Single versus dual bladder wings

[Serota]

I've been puzzling over this topic for a while, so I thought I would throw it out for opinions:

In cave diving we go to great lengths to have double and triple redundancy in all of our life support equipment except in many instances the bladders in our floatation devices. I am aware that many people count on their drysuit as backup floatation (hopefully they have verified this), but since I usually dive wet I am interested to know how I would get out alive after a bladder failure from from lets say, a modest 500' into Peacock I, let alone any futher/deeper. I'm not sure what assistance a buddy could provide in this situation, so assuming none (which may be a wrong assumption), I guess I would have to basially crawl out along the bottom, which would silt out the entire passage, endangering anyone else in there, damange the cave floor and then getting up the more of less vertical slope from the cave to the cavern would be interesting as well. Upon reaching open water, I assume the procedure would be to try to do any required deco and then remove gear and swim to the surface.

Secondly, it so happens that I own a dual-bladder wing complete with bunges. I cannot maintain even trim with it and suspect removal of the bunges would help a lot. To date rather than modify it, I have just used a single bladder wing with no trim problems. However, if I do get around to removing the bunges and making sure the bladders inflate evenly - why not use it just in case?

All constructive comments are appreciated!

[Walter Pickel]

When I dive wet with doubles I carry a lift bag in one of my pockets. I used it in the Nest once from the mound to 70'...Works as well as you would expect but it works...

[Dave Lizdas]

got a buddy who modified his giant dual bladder DR Super Wing for this. He removed the bungees, folded it over, and tied it down. It ended up the size of my DR Classic, smooth on the outside, with a backup hose placed neatly out of the way. He had some issues with too much gas going into the top arch of the wing. it took a few evenings of tinkering and a few dives to get it right, but its possible.

I use a drysuit, and yeah - i verified it - its totally sweet - just as easy as the wing. It probably helps that my drysuit is snug in the legs.

[Tegg]

When I dive wet with doubles I carry a lift bag in one of my pockets. I used it in the Nest once from the mound to 70'...Works as well as you would expect but it works...

For some reason I am laughing at the image produced by your description...

The lift bag inflated and clipped to your crotch strap d-ring and you hugging the line with the lift bag above your head... hahaha

[aw]

I guess I would have to basially crawl out along the bottom, which would silt out the entire passage, endangering anyone else in there, damange the cave floor and

And you'd have everybody on every forum bitching about how careless full-cave divers are now adays versus what they used to be back in 1901.

I wanted to see if I could survive a bladder failure too. So I started at 2000 ft upstream in Bonnett and bellycrawled out. . . . . . .

JUST KIDDING!!!!!

Take a car tire innertube and cut it like a horseshoe collar. Place it around the bladder inside the zipper of the wing. This will give extra protection against sharp edges, tears, and cuts.

[andrebasso]

Here's an idea. I've never tried it but I'm sure it will work. -> Sandwich two wings together behind the backplate. A smaller backup wing goes in front and the larger active wing stays in the back. When you're diving, the active wing inflates normally and rises up to hug the sides of the tanks, the backup wing lies dormant underneath and doesn't get in the way at all. For the backup wing, swap the dump valve and the inflator valve so that the inflator hose come from the bottom right corner where the dump normally resides - this way it can be clipped to the left D-ring and not confused with the active hose coming over the shoulder.

Just an idea I've thought of implementing, gives total redundancy and because both bladders are not in the same wing, air does not get trapped in any way.
.

[Gary]

At least for me my bouyancy needs towards the end of a dive are fairly slight and partial wing functionality would be sufficient. I've often wondered what would cause such a catstrophic failure of a BC that is would provide inssuficient bouyancy to turn the dive and get out - and whether it may take out the 2nd BC along with the first.

For some dives I have a second wing on the screw mounts (basically as andrebasso has suggested above). Probably more drag then most double bladder BCs but also two seperate protection mechanisms instead of 2 BCs in one protective wrap that might puncture or tear together (not specifically better - just another option).

In dual BC mode I favor a smaller, maybe even single tank BC (for less drag and less area exposed to whatever may have hurt the primary BC) with the auto inflator unattached. I've heard of a few power inflator free flow incidents sending people uncontrolably upwards but no/few BC failures that sent them uncontrolably downwards. In an emergency I'm satisfied that I can hook up the air supply to the 2nd power inflator or orally inflate. In the opposite situation (uncontrolsed inflate) having 2 BCs (both supplied) to contend with may make it impossiable to determine which is the problem to try to vent and unhook it from supply air before the attempted fix is moot.

Another option in a emergency: some wetsuits, especially one piece suits and semi drys, can hold air also. Its won't power inflate but can orally fill through a sleave or with a regulator.

[Genesis]

I've tested using a lift bag in the ocean as a means of emergency buoyancy. It works but of course trim is impossible.

In a cave I'm not sure if it would help or hurt, and due to the horizontal distance issues you might run out of gas attempting it in either direction.

But when I cave dive I am basically always diving dry, so I have the suit. That's a lot of "fun" to try to manage too, but its easier than a bag is, and at least you can swim.

[nic160]

If you're not solo, what about getting on your buddies back and using his wing to give both of you lift ? I know swimming/trim and restrictions would be PITA. But as long as you don't have 14 stage bottles wouldn't this be an option. I'm no way saying that you should count on someone other than yourself in an emergency. But if someone is sunk like an anchor isn't it worth a try.

[Genesis]

If you're not solo, what about getting on your buddies back and using his wing to give both of you lift ? I know swimming/trim and restrictions would be PITA. But as long as you don't have 14 stage bottles wouldn't this be an option. I'm no way saying that you should count on someone other than yourself in an emergency. But if someone is sunk like an anchor isn't it worth a try.

Ever tried this? You should sometime - I did as a simulated "recovery" of a "dead" person. It doesn't work real well with the buoyant person on the bottom as the CG is all backwards - you tend to try to flip over BIGTIME.

Let me just say that this little exercise was the toughest 300' I've ever swam in a cave.....