Female Diver Missing on The Yukon, San Diego

[Ken Kurtis]

This may or may not be germane to this specific accident, but it certainly does bring up interesting points.

Here's simulation of BC failure in a 7mm wetsuit diver wearing a 13lb weight belt on a 90 ft dive

I watched the whole video. It's not the simulation but only two divers talking about simulated BC failure. Unfortunately, there's no video of the actual simulation and that could have provided some info on other parameters that affected the outcome of the simulation.

Note that she is unable to overcome the negative buoyancy just by finning . . .

That's what she says. But there are a number of things we'd need to know to see if that was really the case. These include:
• Bouyancy of tank worn
• Amount of air in said tank
• Actual weight worn. (The weights looked heavier than 6 kilos - 13.2 pounds in a 7mm suit w/a 5mm shorty as well - but we'll have to accept that)
• Fins she used (some kick better than others)
• Her kicking technique

The last point, to me, may be the most critical. If she bicycles, she won't get anywhere (unless she's wearing Force Fins which are designed for that). So until you know how good the mechanics of her kick are, you can't definitively say that she can't kick up against 13 pounds of weight + the weight of the tank/air.

. . . and after she dumps her weight belt she still has to fin to ascend.

Well, she said she took a breath and then it was easy to fin up. Again, buyoancy of the tank may factor in.

If the diver is able to, she can dump part of her weights--

She showed a single belt with 4 weights on it so in this particular case, partial dumping not an option.

. . . but this would still result in positive buoyancy at shallow depths and excessive ascent rate.

Still beats the alternative.

A better solution is to deploy the SMB.

If one is carried. Most recreational divers do not carry one. But if you've got it, and if you've got the presence of mind (and available air) to fill it, yes, that's a good option for additional buoyancy to at least get you close to the surface. (Since it's on a line or you'll hold onto the bottom, it'll likely get you very close, but not necessarily above, the water's surface.)

But the overall point of the video is correct and something divers don't think about: You become significantly over-weighted at deeper depths due to wetsuit compression. And if you START the dive over-weighted (I'm not at all implying that's what Staci did), then that condition becomes more exaccerbated as you descend.

- Ken

 

[nimoh]

This may or may not be germane to this specific accident, but it certainly does bring up interesting points.



I watched the whole video. It's not the simulation but only two divers talking about simulated BC failure. Unfortunately, there's no video of the actual simulation and that could have provided some info on other parameters that affected the outcome of the simulation.



That's what she says. But there are a number of things we'd need to know to see if that was really the case. These include:
• Bouyancy of tank worn
• Amount of air in said tank
• Actual weight worn. (The weights looked heavier than 6 kilos - 13.2 pounds in a 7mm suit w/a 5mm shorty as well - but we'll have to accept that)
• Fins she used (some kick better than others)
• Her kicking technique

The last point, to me, may be the most critical. If she bicycles, she won't get anywhere (unless she's wearing Force Fins which are designed for that). So until you know how good the mechanics of her kick are, you can't definitively say that she can't kick up against 13 pounds of weight + the weight of the tank/air.



Well, she said she took a breath and then it was easy to fin up. Again, buyoancy of the tank may factor in.



She showed a single belt with 4 weights on it so in this particular case, partial dumping not an option.



Still beats the alternative.



If one is carried. Most recreational divers do not carry one. But if you've got it, and if you've got the presence of mind (and available air) to fill it, yes, that's a good option for additional buoyancy to at least get you close to the surface. (Since it's on a line or you'll hold onto the bottom, it'll likely get you very close, but not necessarily above, the water's surface.)

But the overall point of the video is correct and something divers don't think about: You become significantly over-weighted at deeper depths due to wetsuit compression. And if you START the dive over-weighted (I'm not at all implying that's what Staci did), then that condition becomes more exaccerbated as you descend.

- Ken

I watched the whole video, and although the first half was talking about the exercise, the second half was the in water demo.

However, her fin kicks were really not very good, to me it appeared that she was purposely trying to kick such that she wouldn't go up. But then after dumping the weight, she started making some very nice smooth frog kicks and was able to get up.

 

[Power Scuba]

Bringing all this around to the incident at issue once again: A thought just struck me. The Humboldt is outfitted with steel 85s. Part of their welcome & safety speech always (on the many trips I've been on) addresses this difference. They speak of the need to drop weight from that which a person with an Al 80 would normally use.

{Conjecture}
If the deceased was even a few pounds overweighted normally (let's say 2-4 pounds, which many divers tend to be) AND she used a boat-provided steel 85 without adjusting her weight loadout, that could have made her significantly overweighted. What I can't figure out is why she wouldn't have sensed this immediately after jumping off the Humboldt. I'm still betting on a BC failure once she decended, but significant overweighting might have had the same effect... inability to achieve neutral/positive buoyancy at depth and her buddy feeling he needed to "drag" her up to the surface.
{/conjecture}

Bill

 

[flots am]

Bringing all this around to the incident at issue once again: A thought just struck me. The Humboldt is outfitted with steel 85s. Part of their welcome & safety speech always (on the many trips I've been on) addresses this difference. They speak of the need to drop weight from that which a person with an Al 80 would normally use.

