VTernovski
Contributor
BILLB:Lets take this a bit farther. Supposed your pony bottle had a cracked neck? (I have observed several pony bottles with cracks).
What if one of your doubles had a cracked neck or slow leak? Would you continue to dive? My terminology was not entirely correct (thanks for the correction). But the point made was that if you are uncomfortable or have no experience with doubles, H-valves on single tanks offer a next level degree of safety (fully redundant regulators/back up gauges/computers, Etc.) Diving with a pony tank plays havoc with trim unless you sling it in front but the extra drag is still there. And, to do the depths that NJ diving attractions require, a pony would need to be 30 Cu Ft or more to do a "safe" ascent (and probably no safety stop).
Obviously, diving doubles is the ideal. No argument here.
form that picture, doesn't look like it's a pony. it's a deco bottle since he just mentioned he is going into deco on those dives.
If one of the doubles has a cracked neck, you will need to shut down the isolator and abort the dive, at least you can maintain your full stops. What are you going to do when your single tank has a cracked neck? that's where H-valve is useless, at this point you will have no choice but to ask me for gas. I agree that a pony has to be at least 30cu.ft. anything smaller and it's useless.