jgarysmith:
Just bought a LP121 new steel tank. I hope I made the right choice. I wanted a tank that would give me the max time I could get diving wrecks at 100 to 120 ft with out going to doubles. I uae a Mares semi dry Isotherm suit. Did I make the rright choice. I have a steel HP100, which I love and was conflicted about buying a 120hp instead. I haven't been getting full 3500 fills which doesn't give me the 100 CI of air. Did I make the right choice? What other suggestions are there? :dazzler1:
From reading your post, and reading a bit between the lines, I'm sensing that you're somewhat new to the sport, or at least not a frequent diver.
That 121 when filled to 3000 to 3200# gets you close to 150cft .... That's a massive amount of backgas .. you can get into some really deep ka-ka with that much gas and little knowledge/understanding of how to properly manage it.
When diving air in that 100 to 120' range, most intermediate level and up divers run out of NDL before they run low on gas, and that's with an 80cft tank. If you're on Ean with it's increased NDL, then an 80 is a bit on the small side, I agree, especially if maxing the bottom time as you describe for a relatively square profile like a wreck. But not by a lot.
If you're experiencing low gas volume problems with your 100, even if it's filled to a bit less than 100cft, Especially, if it's on air! and you're within NDL's, You really need to be working on your sac rate and overall skills and experience as your first priority, save the wrecks and deeper, more advanced dives for when you find yourself limited by NDL, not PSI anymore.
120+ cft of gas can get even a major hoover into more deco than they'd ever imagine. The big risk being you don't have enough gas left to satisfy all your deco obligation. ... not to mention everyone's back on the boat, and you still owe 30 more minutes hangtime.
As far as the LP121, it's a great tank, I've got the Faber version, and it's nice and light empty, good for me, since I dive wet here. It trims easily and requires about the same weighting as an al80. It's the only "single" tank I own .... although I never use it for a single dive. Decently filled, it lasts as long as 2 80's.... I only have to blend once, and don't have to switch over on a rocking boat.
Hang onto the one you got, someday you'll put it to good use. To Need That much gas for a single NDL dive points to other more primary issues to tackle. If you're thinking of using it for longer deco dives, then that points to other issues. (nothing you said points towards deco training, or equipment configs for some level of redundancy)
I'm sure there will be many opinions to follow, but I'll bet most echo similar thoughts.
Homework first, then dive ....
Darlene
