Free diving, tank sharing fatality - Australia

I believe this is an urban myth. The pressure from a large wave would not be great enough or the decrease in pressure from a large trough is not enough to cause an embolism.

 

The conclusion of the DAN article quoted earlier was that ascent from as little as 1.2 metres of sea water was enough to potentially cause a tear in the lung. Many years ago a good friend of ours, and a very experienced diver, suffered a pulmonary barotrauma during a very large swell. It most likely happened during a shallow "safety" stop. Luckily her only symptoms were a "crackling" sensation under the skin, and everything resolved fine with treatment, but the air bubble could have gone anywhere.

It used to be a classic source of accidents: someone completely untrained would "try out" scuba gear in a swimming pool, thinking that because it was shallow water it must be safe; but breathing compressed air underwater is a hazard which shouldn't be taken lightly, even if the depth is only a few metres.

 

The problem being - we will never know... It is highly unlikely that is what happened - unless she took a full breath, held it and proceeded to surface. But as you say she was a very experienced diver... So right now all we have is guessing and hearsay...

 

I have never understood how a community of divers that are so evangelical about training and planning consistently do not apply the ethos when commenting about freediving. As many folks have said earlier, regardless of how this exactly happened, the diver was well outside of the acceptable practice of trained freedivers. RIP.

 

1m+ possibly, but in this particular case he was pulled out from shore. Which means he/they were shore diving in hang-ten-level surf. One could do that of course. I personally wouldn't I think, but then I'm twice the guys age so...

 

Are you saying you have documented proof of an embolism being caused by a "rogue" wave? I would love to see that...

So if someone is in Hang-Ten-Level surf and being pulled out from shore - you don't think there is a possibility that they panicked and held their breath? Because I can see that as a butt pucker of a situation and who knows I might even take a deep breath to try and settle down and get out of that situation...

Still seems hypothetical that a wave that large caused any damage - first is the wave passes quickly - second is have you ever been under a large wave because you do not stay stationary due to the water being pushed and pulled and you are being pushed, pulled and lifted by the wave... Again I would love any documented proof that you could proved.

Thanks - waiting with baited breath...

 

From South Pacific Underwater Medicine Society (SPUMS) Journal Volume 33 No. 3 September 2003

It is accepted that transpulmonary pressures of around 100 cm of water are sufficient to cause lung rupture in some circumstances.
Barotrauma has been reported after breath-hold ascent using scuba from a depth of around one metre, and this fits with experimental results. Malhotra and Wright studied fresh, unchilled, human cadavers and showed that the intratracheal pressure at which pulmonary rupture occurred was around 75 mmHg (100 cm of water; 10 kPa).​

If you over-inhale air into your lungs just before a freedive (buccal pumping), the maximum pressure buildup you can reach in your lungs-trachea-mouth is equal to the pressure at 86cm depth in water.

Turn that around:
take a full breath of compressed air with your mouth level at 86cm depth, hold it, bend your chin to your chest and stand up. Your lungs are at their maximum tension. Doing this deeper than 86cm below the surface is almost a guarantee for a lung over-expansion injury.

The closer you get to the surface, the more dangerous the ascent becomes.

Most dangerous part of scuba diving: confined training in a pool.
Students kneeling on the bottom will push themselves off when panicking and want to surface instantly. Fortunately they will instinctively look up towards the surface, which makes it very hard to achieve the required lung over-pressure for barotrauma.

86cm = 2.82ft

 

This is the first time I've heard about swells and troughs effect. What I'm wondering is this....when a large wave goes overhead, does it only change the pressure in the column of water directly beneath it? The trough would be coming right after it, so does the pressure constantly go up and down if the diver is stationary?

 

It is a ghost - an urban myth if you will... been discussed multiple times - multiple ways - no proof or documented occurrence...

 

Yes, but not all the way to the bottom. I looked around for a drawing I saw about it, but couldn't find it. I believe it will affect it to a depth of 1/2 the frequency of the wave, and the effect would decrease as you approach that depth. Below that there would be no effect from the wave. I'm doing this all on memory, and I'm getting old, just to clarify.



Bob