Triggers of Dive Accidents

[gcbryan]

How did the poor feller get CAGE, whatever that is, at 10 ft?

It was a she and she ran out of air and (apparently) held her breath. It doesn't take much of a pressure differential.

 

[knowone]

Generally speaking, society is under constant change and there is a cross section of society that undertake most endeavours.
There have been a couple of posters that have mentioned not reading all posts. One furnished an apology another cited repetition and yet posted for what must have been for only their satisfaction.
It indicates to me that this thread is of more importance to us than it is to them, those that are being discussed.
Today "sorry" is utilised to excuse irresponsible behaviours by those being irresponsible without a view to modify any irresponsibility.

The teachers comment on the result of one of my maths exams was "Squaring it wouldn't help." :dunce: We didn't get on but his class results were the lowest in the BIG, top academic school in the state.

So with my limited math ability and due to all the buzz about PSI, I have calculated that
it is far safer to be surfacing with 500psi in a 63cf tank than with 250psi in a 125cf tank?

Any input would be much appreciated because if I am anywhere close to correct I would like to be able to think that today I could stick it up im without the necessity to square anything.

It is also suggested that at school you are taught what they choose to teach and on leaving begins education.

If you choose :read: :goingdown: :read: :goingdown: :read: :goingdown:

I apologise for not reading the last hours posts and for being repetitive.



Honkers. What honkers. You couldn't even notice the first stage operating for the second screaming at you and vibrating your teeth like a jackhammer in your brain. A bane unto sea creatures everywhere and unto man.
We could try the one with the tank banger on the inside of the tank?

Hey agamemnon stop beating yourself up and come back and post something different.

 

[lamont]

So with my limited math ability and due to all the buzz about PSI, I have calculated that
it is far safer to be surfacing with 500psi in a 63cf tank than with 250psi in a 125cf tank?

You don't have to do any math.

Due to gauge error the larger tank may have nearly zero gas in the tank, while the small tank should have enough gas to give you a couple minutes of a safety stop.

 

[danvolker]

Maybe it's better viewed as a metaphor. Is there no physiological benefit to a safety stop, or two stops, or a 15 ft/sec vs 30 ft/sec ascent rate? Safe, meaning 'no documentation of an increase in immediate DCS manifestation' (my assumption about the state of harm prediction, is this incorrect?) means it's a step function, no point to any more conservative approach? On the other side of the balance, what's the risk from running your tank down while hovering at 15 ft? It's bigger?.

Spoolin,
The idea of a safety stop is to reduce risks....If a new diver is "planning" a dive, they should be planning to come up with around 1000 psi, AND planning on doing a safety stop.....they will have plenty of air to come up slowly, and plenty of air to do the stop.

And...plenty of air to inflate their BC on the surface and chill till boat pickup...

So when a new diver blows the plan, and at 60 feet down, realizes they are at 500 psi, the safest thing they can do ( after making a very unsafe lapse in attention to spg) is to collect buddy and make a nice controlled slow swim upward to the surface...Once on the surface, they can inflate the BC, and still gain some offgas benefit floating on the surface ( still in the water).

If the new diver feels threatened by missing the safety stop at 15 feet, I would rather they suck O2 on the boat for 10 minutes.....It will be negative reinforcement ( peerwise and boat-wise) for inattention to the spg on the dive, and it will add the safety measure ( or more) of the safety stop. Remember, this is NOT a required deco stop.
The next time they dive, with the big scene of having to suck O2 on the boat, they may well be more likely to watch the guage, and begain ascent at 1000 psi.


Also,
Different fitness levels of divers will have different needs regarding the safety stop. Let's say you are a novice diver who is also an elite level triathlete( and you do NOT have a PFO) , and your buddy is 60 pounds overweight, and has not run further than the bathroom or kitchen in 10 years....You just did a 60 foot dive for 45 minutes.... a nice slow ascent for you ( without safety stop on this No Deco Dive), should give you a larger margin for safety than your buddy doing the same ascent and holding at 15 feet for 3 minutes...
Your buddy, if he trully wants safety, may require 3 minutes at 25 feet, and 3 minutes at 10 feet...and he could benefit by beginning to do cardio training to enhance perfusion (bloodflow) throughout his/her body...For someone to pontificate about how they want more safety, and completely ignore the huge safety margin of good physical conditioning, is just a little disfunctional.
You could say that the very non-fit new diver, may find it desirable, to have a contingency for the day they ignore their spg and have to come up with no time or air for safety stop---the contingency would be having their own oxygen tank on the boat, and using it on the boat, if this occurs...

