Oh no! My 72s are too small for tech classes! :(

[Manatee Diver]

1/3rds of a single is dumb

Which is why the options of H-valved singles was removed when NSS-CDS updated their curriculum a couple of years ago. The hope is that trickles down to other agencies.

 

[ofg-1]

If double 72's were good enough for Mike Nelson, then by gum they are good enough for me.

BTW, they are not bad side mount tanks for shorter dives in a wet suit.

 

[flymolo]

i don't see why someone couldn't go diving with a set of double 72s if their buddy was tank matching (or at least gas matching). i thought 72s were used by lots of divers in the past?

 

[rjack321]

i don't see why someone couldn't go diving with a set of double 72s if their buddy was tank matching (or at least gas matching). i thought 72s were used by lots of divers in the past?

In a cave?

Not really, back in those days they actually didnt even dive 1/3rds (1/2s and a bit was common due to the flow in many systems)

 

[O-ring]

i don't see why someone couldn't go diving with a set of double 72s if their buddy was tank matching (or at least gas matching). i thought 72s were used by lots of divers in the past?

I used to dive them all the time in teams where the other dudes had double 80s. That was open ocean stuff though, not in caves.

 

[KevinNM]

3. LP 85 nominally gives 81.1 cu ft at 2,640 psig. I understand that these are routinely (perhaps unwittingly) filled to 3,000 psig, so, 92.2 cu ft.

Or 3500. Or 3800…

 

[Manatee Diver]

Or 3500. Or 3800…

Or 4,250...

 

[rx7diver]

Which is why the options of H-valved singles was removed when NSS-CDS updated their curriculum a couple of years ago. The hope is that trickles down to other agencies.

My NACD/NSS-CDS Cavern course and Basic Cave course (each 2-days, back-to-back, at Ginnie Springs FL, ca. Christmas 1988) required a single cylinder with Y-valve. Doubles were verboten for the classes. We rented a LP Scubapro 75 (?) there. I was still a relatively new scuba diver. This was the first time I was ever asked, "How much air [how many psig?] do you want in it?" The very first time, I actually thought the employee was making fun of this obviously brand new cave-diving student.

Note: At that time, there were only the three certification levels Cavern Diver, Basic Cave Diver, and Full Cave Diver. Basic Cave was intended to be a "learner's permit" that allowed you (restricted) access to caves where you could practice techniques. You were expected to get plenty of practice, including practice with doubles (but doubles only in open water) before you returned for Full Cave Diver training and certification. I never did the Full Cave level. (I've never preferred going in things, including shipwrecks.)

Note: Today, for my solo recreational diving to moderate depths, I actually prefer to use a single (usually, my old-school steel 72) with a Y-valve. I hope to one day switch in a LP 85 (for the 72) to see how this works for me.

rx7diver

 

[rx7diver]

72s filled to 3000psi are basically 85s, too bad the only shops that will consistently do that are in North Florida.

My plus-hydro'd 72 (PST/U.S. Divers with first hydro 1970, IIRC) often comes back filled to 3,000 psig. I think this is because scuba shops in SW MO and NW AR have their fill stations set up to automatically fill Al 80's.

rx7diver

 

[Manatee Diver]

This was the first time I was ever asked, "How much air [how many psig?] do you want in it?" The very first time, I actually thought the employee was making fun of this obviously brand new cave-diving student.

They don't ask you that anymore. Bank pressure or bust.