TSandM: Missing Diver in Clallam County, WA

[Akimbo]

There's a difference between rates that ambient pressure changes underwater with depth, differential pressure across the lungs/alveoli increases with volume change, and gas expansion rates per unit of depth.

The pressure per unit of sea water is constant regardless of depth — 0.445 PSI/FSW (Feet of Sea Water) or one atmosphere per 33FSW (rounded). So, if you go up or down 10' from any given depth the pressure change will be 4.45 PSI.

However, gas expands and compress as a function of the atmospheres of pressure acting on it. It is not a continuous rate like pressure change with depth. For example:
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Depth in FSW​

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ATA​

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[TD]

PSIG​

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[TD]

Volume​

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[TD]

Volume​

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0​

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1​

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0​

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[TD]

1​

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[TD]

7​

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33​

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2​

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14.7​

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0.5​

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3.5​

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66​

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3​

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29.4​

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0.333333​

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2.333333​

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99​

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4​

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44.1​

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0.25​

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1.75​

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132​

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5​

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58.8​

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165​

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73.5​

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1.166667​

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198​

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7​

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88.2​

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1​

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Healthy human beings can voluntarily inflate their lungs as much as their muscles allow without giving themselves an embolism (thankfully). Thus the point at which the gas expands in a lung of trapped gas causes an embolism varies with the expansion rate of the gas AND the level of lung inflation when the gas is trapped. The differential pressure, which actually causes an embolism but results from gas expansion, increases at a non-linear rate. The curve starts pretty flat and increases dramatically as you approach and exceed maximum voluntary expansion.

Therefore a fully inflated lung might result in an air embolism with a 10% over expansion. That same lung starting at half-full would require about a 110% increase in volume before failure.

Don’t try this at home since nobody can precisely estimate “half-full lungs” or how much beyond the voluntarily fully-inflated level their lungs can expand without failure/embolism. The risk of underestimating is a pretty ugly death.

 

[lamont]

Therefore a fully inflated lung might result in an air embolism with a 10% over expansion. That same lung starting at half-full would require about a 110% increase in volume before failure.

The 4' change causing an embolism is from someone standing up on the bottom of a pool, so the percentage overexpansion is less than 10%, and may be closer to 6% overexpansion as the threshold of injury. Lungs are basically a wet paper bag.

 

[Akimbo]

The 4' change causing an embolism is from someone standing up on the bottom of a pool, so the percentage overexpansion is less than 10%, and may be closer to 6% overexpansion as the threshold of injury. Lungs are basically a wet paper bag.

There is a lot of human variability. I understand medically compromised individuals have given themselves embolisms during voluntary lung inflations lying in hospital beds. Some over-expansion is still required to embalize a “healthy” diver and over expansion starts somewhere beyond voluntary full expansion. I doubt my 64 year old lungs are as elastic as they were when I was 20. The percentage is not the same for everyone and possibly varies with hydration and humidity throughout the day.

 

[John C. Ratliff]

No diver is going to go against more than .5 kts for long.

This is extremely dependent upon several variables. I have been finswimming/diving in rivers for many years, and have found that these variables affect how well a diver can handle current:

1. Equipment configurations. The less equipment, the less the drag. Single tanks handle current better than doubles. I would think that back mounting the tank(s) is better than side-mounting, but have never tested this. My reasoning is that side-mounting doesn't present the most streamlined shape (due to tilting of the tanks).
2. Use of a wet suit verses a dry suit; dry suits present more drag to the water's current than does a wet suit.
3. The type of BCD. Some types present more drag than others.
4. The level of physical conditioning of the diver.
5. The ability of the regulator to handle high air volume requirements.
6. Type of fins and style of kicking being used.

I don't know the equipment configurations that Lynne and Peter were using, and so cannot comment directly on this aspect. But they were using dry suits, which would have made the down-current they experienced a greater problem for them because of the increased drag.

I have handled currents greater than 0.5 knots for extended times though. I would say that more than one knot is very difficult. Bill High, in his book, stated:

I dove on a trawl from the University of Washington's fishing research vessel Commando in 1958. Dale Dean and I used state-of-the-art double hose regulators. We promptly discovered that design could not supply adequate air at the three-know towing speed. These soft hoses bent closed from the force of passing water. Mostly, our objective, once we got into the net, was to survive that first dive. Our meaningful observations were few indeed..."*

I have been under rapids holding onto rocks in currents that were quite fast (though not measured), and would estimate the ability to hold onto the bottom to be difficult at 3+ knots.
*High, William (Bill) L., Beneath the Sea, A Sampling of Diving and Other Adventures, Best Publishing Company, 1998, page 160

SeaRat

 

[bowlofpetunias]

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[guyharrisonphoto]

I am still in a state of disbelief about this. To say it makes me re-think my own confidence and procedures while diving is an understatement. There are many people on this Board that I would like to meet in person one day, but I have to say Lynne was near the top of the list. Seeing this thread has been a sobering experience for me. In the spirit of this thread, I am going to dip my toe in on what might be learned . . .

