Steel Stage Bottle for Sidemount?

[J-Vo]

You understand that on 6ths you can get two dives out of a set of tanks, right? The 6ths limit is there not for gas planning, but to limit the amount of penetration. So as an example, with 2 AL80s the first dive you penetrate to 2500, exit with 2000. 2nd dive penetrate to 1500, exit with 1000. We did this routinely in my intro class./QUOTE]

I'm a new cave diver, but my math says 1/6th of 2000 rounds to 300psi. 500 of 2k is turning one quarter. Part of the point of 6ths is making sure intro divers have adequate time to solve a problem as they will likely be held up longer de to lack of experience.

 

[halocline]

The limit of 6ths for intro divers applies to the total volume of doubles. When diving a single tank with H valve, intro divers are allowed to go to 3rds. At least that's how I remember it, it's been several years since my intro class. Anyhow, practically no one dives single tank/H valve anymore, so the real-world limit is 1/6. But again, that is not a gas planning rule, it's there to prevent longer penetration for intro students regardless of gas. The normal cave gas planning rules still apply, traditionally diving to thirds when conditions allow. The difference is that intro divers are simply limited in any scenario from exceeding a penetration of 500 PSI. This is to keep them closer to the exit. If the 1/6 rule were for gas planning, it would also apply to the single tank scenario.

Another factor is that of course you want a sizeable amount of gas as a reserve regardless of fraction used for penetration. In my class that was 1000 PSI minimum for planned gas upon exit. That way you are never exiting the cave with less gas than would be present on a 'normal' cave dive to thirds. And keep in mind that these are much shorter penetrations (half that of 'normal' dives).

 

[Addison Snyder]

You seem to be trying to solve a very minor issue (trying to save a little money on fills)

I just don't understand how this equates to any savings on fills.

Not trying to save a few bucks (besides, 90% of the places in cave country charge by the cu ft). Was looking at getting more dives out of 4 tanks, with the majority being on fully cave-filled tanks. Saves trips, and in theory nice and convenient.

You understand that on 6ths you can get two dives out of a set of tanks, right?

Yup, see above. Normally get about 2 trips out of each set of doubles.