The 'Jascon 4' rescue video - 3 days at 30m and lived!

[Tigerman]

Ha!... That wouldn't surprise me!

It would surprise me if there ISNT

 

[Akimbo]

... I'm sure there is much more to the story than the news media got right.

One newscaster stated that the water temperature was below freezing. Granted, sea water freezes at 28° F/−2 °C, but 5° above the equator in 100'/30 Meters of water… I don’t think so. I guess journalism school doesn’t require physiology or geography.

Another newscast showed an image of the Jackson 4 tugboat and said it was the rescue vessel. The rescue vessel was the 289'/88 M long Lewek Toucan, which appears to have been built as an Anchor Handling Vessel and converted. Lots of images here:

LEWEK TOUCAN Ship Photos - AIS Marine Traffic

I tend to trust reporting by Subsea World News on something like this.
Subsea World News - DCN Divers Rescue Survivor from Jascon 4 (Nigeria)

Here is an image of the bell and moonpool.

 

[DandyDon]

One newscaster stated that the water temperature was below freezing. Granted, sea water freezes at 28° F/−2 °C, but 5° above the equator in 100'/30 Meters of water… I don’t think so. I guess journalism school doesn’t require physiology or geography.

NOAA buoy Station 13010 is the nearest, currently showing 82.4 F water - and I doubt that it changes much nor has a thermocline. I'm sure the trapped cook was "freezing."

 

[Akimbo]

NOAA buoy Station 13010 is the nearest, currently showing 82.4 F water - and I doubt that it changes much nor has a thermocline. I'm sure the trapped cook was "freezing."

I’m not sure that is a fair assumption. A big clue was the sat diver just brought a Kirby-Morgan band mask and harness. If the sea water was even moderately cool they would have put him in a hot water suit first. Also the video didn’t show the sort of erratic muscle movement of someone who felt cold.

Moderate hypothermia is a core temperature of 28–32 °C (82–90 °F). It looked like he could keep the majority of his body out of the water and the air temperature was probably in the high 70s to low 80° F. range.

I suspect he didn’t “feel freezing” until the swim back to the bell because (I assume) they were on HeO2. Low 80s F, especially unprotected in the water, is excruciatingly cold on Heliox. The bell and chamber at that depth are probably kept around 88-89° F to be comfortable with a comfort zone in the +/-½° F range.

 

[CT-Rich]

I’m not sure that is a fair assumption. A big clue was the sat diver just brought a Kirby-Morgan band mask and harness. If the sea water was even moderately cool they would have put him in a hot water suit first. Also the video didn’t show the sort of erratic muscle movement of someone who felt cold.

Moderate hypothermia is a core temperature of 28–32 °C (82–90 °F). It looked like he could keep the majority of his body out of the water and the air temperature was probably in the high 70s to low 80° F. range.

I suspect he didn’t “feel freezing” until the swim back to the bell because (I assume) they were in HeO2. Low 80s F, especially unprotected in the water, is excruciatingly cold on Heliox. The bell and chamber at that depth are probably kept around 88-89° F to be comfortable with a comfort zone in the +/-½° range.

I hadn't thought of that, helium will transfer heat much fast than larger atoms. But in fairness, after being in the water for 3 days, Harrison must have been exhausted and pretty beaten up. In that state, even a temperature in the high 70s would be slowly draining his strength. If he didn't run out of air, he would have eventually died of exposure, it would have just been a matter of time.

 

[Akimbo]

This thread explains a lot about living in a Helium atmosphere.

http://www.scubaboard.com/forums/commercial-divers/467739-what-saturation-diving.html

Around 50% of our thermal loss is through respiration. The surface area of adult human lungs are in the 70 M²/750 Ft² to 100 M²/1076.39 Ft² range. Add to that a lot of blood pumping past the lungs and you have very rapid loss of core temperature when you fool with the thermal conductivity of the gas you breathe.

This is an interesting reference:

[TABLE="width: 693"]
[TR]
[TD]Times as conductive as air
[/TD]
[TD]W/(m·K)
[/TD]
[TD]Name
[/TD]
[/TR]
[TR]
[TD]1.0
[/TD]
[TD]0.024
[/TD]
[TD]Air (gas)
[/TD]
[/TR]
[TR]
[TD]0.7
[/TD]
[TD]0.016
[/TD]
[TD]Argon (gas)
[/TD]
[/TR]
[TR]
[TD]0.6
[/TD]
[TD]0.0146
[/TD]
[TD]Carbon dioxide (gas)
[/TD]
[/TR]
[TR]
[TD]5.9
[/TD]
[TD]0.142
[/TD]
[TD]Helium (gas)
[/TD]
[/TR]
[TR]
[TD]7.0
[/TD]
[TD]0.168
[/TD]
[TD]Hydrogen (gas)
[/TD]
[/TR]
[TR]
[TD]90.8
[/TD]
[TD]2.18
[/TD]
[TD]Ice (0°C, 32°F)
[/TD]
[/TR]
[TR]
[TD]1.0
[/TD]
[TD]0.024
[/TD]
[TD]Nitrogen
[/TD]
[/TR]
[TR]
[TD]1.0
[/TD]
[TD]0.024
[/TD]
[TD]Oxygen
[/TD]
[/TR]
[TR]
[TD]24.2
[/TD]
[TD]0.58
[/TD]
[TD]Water
[/TD]
[/TR]
[/TABLE]

The tricky part is that cold water contact with skin causes constriction of blood flow to preserve core temperature. Even though Helium is only 5.9x as conductive as air and water is 24.2, the effect on core temperature doesn’t correlate anywhere near these proportions.

The poor guy would have been in much rougher shape had he not been able to keep most of his body out of the water. It would be interesting to know if they pumped air into the space while they were dressing out.

 

[CT-Rich]

Afterdark and I were chatting on the phone earlier and we were discussing whether or not he was narc'd or not. When he was rescues things went very well getting him to swim out of the wreck to the bell. One of the things that occurred to me during the discussion was what he breathing by the time he was rescued. In addition to the water temp, another factor would be the CO2 levels. I suppose you would get some gas exchange from the water to the air, but I figure that would be negligible. I was also thinking that he might have been in a much larger air pocket that was simply beyond the confines of his cabin's space that we couldn't see and he couldn't access (the walls of the cabin made with thin paneling versus a structural bulkhead for example). some one with more experience/knowledge might want to make a comment to that. the other question would be is how much of an air pocket would be required to keep a man alive for 3 days? I do know that a big factor is the build up of CO2. When it hits about 5%, your blood stops off gassing CO2 and you can't absorb oxygen and you suffocate. Anyone have any thoughts?

 

[DandyDon]

He was very calm, but he'd already been thru hell so anything could be an improvement. I don't know that he actually heard fish eating his crew mates - but he thought he had, and he'd be entombed in pitch black darkness for days waiting to die. He's a tougher man than me...!!

He's is also Nigerian, so his life experiences have certainly been far more demanding than mine - but on the other hand, he was a tug boat cook in Nigeria so I presume accustomed to doing what he was told - period.

 

[kwinter]

Can one of you sat divers out there explain to me why the cook was put on heliox for his removal? Is it because they can only pump down one gas through both umbilicals? Or was it because getting some He into him was necessary before the long decompression in the chamber? Seems to me they wouldn't be breathing helium in the chamber.

 

[Andyoak]

Not a sat diver, but have many mates who are. They most definitely breathe helium in the chamber, if they did not they would all be narked all the time.