directing valves inside (to the chest)?

[Mike1967]

The knob is rotated back to horizontal and "out" by the bungie in that rig. So the regulator ends up being down. Even in lp50s (which are skinny tanks) the tank is much lower than the actual regulator. And if the neck bungie is sized right (both diameter, stretch, and length) the tank rides on your side and even those of us who have no beer gut bump our guts before the regulator hits anything. In 8" tanks like 95s,108s etc the bottom of the tank is in the same plane as the beer gut.

Ok couple of questions.
If you roll onto your back wouldn't the tank roll as well potentially letting the bungee slip off the handle?
And I get the bottom of the tank sits lower than the down facing reg but how does that stop the reg smashing into a rock, for example, or anything else jutting up/out?
What makes this way better than wrapping the bungee around the stub and reg facing up? à la Steve Martin, and probably the most common way.
SM noob here just trying to understand.

 

[rjack321]

Ok couple of questions.
If you roll onto your back wouldn't the tank roll as well potentially letting the bungee slip off the handle?
And I get the bottom of the tank sits lower than the down facing reg but how does that stop the reg smashing into a rock, for example, or anything else jutting up/out?
What makes this way better than wrapping the bungee around the stub and reg facing up? à la Steve Martin, and probably the most common way.
SM noob here just trying to understand.

Roll onto your back lol Yea you've been watching too many Bogarts videos.

The "most common wrap" that you are talking about doesn't work with steel tanks heavy with nitrox. You can't do that with 3/8"+ bungie and they hang too low. The old school bungies which were first diagramed on that old armadillo page (even if they predated that) are about 50% thicker than a Mexican al80 bungie to hold up a 95 or 108 *at your side* which the long single bungie used in Mx does not succeed at. You wont find many people in FL wrapping the stub so "most common" only really applies in certain areas and environments

 

[Mike1967]

Roll onto your back lol Yea you've been watching too many Bogarts videos.

The "most common wrap" that you are talking about doesn't work with steel tanks heavy with nitrox. You can't do that with 3/8"+ bungie and they hang too low. The old school bungies which were first diagramed on that old armadillo page (even if they predated that) are about 50% thicker than a Mexican al80 bungie to hold up a 95 or 108 *at your side* which the long single bungie used in Mx does not succeed at. You wont find many people in FL wrapping the stub so "most common" only really applies in certain areas and environments

Doesn't everyone roll onto their backs for fun? Lol
And I'm assuming that because the tanks are higher the regs have to be face down to put them in the same position they're in when the tanks are lower?
So I'd just swap left and right tanks, shorten the bungees and bottom clips stay where they are, inline with the stub?

 

[Doby45]

Doesn't everyone roll onto their backs for fun? Lol

Not in caves or wreck penetration.

 

[MichaelMc]

I sidemount in OW with LP50s or AL40s and roll onto my back to:
- engage more easily with the harbor seal chewing on my fin
- look at the kelp and fish in it above me
- look for my dive buddy who likes swimming above me
- check for leaks
- have fun swimming facing the silvery mirror of the surface

On tank loss, I have modular valves and the loop bungee is fairly far around the valve, and the bungee is anchored to my back and to the front strap as well, so a) the valve does not seem to shift backward very much from the flip of gravity, and b) the tank would need to unroll quite far to free the bungee from the modular valve stub. I think the back end falls the other way when I invert, which I try to be conscious of when I am close to the bottom that my tanks do not hit anything. Plus, my, tiny, tanks are closer to neutral than many.

 

[Mike1967]

modular valve stub

He was explaining the method that has the bungee around the knob not the stub.

 

[MichaelMc]

He was explaining the method that has the bungee around the knob not the stub.

Ah. (other than use a modular valve, or double wrap the valve...) Way too many forces at play.

Edit: Someone with more experience should answer that. I could only speculate....

