Doc Deep dies during dive.

[Grender]

If you look at the video from one of his workup dives he says he's going to 550 fsw in "hopefully less than 5 minutes". I don't know what his descent rate to 1200 fsw was but use the rate from his workup dive as a baseline and compare it to the descent rates that Akimbo posted from the Navy Diving Manual for saturation diving.

Best regards,
DDM

He was supposed to descend and and than ascend to reach his safety team at 380' in 38 mins. You may be able to work backwards to his descent rate if he is using some kind of standard ascent rate.

 

[cerich]

He was supposed to descend and and than ascend to reach his safety team at 380' in 38 mins. You may be able to work backwards to his descent rate if he is using some kind of standard ascent rate.

53.15 fsw/min both ways if constant...aka "terminal velocity"

---------- Post added August 16th, 2015 at 04:13 PM ----------

Table 15‑6. Saturation Diving Compression Rates. Page 15-24

Depth Range	Compression Rate
0 – 60 fsw	0.5 – 30 fsw/min
60 – 250 fsw	0.5 – 10 fsw/min
250 – 750 fsw	0.5 – 3 fsw/min
750 – 1000 fsw	0.5 – 2 fsw/min

Just to remind...

assent rates are 6 fsw an HOUR from 1600 to 200 on US Navy Heliox scheds.

 

[tomfcrist]

That's for sat dives though

 

[Akimbo]

If you look at the video from one of his workup dives he says he's going to 550 fsw in "hopefully less than 5 minutes"...

As DDM knows, HPNS isn't the only bad actor in "fast descents".

... Slow compression not only virtually eliminates HPNS symptoms in depths above about 1,000', it manages joint cartilage compression (compression arthralgia). My brother was on a fast blow-down to about 600' in the mid-70s... within about 20 minutes. He and the other divers could barely climb into the bell on top of the transfer lock from pain often experienced by joint replacement candidates. It took them about 12 hours to recover, though minor pain persisted for days...

Think about it. Would you start a high risk and demanding dive knowing your movements will be so painful that operating valves or grabbing a line may be difficult to impossible? That's the compression arthralgia part. Now, would you start a dive knowing there is a high likelihood that you will get tremors that you probably have little or no experience with? That's the HPNS part.

On the other hand, you could be the first person discovered in human history who is immune to both maladies; providing you don't die from the bends, oxygen poisoning, hypothermia, or gas management problems first. Like NetDoc wrote, what's the point?

 

[scagrotto]

I just wonder what went wrong so fast.

It may seem fast considering that the first 38 minutes was less than 7% of the total planned run time, but as near as I can figure (and I'll admit to knowing very little about deep diving) the first 38 minutes probably accounted for something over 90% of the risk. Besides that, even for a simple rec dive to 100' or less how long does it take for things to go from fine to really bad to unrecoverable?

I will still applaud his courage.

I don't know how much courage had to do with it, but sometimes what looks like courage is really a failure to adequately understand the risk. Most of the OW divers who die in caves are good examples of that.

 

[Akimbo]

That's for sat dives though

True, but if you actually want to be able to do anything at depth that a ROV (Remote Operated Vehicle) can't do better, cheaper, and safer then you are effectively committed to a sat decompression schedule anyway. A compression arthralgia and HPNS free descent to 1200' is in the 20 hour ballpark. There is a reason that the deep bell bounce dives in the 1960s don't exist today... and they were only in the 300-600' range.

 

[tomfcrist]

Unfortunately you are correct in everything you just said Chris. I'll stay above 400' on OC and above 300' unless I find Atlantis. RB??? Maybe a bit deeper. 1200'? Leave that to the 22yo commercial guys with an umbilical.

 

[Duke Dive Medicine]

As DDM knows, HPNS isn’t the only bad actor in “fast descents”.... Think about it. Would you start a high risk and demanding dive knowing your your movements will be so painful that operating valves or grabbing a line may be difficult to impossible? That’s the compression arthralgia part. Now, would you start a dive knowing there is a high likelihood that you will get tremors that you probably have little or no experience with? That’s the HPNS part.

Not to mention gas density and temperature. I wonder how he reassured himself that his regulators would perform at that depth.

 

[Akimbo]

Not to mention gas density and temperature. I wonder how he reassured himself that his regulators would perform at that depth.

Not sure he bothered. Kirby-Morgans are the only ones I know of that have actually been tested that deep in a chamber on breathing machines. I'm not sure that any of these new KM regulators have been used on 1200'+ working dives, but a lot of the older models have:

Regulators | Kirby Morgan

 

[meatsim]

The Captained also said that Dr. Garman’s body would not be retrieved from the ocean until an attempt next week, as plans were being made to obtain equipment required to lift the descent line.

Can someone provide some insight on how a descent line is normally setup and why special equipment is required to lift it? Also how are divers normally attached?