REgards,
DanV

 

[MXGratefulDiver]

I've read most of the threads on this post (most have been too repetitive) the one thing in common is to READ YOUR SPG!!! PERIOD.

That doesn't always give you sufficient information to know when it's time to ascend.

An SPG is like a gas gauge in your car ... all it gives you is a relative indication of how full your tank is. To extend the analogy, let's say you know you're 60 miles from the nearest gas station ... to relate this back to diving, let's say that "gas station" is the surface.

You need two other pieces of information in order to know whether or not you'll make it there before you run out of gas.

- you need to know how much gas your tank holds
- you need to know how many "miles per gallon" you get

Without that information, reading your gauge really doesn't really give you enough information to tell you whether or not you're going to make it.

... Bob (Grateful Diver)

 

[MXGratefulDiver]

Might I recommend repeated application?
Might I recommend repeated application? Oh, and periodic practice.

... sure, you can recommend it all you want ... but the reality is that the vast majority of dive instructors and recreational divers won't follow your recommendation ... because it's inconsistent with what they were taught.

People "follow their training" ... when the training teaches them that once is sufficient, that's what they believe ... until an emergency situation changes their thinking. Those who survive the emergency will often then decide that their training was insufficient, or they'll decide that diving's not for them and go find something else to do.

... Bob (Grateful Diver)

 

[MXGratefulDiver]

But, if our bodies always behaved according to tables, no one would ever take an undeserved hit.

No one ever does, in fact, take an undeserved hit ... they have just for one reason or another neglected to take all the predisposing factors into account during the planning or execution of the dive.

Tables and computers know nothing about your body ... they're just mathematical models designed to give you an easy "rule of thumb". They are designed around an idealized "body" that functions in an idealized "condition" ... things such as your age, physical condition, hydration level, amount of rest, condition of your circulatory system, and a host of other predisposing factors aren't considered. You're supposed to know your body better than your tables or computer, and factor any predisposing conditions into how you use it.

If you fail to do that and get bent, it isn't an "undeserved" hit ... you just didn't realize you deserved it ...

... Bob (Grateful Diver)

 

[MXGratefulDiver]

So with my limited math ability and due to all the buzz about PSI, I have calculated that it is far safer to be surfacing with 500psi in a 63cf tank than with 250psi in a 125cf tank?

... this is true ... SPGs are notoriously inaccurate. I own 11 regs, and if I put them all on the same cylinder there will be about a 300 psi variance between the highest and lowest reading.

This is one reason for the 500 psi reserve rule of thumb in the first place ...

... Bob (Grateful Diver)

 

[Freezerbrn]

If as a new diver, you find you or your buddy have neglected your air consumption so much that you suddenly see you or they are at 500 psi....you just ascend...no safety stop.

When you don't have air in reserve, a safety stop is a dangerous mistake.....the stop is more for longer durations than new divers are likely to experience, and your believing that it is as important, as your being able to breath, is just insane....

I don't blame you for this ( as a new diver) ..,.I blame the system for this.....of course, this whole thread is about looking for a better way.....

Regards,
DanV

New diver I am, but lacking in common sense I'm not. I would not make a SS if I was too low on air to make a stop. Yes it would be insane to do that. My dives have been in the 70-80 fsw range with an LP95. Mine is more of an issue keeping track of the bottom timer for NDL during a 50 min dive. As a habit and what was taught to me, I orally inflate my BCD on the surface and sometimes at depth. Since it's unlikely that two divers would have the same SAC, it's plausible that one you would have enough to share if needed to complete 3 min at 15 feet (do what you can air permitting).

Having said that, my intent was not to focus on the SS. It was to tell of my PADI OW instruction that IMO did not put enough emphasis on the individual diver and buddy to monitor their air consumption. The skills training is necessary, and there is a lot put into a short amount of time. But all the skills IMO wont help you if you run out of gas and can't make it to the surface.

Thank you for your insight and comments.

 

[Garth]

Back on track though... OOA kills divers. So it would seem gas planning would be number one for most people as having enough gas is not a recommendation it is a requirement.

"It's a choice to decend, but the ascent is mandatory."

Don't be ridiculous the extra few minutes you have when sucking your tank dry aren't worth it. If they are then you better consider carrying more gas and take decompression training. End of story.
Sorry to the people who think it's cool to do a cesa, but there are plenty of divers that have hundreds of dives and have never had the need for them. Be responsible.