 

[tbone1004]

And he also has the bungee wrapped around a down facing valve knob?

yes but it's a non issue as mentioned above. I know it's mind boggling to think about with so much of the nonsense talked about online or in some sidemount circles, but plenty of seriously restrictions are navigated with valves facing down. If your tanks are flat, the tank still hits long before the valve does.

Tank won't roll out when you go upside-down because the forward attachment point for the bungee won't let it go too far up. I don't go upside-down all that often, but the bigger issue when going upside down is the lower attachment points cause the tanks to drop quite low since they don't float like an AL80 does.
The advantage vs. valves up are that you can lollipop your SPG's which make them significantly easier to read when on a DPV, and in general when you have your tanks in tight trim with loop bungees. You also generally need thicker bungee with the big steel bottles we use in Florida which means that checking those SPG's are a two-handed operation which is really annoying when on a DPV.
Most of the Mexico style cave divers have their necks hanging relatively low which makes checking them less annoying.

Note Steve's bottle position

and mine. If the tank was rolled over 180*, the spg's would be laying almost inline with my spine and would be very difficult to reach back and read. With the forward facing spg's I just have to look down. You can see the spg hose is actually bent down by my armpit so they are not dragging at all.

 

[Mike1967]

@tbone1004
Thanks for that mate, you always make a lot of sense.
Got a few other questions now sorry.
What do you mean forward attachment point for the bungee, it looks like it's looped around the knob and goes straight to your back?
You obviously don't use the fifth port?
And is that a butterfly clip your using at the bottom and are they attached in line with the valve stub? Your tanks sit nice and high considering you're not using a butt plate.
I'd like mine to sit high like yours so I'm still toying with ideas, I use transmitters so reading SPGs isn't an issue.
TIA, Mike

 

[tbone1004]

@Mike1967
forward attachment is the leash that goes from the loop bungee to the chest d-ring or wherever it attaches. Keeps the loop from flopping around when disconnected but also prevents it from falling too low. When you go inverted, the bungee can only come back so far, and the friction from the inflator/regulator hoses tends to keep it in place the rest of the way. I have my tank bands up very high *those are HP120's so rather long*, and the tanks don't want to see saw very much because of that which also helps keep them normal.

No 5th port on that first stage, though I do have swivel turret regs. I never found a situation where the 5th ports did anything for me that were really beneficial. On the long hose side they can help if you're diving dry during an air share, but that was really the only benefit. I dive with a 9ft hose and since I'm cave diving the odds of ever having to donate are low enough that I'll deal with the drysuit hose turning up during a single-file air share. I find the hose routing to be cleaner without using them.

Butterfly clips on the bottom make clipping them in significantly easier. With AL80's it's less beneficial, but remember that these tanks are quite negatively bouyant at the start of the dive and it's a fairly long lever arm. If you ever have to go bottle off, it makes putting them back on much easier. If I was diving with AL80's I'd still probably use them because I like them, but they aren't as critical.
They're not quite in line with the valve stub, there is a bit of clocking but not much. With the regulators that are on there *Poseidon 3960's for reference*, they are quite comfortable in that position. With my MK25's I have to clock it a bit more for comfort.

No butt plate, but I do use drop d-rings mounted as high back on the waist belt as I can with that rig. I don't like normal d-rings because they rotate which allows the tank a good 4" of movement when you roll. These are the same basic design that @cool_hardware52 came up with for the Razor for the butt pouch attachement, and were actually originally designed as an offset d-ring for use under the counterlungs of a rebreather. They're quite nice and really help to keep the bottom of the tanks in close.

These are LP120's vs HP120's *19 liter vs 15 liter, but the clips are in the same spot. For top attachment, it's really just getting the bungee loop the right length for your body. Most people struggle with that and you end up making the bungees much shorter than you'd think and their attachment to the front of the harness significantly longer.
I'm using transmitters now as well, but haven't really changed anything on the LP side or the orientation as the hoses are routed comfortably so never felt a need to change them. As said above, before those regulators are going to hit something, whatever that something is has to hit your shoulder, chest, and tank so it'll have to be pretty stabby to get inbetween your armpit and the tank