High Pressure Hose Configuration

[sigxbill]

Sorry guys, but I have to roll my eyes here. I dive a(n) Air2 on my singles rig... Can anyone explain to me how eliminating ... a second stage plus a LP hose REDUCES streamlining?

Tbone1004 is spot on:

the air2 is more bulky than a normal inflator and creates a larger drag profile than a necklaced secondary because it is hanging below you vs. under your neck. It also has the significantly longer hose which is typically not restrained properly *because there is no real way to restrain it properly* so is often dangling.

Additionally, the Air 2 / Atomic SS1 are horrible options for air sharing!
1. the short length of the donor's primary hose places the recipient so close that it is difficult to focus or do anything.
2. Short hose length limits options to only direct ascent. Very little option of swimming back to up-line.
3. Short hose length limits ascent orientation to vertical instead of horizontal
4. Since bcd control is in donor's mouth, donor ascent buoyancy control is difficult
5. Since donor's right hand is holding onto recipient's right shoulder, left hand is presumably trying to control ascent, and short hose has team super close together, it is difficult to find / hold / view depth gauge to monitor ascent.

I'm probably forgetting other issues with Air 2 / Atomic SS1 ...

I have seen many students struggle with these issues, and consequently the issues are usually ignored and glossed over - leaving the student in greater risk than they realize or have knowingly accepted ...

 

[stuartv]

Tbone1004 is spot on:


Additionally, the Air 2 / Atomic SS1 are horrible options for air sharing!
1. the short length of the donor's primary hose places the recipient so close that it is difficult to focus or do anything.
2. Short hose length limits options to only direct ascent. Very little option of swimming back to up-line.
3. Short hose length limits ascent orientation to vertical instead of horizontal
4. Since bcd control is in donor's mouth, donor ascent buoyancy control is difficult
5. Since donor's right hand is holding onto recipient's left shoulder, left hand is presumably trying to control ascent, and short hose has team super close together, it is difficult to find / hold / view depth gauge to monitor ascent.

I basically agree with you. But, to be fair (as in not give easy ammo to the opposition), #s 1 - 3 and #5 could easily be addressed by having a 40" hose and swivel for the primary. With that, you could donate your primary, stay in horizontal trim, breathe off your Air2, and vent using a butt dump. In other words, if your student just says "okay, I'll put a longer hose on my primary," then most of your reasons against an Air2 are right out the window.

But, even with a 40" primary, it still seems to me that a short hose to a 2nd stage on a bungee necklace is both better for emergencies and also more streamlined. Not to mention more versatile (use your reg set on any BCD), more comfortable to breathe from when you do have to use it, probably going to also breathe better, and leaves you free to manage your ascent however you always do it, versus potentially doing something different than your "normal" in an emergency situation. Having buoyancy management be the same, during an emergency, as it is at any other time, seems like a good idea, to me.

 

[CuzzA]

Tbone1004 is spot on:


Additionally, the Air 2 / Atomic SS1 are horrible options for air sharing!
1. the short length of the donor's primary hose places the recipient so close that it is difficult to focus or do anything.
2. Short hose length limits options to only direct ascent. Very little option of swimming back to up-line.
3. Short hose length limits ascent orientation to vertical instead of horizontal
4. Since bcd control is in donor's mouth, donor ascent buoyancy control is difficult
5. Since donor's right hand is holding onto recipient's left shoulder, left hand is presumably trying to control ascent, and short hose has team super close together, it is difficult to find / hold / view depth gauge to monitor ascent.

I'm probably forgetting other issues with Air 2 / Atomic SS1 ...

I have seen many students struggle with these issues, and consequently the issues are usually ignored and glossed over - leaving the student in greater risk than they realize or have knowingly accepted ...

The length of the primary has nothing to do with the length of the Air2. My 40" hose is more than adequate for an OOG ascent. Hell, I could use a 7 foot hose if I wanted to. But that doesn't make sense to me unless you're in a wreck/cave.

Swimming back to an up line is how people die. This exact thing happened recently off the coast of NC. Both divers perished.

I disagree with TBone, but that's ok. One fewer hose and one less reg is less mass and more streamlined.

I mount my Air2 to a magnet that keeps it tight to my harness.

The only negative is simultaneous breathing and buoyancy control. Practice and it's not a problem in the rare event someone goes OOG.

 

[tbone1004]

The length of the primary has nothing to do with the length of the Air2. My 40" hose is more than adequate for an OOG ascent. Hell, I could use a 7 foot hose if I wanted to. But that doesn't make sense to me unless you're in a wreck/cave.

Swimming back to an up line is how people die. This exact thing happened recently off the coast of NC. Both divers perished.

I disagree with TBone, but that's ok. One fewer hose and one less reg is less mass and more streamlined.

I mount my Air2 to a magnet that keeps it tight to my harness.

The only negative is simultaneous breathing and buoyancy control. Practice and it's not a problem in the rare event someone goes OOG.

reduced mass does not = more streamlined, nor does one less hose = more streamlined

If you are using a magnet, that is the least bad way to mount them since it will hold it close, but it is still creating a larger drag profile on the bottom of your chest than a properly routed secondary on a necklace and a sufficiently short inflator that is on the front of your shoulder.
Is it significant? No, obviously not, but streamlining is not the reason you go to an Air II. Hopefully you are also using a normal regulator hose with an adapter to the QD because the dedicated hoses certainly make the whole prospect ridiculous since the AirII costs more than an inflator and a secondary, and the custom hoses are obviously not regularly available and are always more expensive than a standard reg hose.

 

[BoltSnap]

I use a 40" for the primary when using the AIR II and no issues whatsoever of any kind in about 20 years of diving with it.

 

[charlier]

Cuzza, I am with tbone on this topic. While teaching gas sharing with a student using an Air2 or Atomic SS1:
a) it is not easy or comfortable breathing from the short and bulky corrugated hose, in particular if one has to travel back to an easy exit point.
b) donor’s BCD control is not easy or straightforward. Plus it’s an OOA situation, it’s nice to face each other for eye contact.
c) with the short corrugated hose, it hard to have much separation between team members, it’s hard to fin, deploy a SMB, monitor ascent rate/look at a computer, or dump air from BCD or wing. Lastly, the SS1 or Air2 dangles too low, in particular while diving with moderate or strong currents along a reef. Such a configuration would not be optimal as a dive guide.

 

[sigxbill]

@CuzzA and @BurhanMuntasser

I'm just curious - how do you route your 40" primary hose? Under or over your right arm? Around your neck? I assume you only plan on vertical ascents for OOG?

 

[stuartv]

I don't know about them, but I use a 40" hose under my right arm on my primary of my single-tank reg set. If I donate it, I will sweep my arm under it to fully deploy it from the 1st stage, over my right shoulder, and to the recipient, just like I would as the final part of a 7' hose deployment.

Maintaining horizontal trim during an ascent should not be a problem.

 

[HantsDiver]

Maintaining horizontal trim during an ascent should not be a problem.

Nor should it be a consideration to any diver apart from on the internet. Who cares if they ascend in trim or not if they are genuinely out of gas... If I'm ever close to drowning I don't care how pretty I look. Nor do I care if I can fine tune my buoyancy control...

 

[decompression]

And that is an issue.....treating what should be an “inconvenience” as an emergency. Again with proper gas planning (rock bottom) and drills (long hose donation while ascending) this is a simple ascent not a panic to forget about skills and just get to the surface.