What's your pony setup?

[sabbe]

Not sure if you're considering tec in the future but AL40 is the smallest useful tec size so you don't potentially have to buy extra tanks.
Many years ago I tried a pony mount on my back tank and felt too lopsided. I now rig either on my front left side tec style or my recreational teaching BC has a few less mount points so I'll sling it a little diagonal from upper right front to lower left front.

 

[Jim Lapenta]

I'm an SDI Solo Instructor and my IT was the guy who wrote the SDI Solo course. I normally dive sidemount so that takes care of my redundant supply. With students I recommend their redundant supply be based on their SAC/RMV and take into account how deep they plan to actually go and what their gas needs will be for a doubled SAC/RMV should they need to bail out. Some get by with a 19. Most choose a 30 or 40 when they actually run the numbers.
Your Solo class should have you calculating your RMV and basing the redundant supply on that. If it's not, I'd think about finding another instructor. You should know your SAC before you take the class and have the gear bought to handle your needs.
Sometimes my redundant supply is an al80 because the depth and time call for that as backup.

 

[CWK]

Sometimes my redundant supply is an al80 because the depth and time call for that as backup.

We are talking SDI so I’m assuming solo recreational diving with max 40m depth and no deco (as opposed to technical diving).

I’d be interested to know what combination of depth/time/SAC would indicate an al80 as a redundant air supply to get you from a max depth of 40m to the surface in event of the failure of your primary air supply.

 

[lowviz]

I'm taking the SDI Solo class soon and am looking into a pony rig. Something between a 19 and a 40 I imagine. What do you use, how are you carrying it?

You are a DM posting in solo so I assume you know some stuff.

IMHO:
To a real solo diver, a pony is just another thing that you strap on at every dive. Like a dive flag, it is a PIA. It is something that you will never use, but I take mine anyway. I like a big pony, 19 cuft. Last horse out of Dodge...

Pay attention to REAL solo divers like @uncfnp and @Soloist. They dive 'together' as solo divers. She dives a 13 and he dives a 19. My opinion is that if you need more than a 19 then you REALLY need a buddy.

A 30cuft is the most useless cylinder ever produced and a 40 is just stupid as a pony. It is a deco tank. You will end up leaving it on the surface by convincing yourself that this is an 'easy' dive and I don't need it...

My 19? Slung.


And you will soon buy a transfer whip because it gets tiresome and expensive to keep your pony topped off. You charge, turn off, then dive. It adds up fast...

 

[loosenit2]

I'm an SDI Solo Instructor and my IT was the guy who wrote the SDI Solo course. I normally dive sidemount so that takes care of my redundant supply. With students I recommend their redundant supply be based on their SAC/RMV and take into account how deep they plan to actually go and what their gas needs will be for a doubled SAC/RMV should they need to bail out. Some get by with a 19. Most choose a 30 or 40 when they actually run the numbers.
Your Solo class should have you calculating your RMV and basing the redundant supply on that. If it's not, I'd think about finding another instructor. You should know your SAC before you take the class and have the gear bought to handle your needs.
Sometimes my redundant supply is an al80 because the depth and time call for that as backup.

@TDiddy this thread has a good spreadsheet that @wetb4igetinthewater did last year for calculating what size pony you may need.

Spreadsheet for helping pick a pony bottle

 

[happy-diver]

Don't even remember it's there

Probably won't even remember it's there

 

[Divin'Papaw]

You are a DM posting in solo so I assume you know some stuff.

IMHO:
To a real solo diver, a pony is just another thing that you strap on at every dive. Like a dive flag, it is a PIA. It is something that you will never use, but I take mine anyway. I like a big pony, 19 cuft. Last horse out of Dodge...

Pay attention to REAL solo divers like @uncfnp and @Soloist. They dive 'together' as solo divers. She dives a 13 and he dives a 19. My opinion is that if you need more than a 19 then you REALLY need a buddy.

A 30cuft is the most useless cylinder ever produced and a 40 is just stupid as a pony. It is a deco tank. You will end up leaving it on the surface by convincing yourself that this is an 'easy' dive and I don't need it...

My 19? Slung.
View attachment 590007

And you will soon buy a transfer whip because it gets tiresome and expensive to keep your pony topped off. You charge, turn off, then dive. It adds up fast...

A 13 cf or 19 cf cylinder may be absolutely fine as pony bottles based upon your needs for a given dive, but 30 & 40 cf cylinders also make perfectly fine pony bottles and are actually the better choice for some dives based upon SAC and depth.

Also, your argument about needing a transfer whip is one argument for a larger pony. My 40 cf doesn't need to be 100% full to be an effective redundant air source for the majority of my dives. I have 2 AL40s that I rarely have filled other than the annual VIP.

 

[lowviz]

but 30 & 40 cf cylinders also make perfectly fine pony bottles and are actually the better choice for some dives based upon SAC and depth.

Our mileage differs, no prob.

If I need more than a 19 to get to the surface, then I'm somewhere that I shouldn't be without an attentive buddy and min gas rules. I just don't care to dive solo that way...

 

[Divin'Papaw]

Our mileage differs, no prob.

If I need more than a 19 to get to the surface, then I'm somewhere that I shouldn't be without an attentive buddy and min gas rules. I just don't care to dive solo that way...

Carrying a 40 doesn't feel much different than carrying a 19 honestly so I prefer to (1) err on the side of caution and have more gas than any emergency would require and (2) have the flexibility to dive with a half full bottle and still have the gas I need for all but the deepest recreational dives. But I've been trained as a tech diver and I've carried either a 30 or 40 for over a decade so there is that acclimation factor to take into account.

But yes, these are personal decisions that one has to make for themselves. I'm not saying you're wrong and I don't believe you're saying I'm wrong. Everyone has to decide what works best for them. Except for a Spare Air. That's always wrong.

For me I am willing to do any recreational dive solo that I am willing to do with a buddy. Solo is solo whether you're @ 120' for 60'. You're in a world of hurt without a redundant gas source at either depth.

 

[HKGuns]

This is a nice setup. As per @saxman242 suggestion, I'd add a simple chocker which comprises of a simple double bungee loop around the cylinder neck. This feeds through the boltsnap gate which is then clipped off on your left shoulder D ring. In water this will keep the cylinder nicely tucked under your arm whilst still being able to pull it down for access. In addition to extra streamlining it prevents the pendulum effect, although this is more common with larger cylinders.

Something like this
View attachment 589893

Thanks very much. I will do just that..............