What cylinders work as slung stages / bailouts?

[Firebar]

So this is something that I have searched the internet for and wanted a range of experiences.

What cylinders work as stages or bailouts that can be slung? Obviously the most common is the ubiquitous Ali80 / 11.1l but what else works well? 7l steels? 12l steels even? Are there any that really don't work? What's everyone's thoughts?

 

[EireDiver606]

Stages and bailouts are completely different things. They can’t be used interchangeably. Stage is for a stage of the dive eg deco, or bottom. Bailout is what’s used if a rebreather has a problem that cannot be safely fixed.

Many use Al 80 for EAN50 and Al 40 for O2.

 

[JonG1]

Pretty much anything can work, I use a mixture of steel and alloy depending on the dive.

E.g. steel 12 with deep bailout cos it's floaty and can be overpressured with less risk long term, and an ali 80 of nitrox for deeper stuff (60-65).

In mines and shallow caves it's 7 l alis, but I also have a 300b 3l that I use for intermediate stops on CCR bailout with 2x7s to reduce big lumpy tanks on boat dives.

Once you can dive stages/bailouts you can pretty much use anything up to a max of 3, then leashing comes into play which is a different ball game altogether and needs careful thought about mix and cyl choice (he, even in a nitrox deco bo helps them float)

 

[Scoobadoobiedoo]

I started with a 20cf pony when I first started deep dives (AOW -60 feet +). The pony was attached to the back of my main tank, which presented its own problems. I started doing deeper (60-110ft) dives more often, so I decided to ugrade my pony. Originally I was going to go with a 30cf before my LDS recommended a slung 40cf instead. The reason being that a 40cf tank is more neutrally buoyant than a 30cf. If I need to unclip the pony for whatever reason (give someone my pony for ex), the fact that it stays neutrally buoyant is very beneficial.

20cf ponies aren't enough for deep dives (rapid breaths during emergencies, safety stops, etc).
30cf are sufficient, but aren't buoyant
40cf float under your armpit when slung. They don't sink as soon as you unclip it. They provide ample gas. I sling it even during shallow shore dives. The only disadvantage is it weighs a tad more while slinging it during a shore dive---but it's ust a few pounds. It's awesome, doesn't cost much more, and provides excellent redundancy.

 

[Graeme Fraser]

As a personal preference I like ali stages as they tend to be close to neutral rather than perminantly negative. I also find they have less of a tendency to 'pendulum'. Regarding capacity, I'm quite a fan of the 7L ali, which I find quite modular for UK diving, with 1x7L at 50% for tech light to 2x7L 50% + 80/100% for most things up to <60m and 90min runtime.

 

[KenGordon]

So this is something that I have searched the internet for and wanted a range of experiences.

What cylinders work as stages or bailouts that can be slung? Obviously the most common is the ubiquitous Ali80 / 11.1l but what else works well? 7l steels? 12l steels even? Are there any that really don't work? What's everyone's thoughts?

Typical ‘normal’ is Ali80, Ali 7 or Ali40. I have a buddy that uses steel 10s happily. An Ali80 is quite large and annoying on a boat, I can just stand up with two... if I just want bailout for a no/very short deco dive I use a 7 as it is less hassle. Personally I dislike small steels as they are quite negative, you start getting into questions about whether they count as weight or not.

I’ve not tried a 12l steel but would guess it would be nasty. Maybe for very deep so lots of helium, but...

 

[1atm]

I’m also in the Ali camp due to buoyancy characteristics. I’ve got an Ali 7 for 100% oxygen and a few Ali 80s for 50% oxygen, Nitrox 32 (long shallow dives), 18/45 (bottom stage).

Some of the sizes are a matter of taste, eg many would opt for an Ali40 for oxygen rather than a 7. Also some would opt for an Ali7 for 50% rather than an 80. I went with the bigger option in each case, as I find it doesnt make much difference under water, and having more gas is always better. The only thing to watch out for is when filling the Ali7 with 100%, if you pump it up to 220bar it does become quite heavy. Other than that, I can get 2-3 dives out if the 7, and I always have some extra emergency O2 on land.

Steels arent never an option for me due to the negative weight under water. I dont dive so deep that the helium in it would off-set it.

Come to think of it, if you’re looking for some redundancy on rec dives and may have tec on the horizon, and Ali7 would portability be the most versatile choice for a first bottle. You cant really go wrong with an 80 or a 40 either though.

 

[JonG1]

1845 in a steel 12 is still floaty in my experience but there are differing characteristics between cylinders from different manufacturers

 

[miikey87]

I take a Luxfer s40 with me on solo shore dives, snugs in under my arm especially after a few breaths, you forget you have it rather quickly.

 

[Firebar]

Thanks for the input all, I’m in the position of being on the verge of wanting to extend my dives a little, so I’m going to have to get a second set of regs and tweak my hose layouts a little.

I’m trying to work out the best thing to do, straight to twins? Get a stage/pony of an appropriate size to be used later?

As a target point for what I’m looking at is doing dives in wrecks like the M2 and Kyarra, lying in approx. 30m for a decent amount of time, potentially building up to some minor deco in the future.

I’m limited on space, and what I can sneak into the flat without my girlfriend noticing, so I’m trying to make considered choices and ones I can justify (like I got a second set of regs for you when we go diving on holiday.....).