Instructor bent after running out of air at 40m

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The only thing the instructor needs to do to administer the test is to start and stop the timer. Pretty much any drunken idiot can start and stop a watch. And considering that the test was done at 70 feet, an experienced diver will probably not be significantly impacted to administer the test.
He needs to start and stop the watch - at the correct time that actually matches the diver performing the test.

Otherwise, the test is wrong.
 
Excellent points, John. I would just add one comment.

I don't think that it's a bad thing to let new divers know that it is possible to get bent while doing a recreational dive and staying within NDLs (it happened to me!). It's not that we want them to scare them off, it's just that I think that people should understand that no matter what the magic bracelet says, decompression stress is still poorly understood and there are some variables (hydration, general health, individual susceptibility and anatomy, etc..) that you just can't plug into your dive computer. That also might make people less resistant to getting treatment if they don't have the idea that as long as they followed the DC, any symptoms they have can't possibly be DCS.

In many of the discussions here, new but aggressive divers go on and on about needing the least conservative computer possible so that they can get the most dive time in by going right up to "the line", as if that were the way things work. A little perspective isn't a bad thing.

But I totally agree with you - statistically, you are extremely unlikely to get bent if you follow ANY established algorithm.


Wowzers. Reading this, it absolutely astounds me that I didn’t get bent on the Kona Blackwater dive. I could not get my bearings and bounced from 50 ft to the surface a number of times. It was horrible. I aborted pretty early on. Worst $250 I’ve ever spent.
 
A friend's dad used to dive with the US military NATO base in Turkey in the 60s and 70s. This was his capillary depth gauge. Also made in Italy.
It's also meant to help work out the stop times based on bottom times, but I can't figure out how.

View attachment 473820
clip_image001.jpg

It may be the precursor to the "Bend-o-magic" shown by АлександрД in the post after yours. I wouldn't be supprised to see a similar gas bag inside the gauge.


Bob
 
Were you not tethered to a downline or hanging from a liftbag? I can't imagine making an offshore dive like that swimming freely.

When I did it there were six of us in the water. We were each tethered to a 50 foot vertical line that hung from the boat with weights at the end (six separate lines: two at the bow, two mid-ship, two at the stern.) Our "tether" to the vertical line was a 10 foot horizontal line. So we had 50 feet of vertical freedom and a 10 foot radius of horizontal freedom from that vertical line.

Maintaining vertical position in that situation, with no visual reference at all, can be a little tricky. And no one wanted to hang at the end of the vertical line: the thought of somehow slipping off the end was worse than he thought of what creatures were lurking in the deep dark water below.
 
When I did it there were six of us in the water. We were each tethered to a 50 foot vertical line that hung from the boat with weights at the end (six separate lines: two at the bow, two mid-ship, two at the stern.) Our "tether" to the vertical line was a 10 foot horizontal line. So we had 50 feet of vertical freedom and a 10 foot radius of horizontal freedom from that vertical line.

Maintaining vertical position in that situation, with no visual reference at all, can be a little tricky. And no one wanted to hang at the end of the vertical line: the thought of somehow slipping off the end was worse than he thought of what creatures were lurking in the deep dark water below.


Exactly this.
 
It may be the precursor to the "Bend-o-magic" shown by АлександрД in the post after yours. I wouldn't be supprised to see a similar gas bag inside the gauge.
Bob

Yes Bob

air in a bag being pressed through an identical 10mm long
and slightly bigger diameter than a pencil lead, ceramic filter.

But instead of a mechanical bourdon tube gauge, the air
in the top instrument it is pressed against a sealed air filled
corrugated tube with the corrugations acting as a return spring

next one has an added spongy filter?

and in the bottom gauge, in the corrugated tube filled with air
the silver lump to the left of centre is mercury

full.jpg



analogical dive computers | BluTimeScubaHistory
 
Unbeknown to most people and the one silver lining to this tragic “unavoidable” mass out-of-air near death event was that these extremely experienced professional divers became technical advisors on the movie ‘47 Meters Down’.

That would explain a lot about that particular film.
 
Enjoy shedding this story ...

The scuba dive that crushed my spine

It had been meticulously planned - a deep dive for four experienced scuba diving instructors. But halfway through the session, two oxygen tanks ran out, setting off a catastrophic chain of events.


So meticulously planned that not one but two out of gas ... then all four.

I don't understand how in the Hell this could happen. When I'm diving deep, I'm constantly checking my air supply, TTR, depth..etc. This article makes it seem like it was something else besides stupidity. ""a disparity between what was planned in terms of breathing rates and what actually happened on the dive". A disparity? why don't you call it what it is, you failed to plan your dive or you failed to dive your plan. Simple as that.
 

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