Pony bottle

[Nemrod]

No, you don't need one.

Check 23.8 for required equipment.

https://www.tdisdi.com/wp-content/uploads/files/sandp/currentYear/SDI/part 3/pdf/individual/SDI Specialty Standards_23_Solo_Diver.pdf

Okay, then a Spare Air, or another fully redundant air source of which for single tank diver a pony is the most practical.


Required Equipment

Basic open water scuba equipment as described in section three of this manual with exception of a safe second, or octopus, is not allowed as a redundant air source.

One of the following must be used to provide an additional independent regulator attached to an air source: pony cylinder, twin cylinders with isolation, H-valve, independent doubles, or SpareAirTM

N

 

[Slym]

The OP might not realize that SDI Solo requires 100 or more dives beyond AOW before you can even take the class.

Yea I know I need the 100 dives, I'll still be diving up here and next spring I'll get plenty of diving in before the course starts, so the 100 dives isn't an issue

 

[Bob DBF]

There's a thread in the accidents forum here on SB (Bonaire Close Call) where a diver had a 2nd stage flood. Buddy was 20ft away but both were fighting a current. Diver panicked, did a 60 ft CESA, and got bent despite only 10 min bottom time.

Your post seems to imply that you can get bent after only 10 minutes at 60', to clarify this was dive #6 on the second day of diving which changes the picture dramatically. The major issue is that once a diver panics, no configuration of gear or procedure will be of any use.


Bob

 

[2airishuman]

Pony bottle threads have got to be one one the most frustrating threads on SB with the possible exception of deep stop threads. I do not understand why people that don't dive or even believe in pony bottles insist on giving advice in a how to thread.

To the OP. You are correct. You will need some form of redundancy for solo class. The vast majority of divers choose to use a pony. H values do not give full redundancy and doubles or sidemount is just plan nonsense for most recreational divers, even solo ones.

I think a pony bottle is a wise choice for solo rec dives. While doubles are an appropriate choice in some cases, using them complicates gas logistics for simple dives. Consider a day's diving involving three dives. With singles and a pony, you bring three primary cylinders plus the pony. If you're diving manifolded doubles you would either bring three twinsets, or would bring two twinsets and dive one of them twice. At best you're paying for an extra gas fill, entering and exiting the water with about 20 pounds more dry weight, and handling a twinset that weighs around 80-100 pounds full instead of 40-50 pound singles. There is also the cost of a doubles wing and the manifolded twins themselves.

I dive a twinset on longer and deeper dives. I dive a single and pony on dives of moderate depth.

An often overlooked alternative is the use of independent backmounted doubles. I am planning to experiment with this configuration, with a setup that allows them to be fastened in place with cam bands. Could offer some of the advantages of each.

It is usually necessary to adjust weight and trim to counteract the negative buoyancy of the pony bottle assembly (including valve and regulators). In most cases this will mean reducing the total amount of weight carried and moving some of the remaining weight to the opposite side of the body from the pony.

 

[Nemrod]

I asked the instructor I did the Solo Cert with his prefered student configuration and also asked what the usual student configuration is. The answer for both was back mounted single and a slung pony of 19 or 30 cf.

N

 

[tbone1004]

I dive indy doubles and have a set of bands that use cam bands. They're quite nifty.

the three dive day is interesting though as a lot will depend on the size of your tanks and the reserve pressures you have. Using 3000psi tanks, you have 9000psi total, but have 1000psi of each reserved, 6000psi usable. With doubles you can drop that reserve to 500psi because the CF reserve is the same and you have 5500psi of available gas. 10% less total dive time, but 2 less bottles, and no changing of equipment between dives.

 

[Ojai Diver]

Statements to the effect that " You need a pony of x size or You're Gonna Die" (common on this subject) are rather glib. Among other factors, not everybody will diving at 100 feet or more and spending one to three minutes at depth for "assessment" after an out of air emergency.

 

[tbone1004]

ever tried to stabilize a panicked diver when they go OOA? takes longer than you'd think before you can make a safe ascent

 

[Ojai Diver]

ever tried to stabilize a panicked diver when they go OOA? takes longer than you'd think before you can make a safe ascent

I don't see the relevance to pony bottle size. An OOA buddy will not be getting my pony; they will get my back gas, and my bottom time and gas calculations will already include the possibility of such an emergency.

 

[EricTheDood]

to clarify this was dive #6 on the second day of diving which changes the picture dramatically.

Not nearly dramatic enough. In fact, still quite conservative. Plenty of rec divers might find themselves with similar levels of tissue saturation before their dive trip ends.

So my point is that you don't have to be riding the limits, depth nor NDL, to get bent from a CESA. A CESA should be a last ditch effort, not just "another tool in the box", and a redundant air source is the best way to avoid having to resort to a CESA.