Why a 120 tank?

[maniago]

....yet it is the reason one may select the 120 you asked about.

If this is indeed the no kidding reason, I get it. I totally get it. Totally. Rockbottom = 120 Got it.

---------- Post added June 26th, 2013 at 06:31 PM ----------

So you are following roughly the same plan as the guys with 120's who are running Rock Bottom, albiet unintentionally.

I'm not trying to be adversarial, I'm genuinely interested in what risk management you're refering to that would take the place of Rock Bottom in this dive profile?[/QUOTE]

Per our dive plan, buddy and I are diving the same tanks: 100+19pony. Same size, same colors. No overheads, picture taking only. Square profile. 1/3 dive rule. Out together, back together, deep stop@60, safety stop 15@3. Min 1000psi start up no matter where we are. No deco. Sausages, Nautilus VHF radio, horns, whistles, mirrors, 100' spools, knifes left leg+2 cutters each. Only difference was he had necklaced octo, I have Air3.

Thoughts?

 

[rhwestfall]

http://www.scubaboard.com/forums/advanced-scuba-discussions/337284-what-size-tank-pony-2.html

get and try the spreadsheet on post #15......

 

[maniago]

http://www.scubaboard.com/forums/advanced-scuba-discussions/337284-what-size-tank-pony-2.html

get and try the spreadsheet on post #15......

Hmmm. I don't accept the premise that a pony is supposed to get you from where ever you are, deco and stop obligations included to the surface. I accept that its purpose is to help you survive a CESA, and that's its only purpose. That's the premise behind SpareAir, and I like the premise. But hey, I also like a little added insurance too. So I guess I'll go buy a 120 and put my pony on it to boot.

Thanks to all who've posted to this thread! I've got lots of good info to chew on. Cheers!

 

[rhwestfall]

FWIW - I dive a HP120 here for those depths, calculating gas needs on that tank only, and sling a 30. Cold water here is unforgiving... and bent is unacceptable.

 

[maniago]

Just as a final follow up, I talked to the boat captain, and as it turns out all the tanks he had on board were LP AL100s - I was mistaken in my observation. So everyone was diving the same gas volume, except myself and my buddy, who had 100+pony. He said that's what he's been doing for years to that depth, and noone seemed any out of sorts about it. Would seem that rockbottom is either a new religion, a very conservative one, or both. Different strokes for different folks.

 

[swimmer_spe]

Post dive trip thoughts, and I can't noodle this out. 4 dives off Hatteras this past weekend with a single 100 (and 19cu pony). On 28% I got about 14mins bottom time (~120FSW), which seemed the same as the 120 guys. My computer was flipping between gas time and NDL time as my limiting factor at depth.

So what am I missing? What's gained by a 120? Is it just that their 120= my100+pony? (and no, I wasn't burning into my pony)....any insight is appreciated. Thanks

I use my steel 120s so I can have the same bottom time as those who are using AL80s. I am an air pig, but I am improving.

 

[Mike2Fst]

I dive 2 steel HP 120s, I'd rather have gas I don't need at depth that to need gas I don't have at depth.