Catastrophic Failure - How much weight to drop? Theoretical Discussion

[danvolker]

Dan, you're right. I wasn't suggesting, however, that DCS is the main concern with an uncontrolled ascent on a recreational dive. Lung over expansion injury, however, is a real risk. I've seen three and heard of more (locally) and they are ugly. Buddy separation is also not something you want to add to the cluster*** that was apparently already happening when someone decided that ditching their weights was the right maneuver, or they slid out of their pockets unbidden. And then there's panic, which can kill someone at depth OR on the surface. A panicked diver will do all sorts of things you don't expect. Like kneeling on the bottom frantically dumping gas out of their wing, trying to go up. Uncontrolled ascents can cause panic.

Also, subclinical DCS, though not life threatening, sucks, and an uncontrolled ascent will usually cause some symptoms. Combined with other things, an uncontrolled ascent CAN hurt a recreational diver. Remember we are not talking about hugely vascularized Irvine types who go for a run after a deep cave dive just to see what the Doppler says. we are talking people like me.


Maggie

Hi Maggie,
No argument, that if they hold their breath on ascent, that they will be hosed....

For those people that SHOULD BE divers......the ones with some aptitude, just being told to exhale all the way up, and their knowing this, should be all that is needed. It is incredibly easy.
Back in the 70's we would practice free ascents from 100 feet....your lungs were like an air factory, and there was nothing easier than doing this..and it was fun.

An Asthmatic that can't reliably exhale at beyond a very slow exhale, or a diver so afraid that they are in a state of panic and unable to concentrate on a slow gradual exhale--can't really be expected to do a buoyant ascent safely ( meaning getting to the surface really fast)....But with healthy lungs, even a buoyant ascent with a large BC and the huge speed potential it represents, is easy to exhale all the way up.

 

[raftingtigger]

My apologies. Most don't have a clue how to do a buoyancy check. I had to learn. And the beauty of a buoyancy check is it doesn't matter how much your individual gear weighs. Also, I didn't realize you were counting your tank in your total. I usually think about how much weight I need to dive a particular set of tanks. My bad.

who made your backplate? Did you weigh it without the webbing, just bare? Irrelevant but I'm curious now who is making 9# backplates.

Maggie

Apology accepted. My point of the original post was that negatively buoyant gear (tank, backplate, lights, etc.) is ballast. A point often overlooked.

As for who makes a 9# backplate. I have no idea. I bought it off eBay and when I received it realized it was homemade. Not that it matters at all. And the measurement was with harness (soaking wet, just got done diving).

 

[flots am]

You should have been trained to only drop weights on the surface. Swim to the surface, orally inflate (either off your regulator or just use the atmosphere -- depending on sea conditions and your gas supply) and *then* drop your weights.

OW divers are taught to drop weights as a last-ditch attempt at not dying. As such, it's not the recommend way to end a dive, but is reasonably safe compared to the alternative of "death".

I actually teach weight ditching at depth, and explain very clearly that it's only for divers that have managed to hit an 11 out of 10 on the "stupid-o-meter" and have managed to lose all their gas and their buddy and are too over-weighted to swim to the surface.

OTOH, embarrassed is still better than dead.

flots.

 

[Whirling Girl]

While most SS plates are 5 or 6 lbs, FredT has made (and maybe still making) 9# and 12# backplates.

Is that Koplin? I bought a 12# from him years ago and it's still my favorite backplate.

I honestly think that teaching people that ditching weights at depth is even an option is a bad idea. Mindset is an important thing in diving. Learning to solve problems at depth and not having the 'option' of ditching is better than the false sense of security created by the thought that "if things go really wrong I can just ditch my weights." I guess that needs to be in context, though; if someone isn't diving balanced and can't swim up their gear, they are unsafe. But solving that problem with ditchable weights is not actually solving that problem.

Maggie

---------- Post added March 11th, 2013 at 12:46 PM ----------

Apology accepted. My point of the original post was that negatively buoyant gear (tank, backplate, lights, etc.) is ballast. A point often overlooked.

As for who makes a 9# backplate. I have no idea. I bought it off eBay and when I received it realized it was homemade. Not that it matters at all. And the measurement was with harness (soaking wet, just got done diving).

Um, you know that webbing soaking wet is heavy on a scale and functionally weightless under water, right? Just fyi. Plus your stainless is added in there if you use stainless; though it counts as weight, overall, I was asking how much your actual backplate weighed. I'm guessing its a 6#. Again, irrelevant, but I was curious.