If she was actually snarled in line as the news report indicated, I'm not sure weighting would matter much. Cutting tools would have been useful, however. Anybody know if she had any?

I've been trapped underwater in line before without cutting tools. Now I won't even get in the pool without them.

flots.

 

[dumpsterDiver]

The answer to this question is clear, once you realize that water has no weight underwater. If you are correctly weighted, you are negative by the weight of the gas you intend to consume, when you are at the surface. The weights you wear are primarily to neutralize the buoyancy of your exposure protection. As you descend, you lose buoyancy from anything that can compress, so in a thick wetsuit, you can be quite negative at depth, which is why you put air in your BC. But if your BC will not hold any air, and you are so negative that you cannot swim up (and the wisdom of diving a configuration that permits that is something else to think about), then if you drop your weights, you will now again be no more negative than the air in your tank, and everybody can swim up five pounds. The big problem in that situation is controlling your ascent, once your neoprene reexpands.

In practice, it is difficult to have a failure that completely disables a BC. About the only one that will do it is pulling the corrugated hose off the air bladder altogether -- and even that won't cause a disaster, if you are horizontal.

I've had at least two total BC failures at depth.

I wonder if you can share some video of being able to use a bc with a disconnected (corrugated) hose and horizontal position. It would be so easy to do in the pool, wear a little extra lead, disconnect the BC hose and film the result... You would need to wear 12 -15 lbs of excess lead to simulate the situation that would occuur at considerable depth with suit compression.

 

[peterbj7]

What sort of failures? I can't envisage what might happen at depth, short of physical damage like ripping the fabric on a wall or wreck.

I've had quite a few "tech wannabe" divers turn up at my shop, with heavy SS backplates and no lead but still quite negative at the surface. These people are an accident waiting to happen, with no dumpable weight and totally dependent on their (usually skimpy) wings.

 

[Ken Kurtis]

I watched the whole video, and although the first half was talking about the exercise, the second half was the in water demo.

My bad. When it faded to black after the discussion and she said she'd dive in her drysuit, I thought that was it and I clicked out. That being said . . .

I jus tnow glanced at the beginning of the in-water demo. IMHO, she's starting out a good five pounds over-weighted. Again it would help to know what size tank she had and the bouancy but I don't think she should be sinking that far at the surface with no air in the BC. I think she should easily be able to keep her head/mouth above water and then when she descends just a few feet, wet suit compression takes care of the rest.

- Ken

 

[FM1520]

IMHO, she's starting out a good five pounds over-weighted. Again it would help to know what size tank she had and the bouancy but I don't think she should be sinking that far at the surface with no air in the BC. I think she should easily be able to keep her head/mouth above water and then when she descends just a few feet, wet suit compression takes care of the rest. - Ken

The point of video is to illustrate that at 90 feet, wearing a 7mm wet suit and a failed BCD it may be hard (impossible for some, not for others) to swim up without ditching your weights - especially if you are over weighted (even a little) to begin with. Add panic and/or task loading and it could be problematic. This may be a factor in this accident.

 

[Ken Kurtis]

The point of video is to illustrate that at 90 feet, wearing a 7mm wet suit and a failed BCD it may be hard (impossible for some, not for others) to swim up without ditching your weights - especially if you are over weighted (even a little) to begin with.

Well, the instructor in the video is talking about how she's now properly weighted at the surface so I don't think he thought this demonstarted difficulty while OVER-weighted but illustrated difficulty while PROPERLY-weighted and it would be even harder if over-weighted.

Add panic and/or task loading and it could be problematic. This may be a factor in this accident.

Agree to the first and possible to the second but we likely won't know more until the investigation is complete.

Be aware that San Diego has a specific Diver Death Review Committee (Coroner and various first-responding agencies including reps from cert agencies) that will meet once all the various agency investigations are done and will issue a consensus report on the accident, which is available to the public. They will give some detail on what they found along with lessons learned and recomendations, if any.

- Ken

 

[Power Scuba]

We don't know if she was snarled in line before or after she expired. The crevice on the Yukon tends to be a place where a conscious diver has to TRY to get down into (though an unconscious diver could easily be rolled down into it). Even so, as I stated in a previous post, a conscious diver would have a pretty tough time getting themselves inextricably caught up in the line that is there (old mooring lines, a lobster trap line or two, and railing lines).

{Conjecture}My vote is that if she was indeed found tangled in line in the crevice, it happened after she died.{/Conjecture}

Additionally, according to the lifeguard interview on the news, she had some type of BC {or weighting, I'm conjecturing} malfunction necessitating her buddy to attempt to physically assist her up to the surface. He lost his grip, shot to the surface, and was reported as having to go to the chamber (either in Hillcrest or Coronado. I've seen both mentioned). She never made the surface. So, her weighting could very well have played a major part in this incident.

Bill

If she was actually snarled in line as the news report indicated, I'm not sure weighting would matter much. Cutting tools would have been useful, however. Anybody know if she had any?

I've been trapped underwater in line before without cutting tools. Now I won't even get in the pool without them.

flots.