18 replies to this topic

[Dive_Girl]

I really don't think that many, including myself, could hold a spot for very long while shooting a bag in blue, bottomless water with negative equipment in an emergency. I am the first to admit that it is a bit of fantasy to think that one can hover, shoot a bag, and swim up a rig if other than slightly negative or neutral under these circumstances.

I also don't think that I could hold stops for an hour or so while doing decompression with negatively buoyant equipment. I normally dive dry, and I carry two bags of some sort. I am able to ditch my light and my EPIRB if I need to.

I hope that I have the right stuff to get me back alive should something really bad happen in blue, open water. Don't be so confident that this is such an easy thing to do. I'm not willing to bet my life on it.

And that is where I was going...we all talk about our options 2, 3, 4...but when have we actually thought them through or practiced them?

In addition to another thread sparking this topic, when I was in NC and my tank took a tumble, it snapped my wings lower dump valve. The valve didn't leak air, but I had no way of quick dumping from it without the pull bobble (or whatever the heck it's called - 6gill where are you with the terminology?). VADiver was concerned and I appreciated it, so I explained that I would rely on my drysuit more for the remaining dives just in case. I swapped it out when I got home with my back-up singles wing and a new dump valve part has been ordered.

[Dive_Girl]

For option 2, if you are solo, tread water slowly while you deploy the bag, or sit on the bottom and deploy the bag. If not solo, buddy gives you buoyancy temporarily by holding your tank, d-ring, manifold, etc., and you shoot the bag. Or the BUDDY shoots the bag while you tread water and then you ascend with his spool/reel.

So you ascend by pulling yourself up along the line with your lift bag on the surface? What if your lift bag doesn't deploy properly or as you are ascending it floods and sinks?

The only case where I can see a real need to use a lift bag to establish redundant bouyancy is during decompression diving where no drysuit is used or where a drysuit also fails for some reason. Assuming a relatively balanced rig, it isn't hard to swim up, but agreeing with another poster, I too would not want to try and hold my stops for an extended period while negatively bouyant due to the difficulty maintaining precise depth as well as the increased workload.

I have practiced using a lift bag for redundant bouyancy on multiple occasions, and when doing so I will clip it off to my shoulder d-ring. While most may advocate leaving the bag at the end of the line and shooting the bag to the surface, if I need it four bouyancy I want it attached to me so that I have the best control of the bag.

I only add enough air to become neutral, then can conduct a easy controlled ascent just as with a BC. Dump air with the pull dump and add air with small purges from my regulator. If it starts getting uncontrolled, all I have to do is grab the top of the bag and invert it to dump all of the air. Requires practice, but it's quick to deploy and easy to control.

Aha! Someone who has tried a method for option 2!

Interesting tips on the actual lift bag. Mine fits that description only by sheer cooincidence, not because I had thought through these things when I purchased it.

[PerroneFord]

To me, this is all about the ability to problem solve. I've never tried to inflate a bag just enough to get buoyant. Seems like it would be a PITA. Unless something prevented it, I think I'd rather shoot the bag and worry about spooling and clipping off rather than my bag trying to send me on a rocket ride to the surface with mandatory Deco to worry about.

To each his own. I wonder if that fellow who died on the Doria the other week tried this. It fits the description pretty well. Bag deployed, only a little line off the spool...

[6Gill]

it snapped my wings lower dump valve. The valve didn't leak air, but I had no way of quick dumping from it without the pull bobble (or whatever the heck it's called - 6gill where are you with the terminology?).

Pull bobble works for me...
I don't have one,I just use a plain line but I then took shrink tube(a rubber tube that shrinks when heat is applied,used when splicing electrical wire and you to seal it watertight).This does several things,it stiffens the line making it easier to locate and grab along with creating more friction then just plain wet line.Other things you can do in an emergency is tie an o-ring to the end of string to give you something to grab.