TSandM: Missing Diver in Clallam County, WA

[gcbryan]

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

 

[Storker]

have dived in 9 to 10 or so knot

If your estimate is anywhere close to reality, it must've been quite a rodeo. 10 knots is about 18 km/h or 5 m/s (some 11 mph for you metrically challenged), i.e. a decent bicycle commuting speed, or 100m in about 20 seconds. That's only twice the world record for a 100m sprint.

Close to the marina where I have my boat, we have a tidal current through a narrow sound. That current has a recorded speed of about 6 knots at max, and it's a good place for a drift dive due to the benign bottom profile. However, I wouldn't jump in at max current, that's way to hairy for me.

 

[rhwestfall]

We drift dive the Niagara River here. There is no stopping unless you can grab something big enough. If you look to the side, you can lose a mask... This is a 2-3 kt flow. You are there only for the one way ride.

 

[The Chairman]

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.

 

[scagrotto]

However, the lungs must start nearly full

I know that you know the lungs contain millions of alveoli, and aren't at all like a pair of balloons. Just because your lungs are "only" 60% full doesn't mean that every single alveolus is only 60% full; there's always going to be some variation in how full individual alveoli are. Not that I can find it for a cite right now, but I've read something that says that an AGE can result from a rupture of a relatively small region of the lungs. I don't recall ever seeing any info on the normal variation in how full individual alveoli are. I totally understand your reasoning about volume and expansion relative to depth, but much of what I've read comes back to the idea that the pressure difference of just 4' of water is enough to rupture alveoli, and that 4' pressure differential is the same at 10' deep and 110' deep. Whether it's the theory that your lungs are only half full and a 100% expansion would be required to start rupturing alveoli or the theory that holding your breath while ascending from 104' to 100' may rupture enough alveoli to cause AGE I've got no interest in conducting an empirical test. I agree that shallower depths make it much more likely, but as near as I can tell it's also possible over short distances at depth.

I'll also suggest that while the situation almost certainly resulted in elevated heart rate and more rapid respiration it's still possible to unconsciously hold your breath for a few seconds while dealing with problems.

Of course I've got no idea what happened and there are plenty of possibilities besides barotrauma, but I'm inclined to think that some kind of medical event offers the most likely explanation for not surfacing. A rapid ascent isn't desirable, but it's highly preferable to dying. I would figure that at some point a diver who is capable of doing so is going to hit the up button in an effort to deal with the outcome on the surface.

 

[wetb4igetinthewater]

We drift dive the Niagara River here. There is no stopping unless you can grab something big enough. If you look to the side, you can lose a mask... This is a 2-3 kt flow. You are there only for the one way ride.

When I was in Maui with Maui Dive Scooters, I could feel my mask being pushed pretty hard if I did not look straight ahead while riding on an Apollo AV-2. I own one, and in my cold water setup, the drag is so much greater that I don't experience this.

Water is a powerful force.

 

[gcbryan]

I know that you know the lungs contain millions of alveoli, and aren't at all like a pair of balloons. Just because your lungs are "only" 60% full doesn't mean that every single alveolus is only 60% full; there's always going to be some variation in how full individual alveoli are. Not that I can find it for a cite right now, but I've read something that says that an AGE can result from a rupture of a relatively small region of the lungs. I don't recall ever seeing any info on the normal variation in how full individual alveoli are. I totally understand your reasoning about volume and expansion relative to depth, but much of what I've read comes back to the idea that the pressure difference of just 4' of water is enough to rupture alveoli, and that 4' pressure differential is the same at 10' deep and 110' deep. Whether it's the theory that your lungs are only half full and a 100% expansion would be required to start rupturing alveoli or the theory that holding your breath while ascending from 104' to 100' may rupture enough alveoli to cause AGE I've got no interest in conducting an empirical test. I agree that shallower depths make it much more likely, but as near as I can tell it's also possible over short distances at depth.

I'll also suggest that while the situation almost certainly resulted in elevated heart rate and more rapid respiration it's still possible to unconsciously hold your breath for a few seconds while dealing with problems.

Of course I've got no idea what happened and there are plenty of possibilities besides barotrauma, but I'm inclined to think that some kind of medical event offers the most likely explanation for not surfacing. A rapid ascent isn't desirable, but it's highly preferable to dying. I would figure that at some point a diver who is capable of doing so is going to hit the up button in an effort to deal with the outcome on the surface.

You are simply incorrect regarding your statement that a 4 ' pressure differential from 110 fsw or 10 fsw is the same.

A 4 ' pressure reduction from 10 fsw is greater than the same from 110 fsw just as 4 is a greater percentage of 10 than 4 is of 110.

Conceptually, you'll agree that your body is under much greater pressure at 110 fsw than at 10 fsw so reducing that pressure by 4' isn't doing as much when your body is at 110 fsw.

 

[nolatom]

I've been away a few days (ironically in Seattle) and so was unaware.

I'm sorry for the family. She was always nice to me on the web, obviously knew way more than I did but she had a kind way of educating me, and us.

 

[finnks]

If your estimate is anywhere close to reality, it must've been quite a rodeo. 10 knots is about 18 km/h or 5 m/s (some 11 mph for you metrically challenged), i.e. a decent bicycle commuting speed, or 100m in about 20 seconds. That's only twice the world record for a 100m sprint.

Close to the marina where I have my boat, we have a tidal current through a narrow sound. That current has a recorded speed of about 6 knots at max, and it's a good place for a drift dive due to the benign bottom profile. However, I wouldn't jump in at max current, that's way to hairy for me.

In the bolded portion above - did you mean twice the world record speed? According to Wiki 100m long course world record from 2009 is 46.91 s - so more than twice the time above. Of course that's done in a skin tight ultra-low drag suit rather than high-drag full scuba. Not to mention world class athlete at top of their game rather than typical middle-aged, overweight recreational diver. At this point in my life if I swim about half as fast as I could in my youth I can maintain pace for almost 10% of the distance.

In short I strongly agree with your assessment.

 

[knotical]

We’ll probably never know but most posters seem to think it was a combination of at least two factors, with quite possibly several contributing.
It might be instructive to categorize the potential factors from
rather likely (water movement, medical event)
through reasonably possible (e.g. equipment problem)
to less likely (e.g. human error, vertigo, narcosis, etc, etc. …)