Redundant Gas - thinking through my options

[markbuk]

Hi,

I'm a UK diver (BSAC Dive Leader), and I also do a fair amount of holiday diving in warm waters.

So far all my diving has been on single cylinders (12L or 15L), but I'd like to get into slightly more adventurous UK diving (gentle wreck penetration, light deco etc). With this in mind, I'm thinking I should have a redundant air supply, but I have a few options going round in my head and I'd love some advice on the pros and cons.

I currently dive with a backplate and wing and single tank adaptor plus 'recreational' set of regs (so long hose octopus stowed on a quick release clip on my front). I'm starting off down the BSAC instructor route, so will need to keep these regs for that, but would also consider getting a separate long hose/primary donate setup too (especially if I end up on twinsets).

The options as I see it are as follows, but I am totally open to suggestions!

• Twinset - this will be expensive and bulky but definitely ticks the box for redundant air supply
• Pony cylinder - this means I can keep my current setup and bolt this on, but won't give me much extra gas. For anyone advocating this I'd be interested to know where your pony regulator and SPG gets stowed
• Some kind of slung stage cylinder and then stick with a single cylinder on my back (though the additional cylinder would presumably be filled with the same mix as my back gas) - I'm not sure if this is sensible because I could get a 7L cylinder or something and then it's not too big and bulky, or if this is really faffy and I should just go for a twinset

I'm genuinely not sure what the best option would be, and would love to hear your experiences of what more experienced divers do. I don't have aspirations at the moment of going especially deep (certainly not past the 50m I'm technically qualified for at the moment) or doing caves or serious wreck penetration or anything like that, but I do want to be taking a redundant gas supply with me for longer and deeper dives.

Thanks in advance for any advice you have for me.

 

[happy-diver]

Dude 15L Faber with a 3L Faber with 50%

Steel mate because you can pump em, and all the other reasons

 

[splitti]

Sidemount is missing on the list.

As far as I can say, consider going for a twinset or sidemount if you know you are en route to deco and overhead environments (e.g. wreck penetration.

They are flexible configurations that grow with you, should you want to push further and they give you a lot of gas for exploring and contingency. Each of the two has its own set of pros and cons but it's a solid foundation for your dive career, should you go on to even more adventurous dives.ä

You can also start with a stage cylinder. You can clip that on the d-rings of your harness and later use it for deco gas (or depending on the tank and your dives and needs, as a small sidemount cylinder for less demanding dives.

If you can, try the different options and see which option feels best for you, both right now and into the mid to long term future.

 

[johndiver999]

You mention longer and deeper dives, but you also mention deco. I think the first thing you want to clarify in your mind is the deco aspect. If you are expecting (or planning) to go into deco for more than 3-4 minutes, then the practicality of a pony bottle becomes questionable.

 

[barth]

Dude 15L Faber with a 3L Faber with 50%

View attachment 814919

Steel mate because you can pump em, and all the other reasons

A single cilinder with bottomgas + a pony bottle with decogas is not redundant gas.

 

[GF99/99]

(gentle wreck penetration, light deco etc). With this in mind, I'm thinking I should have a redundant air supply,

Yes your thinking is very correct. But it is more of you MUST have a redundant gas supply when your in an overhead environment or have mandatory deco obligations.

Remember if your on a single tank and you run out of gas or have some type of equipment malfunction your SOL.

My suggestion is to take the correct training for diving like this. ANDP is a good starting point. You will learn about various redundant gas systems and how to use them, how manage them, and how to plan a dive with them.

It is just as important to know how to manage and plan a dive with multiple gas systems as it is to carry them.

 

[johndiver999]

I am not one to worry too much about semantics, but to me, a pony bottle means a bail out bottle (I can use on the bottom) and a bottle holding deco gas should probably be called a stage bottle, if we want to limit confusion. Can you wear a stage bottle on your back? LOL?

 

[formernuke]

I am not one to worry too much about semantics, but to me, a pony bottle means a bail out bottle (I can use on the bottom) and a bottle holding deco gas should probably be called a stage bottle, if we want to limit confusion. Can you wear a stage bottle on your back? LOL?

Bail out is for rebreathers.

 

[SlugLife]

I was about to link my pony size guide, but this thread is a little different.

I would recommend looking into SideMount. Your main expense there will be a SM class, and the SM BCD.

A lot of people love sidemount for both the redundancy, and it's abilities around wreck/cave penetration diving. You don't have a tank on your back that bumps into things, you can fit through narrower passages, and even unclip tanks to fit through tight passages. (Disclaimer, my experience with penetration diving is limited, so consider this me repeating what others say.)

With sidemount, you can re-use your regular full-sized scuba tanks, or rental tanks, or even smaller tanks (2x AL50s, or AL40s, etc).

Pony cylinder - this means I can keep my current setup and bolt this on, but won't give me much extra gas. For anyone advocating this I'd be interested to know where your pony regulator and SPG gets stowed

Broadly speaking, the "pony" is intended for redundancy and emergencies. If you're using a 2nd tank for other purposes, such as to extend a dive, it's usually not called a "pony."

This may seem a little semantic (word play), but you should be mindful of whether the redundant gas you have with you is part of your gas planning and intended to extend a dive (i.e. doubles, independent doubles, sidemount, slung cylinders, etc) or primarily intended for emergencies.

My suggestion is to take the correct training for diving like this.

This too. What OP is talking about is essentially "technical diving" and not simply redundant gas. Specifically, getting into penetration diving, additional air, longer/deeper dives, deco, doubles and slung cylinders, etc. Some of these skills can be picked up without going "full tech" (I learned sidemount), but when put together, we're essentially talking about tech-diving.

Putting the skills together, also has subtleties and interactions you may not pick up learning skills in isolation as well.

 

[markbuk]

You mention longer and deeper dives, but you also mention deco. I think the first thing you want to clarify in your mind is the deco aspect. If you are expecting (or planning) to go into deco for more than 3-4 minutes, then the practicality of a pony bottle becomes questionable.

I'm not planning to go into long deco (and hence, probably not planning on doing ANDP either as the AN aspect of it is unnecessary for the diving I want to do - though I am prepared to be talked round on this).

I'm just aware that on some of the dives I do I am limited by my NDL, whereas if I had a redundant source this would be less of an issue - I'm only talking of a very few minutes of deco, which quite often I would expect to clear during my ascent and/or be no longer than my current safety stops, I'm just aware that a gas failure with a deco obligation would be less than ideal. I guess a pony is the easiest option for me to bolt onto my current kit configuration, so it's useful to hear arguments like this as to why maybe it's not the right option!