Suit filed in case of "Girl dead, boy injured at Glacier National Park

[Esprise Me]

The story gives information about the Hubbell case which we were otherwise unable to discover.

Last July, according to records, Ellen Hubbell sued Gull Dive in the death of her husband Jesse who drowned in Canyon Ferry in June 2019. Jesse hadn’t scuba dived in more than 25 years so he wasn’t certified, but Gull Dive still rented equipment to him and it was later found Hubbell’s regulator was on backward.​

The complaint said he was not certified, but this article said he had not dived "in more than 25 years so he wasn’t certified." The reporter likely did not know that certifications do not expire. If he was certified 25 years ago, then he was certified when he rented the equipment and when he dived. Perhaps he was not certified 25 years ago. I do not know what it means that a regulator was on backward. It is possible that the tank was set up with the valve on the back rather than toward the head, but in that case the regulator would work.

The Hubbell case is still ongoing but hadn’t gotten far by the time Linnea started interacting with Gull Dive. But there was no way for students like Linnea to know about the Hubbell case because Gull Dive didn’t report it to PADI in 2019 and kept using the PADI name.
​

This, too, contradicts the complaint, which faults PADI for not dealing with the dive shop over the Hubbell case.

I'm curious as to their source on this--what records did they review? I'm also not sure I trust their understanding of those records.

 

[MrVegas]

Snow and Liston simply advised Linnea that she could enter the water without an operational dry suit and use her BCD as her sole means of buoyancy control.

It seems to me that this line from the Complaint could characterize any number of possible conversations. Here is a purely imaginary, hypothetical conversation -- specifically not supposed to be this exact case:

Imaginary hypothetical:

Diver: "That friend of yours had a drysuit for sale after all, and it looks like it fits OK."
Instructor: "Great, let's hook up the rest of the gear . . . uh oh . . . "
Diver: "What's wrong?"
Instructor: "It looks like the hose connector doesn't match your inflator."
Diver: "What does that mean?"
Instructor: "It means that you really shouldn't dive in that suit."
Diver: "But I spent all that money and time and I really don't have another chance to finish this class anytime soon. Can't I just use the BC for buoyancy?"
Instructor: "Well, I guess if you're careful and you don't go too deep you can try it."

It only takes a momentary lapse of judgment to create a dangerous situation. In most cases, in all areas of life, most lapses of judgment luckily have few consequences. Sometimes, though, such lapses have horrible results. We would all hope that no instructor would ever finish the above hypothetical conversation in that way, but real life is messy.

In the real case at issue, that conversation could have looked completely different than the hypothetical, of course. I'm not suggesting this is representative of anything that actually happened.

 

[wetb4igetinthewater]

Also, for any who are interested, Ms. Mills’s obituary, which appears not to have been posted yet. Linnea Mills Obituary (2002 - 2020) - Missoula, MT - The Herald

That was a hard read. Stupid onions.

 

[R80]

I don't know whether this part of the complaint is confusing or misleading.

97. Training in how to safely conduct dives at altitude is important because higher altitude adversely affects a diver’s buoyancy, making the diver more negatively buoyant, and the diver must compensate for the effect of altitude to avoid suffering from decompression sickness and gas expansion injuries.​

1) I am not sure what they mean about altitude making the diver more negative. 2) Altitude does indeed affect buoyancy, but not as described, and at that altitude, I doubt an expert with thousands of dives could detect the difference. 3) With the planned dive, altitude would make no difference in DCS planning. 4) I have no idea what they are talking about regarding an increased concern about gas expansion injuries.

1) Their point is poorly expressed. The way that I can read it and make it true / make sense is that the change in pressure is higher per foot of depth. Imagine a neutrally buoyant diver at 2 ffw who descends to 10 feet without compensating in any airspace. On the back of a paper napkin I show that they are 5% more negative if the surface is .8 ATA vs 1 ATA. The buoyancy change per foot is higher at altitude than at sea level (which is exacerbated by overweighting). I suspect this is the concept they are attempting to convey but they did a poor job simplifying it for a non-technical audience.
2) already spoke to part of this, but I would say for a diver with an excessively large airspace to be neutral (overweighted) that it would be much more noticeable than for a properly weighted diver and then even more so at altitude. I would expect a reasonable buoyancy-aware and capable diver to be able to detect the combination.
3) DCS difference is likely minimal and may be addressed through a computer as you're well aware. I haven't gone back to the complaint to check whether she was using a computer and whether the model compensates for altitude if it's reported. However, it strikes me as strange to include the DCS matter in this paragraph as it can be compensated for in direct ways even if it is a factor. Again, excessive simplification of complex topics.
4) Gas expansion injury risk is increased for the same reasoning discussed in #1. Change in absolute pressure per foot depth is higher at altitude than at sea level. Less depth change is needed to achieve injurious overexpansion when at altitude vs at sea level.

If I've made a mathematical or logical mistake please let me know. The goal was to try and interpret what they may have been thinking or intending even if it wasn't communicated in a reasonable or even a broadly correct way. I am aware that you are vastly qualified to discuss the topic and I look forward to learning more even if you flatly disagree with what I've said.

 

[boulderjohn]

2) already spoke to part of this, but I would say for a diver with an excessively large airspace to be neutral (overweighted) that it would be much more noticeable than for a properly weighted diver and then even more so at altitude. I would expect a reasonable buoyancy-aware and capable diver to be able to detect the combination.

I haven't taught a DM class in awhile, but when I did, I made them calculate the difference in buoyancy between the altitude at which we dive in (New Mexico and Colorado) and altitude at sea level. We are close to twice as high in elevation as this incident. I also spend a lot of time at sea level. I can't tell the difference.

