Advice on slinging an AL40

[Marie13]

I carry an AL30 with the valve ON. My thinking is that if I need it, I don’t want to be fumbling with the valve to turn it on.

 

[Bierstadt]

I will be slinging an al40 this summer. I am also waffling, but I figure the best thing to do is practice it both ways and then decide. Valve off and charged means little chance of a drained tank, but by the time I go from primary to secondary to pony with whatever task loading I'm under I might be better off just having the valve on and keeping an eye on it during the dive. A sidemount bungee on the valve is supposed to help streamlining but requires time for finetuning/playing with it.

 

[The Chairman]

yet we never get free-flows on our ponies.

Let me clarify that: if you have a free flow, it's guaranteed that you won't notice it, especially in a current. I've seen it happen twice and if I didn't intervene, their deco tanks would have been empty. There are several conditions that might cause a free-flow. Currents can, but they're not the only thing that can happen. Charge it and turn it off is my protocol. I see no compelling reason to do otherwise.

 

[doctormike]

Charged and off. Probably the most common recommendation, and you can definitely have an unnoticed free flow from a slung bottle.

Now when I dive a slung bailout bottle, the valve is turned on but that is a totally different thing from redundant gas for OC diving. With bailout, I may need to instantly get off the loop while in the throes of a CO2 hit, making even minor procedures very difficult. The first sign of a problem might be that sensation of something being very wrong. Anything that slows you down is no good, which is why I have that second stage bungeed around my neck (it also makes it easier to detect a free flow). That's also the rationale behind the bailout valve, which saves you even the time it takes to switch mouthpieces.

With a surprise OOG emergency on OC, you should be able to just hold your breath for a minute or so, even if your reg suddenly goes dry. More than enough time to pull out your backup second stage, stick it in your mouth and open the valve from a slung pony. And realistically, the only "acceptable" OOG emergency on OC should be something like a blown LP hose, which will give you plenty of notice.

One more thing - if the OP is converting to a solo configuration, get rid of the backup second stage ("octopus") on your backgas. That's only for a buddy, you don't need it if you have a completely redundant gas source with regulator, and it's one more thing to potentially free flow.

 

[Compressor]

I charge and turn off as well. And during the dive I make it a habit to check spg on redundant supply whether its pony or sling 40. I can see both sides to the argument but I prefer to charge and close.

 

[EricTheDood]

Let me clarify that: if you have a free flow, it's guaranteed that you won't notice it, especially in a current. I've seen it happen twice and if I didn't intervene, their deco tanks would have been empty. There are several conditions that might cause a free-flow. Currents can, but they're not the only thing that can happen. Charge it and turn it off is my protocol. I see no compelling reason to do otherwise.

Absolutely agreed that a deco tank should be charged and turned off. A deco gas switch is (supposed to be) planned.

However, a pony is a bailout. For rebreather divers, what's the standard procedure for bailout tanks? Open or closed?

 

[doctormike]

Absolutely agreed that a deco tank should be charged and turned off. A deco gas switch is (supposed to be) planned.

However, a pony is a bailout. For rebreather divers, what's the standard procedure for bailout tanks? Open or closed?

OC "bailout" (AKA redundant gas supply) and CCR bailout are different things. See my post on this topic above.

 

[Cowfish Aesthetic]

Thanks for the advice everyone. If nothing else, the lack of consensus gives me confidence that neither answer is obviously wrong.

One more thing - if the OP is converting to a solo configuration, get rid of the backup second stage ("octopus") on your backgas. That's only for a buddy, you don't need it if you have a completely redundant gas source with regulator, and it's one more thing to potentially free flow.

Not going solo yet, but going to be buddying up with unfamiliar divers in cold water, so having redundant air seemed like a good idea. I agree with you though; if I was going solo, I'd put the pony second stage on the necklace, leave it on (since I'd notice a freeflow under my chin), and skip the octopus.

 

[Compressor]

I'd put the pony second stage on the necklace, leave it on (since I'd notice a freeflow under my chin), and skip the octopus.

@Cowfish Aesthetic: Where is your second stage not on the pony? Many ways to accomplish things but one common way is to place 2nd stage on short hose (22-24") and necklace it. Pony or Al 40 with indepandant air supply rigged and ready for deployment. If the primary air supply is compromised then the 2nd stage from redundant supply comes over neck and gets necklaced. To accomplish this, the hose on redundant supply should be around 40" and be on the left side of diver.

This is not the only to do things. Some put the pony on the right side but have access to regulator on it with right hand. Most Al40s or deco bottles go on the left side.

Pic from here on SB.

 

[RyanT]

With a surprise OOG emergency on OC, you should be able to just hold your breath for a minute or so, even if your reg suddenly goes dry. More than enough time to pull out your backup second stage, stick it in your mouth and open the valve from a slung pony. And realistically, the only "acceptable" OOG emergency on OC should be something like a blown LP hose, which will give you plenty of notice.

+1 for charged and off. Also, if you rig your bottle well, and make sure the valve is pointing out. It is easy to find the valve. In an OOG emergency, all it needs is one good half turn to start delivering air.