Why a 120 tank?

[maniago]

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

 

[victorzamora]

Maybe ally vs steel? Maybe a SAC rate difference. Maybe they like the 120's for different dives, and just happen to use the 120's when they dive off Hatteras as well??

 

[maniago]

yeah all good thoughts. I'm sacing at .74 so nothing to write home about. All theirs were AAs like mine. But I was the only one with smalls...short of the rebreather guys!

 

[herbdb]

Good question, Mitch. Some of us just use more gas and the larger tank lets us reach our NDL. Given the choice, I like the weight and feel of steel tanks. Next time we get together at Dutch you can try one of my steel 120s.. How was the diving in NC? We had a trip scheduled Earlier in the month, but it was scrubbed because of that early tropical storm.

 

[drbill]

I always loved diving with my 120s... could easily get two long dives out of a single tank. Much more economical with fills being $7 and doing 300+ dives a year. With an 80 I'm limited to two dives in the 35-45 min range.

 

[maniago]

Hey Herb, welcome back from your travels. I hope all was well for you! Hatteras was wicked good. Viz could have and should have been better, bit quarry-ish sometimes. Still lots of good pics and vid and challenging boat conditions, which is what I needed. I posted a nice pic inthe SE mid atlantic forum (can't quite figure out how to do the link back thing here).

How are your mondays looking? Mick

---------- Post added June 26th, 2013 at 10:56 AM ----------

I always loved diving with my 120s... could easily get two long dives out of a single tank. Much more economical with fills being $7 and doing 300+ dives a year. With an 80 I'm limited to two dives in the 35-45 min range.

Well I get it at higher depths where youre not NDL limited, but not down low, say @120FSW...I mean, where is the 120's sweet spot in the curve of Nitrox% vs depth vs time?

 

[redacted]

I suspect that for many, the tank selection is largely influenced by what you have available. Did you have a choice between using either a 100 or a 120? When you are close to both the NDL and gas capacity limits and have such a choice, why would you not pick the 120 and eliminate one of the limiting parameters?

 

[maniago]

I suspect that for many, the tank selection is largely influenced by what you have available. Did you have a choice between using either a 100 or a 120? When you are close to both the NDL and gas capacity limits and have such a choice, why would you not pick the 120 and eliminate one of the limiting parameters?

nah, I own my 4x100s. Was just thinking of adding 120s to my stash, but not sure why I would want to do that. My back won't tolerate double 100s so its only a single tank question.

 

[redacted]

nah, I own my 4x100s. Was just thinking of adding 120s to my stash, but not sure why I would want to do that. My back won't tolerate double 100s so its only a single tank question.

I have only one HP100. I bought it for specific dives that were gas limited when diving AL80s with a dive op that did not permit tanks larger than 100 cf. In your situation, I'd just stick with the 100, but I would dive a 120 if I had one.

 

[herbdb]

How are your mondays looking? Mick

Mick, I can dive Jul 1, 8, and 15 if any of these work for you. I leave for Florida on the 23rd (lobster season - yum!) and want to take dry gear. Let me know. Herb