Aluminum doubles

[wrybosome]

Sure, they're fine with a wetsuit, but why are you diving doubles in the Northeast if you aren't diving dry? Your "team" doesn't need that much gas for a recreational dive. Doubles certainly have their place, but they don't make much sense for touring a quarry in shallow water.

It wasn't a team consideration, just looking to do some longer, deeper dives and still have a safe gas reserve. My limitations now are based more on gas than warmth so it seemed like a natural progression since they seem easier to learn than drysuit and I thought they'd have more immediate benefit.

Not looking to do serious 'tech' diving, just longer bottom times on boat dives at 90 -130'. For the quarry and shallower I'll stay single tank, out of not wanting to hump the things around if nothing else .

After the drysuit, I'd say take Fundies before considering doubles. That class is about the same cost as the double Al80s and I assure you, the former will help your diving a lot more than the latter.

Thanks, I'll consider what you say.

 

[GrumpyOldGuy]

Buy a big steel tank (119/120/130) if you want / need a bit more air. It is more cost effective and a heck of a lot less hassle to dive with than doubles.

 

[Rainer]

Exactly.

A single HP130 (130cf) is almost as much gas as double Al80s (154cf), but doesn't require you to buy bands, a manifold, two cylinders, and an extra first stage. It also weighs half as much as the double Al80s (once you add a v-weight). Plus fills are half as much money.

Buy a big steel tank (119/120/130) if you want / need a bit more air. It is more cost effective and a heck of a lot less hassle to dive with than doubles.

 

[liuk3]

If you hump a HP130 single tank, you'll get almost as much gas as the twin AL80s. Plus, you'll have less drag than a set of twin AL80s. If you feel that you are getting limited on gas on your dives; dive experience (i.e. dive more), good training and cardiovascular exercise will go a very long way in terms of dramatically improving your SAC rate. I'd agree with above regarding recommending a drysuit purchase first, along with a GUE Fundamentals class or drysuit primer class if you need it.

You're lucky to have easy access to a GUE Training Director Bob Sherwood relatively local to you. He does much of his teaching out of Dutch Springs. He also can help get you squared away with whatever equipment you might need as he's got a fully stocked trailer he drags along with him. At the very least, I would give him a call to feel him out in terms of personal chemistry and advice on your dive progression. GUE Instructor résumé | Global Underwater Explorers

Regarding doubles, I don't think that twin AL80s are a bad choice at all, and they can last you a long ways in terms of your technical diving progression if you eventually decide to do so. Good luck and have fun!

 

[sabbath999]

Exactly.

A single HP130 (130cf) is almost as much gas as double Al80s (154cf), but doesn't require you to buy bands, a manifold, two cylinders, and an extra first stage. It also weighs half as much as the double Al80s (once you add a v-weight). Plus fills are half as much money.

Not only that, but if you dive some shallower dives and have decent air management you can get two dives out of a tank... I can stay down about 2 hours on a full LP 120 in the local quarry... that can be one LONG dive or two shorter ones (keeping in mind NDL of course).

 

[TSandM]

Double 80's are great in warm water. I dove them in the Red Sea and loved them, and dive them in Mexico in the caves.

In cold water . . . not so much.

I totally agree with the folks who say that, if increasing your gas supply is your goal, a steel 130 is a good idea. The only place where I'd change that is if you are thinking about redundancy against freeflow in the winter -- but I'd imagine you aren't wetsuit diving in the winter where you are.

I wouldn't dive doubled 80's here in Puget Sound -- but I know someone who does, because they solved trim issues she couldn't figure out any other way. Me -- I don't want to carry the weight of the heavy tanks AND the weight required to sink them.

 

[bleeb]

It wasn't a team consideration, just looking to do some longer, deeper dives and still have a safe gas reserve. My limitations now are based more on gas than warmth so it seemed like a natural progression since they seem easier to learn than drysuit and I thought they'd have more immediate benefit.

It's not obvious where you are on the breathing curve, what you're wearing for insulation or how cold you're feeling during/after one or more dives, but a dry suit also has the potential to improve your gas consumption. Being cold or even cool means breathing more to stay warm, and in our cold northern waters a decent SAC in a wet suit can be 50% higher than in the tropics. A dry suit probably won't help quite that much, but may still be a significant improvement, especially on that second dive.

Another issue to consider for cold water divers using Al doubles at the depths you mention (90-130') is that you loose loss of buoyancy at depth due to wet suit compression. In the event of a BCD failure, you'll be very heavy, possibly too heavy to swim up from the bottom. Some divers plan for handling this contingency by considering their dry suit their alternate source of lift. A lift bag is another possibility.

 

[carrielsal]

I have a set of AL80 doubles that I use for my tech training. It was my first set of doubles and I still use them today. I have to use a low hanging v-weight on the back, because they become butt light as I breathe down the gas.
If I ever decide to break them apart, they will make good stage tanks.
I was taught that a 50# lift bag can be used for redundancy in the event of a wing failure, but a few months ago another instructor posed this question to me. If I have a wing failure and I don't have a hard bottom below me, how long will it take me to deploy my lift bag in a stressful situation? Do I really want to rely on my lift bag in this scenario?

 

[ianr33]

I dont worry about wing failures in warm, open,water.

In a thin wetsuit at least I can swim up a set of Al 80's with an empty wing (might be different in a 7mm with a couple of stages)
Chance of a complete wing failure is tiny. Sure you can puncture it inside a wreck or something,but thats not open water.
Worst case my buddy grabs me and provides some buoyancy until I get the liftbag sorted out.

 

[carrielsal]

I dont worry about wing failures in warm, open,water.

In a thin wetsuit at least I can swim up a set of Al 80's with an empty wing (might be different in a 7mm with a couple of stages)
Chance of a complete wing failure is tiny. Sure you can puncture it inside a wreck or something,but thats not open water.
Worst case my buddy grabs me and provides some buoyancy until I get the liftbag sorted out.

I can also swim up the AL80's with an empty wing, but I have yet to try a set of steels with a wetsuit.