Female Diver Missing on The Yukon, San Diego

[diverrex]

Isn't there a difference in buoyancy between a live diver breathing with air in their lungs (even just after exhaling) than there is to a deceased diver presumably with no air in their lungs?

 

[Hatul]

Isn't there a difference in buoyancy between a live diver breathing with air in their lungs (even just after exhaling) than there is to a deceased diver presumably with no air in their lungs?

Good point. Nominally with full tidal volume we have an air filled volume of 3L so that can explain a loss of 3kg or 6.6 lbs of buoyancy. The regulator is another few lbs. Is that enough to explain negative buoyancy with 7mm wetsuit at 100 ft?

 

[antattack]

I have a new appreciation for the power of a surge over a reef or wreck.

This is a good reminder for me to PRACTICE rescuing an unresponsive diver at depth. If you are diving with me this weekend, expect to practice that one skill.

 

[TSandM]

Some folks I know did an experiment with a 7 mil wetsuit. They took it to 100 feet, to measure how much buoyancy it lost, and they came up with 23 lbs. I don't know what size suit it was or how new, but that was what they got. That's one of the reasons some folks recommend that people doing deep dives in cold water either dive dry, or have some redundant source of buoyancy.

 

[Notso_Ken]

Some folks I know did an experiment with a 7 mil wetsuit. They took it to 100 feet, to measure how much buoyancy it lost, and they came up with 23 lbs. I don't know what size suit it was or how new, but that was what they got. That's one of the reasons some folks recommend that people doing deep dives in cold water either dive dry, or have some redundant source of buoyancy.

Also, was it a 1 piece 7mm, or a 2pc?

That is a good thought on the dry suit for cold water. I dive a 2 pc 7mm or a dry suit in cold water, maybe I will tend more towards the dry suit now.

 

[Power Scuba]

Hatul, The DM reported he did not interface with a (her) weight belt, but the report doesn't state whether she had the weight belt on at the time the DM found her. (One would hope the DM's first or second move, when attempting to bring her up, would be to remove the belt (if it was still on). The report does say at the time the city recovery team found her the next day, her weight belt was not on (and found a small distance away on the bottom). (It could have been removed either by her, the DM, or the Humboldt divers who went down and tried to recover her.)

The Humboldt's standard blurb, in their welcome speeches, about the boat tanks (steel 85), is to drop six pounds from what one would normally use with an Al 80. That sounds, then, like the tank would be negative, yes?

Yes, the bit about the BC holding air well when the city recovery team brought it up caught my attention as well. I'm told by an insider that the BC may have been a tropical version (read: Not much lift capacity). If Staci still had her weight belt on when the DM tried to bring her up, is it possible the BC wouldn't have been effective even when inflated? (Pure conjecture.) That's one thing we may never find out as I don't expect the DM to ever speak about this in public.

Staci was ~112 pounds and extremely fit. I'm told she may have had very low body fat... which would have affected her buoyancy. "Standard" weighting guidelines may not have applied to her. That's the only thing I can't figure out here. The part about her being negative on the bottom even w/o her belt on is giving me serious pause. (Nothwithstanding the previous posts about air within a living vs deceased diver.)

Bill

 

[merxlin]

Knowing how much weight she was carrying would be very helpful here. I can't see a scenario where she had a full BC and was heading up, with help from someone else with a full BC, and them not been able to rise (and definitely not making her sink) unless she was severely over-weighted. It also points to the weight belt being lost at depth, probably after she hit the bottom.

 

[Power Scuba]

Merxlin, Staci's weight belt had 8 pounds on it.

Her tank, at Empty, was reported as being slightly buoyant.

The only thing we're left with, then, is the crushing of her (well-worn, perhaps?) wetsuits neoprene cells to a degree I'd not fully considered possible prior to this accident... and her low body fat percentage.

Bill

 

[MacDyver60]

As for bouyancy issues, thats explained by tissue saturation of salt water (osmosis) and reduced air spaces at depth carrying a depleted steel tank. she was recovered the next day remember? her gear was properly set up for aluminum tanks here on the east coast.

What puzzles me is the empty tanks???

---------- Post added March 17th, 2013 at 01:01 PM ----------

Can you share how you found that information? Is this available to the public?

I am her Father.

 

[Hatul]

Merxlin, Staci's weight belt had 8 pounds on it.

Her tank, at Empty, was reported as being slightly buoyant.

The only thing we're left with, then, is the crushing of her (well-worn, perhaps?) wetsuits neoprene cells to a degree I'd not fully considered possible prior to this accident... and her low body fat percentage.

Bill

8 lbs seems very little weight on the belt. I use 14 lbs plus 4 lbs on tank bands and my tank is 2-3 lbs more negatively buoyant than the Faber LP85 of the Humboldt. Was she wearing any other weights attached to her tank that were non ditchable. Perhaps a steel backplate?