2airishuman
Contributor
I want to get a pony/back-up tank.
Good for you
There are numerous sizes and configurations. I just cannot seem to sort it out. Not sure best way to mount or carry. I want it to be a none complex issue if i need to use. Tank mount look good < But how easy is it to access??
There are no widely accepted best practices.
Tank mounted ponies pose potential safety problems. There have been fatalities when divers with that configuration make a mistake and breathe off the pony regulator when they think they are using the regulator for their main cylinder. The best practice for back-mounted pony cylinder, if you do decide to use one, is to connect the pony to a regulator that is bungeed under your chin, and then use an Air2 (or other integrated power inflator) as the backup regulator for your main cylinder.
I use a sling-mounted pony, that is, one carried exactly the same way as a stage bottle or deco bottle would be carried by a technical diver. Because the valve is visible and accessible, it is easier to determine for certain which regulator is which.
A LP30 seems sufficient.
Sizes of pony/bailout cylinders are a controversial subject on scubaboard. There are two schools of thought.
One school of thought is that, for recreational dives, the pony cylinder is a piece of emergency equipment intended to provide enough air for an immediate, controlled, direct ascent to the surface. People who use this approach may use cylinders as small as 9 cf, depending on the depth of the dive and other factors.
The other school of thought is that a pony cylinder should provide sufficient gas for some amount of problem identification/resolution at depth, usually 30-60 seconds, followed by a controlled ascent at standard rates, a safety stop, ascent to the surface, and some amount of surface reserve. People who use this approach typically determine that a 30 cf cylinder is the minimum size that will meet their requirements, and often end up purchasing a 40 cf cylinder because of trim and buoyancy considerations and the fact that 40cf cylinders are widely used as stage and deco cylinders in technical diving.
There is wide consensus that the 1.5 and 3.0 cf cylinders are too small.
My LDS told me I needed a Technical Cert. to use double tanks.
Some LDS feel this way, most do not. I dive doubles, and do not hold a technical cert.