Arrest uncontrolled ascent by perforating BC: opinions?

[WaveMan1978]

Please pardon my posting this question on multiple forums. I originally posted on this issue in the "knives/cutting tools" forum, but I believe more people will see my question here. Besides, it is more a question of procedure/technique, rather than hardware.
I have heard and read about some divers having stuck BC inflate valves, resulting in uncontrolled ascent on a ballistic scale (with potentially lethal consequences). In such an emergency, it seems to me that the fastest dump valve is about a 12" gash in my air bladder, using a dive knife (preferably pointed, for this purpose). I'm not aware of any agency teaching this, just pure speculation on my part. I'm not too keen on destroying an expensive piece of equipment...but it sure beats rocketing to the surface (and beyond) from 80 ft. like a Trident missile from a sub.
In your opinion, would this be a valid technique in a serious uncontrolled ascent emergency? Why, or why not?

(My original post is here: http://www.scubaboard.com/t46376.html )

[FredT]

I'm not too keen on destroying an expensive piece of equipment...but it sure beats rocketing to the surface (and beyond) from 80 ft. like a Trident missile from a sub.
In your opinion, would this be a valid technique in a serious uncontrolled ascent emergency? Why, or why not?

(My original post is here: http://www.scubaboard.com/t46376.html )

A fast ascent will NOT kill you if you keep your head! I've done one from about 160' with 80 pounds of positive buoyancy lift on me. That rocket ride probably saved my life. Granted that was VERY special circumstances, and the only time in my 35 years of diving the rocket ride was the correct answer.

OTOH there is no need to take that ride if you don't want to. The "runaway inflation" is simply a case of air going into the BC faster than you get it out. The solution is to stop putting air into the BC! The quick disconnect on the BC (or drysuit) fill valve hose is there to allow instant disconnection from the air source in such an instance. Disconnecting the hose from the BC is faster than fetching the knife, and still allows regulation of buoyancy during ascent. If by some chance you won the lottery and THAT fails at the same time too cut the corrugated hose near the valve. This stops the air input and still allows you to control the air remaining in the bladder by positioning the hose end. Loss of all buoyancy capability can be a bad thing, especially given the current trend of overweighting new divers during instruction.

FT

[WreckWriter]

Clearly Fred's answer is correct. Simply disconnect the hose. hello?

WW

[WaveMan1978]

Fred,
That makes good sense. I was concerned about the difficulty of disconnecting the inflate hose, under stress, with a glove on...but I haven't tried to do that yet. The "yank and shank" maneuver seemed to be more of a gross motor movement...and these tend to be much easier to pull off under extreme stress (this is my understanding from other pursuits unrelated to diving). Again, the whole idea was purely speculation on my part. I will practice the technique you advised (note: it was not taught in YMCA OW course).

[WaveMan1978]

Clearly Fred's answer is correct. Simply disconnect the hose. hello?

WW

Hello to you, as well, WW! Thank you for your swift and thoughtful reply, I hope I didn't pain you too much with my request for information.

[NWGratefulDiver]

Well, it does bring up a good point ... one should always practice being able to disconnect inflator hoses underwater. This is particularly important for those of us who dive cold water with heavy gloves on.

Waveman, if you wear a drysuit, that goes for the drysuit hose too.

I've seen these get stuck before ... requiring a quick response to disconnect the hose. However, more often than not what you'll end up doing in real dive situations is the reverse operation ... connecting hoses you forgot to connect before the dive commenced (usually while attempting to arrest the speed of your descent).

... Bob (Grateful Diver)

[Scubakevdm]

Fred,
That makes good sense. I was concerned about the difficulty of disconnecting the inflate hose, under stress, with a glove on...but I haven't tried to do that yet. The "yank and shank" maneuver seemed to be more of a gross motor movement...and these tend to be much easier to pull off under extreme stress (this is my understanding from other pursuits unrelated to diving). Again, the whole idea was purely speculation on my part. I will practice the technique you advised (note: it was not taught in YMCA OW course).

When you practice disconecting your inflator hose, which by the way we do teach in our YMCA OW course, you may want to operate the dump while you are disconnecting the hose, which by the way we also teach. I do see inflators stick open occasionally, so its good that you were thinking about what to do, and even better that you asked about it before you stabbed your jacket. Stab-Jacket. I crack myself up.

[WreckWriter]

Hello to you, as well, WW! Thank you for your swift and thoughtful reply, I hope I didn't pain you too much with my request for information.

You didn't pain me at all.
WW

[NWGratefulDiver]

I would prefer to emphasize to new divers that the only stupid questions are the ones not asked. In scuba, what you don't know can, in fact, kill you.

There may be more elegant solutions to many problems than the ones that come to mind when one has to think about them under stress. It's much better to ask (and perhaps have to deal with a bit of embarrassment) than to find out the hard way.

... Bob (Grateful Diver)

[DA Aquamaster]

Even with a fully inflated BC or wiong of largish capacity, a sky diver style flare will add LOTS of drag and slow the ascent. (This is the same thing you would do with a grossly over inflated dry suit.) You'd be surprised how relatively slow the ascent rate actually is. It's not exactly within the 60 fpm limit but is drastically less than the ICBM launch that results if you stay vertical in the water.