Preventing an uncontrolled ascent

[Teamcasa]

I was reading a thread where a diver had an uncontrolled ascent and found myself asking, why not pull the knife and cut the end off of the inflator hose and should that fail, slice open the BC?

First let me say that I’ve never had a problem with my wing or any other BC because I do check valve operation before every dive but should all the valves fail to open would I have the presence of mind to pull my knife and give the wing a careful slice. I can always buy a new wing but I would rather not get bent if I can help it.

 

[Doc]

would I have the presence of mind to pull my knife and give the wing a careful slice.

No. Nor the time or opportunity or manual dexterity under stress.

99.99% of all dive knives could not perform a slice through ballistic nylon fabric much less the plastic of the bladder.

Your "hole" would have to be made at the uppermost point of the BC, so that would mean that you would then have to pivot to go chest up. Unless you stabbed yourself in the back.

Aint gonna happen.

Can we talk about pointy dive knives in this thread?

 

[300bar]

Well it posses some new problems,once at the surface.
BC can't be inflated any more, so you have to dump weights or full gear
depending on weather there is a suit or not.
When wearing no suit,it won't be a good option, when you have to wait for some time to be picked up.
No thermal protection no floatation.

 

[Jim Ernst]

Dave.

Slicing the BCD is an alternative....

Though you have a few things to consider, With no lift from your BCD can you still make the surface, Do the fins you use give you enough power to make it??

Also once at the surface you would have to dump your weights, If you dumped your weights before the surface you are back to square one with a run-away ascent again.

Also something to consider, Are you , The diver, using a dry-suit, If so then you don't have as big a problem as you still have a flotation device.

I guess my point is that it would all depend on many different possibilities and or scenarios.

 

[300bar]

Most dive knives could not perform a slice through ballistic

But you could cut the inflator hose,not wise but can be done.

 

[Ann Marie]

I didn't read the thread that you are referencing so I'm not sure of the specifics. Why go to the trouble of the whole knife thing? Why not pull on one of the exhaust valves and then make a controlled ascent? I would think that most would dump air faster than the LPI will fill the BC.

 

[Doc]

But you could cut the inflator hose,not wise but can be done.

Same answer as above:

-Most dive knive aren't aggressive enough, the rest are just plain dull.

-Overcoming the loss of fine motor skills in time allotted negates any possibility of success.

 

[Charlie99]

In the case that triggered this thread, it was simply a case of not being able to dump the air out of the BCD. There wasn't any inflator problem.

I doubt that the diver had tried using the other dump methods. Most BCDs have at least two ways to dump --- both pulldump and oral inflator from the left shoulder, and then another dump valve somewhere on the BCD.

The diver blamed the problem on faulty maintenance of a rental BCD that made it impossible to dump air from the BCD.

Before pulling out a knife, I'd try the other dump valves.

http://www.scubaboard.com/forums/3525786-post1.html

Last August, I had been using my own BCD with no problems but on the last day of holiday diving, I stupidly used a BCD from the back of a dive schools supply. I confess that I did not test the deflate properly. Yep ..... you've guessed it, it wouldn't. I was only about 14m and slowly rising, trying to let air out of the BCD but it would not deflate. I tried everything I could think of as well as splaying out for drag and exhaling as much as poss before taking in a short breath and exhaling. I could not stop the uncontrolled ascent.

 

[Ann Marie]

In the case that triggered this thread, it was simply a case of not being able to dump the air out of the BCD. There wasn't any inflator problem.

I doubt that the diver had tried using the other dump methods. Most BCDs have at least two ways to dump --- both pulldump and oral inflator from the left shoulder, and then another dump valve somewhere on the BCD.

The diver blamed the problem on faulty maintenance of a rental BCD that made it impossible to dump air from the BCD.

Before pulling out a knife, I'd try the other dump valves.

http://www.scubaboard.com/forums/3525786-post1.html

Thanks for the clarification! Checking the pull dumps should be part of the buddy check for everyone.

 

[BarryNL]

In the case that triggered this thread, it was simply a case of not being able to dump the air out of the BCD. There wasn't any inflator problem.

I doubt that the diver had tried using the other dump methods. Most BCDs have at least two ways to dump --- both pulldump and oral inflator from the left shoulder, and then another dump valve somewhere on the BCD.

The diver blamed the problem on faulty maintenance of a rental BCD that made it impossible to dump air from the BCD.

Before pulling out a knife, I'd try the other dump valves.

Might also want to ensure that you're not so overweighted that this sort of thing can happen.