What's your favorite set of doubles?

[skewer]

Hi guys,

Looking at getting into doubles as the next logical step in my Scuba journey. The challenge is that my wife and I need to both be able to use the bottles for single tank diving (don't want to buy 4 bottles!).

Would two 12L Faber Steel cylinders (we use the metric system) be a good decision or should we be looking at two 10L bottles instead? I am also not sure about Steel versus Aluminium for doubles.

Also, I am not sure what LP85 LP80 etc means haha. Assume LP = Low Pressure and HP = High pressure? HP being 3500psi? How does 80 etc compare to liters?

p.s. we don't need to do two dives off one tank and yes, the above are noob questions

You are not going to want to pull apart and reassemble your doubles on a regular basis. I would forget about any idea of using them as singles.

As for choosing between 10L (~82 cubic feet) and 12.2L (12.2L x 232bar = 100 cubic feet) I would think the length of your torso would be the deciding factor. Double Faber 12.2L bottles seem pretty standard fit for most people closer to 6ft tall. The 10L bottles perhaps more suited to those closer to 5ft tall.

 

[MichaelMc]

Looking at getting into doubles as the next logical step in my Scuba journey. The challenge is that my wife and I need to both be able to use the bottles for single tank diving (don't want to buy 4 bottles!).

A possible option is independent doubles, with no manifold between them. You would not learn valve drills etc and would need to switch regs during the dive. But you could learn and dial in most of a doubles feel in the water. Likely suitable enough for open water use. Splitting them apart would be loosening the bands and sliding them out. I don't know how easy that is, but is should be much simpler than breaking apart or reassembling the manifold. You could use a standard steel manifold that you would then use for manifolded doubles. Or, there are various block/strap setups to strap two tanks together on the plate.

I dive sidemount and have just four tanks. Independent doubles with steel bands is something I'm considering as an easy way to try how (tiny) doubles feel, while keeping my tanks easy to use individually. When I feel motivated enough to mess with a manifold, I can do the whole disassemble and reassemble the valves/manifold exercise.

My favorite (future) doubles are my LP50/AL40 independent ones that let me sidemount the same tanks after unscrewing 2 bolts, screwing on 2 band clamps, and topping up the tanks.

 

[AGNZ]

You are not going to want to pull apart and reassemble your doubles on a regular basis. I would forget about any idea of using them as singles.

As for choosing between 10L (~82 cubic feet) and 12.2L (12.2L x 232bar = 100 cubic feet) I would think the length of your torso would be the deciding factor. Double Faber 12.2L bottles seem pretty standard fit for most people closer to 6ft tall. The 10L bottles perhaps more suited to those closer to 5ft tall.

Thanks I didn't realize that there was allot of effort in setting them up haha. Just assumed you emptied the gas and then swapped the valves over in the garage depending on the diving we wanted to do on the day. She is 5.9 and I am 5.11 so 12 (100s) probably make sense for singles.

 

[Pilotmaverick]

I also very much prefer the double 12 Liter, 232 Bar with a concave bottom.
It rides perfectly on my back and keeps me in good trim.

 

[Billy Northrup]

Hp120's at 4000k

 

[Ghetto Diver]

Lp45's
Then lp72s

 

[stuartv]

My favorite doubles are the double scrubber baskets on my rEvo.

But, for OC, definitely my PST HP120s. I think they trim out better/easier than the double PST HP100s I used to have.

I like my double 120s so much I use them for any and all my OC diving, unless I'm teaching and have to be in single tank, or I fly somewhere to dive. Shore dive at the Blue Heron Bridge to 25 feet? My double 120s. Trimix tech dive to 200 feet? My double 120s. And everything in between. Heavy on land. Perfect (for me) in the water.

 

[tmassey]

I like my double 120s so much I use them for any and all my OC diving, unless I'm teaching and have to be in single tank, or I fly somewhere to dive. Shore dive at the Blue Heron Bridge to 25 feet? My double 120s. Trimix tech dive to 200 feet? My double 120s. And everything in between. Heavy on land. Perfect (for me) in the water.

I agree completely. Sadly, I just sold off my last set of those, and I’m now suffering serious sellers remorse. Mine had the Genesis slanted manifold with the face-sealed oring and 8” spacing and the terrible 1.5” tack-welded bands - two sets. But I can’t bring myself to spend the $1k that a modern 3/4” valve/manifold/band HDG double HP120 will cost.

I will echo others. If you’re under 6’ tall, the 120’s are rough. I’m 6’2” and with a long torso, so they’re made for me.

They’re just hard to manifold because I’ve never personally seen them in 3/4” thread, and the Genesis manifold (really, the bands that the Genesis manifold requires) are junk. Word to the wise: pay real close attention to these issues if you try doubling 3500 tanks.

Anyone have any single or double HP 120’s they want to unload? PM me while I’m weak!

 

[stuartv]

@tmassey: Both my sets have the angled manifold. I have 2 Genesis manifolds and 1 Sherwood (or vice versa - I can't remember). All angled. The bands are kind of crappy, but they work, so I don't sweat it. I bought both my sets already doubled up, so I had no issues there.

I'm 6' 1", and yeah, much shorter and the length might be annoying, but I love 'em!

I have just switched to CCR, so I briefly considered selling my 2 twinsets. But, then a CCR friend of mine pointed out that he kept his twinsets and keeps one set filled with dil and the other with O2, so he can use them for doing transfills into his CCR cylinders, using his booster, when necessary. That sounds like as good a reason as any to keep mine!

 

[tmassey]

@tmassey: I have 2 Genesis manifolds and 1 Sherwood (or vice versa - I can't remember). All angled. The bands are kind of crappy, but they work, so I don't sweat it. I bought both my sets already doubled up, so I had no issues there.

Sherwood, Genesis: is there even a difference? Those bands are miserable. The sheet metal tack-welded flat between the band bends badly if you tighten the bands enough -- as in correctly. If you don't tighten them enough, they slide a bit, which is not ideal for the manifold... And either way, they make lots of popping noises when you fill them.... I hate them.

I have just switched to CCR, so I briefly considered selling my 2 twinsets. But, then a CCR friend of mine pointed out that he kept his twinsets and keeps one set filled with dil and the other with O2, so he can use them for doing transfills into his CCR cylinders, using his booster, when necessary. That sounds like as good a reason as any to keep mine!

That's a terrible reason to keep them! Use HP133's for that: bigger capacity in less volume. Or with a booster, use smaller and less expensive tanks. And sell the 120's to me!

(Why do I want the 120's back? I managed to find a set of Dive Rite (Thermo?) 7/8" modular valves that accept a standard isolater that I can use standard tank bands with!)

But to the OP: If you're tall, HP120's are great. If you're not, HP100's are also great. Especially for cold water, where you were going to carry lead anyway. LP95/HP117 (virtually the same shape and weight) are heavy and short. LP104/108/112/HP117/119 (again, virtually the same shape and weight) are decent length, but HEAVY. I've only seen LP120's once, but my back hurt just *thinking* about what they must weigh doubled up...

For warm water, I can understand the appeal of a "properly" filled set of 72's. And LP50's are perfect if you want the redundancy but are just doing 60' reef dives. But I dive cold water, so HP100/120's are what I use.

(So many tanks! So little money!)