Steel Stage Bottle for Sidemount?

[Addison Snyder]

Got Intro to Cave a month or so back, and have been diving nearly every weekend since. One of my buddies showed me a little hack where he dives with a stage bottle and breathes off of it exclusively to and back from turn pressure. He converts cubic feet and psi between his backmounted doubles (LP85s) and breathes the equivalent from an aluminum 80 he carries. This allows him to suck a single tank dry while maintaining good sixths (doubles to 3600+psi, so 600psi to use in each tank, so around 1500psi to use in the aluminum 80) for multiple dives. Overall a really beneficial hack (if I need to explain in more detail, let me know). One of the other cool things is that he gets to really practice with stage bottles when in this config (lucky bastard is getting full cave in a week).

This weekend, I wanted to give it a shot. Problem is that I have only 4 steel LP85s in a sidemount configuration (on an old Nomad XT). Is there a proper way to clip a single heavy cylinder for that? Without going into a cave, I initially tried clipping it on the right side to see how bad the tilt would be (it was bad...). Then, I tried having it diagonal from my lower left D-ring on the waist belt to the upper right on the shoulder belt. The 3 or so inches of play from the neck choke I fashioned allows the tank to wobble a lot, and definitely wasn't tight or flush against me. Finally, the buddy suggested that I mount it from my butt plate (like my doubles) to the shoulder ring (whereas my doubles are bungeed near my armpits). This felt tight (neck choker was too short for that). While I could lengthen the neck choker to be comfortable, I'm worried that I'm still going to see the world from a 45 degree angle in that setup.

Is there a proper way to have a third steel cylinder attached in a sidemount config? Should I give up and buy an aluminum? Thanks in advance for advice. Edit: bonus points for video/images of examples.

 

[grantctobin]

No, esp not one without a bunch of helium in it. Also a standards violation. Please don't do this.

 

[Addison Snyder]

Also a standards violation

Explain? If you're saying that this practice breaks the 1/6th rule, he is using the 1/6th volume of his backgas (on his back doubles), just getting it from a third cylinder. This keeps redundancy and effectively limits him to the same penetration as without the extra cylinder. The pro to this is that he doesn't have to top off tanks nearly as much.

 

[tbone1004]

do not dive past your certification level. Stage bottles are not covered in intro to cave for a reason. There are stage cave courses that cover proper use of stage bottles. SOME agencies like NAUI teach the use of buddy bottles in their cave 1 courses but they are not touched in normal diving. The courses teach proper carrying and proper gas use out of the stages as well as how to deal with air sharing emergencies.
While your buddy is not necessarily violating the penetration limits of his back gas, it is certainly not in the spirit of the limits to be diving like that. I do not know what agency you were certified with to say it is specifically forbidden at that level, but I don't think you'd find any instructor that would encourage that behavior.

Steel bottles do not hang well as stages, as you have found out. There is no good way to do it, and it shouldn't be attempted, there is a reason we don't use them.

 

[Addison Snyder]

Gotcha. Will not push those (implied?) limits then.

 

[rddvet]

You shouldn’t be carrying a stage bottle at Intro level. You can’t even make jumps or navigational decisions. So instead take your time and learn to read the cave and learn to relax. You will likely not get that much further with a stage since you’ll be uncomfortable and draggy with it. Take your time and go slow. The people that are rushing to move to the next cert end up being crappy divers who give up within 3 years (one of the reasons I don’t like the nss-cds 4 part system)

the simple fact that you don’t know how to set up a stage or that a steel stage is pretty much used by no one should be an indicator to you to slow down because there’s a lot you don’t know.

 

[Addison Snyder]

You will likely not get that much further with a stage since you’ll be uncomfortable and draggy with it. Take your time and go slow.

Seems you didn't read or understand what I posted. I wouldn't be getting further with the stage, simply would be saving myself tank refills. But the point is moot, not gonna push limits.

 

[tbone1004]

Seems you didn't read or understand what I posted. I wouldn't be getting further with the stage, simply would be saving myself tank refills. But the point is moot, not gonna push limits.

I think that @rddvet worded that a bit backwards. What he was meaning to say is that even if you are using a stage as a stage, you often don't get any farther than just on backgas. I.e. if you can get say 2,000ft of penetration on thirds of backgas 85's *75cf ish of penetration*, when you first start stage diving and are able to use 100cf of penetration, you'd think you would be able to get 2,600ft based on the math. In reality, most people will only get around 2,200ft because the extra weight, drag, etc slows them down and makes them less efficient.
With the set up as you describe, you are actually going to go less far than you would if you were on backgas alone, ESPECIALLY if you're trying to deal with an LP85 as a stage.

 

[Julius SCHMIDT]

saving myself tank refills

Here it is

 

[rddvet]

I didn't word it well. What tbone said.

Either way focus on being comfortable in the cave. That's the whole point of an intro cert.