1. This was an advanced and difficult dive with strong currents and surge, but there was nothing about Lynne’s experience (over 1000 dives in the pacific northwest), training (GUE and cave) or equipment (more than enough safety and back-up gear) that would be a contributing factor.

2. Pre-Dive conditions. Based on Peter’s report of the conditions and what I read about the site, these appeared to be optimum for this site (small surge, no extreme current obvious from the surface, no excessive tide, good surface visibility—no fog or rain), so no issue about whether the dive should have been canceled.

3. Surface support. No issues reported with the drop site or the boat handling, so no contributing factor there.

4. Dive Conditions. The dive did not start well and conditions underwater were not as benign as they seemed at the surface. Upon descending to planned depth, a strong downcurrent took the team down at least 1ATA below their planned depth and nitrox mix, to over 125 feet. This would create physical and mental stress in overcoming this, which apparently they did, successfully, and regained a safe depth but mid-water, and separated by some vertical and horizontal distance (still visible but far enough apart so that a glance away was enough to lose contact) and not where they planned or wanted to be.

5. Buddy Dynamics. The downcurrent was the joker in the deck for any buddy plan. On my deep-night-wreck-strong current dives here in Florida, my buddy plan is simple—touching, and even three feet apart needs correcting on an urgent basis. But, an unexpected current can change everything and separate the team, and a downcurrent creates a special personal emergency for each diver to stop their descent and regain proper depth, that distracts from concentrating on their buddy. It can become a “solo” dive until the crisis is handled. It has happened to me where I lost my buddy with a “glance” away (maybe 5 seconds) in a screaming current, and we had to surface separately. In this case, it seems each diver handled the crisis and recovered proper depth, but they did not have time to link up again before the separation and Peter surfaced after a one minute search per the dive plan. I don’t see how it could have been handled any better way.

6. As to what possibly happened after they got separated, I learned something on this forum I had not known before. These are quotes from other posts, I think these were people who knew Lynne (but I might be wrong on some of them):

“Have no idea if this had anything to do with it, but Lynne had a chronic issue with vertigo whenever she got into a mid-water situation ... I once watched her fall to the bottom of a wall and just lay there, eyes closed, till it passed.”

“I'm thinking the same thing as I'm familiar with her training but I'd completely forgot about the past vertigo issues.”

“I think Lynne falls into the diver category of prepared and safe but that doesn't shield any of us from the unavoidable or unpredictable. She may have become entangled in line or netting (not always an easy exit in strong current), become disoriented from acute vertigo without a visual reference”

It seems the most plausible possible explanation is the one based on the facts that are actually known. Her particular type of vertigo, as reported, was severe, not mere temporary dizziness, but so disabling that it completely incapacitated her and could cause her to fall to the bottom and not even be able to operate her gear. This vertigo issue cannot be addressed by training, experience, or equipment. As reported, it was a sudden, unpredictable, condition that apparently affected Lynne more than once and could be triggered by a situation that occurs in many divies (being mid-water) and which was certain to occur on this dive (live boat), and did in fact unexpectedly occur, under intense stress.

The questions this possibility poses are important and bigger than the particular dive. If a diver suffers from a severe incapacitating condition, that is rare but known to occur during diving, with no predictability and no medication, training or equipment that can effectively address or prevent it, how should that play into a decision to continue with diving as a hobby? Or to do a particular dive? Should a person affected in this way attempt technical dives, or highly challenging dives where the occurrence could likely be fatal?

From a training agency view, what are the medical clearance standards for a diver with such a condition?

One poster said, “I really have no idea if I want to continue to dive, especially as I get older.”

For me, diving has been a big part of my life and who I am for 40 years and I plan to keep diving. I am 56, healthy, in good shape, and have never experienced any evident health issues, on the surface or below, that could affect me while diving. But, one lesson learned is that I am going to get a comprehensive check-up from a diving medicine group, to be as sure as I can that my body has no surprises in store for me.

We are all here on this Board because we love to dive. From her posts, no one loved to dive more than Lynne. We want to keep doing what we love and what gives us fulfillment. We don’t want our bodies to betray us. But, if I ever experience that type of vertigo (or anything similarly incapacitating) more than once, and there is no way to reliably prevent it, I would consider whether diving is the right thing for me.

