Most Redundant OC SCUBA?

[Akimbo]

… You have seen it twice, as a result of what must be significant impact. By that description, it would most likely occur on the surface, either entering or exiting the water. Here, normal emergency procedures would be to drop weights and stay on the surface, perhaps with a snorkel in one's mouth. The likelyhood of this happening at depth is pretty low, IMO…

The bail-out impact was entering the bell hatch… commercial divers aren’t known for gentle movements. The second was on a wreck and the impact was surprising small, it just hit the hose fitting at the perfect angle. He was pulling himself into a small hatch and twisted a little too much. We debated for weeks suspecting a cracked hose fitting at the thread… until we tried breaking one on the bench. It didn’t take much to snap off at all when hit at the right angle.

It is only a 3/8" thread. The root diameter is about 0.343 with a hole that is close to 0.20". That is only a 0.0715 Brass wall. Add a 1½ to 2" long swaged “lever” and it is surprising that snapping off fittings isn’t more common. Too bad stainless fittings are so expensive.

Maybe I missed it but what happens in the unlikely event of a regulator supply hose failure?...

We both agree that such a failure is rare, but then so is the need for a second source of gas in the first place. The question wasn’t intended as a criticism. I thought there might be some check valves I was unaware of, which would negate the problem. Even then, the argument can be made that the cure introduces more failure potential than the problem it is trying to solve.

I am just glad to see that there are people who think beyond the dogma professed by far too many waving the DIR banner. Well done.

 

[Akimbo]

This question was intended for Akimbo:
What valves / regulator(s) are on your doubles ?

DIN balanced flow-through first stages, one Oceanic and one Atomic. Yokes won't fit. The isolation valve points toward the butt and you have to lean forward a little for access. The manifold is a 190 mm Blue Steel:

http://www.piranhadivemfg.com/item/Modular-Manifold-Pro-Type-190mm-170

Bands on the double Faber 72s are shop-made and purchased on the Faber LP-45s.

I have a Rev 1 protector on the bench now that is lighter and improves access a little. Here are shots under the protector:

 

[dumpsterDiver]

DIN balanced flow-through first stages, one Oceanic and one Atomic. Yokes won't fit. The isolation valve points toward the butt and you have to lean forward a little for access. I have Rev 1 on the bench now that is lighter and improves access a little. Here are shots under the protector:

That looks really cool. Although the spg hose looks silly (you don't weigh 450 lbs do you)?

 

[Akimbo]

That looks really cool. Although the spg hose looks silly (you don't weigh 450 lbs do you)?

The console computer has a digital compass so the hose length is about right to get it aligned on my centerline wearing a drysuit with heavy underwear. I have tidied up hose routing a bit but it is still a work in progress. It is also the hose I had on the shelf.

I shortened the regulator and drysuit inflator hoses by 6" since taking these photos. The rig is still more awkward to carry in front of you when maneuvering it on deck than I like. I also want to swap the back plate for my Freedom Plate.

I have to restrain myself not to make too many changes at once. Otherwise it is hard to pinpoint the good bad and ugly. There is also the “getting used to it” factor. Things that are annoying as hell just disappear after getting used to them.

Overall my favorite rig is still the old AGA 324. They are a single regulator only solution, are hard to fill to 300 Bar/4,351 PSI, and are too heavy for tropical suits… but they sure are nice to dive.

 

[EdTeach]

I have many Scubapro Pilot's and Air 1's. They certainly accommodate dual first stage supply. I also have 5 D-series regs. I'm not aware that the D-series regulators support dual supply. I haven't used anything newer than D-series regs, which are close to the Air 1 in performance, but I can't imagine any regulator (except the Pilot) surpassing the performance of the Air 1. It must be phenomenal with dual supply!

 

[Glenn08]

Wow. My twin 50's rig is almost identical; valves down, modified Selpak manifold to have one valve at each tank neck, Genesis Recon BC. I had thought my rig was unique.

 

[John C. Ratliff]

Well, the op ed question has been answered, and my rig is not the most redundant, but it does have its pluses.

Akimbo, I really like your rigs and their setup. Protecting the manifold is very important for some types of diving, and it looks like you've done it well. Here are some "vintage" photos of pararescue that show manifold guards on the double tanks.

EdTech, the A.I.R. I on two regulator first stages, being fed from both sides of the second stage, is an awesome second stage combination. I have used this once before, when I hooked up the A.I.R. I second stage to two lines coming off the U.S. Divers Company UDS-1 system. I have used it both with one hose and with two hoses on the UDS-1, and that is quite a combination too due to the huge openings in the manifold of the UDS-1, and also the integration of the first stage into the manifold of the UDS-1. Currently, I still have my UDS-1, but cannot get it hydroed due to the need for a eddy current test and no one having a one-inch eddy current tester. But I may get this resolved in the next year or two.

I confess that one of my reasons for this experiment was to take it to a different level. This was a phase I test, to prove the concept of using two first stages simultaneously. I have visions of changing the rig so as to allow two regulator first stages to feed into a Sherwood twin-manifold center piece, after machining it to accept an LP hose rather than the ends of the double manifold. That would give me a valve turn-off in the center of the rig, and then I would attach a vintage Mistral single stage regulator. This additional piece would allow me to isolate the left and right lines if there were a malfunction by simply turning off the valve, then going to a safe second on either side. What this would do, however, is put the Mistral on a LP line, in effect making it a second stage. We already know it was probably the best-performing double hose regulators from U.S. Navy Experimental Diving Unit tests, and this would also allow it to be positioned in a variety a places (chest mount, or on the harness, for instance) and not forcing it to be on a HP valve on the tank.

SeaRat

PS, yes, that is yours truely in the parachute harness in my younger days (about 1975), showing the integrated parachute harness and tanks with the manifold guard I talked about. The two photos on the left show Pararescuemen using our twin 42 cubic foot tanks (2100 psig rated, former 21 man life raft bottles) with their manifold guard. The other is also me, in the UDS-1 with the A.I.R. I regulator attached.

PS2, Nope, the Sherwood manifold would not isolate left and right sides (I just did the ol' breath test on that centerpiece); back to the drawing boards on that one. It would allow me to use the Mistral though, which is the main goal.

 

[Akimbo]

Well, the op ed question has been answered, and my rig is not the most redundant, but it does have its pluses...

I am not sure who won, certainly not me. My rigs are nothing more than standard isolation manifold doubles that happen to be valve-down. I vote for this guy... but I never want to be him

 

[John C. Ratliff]

One of the other things about diving I have come to abhor is the lack of streamlining of today's divers. I am the former Fin Swimming Director for the Underwater Society of America, and hanging tanks haphazardly onto a diver's frame seems to go against why I dive, which is to freely swim in any direction more like a fish than walking like a normal person on land. I relish the time, for instance, when I swam fast in current and surprised a Chinook salmon, which normally stay out of visibility range in the Clackamas River. Or the time I came effortlessly up to a 7 foot sturgeon. Swimming in this manner underwater is very difficult in some of today's configurations.

Today's divers use ineffective kicks (the modified frog kick--I'm a former breaststroke swimmer who actually knows what a frog kick is about) to minimize causing silt-up situations, but doing so does not efficiently propel the diver. The frog kick is for very specialized diving in wrecks or caves where silt-up situations are a hazard. I'm also a "vintage diver" who usually is in the vintage equipment forum, but I'm tired of the emergency of technical diving techniques pulling us away from the weightless, effortless diving I have known most of my life.

SeaRat

 

[AfterDark]

Very well said John. I'll second that. I hate the little 19cuft I sling too often.