottle on dives. Just too much gear to carry and assemble on my 18 ft center console.

Huh.

Solo, right? We've been five divers - one with a small twinset, four with two singles each - in my 18'. All in drysuits. Plus the boat tender. It was a bit cramped, and the engine was working pretty hard to lift us into plane, but we managed rather decently. I guess your privacy zone is somewhat bigger than mine.

 

[Hickdive]

It's very simply. A competent diver with a functioning independent air supply can regard a primary air supply failure as simply a nuisance until they can reach an alternative, such as the surface, or a buddy.

A diver without a functioning independent air supply will have to deal with the failure of their primary as an emergency.

The moment you start any kind of emergency response then Murphy's Law will tend to intervene.

 

[caruso]

I guess your privacy zone is somewhat bigger than mine.

It's more a matter of not wanting to mess with the extra tank and regulator on a relatively shallow easy dive from which I can make an emergency ascent with no gas.

 

[scubadada]

It's not difficult diving with a little pony

 

[AfterDark]

The topic has drifted quite a ways from "why do I need a pony when diving solo at an average depth of 5 meters" .

However the issue of a diver confusing the back mounted pony regulator with a primary regulator or octopus regulator is a serious consideration. As mentioned, it has killed people in the past - yet some seem to be skeptical or dismissive of the potential problem. It is a serious consideration - especially if a diver does not recognize the potential problem before the dive!

Carrying three second stages and the increased chance of freeflow, confusion and failure needs to be offset by enhanced utility or safety. Choose carefully.

A very easy issue to remedy. I know which 2nd stage I'm handling by feeling the end of the hose at the 2nd stage. Each hose has a different feature, size or type of nut at the 2nd stage. The primary has a elbow and a shut off, the octo is straight with a shut off, the pony has is straight without a shutoff. This I can tell by touch, my primary has an orange mouthpiece, the octo is black, the pony is clear silicone if the vis is good enough I can confirm what I feel by sight. Common sense goes a long way.

When it's all said and done I'd rather dive my ID's than tote a pony bottle. Two independent bottles and regs on my back beat a pony hanging up my arm and getting my way.