Why extra air when solo?

[Divectionist]

Given that there is no good argument against carrying redundant air on a 'real' solo dive, it must come down to some people wanting to justify not having to spend the extra money and seeking validation due to their underlying uncertainty about whether they are too biased by their own wishes to make the right decision. But the truth is that if money prohibits the purchase of the type of equipment required for the activity, that person cannot afford the activity. And that reality should not be fought.

The creeping path from starting shallow and venturing deeper as (false) confidence grows is an easy one to go down.

Logic says that statistics strongly favour redundancy of equipment. Accounts of experienced divers indicate that some of the assumed drawbacks of carrying redundant equipment, voiced by those who only do so in their mind's eye, are in fact non-issues, especially when measured against their benefits. So to those who are still looking for reasons: just get the right equipment or do not pursue the activity. Or admit that you are risking your life based on an irrational gamble, like anyone who excessively consumes substances known to be harmful. Nobody can stop you from doing it and it is your choice in the end. But there's no winning that argument.

I think that the solo configuration, as proposed by the two common solo diver certifications, should be in fact the standard configuration for all divers. Just as I think tech equipment should be standard for rec diving, the right materials in the right form, and nothing more.

 

[TMHeimer]

Though I have been as deep as 65' (once) and maybe a dozen times to 40' or so, I have not gone down that creeping path (except these rare times, and not down there more than a couple of minutes). A little bell goes off in my head at 30'.

 

[MichaelMc]

Trying to minimize the risk of a slip and fall is the primary reason why I would not carry additional weight (like a pony bottle) on such a dive. Once the diver is in the water, the drag and/or weight is inconsequential.

While the OP asks specifically about a pony, that is not the only redundant option. My tiny AL40 doubles weigh the same as an AL80 + a small bit of my ample lead. I'm fairly sure the difference is in the brass manifold and second valve. Which are close enough in density to lead as to not matter for this discussion. So no extra gear weight climbing over those rocks. I think it was wetb4 who mentioned that sidemount lets you put half your gear down at a time if the rocks are an issue. The 'it has to weigh more' pony is not the only option.

but how to you put two first stages on one tank?

H valve. What's the deal with H-Valves?

 

[johndiver999]

While the OP asks specifically about a pony, that is not the only redundant option. My tiny AL40 doubles weigh the same as an AL80 + a small bit of my ample lead. I'm fairly sure the difference is in the brass manifold and second valve. Which are close enough in density to lead as to not matter for this discussion. So no extra gear weight climbing over those rocks. I think it was wet4 who mentioned that sidemount lets you put half your gear down at a time if the rocks are an issue. The 'it has to weigh more' pony is not the only option.


H valve. What's the deal with H-Valves?

If two tanks are lighter then, that makes sense.

As for slung bottles, if you are getting out with waves onto rocks, I'm not sure how two slung bottles would work. I never dove like that?

 

[Stoo]

Not that I want to sound stupid, but how to you put two first stages on one tank?

H-valve. I had one on a single 95 way back, but it resulted in such a CF of hoses, I abandoned it.

 

[MichaelMc]

As for slung bottles, if you are getting out with waves onto rocks, I'm not sure how two slung bottles would work. I never dove like that?

Waves/surf are a different issue from rocks at the calm waters edge. Lots of trade-offs with sidemount on land/surf. I only do it on calm days, though my tiny AL40/LP50 sidemounts are just the size of small deco bottles. Plus sidemount are pulled in tight by the bungee, not swinging in the breeze like a loosely attached stage. Swinging about loose on just their boltsnaps, they are a pain. Tucked up with the bungee, not really. I've been swept up and down the sand beach a few times in tiny sidemount, plus tumbled lightly, not sure it was really any different than in backmount single.

Tiny backmount AL40 doubles is just like a single, just with a bit wider wing, and two firsts. I think tiny doubles is a no-brainer replacement for single tank. Sidemount is a more advanced change, depending on entry/exit conditions. Either with big tanks is more than I want to mess with out of the water.

Specs from DGX on AL40 and AL80. Two AL40s are actually a hair lighter than an AL80 for whatever weird reason. Not that 80s are the best choice, but a common one. The rest of the doubles is steel and brass, so if you've a bit of lead, they shouldn't add anything. Though they will shift it a bit to the back, though tiny doubles have their mass tighter to the body than a single. So...?
Luxfer:
AL40 15.3 lb -0.7: +1.8
AL80 31.4 lb -1.4: +3.4
Metal Impact:
AL40 15.3 -1.0: 1.4
AL80 31.9 -1.5: 3.3

In steels, the story is not as good.
LP50: 18.9 -2.43: 1.24
LP85: 31.2 -3.80: 2.32
HP100 34.0 -8.4: -0.6

 

[TheSweatyClam]

I always try to stay under 20' when solo. Doesn't sound deep, but when you have snorkeled as many years as I have at 20-30', you appreciate being there without having to leave for air, LOL,,,, after all,, depth doesn't make the dive more enjoyable, the locations contents do.

 

[Angelo Farina]

H-valve. I had one on a single 95 way back, but it resulted in such a CF of hoses, I abandoned it.

View attachment 553307

All single bottles here in Italy have a twin valve as that, not necessarily a complex H-valve. Many have simply a single piece of brass with two valves. Minimal additional weight, much more safety. No one here would buy a bottle with a single valve!
This is very similar to my one (Cressi):

Regarding hoses: I find that using two first stages my hoses are the same number, but better placed than using an Octopus. The main reg has 3 hoses (2nd stage, BCD and pressure gauge-console), the second one has just one hose, for the secondary 2nd stage. 4 hoses in total, as usual.
The main first stage is mounted upside down, so the hoses are well protected, but cannot be rotated easily. Instead the secondary is mounted with its tower up: it is more exposed, but this way the upper part of first stage is free to rotate, allowing easily to bring the reg on the left side, for giving air to a buddy, if required.
My first stages are 4 Scubapro MK5, my second stages are 5 Scubapro 109, all converted to Balanced (156). Searching for a sixt one...
When I am forced to reconfigure as an Octopus, because in some exotic country they have bottles with a single valve (which I hate), then the secondary 1st stage is also attached to the tower of the single main first stage. But at this point the tower cannot be rotated anymore, so giving air to a buddy could become more complicated...
Ok, here we were discussing solo diving, so this is a bit OT. But still I do not like the clutter and the improper alignment of hoses I get from an Octopus configuration, with two first stages all is much easier to setup.

 

[Storker]

not necessarily a complex H-valve. Many have simply a single piece of brass with two valves

Please elaborate. What's the difference between "a complex H-valve" and "a single piece of brass with two valves"? AFAIK those are basically the same. Two valves is two valves. Same amount of parts.

 

[Angelo Farina]

An H system is two pieces articulated, with an O ring, allowing the second valve to rotate. Hence less safe than a single brass fusion...