Uncontrolled descent

[OE2X]

If I can chime in here - the reason that Bob's post is good is because he is an amazing instructor. He has thought things through all the way. Yes I'm biased because he is a good friend and buddy, but take a class from him and you will be blown away by the depth of his knowledge. I have and I'm a better diver because of it.

O.k. Bob - stop blushing.

 

[Papa Don]

Uncontrolled descent. It hasn't happened to me and I hope it never happens to me or to anyone else.
My questions is as follows: What are possible causes for uncontrolled descent? How do you prevent uncontrolled descent (and I don't mean when you hit the bottom of the ocean floor)?

When your dive boat captain tells you it;s a 30 ft dive but doesent tell you to off go off the frount of the boat and its 300 ft behind you and it's a night dive. It happend to me. I was down 130 ft almost instantly.

 

[mrobinson]

When your dive boat captain tells you it;s a 30 ft dive but doesent tell you to off go off the frount of the boat and its 300 ft behind you and it's a night dive. It happend to me. I was down 130 ft almost instantly.

I'm glad you're still around to tell us. :11:

 

[Mike Veitch]

(b) what they're most commonly taught by instructors who don't want to make the effort to teach the skill properly.

The biggest problem with a vertical descent is that it leads to chronic overweighting ... due to the fact that when you're in a vertical position you WILL try to control your descent by finning. In effect, you're propelling yourself upward while your intent is to go downward. This leads to the mistaken impression that you don't have enough weight to sink, and so you add more weight that you don't really need. Overweighting leads to all kinds of buoyancy issues.


... Bob (Grateful Diver)

Ahh thanks for pointing that out. You would not believe the amount of people i see who are already vastly overweighted who come out for their first dive of a trip and then thrash around at the surface and can't get down. The reason? Kicking their fins and flapping their arms. Its amazing. They come to the boat, "i need more weight", "how much do you have?" "so and so amount of pounds", "thats plenty, try this instead...
What i do is have them take the air out of their BCD, cross their arms and legs and voila...instant sinking. Best thing about the crossing of arms and legs? Physics of weighting puts that person in to a slightly downward from horizontal position and away you go into the depths in a controlled manner....Nice!

 

[Avic7]

That good advice NWGratefulDiver, and I plan to try that as soon as I get my drysuit back from the shop.
However what I was trying to ask was if you are in an uncontrolled descent (even if you are an experienced diver) due to some freak situation, why do people not try to become vertical and kick themselves towards the surface? Why do accidents involving uncontrolled descent happen when you could easily slow down your ascent or reach the surface by kicking your fins while in a vertical position?

 

[JaX NeMo]

Hmm, that's a very useful skill to learn. However, I think due to the higher risk at the shallower part, like the first 5m, I guess it would be better if we do it in a vertical position first, that's so that we can still use our finning to control when things don't go right. Then after the 5m then only switch to horizontal position and slowly sky diving down. For an 18m dive, it's still far from the bottom, so, I'm sure as hell wun be kicking up any corals. Mix and match

I have my share of experience controlling buoyancy at shallow waters, its really tough and takes a lot of practice, which my instructor put a lot of emphasis on it, he says I need to master my buoyancy before I can really enjoy my dive. And I fully understand that part, hehehe.

 

[wolves64t]

There is an even simpler way that I have heard of. Basically the story goes the diver gears up, forgets to check their reg/SPG, then giant strides in only to realize they haven't turned on their tank valve.

 

[kazinvan]

That good advice NWGratefulDiver, and I plan to try that as soon as I get my drysuit back from the shop.
However what I was trying to ask was if you are in an uncontrolled descent (even if you are an experienced diver) due to some freak situation, why do people not try to become vertical and kick themselves towards the surface? Why do accidents involving uncontrolled descent happen when you could easily slow down your ascent or reach the surface by kicking your fins while in a vertical position?

One possible thing is narcosis, if it's bad enough you may not even think of it and continue your descent.

 

[jonix]

There is an even simpler way that I have heard of. Basically the story goes the diver gears up, forgets to check their reg/SPG, then giant strides in only to realize they haven't turned on their tank valve.

wow! and this person, i presume, holds a c-card hehehehe

 

[JDostal]

Ahh thanks for pointing that out. You would not believe the amount of people i see who are already vastly overweighted who come out for their first dive of a trip and then thrash around at the surface and can't get down. The reason? Kicking their fins and flapping their arms. Its amazing. They come to the boat, "i need more weight", "how much do you have?" "so and so amount of pounds", "thats plenty, try this instead...
What i do is have them take the air out of their BCD, cross their arms and legs and voila...instant sinking. Best thing about the crossing of arms and legs? Physics of weighting puts that person in to a slightly downward from horizontal position and away you go into the depths in a controlled manner....Nice!

I've used that trick many a time for helping people. "Oh, you are having problems sinking? Here...cross your arms. Good. Now...cross your ankles and don't move.". Zip! There they go

I've never had an uncontrolled descent, but people sometimes think my friends and I do. We like to get where we are going. We descend crazy fast. Looking at my computer from last weekend, we hit 100' in about a minute. Especially wreck diving. Get the s-drills done, get the air out of the suit, out of the BC, and then it's head first kicking like mad til you see the wreck. Get off the rope, coast over the wreck and inflate. We time it just right so you end up flying over the wreck and hitting neutral buoyancy just right for a nice "fly over". Closest thing to flying without wings. It's kinda like the scene in mission impossible where he just about hits the floor of the computer room