O'Malley:
The purchase of a drysuit this spring not only allowed me to begin diving much earlier locally but also exposed me to the technical realm of diving...and the itch to go this route is becoming intense. I am considering the DSS single tank rig w/ the 40# wing and hog harness. I currently own a pair of PST E7-100 cylinders but not ready to double them up presently so...
- Are H valves a good option and is there a specific one compatable for the PST tanks rated 3442 PSI?
I am also slightly confused about weighting. I currently dive a BARE XCD2 Tech (2mm hypercompressed neoprene) drysuit, SP Knighthawk BCD and require 24#'s of weight. The backplate-mounted weights from DSS seem to be a good option.
- What are the thoughts out there on this vs wieght pockets, weight belt?
I read somewhere that most BCD's are 3#'s positively buoyant and according to the DSS backplate specifications, the plate is 5#'s negative. Add the 8.1# backplate-mounted weights and...I still may require approximately another 8#'s of lead based on my limited knowledge of backplates and weighting.
I started using the DSS b/p and 30# wing this winter with my DS (I dive with a single tank). At the same time, I started using Weezle undies, so I could dive in NJ's winter waters. Before that I'd been using a SeqQuest Pro-Unlimited BCD (with ditch pockets), and 300-weight Polartech undies.
I don't understand why for sure, but my total ballast requirement went up! It went from 14# with the jacket BCD to 22# with the b/p and wing.
The increase may be due to a lot of new buoyancy from the insulating air trapped in the new Weezle undies (very warm). But it may also be that I'm overweighted, but if this is so, I know it's not by a lot. I haven't had enough time and dives on the system to prune the weight down carefully or to check it properly at 500 psi. We'll see, eventually.
BTW, the 30# wing works just fine for me.
A very nice feature of the DSS b/p is the bolt-on weight plate that's available. Using this allows me to carry about 10# over my lungs, with the other 12# on my waist. This distribution is working well for trim and bulk. I may try moving a little more weight over my lungs with weight pockets on the tank bands..
I'm still working out the best way to carry the waist weight. Currently I'm using a DUI harness under my DSS Pro-Fit harness. But I might try switching back to a belt, and I might try the smaller-sized DiveRite pockets.
OBTW I love the system design of the DSS b/p and wing. It's rock solid, even without a STA. Furthermore, because there's no STA, it's a snap to remove the wing from the b/p. This makes it easy to rinse it inside, get all the water out, and drain and dry it.
Regarding H-valves, I don't have any direct experience. But I've thought about them. Although they give you two first stages, I concluded they still leave a single-tank diver exposed to single points of failure, namely, the tank's O-ring and the valve mechanism itself (the knob could shatter or come off, for example, or the inner works could seize up). And some divers can't reach their valves anyway, and I think most don't do valve drills. Although tank O-rings seem to fail only rarely, they have been known to fail, and cave divers cite knobs on doubles as needing care.
For safety planning, I think such possible failures and shortcomings need to be accounted for. Consequently, I use a pony bottle for the redundancy I want. I'd still rely on my buddy as my primary life support backup, but the pony makes me completely self-sufficient in the very worst case of my buddy being unable to help. The pony also provides me with bailout gas (purposely ignored in dive planning).
I'm currently acquiring experience slinging the pony, having previously carried it on my back, attached to the tank. That was a bit of a nuisance to switch between tanks, tho, even with the quick-release devices that are available.
I have a friend who thinks the same way about planning for safety, but who dives doubles. He uses one tank as his main and the other as an equal-sized pony. He switches between them on his dives to draw them down evenly and to ensure all his regs are working.
Hope this helps you out. Good luck. Maybe let us all know how the change-over works out for you.
