To my pleasure, I got a phone call the other day from Brian Wiederspan, informing me that Jeff Seckendorff was going to come up for the Essentials class at the Aquarium, and would be bringing a couple of Z-system rigs with him. Did Peter and I, Brian asked, want to join Jeff in the pool to play with the rigs? The answer was obvious . . . So yesterday, through the graciousness of the Seattle Underwater Sports store (which allowed us to use their pool), we got to spend a half hour or so seeing in real life what this system is all about. We shot some photos and video, some of which I'll link in here, and Brian took a bunch more, so I hope he'll add.
My first impression was to be delighted with how compact the system is. The harness, wing, block and second stages all folded up into a bag about the size of a reg bag, but perhaps three times as deep. Jeff got three of these bags into a standard roller duffle.
My next impression was to be daunted by how all the straps and hoses had managed to rat's nest themselves inside the bag . . . I poked and prodded at the thing for a couple of minutes, but then Jeff came over, did a magic trick, and presto! it was all sorted out.
We then spent some time adjusting the harness for each of us. It didn't take very long for Peter, but as usual, dive gear just isn't designed for hobbits, and it took a lot more tinkering for me. In the end, it just wasn't possible to make it perfect, and I did see with interest that, having shortened the back strap as much as we did made the wing bow out away from my back in the water. Of course, as Jeff pointed out, all the components CAN be customized, if it's one's own setup.
I went and changed, and came back and shrugged into the harness. It was quite a bit tighter than I run my standard harness, and a bit of a pain to get in and out of, but again, that's something that would just take tweaking. It is SO nice to put on the harness and regs, without the weight of a tank! Since we were diving the monkey-diving version of the rig, we had 5' hoses, and I found out that a 5' hose fits me perfectly (I'd never used one before).
We went through the use of the QC, and the modifications they have made to ensure that they cannot come undone inadvertently. I have no concerns about the QC connections; they are commonly used for rebreather drive bottles, and if they're good enough for those guys, they're way good enough for me. Mine was easy to disconnect, but a bit more difficult to connect while pressurized, which is kind of important for managing certain possible malfunctions (more about that later).
I tossed my tank in the water (not exactly, out of respect for the pool surfaces, but you get the idea) and comfortably climbed down the ladder and into the water. Hooking the tank on was exactly the same as donning a stage, except for pulling the bungie forward and over the valve knob, which wasn't difficult, even with my arthritic thumbs. I got the QC connected without too much difficulty (need stronger pectoral muscles!), and filled the wing. Floating at the surface was very similar to doing so in the Nomad -- the wing held me up very well, but I did have to lie back on it to avoid going forward. I don't mind that.
In the water, the rig felt very stable and familiar and comfortable, as it ought. I was a bit baffled by searching for the inflator, which was too long (but again, in my own rig, this would be changed). The tank was initially very sloppy, but I wrapped the rear clip around the handle, which snugged it up quite a bit (and Peter did the same).
I played around for a bit with the single tank on, as you can see. But I'm not a big monkey diver, because I just don't like being unbalanced that way, so I requested a second tank, just to clip on to see what it would feel like.
It was immediately MUCH better. I had the same fore and aft stability I had liked so much with my prior sidemount sampling, although the tanks were a bit more mobile than the setup I had used before. This didn't surprise me, because these tanks were stage-rigged, and it's my understanding from my reading that, if you want sidemount tanks to be PERFECT, you will probably have to move the bands around until you find just the right place for them.
More play ensued. I found it very easy to vent the wing through the inflator -- I completely forgot to try the rear dump, to see how it would work. I could swim on my side:
We had such a short window of opportunity, we didn't get to do some of the things we had planned, like air-sharing, but judging from the flow through the block, I don't think it would be an issue.
I spent quite a bit of time talking to Jeff about using the system as a double-tank sidemount setup. I raised the IP question, and he acknowledged that it is an issue, and right now, they are dealing with it by only opening one tank at a time. Initially, it bothered me to think that I'd be swimming around with one of my tanks turned off, but then I realized I swim around with my stages turned off, anyway. However, it does negate the advantage of a manifold, which is being able to access both of your tanks at once.
In the event of a blown hose or disconnection behind you, the strategy would be to disconnect the QC and put a spare 2nd stage on it. Of course, if you're monkey diving, you do just what you would do with a single tank, and go to your buddy for gas . . . which the Z-system makes easily possible, since each of you has a standard long-hose/bungied backup regulator setup. In a cave, especially in a restriction, the idea of fumbling in my pocket for a second stage, and then trying to shove it onto the QC, all the while possibly without anything to breathe, was worrisome.
But the thing that bothered me the most, thinking about it last night, is that, by hooking both regulators up to a single gas source, you've basically lost the redundancy that either a manifold or independent sidemount doubles gives you. This is because the only solution to a major leak anywhere in the system (at least beyond the first stages) is to shut the gas supply to BOTH regulators down.
So I think I came away with several conclusions: The setup is a nice way to allow monkey diving and enable the divers to share gas, without any convoluted hose setups. The harness and wing have a lot of potential as a sidemount setup (probably work great right now with Al80s in warm water, and wouldn't take a whole lot to scale up to cooler water/bigger tanks). But I don't see the block working, for me, in its current form, for technical or overhead diving, because of the loss of redundancy.
Thank you so much, Jeff, for bringing the equipment for us to try. And again, a big thank you to Underwater Sports, for their generous hospitality!