SSI Emergency buoyant Ascent : Training Video

[pauldw]

What is that bobbing in and out up and down holding the nose stuff on the surface dance all about.

Nobody seems understand the bobbing. What is happening is an oral inflation at the suface...bobbing up to grab some air, comfortably sinking slightly to blow it into the oral inflator. To you, it looks like needless and mysterious bobbing; to me it looks like a good exercise and a well-trained student.

Yup, good training. Because a lot of people forget about oral inflation, and practicing it is a good reminder for when the elevator buttons aren't working.

 

[SlugLife]

Wow, watching that was pretty cringe. Starting with the knees, the over-communication of nonsense for 5-minutes, the snorkel, the bobbing. Ugh....

Imagine having to watch several hours of those kinds of materials for an open-water or AOW class.

 

[boriss]

Nobody seems understand the bobbing. What is happening is an oral inflation at the suface...bobbing up to grab some air, comfortably sinking slightly to blow it into the oral inflator. To you, it looks like needless and mysterious bobbing; to me it looks like a good exercise and a well-trained student.

ROFL, I know what it's trying to depict, however, the diver just came from depth with a BC which supposedly had gas in it. It had to offset all those ditchable weights that were just dumped. If you're exhaling on your way up, guess what's happening to the gas in your BC as you go up? Even if the BC did need extra gas, you can fill it without the bobbing.

Anyway, this is all elementary stuff, I get it, it's just exaggerated in the most cartoony way possible and get people off their knees. It's almost like watching a caricature.

 

[tursiops]

ROFL, I know what it's trying to depict, however, the diver just came from depth with a BC which supposedly had gas in it. It had to offset all those ditchable weights that were just dumped. If you're exhaling on your way up, guess what's happening to the gas in your BC as you go up? Even if the BC did need extra gas, you can fill it without the bobbing.

Anyway, this is all elementary stuff, I get it, it's just exaggerated in the most cartoony way possible and get people off their knees. It's almost like watching a caricature.

It's a training drill in a pool, dude. You go through the steps to develop muscle memory, not because you need them.

 

[John C. Ratliff]

Okay, a couple of observations here. First, about the video, didn’t anyone notice that they initiated this buoyant ascent from about 215 feet of depth? That’s actually pretty shallow, and easy to simply swim up. Second, to initiate this ”buoyant” ascent, a maximum of about 8 pounds was ditched. She only used one side of her BCD. Thus, the buoyant ascent was not a fast one.

I may be one of the few here who has been trained in a buoyant ascent, and by the U.S. Naval School for Underwater Swimmers. It was a simulated submarine escape from about 30 feet. We had a life vest on, which was filled completely with air as we held onto a plastic bubble where we had been awaiting our turn. We got the vest filled, thus over 20 pounds buoyant (no suit), looked at the instructor, and on his command looked up, blew out as much exhalation as possible, and released our grip on the bubble. We simply shot toward the surface. Arriving there, we had a completely full vest, and had come out of the water to our chest when we surfaced. We then gave the “Okay” signal to the surface instructor, and swam to our platform. Now, that’s a buoyant ascent; I understand that the Navy no longer teaches that way too (this happened in 1967). If you think about it, if a nuclear sub is down on the bottom, this is the only way submariners get out before really bad things happen inside.

The flaring out as the diver approaches the surface will slow the ascent, but it could still be fairly quick. The diver needs to be exhaling all the way up.

Frederick Dumas trained the original French Navy divers in the Aqualung, and did include a controlled swimming ascent without scuba from about 120 feet in his course. This was in the early 1950s, and was recorded by J.Y. Cousteau in his book, The Silent World.

SeaRat

 

[Ayisha]

She was swept down the wall and went from 40' to 100' in a matter of seconds (30 seconds or so I would guess). I was able to reach her (the DM did not go after her) and grabbed her bed. My computer started alarming as we were at 110'. We kicked as hard as we could and then we were at 120. At that point I started filling her bed in hopes it would be enough to arrest the descent. If not I was going to ditch weights. We did start ascending, and at that point I tried to dump air but we went to the surface anyway. The entire group was spit out eventually and we were all spread out quite wide on the surface.

It sounds like you guys were caught in a downcurrent. Scary.

You sometimes have advance notice of a downcurrent by watching what the particles are doing ahead of you on a wall. If there are converging currents, you can see not only the particles going across, but also down - fast. Give that a wide berth.

It's best to dive a little further away from a wall so you don't get pushed down.

If you do get caught in a downcurrent, inflating a BCD or SMB/lift bag likely won't make much difference, until it spits you out. At that point, you're rocketing to the surface with a full BCD/SMB/lift bag.

Kicking away from the wall is the fastest way to get out of a downcurrent, hopefully before it takes you down excessively.

Encountering a downcurrent later in the dive can be even more of an issue not only because there might not be enough gas to deal with deco or a higher chance of DCI, but running out of gas while you're stuck at depth.

There are several old threads on downcurrents if anyone is interested in exploring that topic.