Perhaps I am all wrong, and that Lynn had received treatment or was medically managing the vertigo or had assurance that it would not recur. If so, then I will simply offer my condolences, and my bafflement that this could happen to a diver as accomplished as Lynne.

 

[EFX]

As this is the Accidents-and-Incidents forum I've tried to be very open minded about the posts. This one however really pisses me off:

"So, getting to the question: Medical issues aside, could the motivation to maintain proper trim have contributed to Lynne's accident?

I'll go on the record of saying yes."

JUST FOR THE RECORD, when I last saw her, Lynne was vertical.

This post was just out and out bull sh**t.

(Mods -- feel free to pull this --I just couldn't not respond.)

Peter,

you aren't alone and I was also upset by this for several reasons. People who are in complete control of their trim can choose any attitude they find necessary. It's certainly no struggle for them to remain horizontal and absolutely no effort to get vertical instantly if they need to.

Why are you upset? Are you concerned about Lynne's reputation? GUE's reputation? The question couv poses is fair but should be restated to say "could the failure to adjust trim have contributed to Lynne's accident"? Yes, it definitely did. Why would she be at 130 ft on EAN32? Being near horizontal which is the preferred position for any diver moving horizontally in the water presents a large surface area for a strong down current to act on. The issue isn't whether she could get to proper trim but how fast she could get there. She had no time to adjust before arriving at depth. She lost control of her buoyancy, through no fault of her own, due to an excessive down current that neither of them were expecting. She probably got suit squeeze and overcompensated having to dump gas at 70 ft. I'm not suggesting that the one event, the descent, was the only contributer to the accident but a host of cascading events. Here are the stressors: rapid unplanned descent, suit squeeze, exceeding safe depth for 1.4 atm on EAN32, loss of buoyancy, physical stress of swimming against current, rapid ascent followed by possible vertigo (she had history and a possible fear of riding it out on the bottom given the depth limitations), stress of buddy seperation, stress of swimming against a lateral current at 70 ft. All these stressors act together to give a total effect greater than the sum of individual stressors. All of these stressors could have led to a medical event preventing a safe ascent to the surface.

 

[Nirvana]

Why are you upset? Are you concerned about Lynne's reputation? GUE's reputation? The question couv poses is fair but should be restated to say "could the failure to adjust trim have contributed to Lynne's accident"? Yes, it definitely did. Why would she be at 130 ft on EAN32? Being near horizontal which is the preferred position for any diver moving horizontally in the water presents a large surface area for a strong down current to act on. The issue isn't whether she could get to proper trim but how fast she could get there. She had no time to adjust before arriving at depth. She lost control of her buoyancy, through no fault of her own, due to an excessive down current that neither of them were expecting. She probably got suit squeeze and overcompensated having to dump gas at 70 ft. I'm not suggesting that the one event, the descent, was the only contributer to the accident but a host of cascading events. Here are the stressors: rapid unplanned descent, suit squeeze, exceeding safe depth for 1.4 atm on EAN32, loss of buoyancy, physical stress of swimming against current, rapid ascent followed by possible vertigo (she had history and a possible fear of riding it out on the bottom given the depth limitations), stress of buddy seperation, stress of swimming against a lateral current at 70 ft. All these stressors act together to give a total effect greater than the sum of individual stressors. All of these stressors could have led to a medical event preventing a safe ascent to the surface.

Obviously, I can't speak for NetDoc or Peter, but the suggestion that she was specially affected by the current due to some obsession with remaining horizontal is very far-fetched. The experience and training she had contradict this thought directly.

For one thing, she was a cave diver with experience in the caves of north florida. Any diver trying to run a reel out of a cave with moderate flow (e.g. Ginnie Springs or Little River) while remaining perfectly neutral and horizontal will get blown out of the cave. That fact that she had done this kind of dive is enough to know that she was perfectly aware that being horizontal is not always the best orientation in the water, specially on the face of significant vertical current.

So the fact is that it is very unlikely that the accident had anything to do with her trying to be horizontal or even that her training had somehow made her think that horizontal trim is always the best posture.

 

[PfcAJ]

Its an absolutely preposterous notion to suggest that trim is what caused this.

 

[Wayward Son]

We all want to know what or how this happened but unless she's recovered we likely won't.

Sometimes things just happen. No one did anything wrong, no one made any mistakes, there wasn't anything that might have been done differently to change the outcome. There are things that are beyond our control. It, what ever it is, happened. This seems to be one of those times.