I also love that backplates are so simple and need no embellishment, upgrading or redesign. They just work.

Maggie

 

[danvolker]

Is that Koplin? I bought a 12# from him years ago and it's still my favorite backplate.

I honestly think that teaching people that ditching weights at depth is even an option is a bad idea. Mindset is an important thing in diving. Learning to solve problems at depth and not having the 'option' of ditching is better than the false sense of security created by the thought that "if things go really wrong I can just ditch my weights." I guess that needs to be in context, though; if someone isn't diving balanced and can't swim up their gear, they are unsafe. But solving that problem with ditchable weights is not actually solving that problem.

Maggie

---------- Post added March 11th, 2013 at 12:46 PM ----------


Maggie

Maggie, did you happen to read through some of the posts in the recent Miami Diver Death? There are certified divers out there that CAN NOT survive on a 25 foot deep reef, or on the surface, by themselves.
You could say they are on the wrong side of the Standard Deviation in Diving....the Average OW Diver will survive....some will be really well trained by the good instructors, and what you speak of will be easy for them.. The 15 % or so on the WRONG side of the Deviation from average, will need to be able to ditch their weight to survive ( due to hopelessly inadequate skills) ...and apparently even this is not enough for some.

 

[rjack321]

I honestly think that teaching people that ditching weights at depth is even an option is a bad idea. Mindset is an important thing in diving. Learning to solve problems at depth and not having the 'option' of ditching is better than the false sense of security created by the thought that "if things go really wrong I can just ditch my weights." I guess that needs to be in context, though; if someone isn't diving balanced and can't swim up their gear, they are unsafe. But solving that problem with ditchable weights is not actually solving that problem.

Over the past year or two we've seen quite a few divers make it to the surface by various means and then drown with their weights on. And basically zero dead divers due to weights ditched at depth leading to uncontrolled ascents and AGE therefrom.

If anything I'd say more people need to remember that ditching their weights (or their buddy's weights) is an important + useful skill. Not something that to be even more avoided than it already is.

 

[NAM001]

With his scenerio i see two meaningfull failures.
#1 blown burst disk. Thatwould be handled by heading up and breathing normalso it is a controled accent to some degree.
#2 the biggy..... A blown wing that was carrying the large neg load. If youhave a bottom you have no problem as you can vent air ect to get to perhaps -18 from the -28. If you dont have a bottom multi tasking expoentially grows. You can inflate your wet suit like a dry suit by purging the mouthpiece into the underside of the wet suit ( shorties are real nice for blowing air up the leg) and burp throught the neck on the way up. I have donre thatbefore adn it takes no preparation compared to rigging a lift bag. If you dont have a bottom multi tasking expoentially grows.

Then i would dropthe weight for the final accent to the surface if needed, of course another blast of air under the leg skirt will do that also. Then dump weight if needed to stay onthe surface.

There is no real winning solution, only a lesser of evils.

I think i would bubble in my suit and vent tanks to 500-1000 as i went shallowin hopes of achieving the low psi tank at safety stop depth. burping the suit as the wet suit carried more pos lift.

 

[Whirling Girl]

Over the past year or two we've seen quite a few divers make it to the surface by various means and then drown with their weights on. And basically zero dead divers due to weights ditched at depth leading to uncontrolled ascents and AGE therefrom.

If anything I'd say more people need to remember that ditching their weights (or their buddy's weights) is an important + useful skill. Not something that to be even more avoided than it already is.

ok, point taken. CORRECTION for the syntax police: Why are divers dying after they have reached the surface with their weights still on? Do we know?

Maggie

 

[dumpsterDiver]

ok, point taken. Why are divers dying on the surface with their weights still on? Do we know?

Maggie

Who said they are dying on the surface?

 

[raftingtigger]

ok, point taken. CORRECTION for the syntax police: Why are divers dying after they have reached the surface with their weights still on? Do we know?

Maggie

Have you ever seen a stressed diver on the surface struggling to stay afloat because they forgot to inflate their BCD? Unfortunately I have all too many times. If they forget the routine task of inflating their BCD, then why are we surprised to find that they forget to ditch weights? That is the $64,000 question. IMHO, the only way to respond properly in an emergency is to practice it, and if actual practice isn't possible then mentally rehearse it.

---------- Post added March 11th, 2013 at 09:35 PM ----------

Who said they are dying on the surface?

I think she meant made the surface and then sank and died.