Any reason to have both double 72's and double al80's?

[Blackwood]

In my opinion saying a set of 72's won't cut it for staged deco as they hold less than the arbitrary 160 cu ft is dogmatic. What is required really depnds on the diver and the situation. The irony of course is that same dogma would also exclude AL 80's as they only hold 154 cu ft.

Yes, it (like much in dive education) is dogmatic, and it's fairly wide-spread amongst the training agencies (as far as I've noticed).

That said, I miss spoke. It's generally quoted as "double aluminum 80s" are the minimum, not "160CF". I believe that, more than anything else, it comes more from the availability of twin sets in exotic locations. I'd be willing to bet that if most "way out there" tech diving operations stocked twin steel 72s, twin steel 72s would be thought of as the minimum.

As you said (or alluded to, anyway), the true gas requirements should be carefully determined before each and every dive.

 

[rjack321]

Back to the original question...
What is your shop filling the 72s to? If you aren't able to get them plus rated and they will only fill them to 2200 that's a "different tank" than getting them 'cave filled' to 2500 or more psi.

 

[Jim Lapenta]

I get mine filled to 3000. Regularly.

 

[Jimmer]

Back to the original question...
What is your shop filling the 72s to? If you aren't able to get them plus rated and they will only fill them to 2200 that's a "different tank" than getting them 'cave filled' to 2500 or more psi.

I do my own filling at my LDS (DM candidate with a key and security code ), so they pretty much never get filled below 2600. Like I said, I was really only thinking of using the 80's, since I had a couple "extras" that dont get used often, but I think the smarter bet would be to sell off the 2 I dont use and buy some 100's or 130's.

 

[willardj]

My 72s go to 3000 all the time with now problem. with first Hydro of '69 I'd say there doing Ok. At 3000 they are a lot better than 80s. 87cf vs 77cf

 

[TSandM]

Weight wise you need an 8lb V weight with the double 80's to maintain the same buoyancy and inmy opinion the steel 72's trim better.

Wow, my experience is the exact opposite. I can't ever quite get the 72s to trim out perfectly -- I always end up having to fin a bit. The 80's have trimmed out well for me both dry and wet, in fresh water and salt.

 

[Blackwood]

I do my own filling at my LDS (DM candidate with a key and security code ), so they pretty much never get filled below 2600. Like I said, I was really only thinking of using the 80's, since I had a couple "extras" that dont get used often, but I think the smarter bet would be to sell off the 2 I dont use and buy some 100's or 130's.

I have a set of twin al80s taking up space in my garage. I'm in the process of looking for used valves. When I do, I'll turn them into stage bottles.

 

[daniel f aleman]

I have a set of twin al80s taking up space in my garage. I'm in the process of looking for used valves. When I do, I'll turn them into stage bottles.

Yep.

But, for general recreational use, I use the twin 72s for fresh water and I use twin AL80s for saltwater.

 

[Blackwood]

I go back and forth on dismantling them.

I have two sets of HP100 dubs that I use regularly, but every time I'm about to break down my 80s, I think "well what am I going to do [-]if[/-] when I have to send in my drysuit?"

I guess I could dive double 100s wet, but I have no idea if I could swim them up.

 

[Gilldiver]

I may be just stupid, but if you put 2 of your 4 80's as a set of doubles, then you have two sets of doubles and 2 single 80's

That sounds like:

Saturday - deep dive with a set of doubles and a shallow with an 80

Sunday - deep dive with a set of doubles and a shallow with an 80

Add in a 30 or 40 for a pony or stage and you are all set for a weekend.

Keeps you from having to run out Saturday night to get your tanks filled.

But I guess everyone else on this list just likes to run out on Saturday night to get the tanks filled, if the shop is still open by the time you get there that is.