 

[boulderjohn]

I was pressed for time on the last post. Here is more complete information. With altitude, especially the altitude of this incident, the difference in pressure at any specific depth is not that important. What needs to be considered is the change in pressure with a change in depth. The key idea is that water weighs the same at any altitude, so the deeper you are, the more water weight is a factor in total pressure, and the closer you are to the same pressure as sea level. In contrast, the closer you are to the surface, the more air pressure is a factor in total pressure, and the farther you are from sea level pressure. This means that the change in pressure, particularly as you ascend, is greater at altitude. Almost all of the difference occurs in the shallowest 30 feet.

In terms of DCS, assuming the diver has been at the altitude long enough to have reached equilibrium before the dive (and that did happen here), the important thing is that when the diver is at depth, the diver is on-gassing at nearly the same rate as sea level. As the diver nears the surface, though, the pressure is much less, especially when the diver reaches the surface. That means the difference in tissue pressure and ambient pressure is greater, calling for more care and time in the final portion of the ascent. Computers will take that into account.

In terms of buoyancy, the same thing is true. During the final 30 feet or so, in accordance with Boyle's Law, there will be a greater expansion and contraction of gas in a BCD or drysuit with a change in depth.

How much difference? The air pressure at Lake McDonald is about 0.9 atmospheres, or 90% of sea level. Let's compare the difference in buoyancy between freshwater at sea level and freshwater at that altitude when a diver ascends from 34 feet (1 ATM of freshwater). The following equation (Boyle's Law) will show how a volume (call it it one liter) of air will increase over those 34 feet.

Sea Level:
1L * 2 ATA = XL * 1 ATA
2/1 = 2 liters at the surface.

Lake McDonald:
1L * 1.9 ATA = XL * 0.9 ATA
1.9/.9 = 2.11 liters at the surface​

That's not a whole lot of change over 34 feet. You would have to be one heck of a diver to notice the difference in buoyancy.

 

[wetb4igetinthewater]

I don't get the discussion on elevation as it related to weighting/buoyancy as the impact is so negigible at even shallow depths.

It is only a factor for DCS. Now that's an issue.

 

[Esprise Me]

So... anyone with the inside scoop know whether an answer has been filed?

 

[Wookie]

So... anyone with the inside scoop know whether an answer has been filed?

There has been no answer filed.

there is not a deadline for the response.

 

[R80]

In terms of buoyancy, the same thing is true. During the final 30 feet or so, in accordance with Boyle's Law, there will be a greater expansion and contraction of gas in a BCD or drysuit with a change in depth.

How much difference? The air pressure at Lake McDonald is about 0.9 atmospheres, or 90% of sea level. Let's compare the difference in buoyancy between freshwater at sea level and freshwater at that altitude when a diver ascends from 34 feet (1 ATM of freshwater). The following equation (Boyle's Law) will show how a volume (call it it one liter) of air will increase over those 34 feet.

Sea Level:
1L * 2 ATA = XL * 1 ATA
2/1 = 2 liters at the surface.

Lake McDonald:
1L * 1.9 ATA = XL * 0.9 ATA
1.9/.9 = 2.11 liters at the surface​

That's not a whole lot of change over 34 feet. You would have to be one heck of a diver to notice the difference in buoyancy.

I'm entirely with you on the first two paragraphs, I believe they are in line with what I suggested. I don't think liters displacement on a one-liter basis is the best way to conceptualize for the circumstances described, however.

1L of water is 2.2 pounds apparently (If a slightly different value should be used for water weight I don't believe it impacts the bigger picture). I suspect the BC needed to compensate for more than 30 pounds of negative buoyancy at the start of the dive with a ~full cylinder however 191 states 29.2 pounds of lift in the BC so lets use that. 29.2 lbs * (1 L / 2.2 lbs) = 13.3 L displacement for the BC. The equations above use a fixed volume at depth to determine volume at the surface. I don't believe this is appropriate for two reasons. We're at the start rather than the end of a dive in this scenario. Also ascending on a full BC does cause gas expansion but does not change the divers buoyancy in a substantial way on ascent as BC displacement is fixed when full and the change in air density inside the wing should be orders of magnitude smaller than we're interested in.

Therefore:

Sea level:
XL * 2 ATA = 13.3L * 1 ATA
13.3 L / 2 = 6.65 L
6.65 L * 2.2 lbs / L = 14.63 lbs

Lake McDonald:
XL * 1.9 ATA = 13.3L * 0.9 ATA
13.3 L * 0.9 / 1.9 = 6.3 L
6.3 L * 2.2 lbs / L = 13.86 lbs​

So a diver with 29.2 lbs of surface BC displacement going to 34 ffw will be .77 pounds more negative when they arrive there if they are at lake McDonald vs Sea level. The elevation is definitely secondary to the overweighting as a factor here, but at nearly a pound more negative at altitude it's reasonable to claim this scenario is more challenging at altitude than at sea level. This will require larger or more frequent gas additions. A capable diver can compensate for this difference at one elevation vs another without any change in their process, but it doesn't change the fact that the change in pressure with depth at altitude will require BC vs lung changes more actively at altitude than at sea level. This is exacerbated by the overweighting.

I'm not saying it would be easy for a diver to determine their elevation based on buoyancy changes at various depths, but it is a factor. Also, much smaller changes in buoyancy are easily detectable by a diver when presented side-by-side. The most dramatic example I can think of for this is depth changes of a few feet on a rebreather forcing airspace changes to maintain neutral buoyancy.

So the conclusion I would reach here is that I can't view the elevation as a first-order issue here, but I believe the argument "higher altitude adversely affects a diver’s buoyancy, making the diver more negatively buoyant" is valid even if there are shortcomings in how the argument was expressed.