Accident in Finland

[Dave Sutton]

Dave is maybe spot on focusing so much on the ADV in respect of this accident.

While I like to think I am good at thinking things thru, my bet is on either 02 off or controller off, not a failed ADV. That's just a statistical guess. It's the simplest possibility.


Simple explainations are generally the correct one. Not always, but...


"When you hear hoofbeats behind you, think horses, not zebras"

(unless you happen to live in Kenya, in which case all bets are off)




ADV failures are rare. Not so rare that we ought to ignore them, but... rare. They are "less rare" on some rigs and "more rare" on others, but they are... rare.

02 system "failures" are far more common. In my experience, they are "most commonly" diver procedural errors, not technical malfunctions. 02 off, controller off, etc.



What to take away as a lesson?

1: Let the rig keep you alive for five on the surface. On an eCCR let the solenoid do it.

2: Don't let hypoxic dil get to your mouth when shallow.






Dave


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[steve6690]

Excellent. Well done to you, and to your instructor.

Academic Question: Was he/she also a Meg Instructor?



Dave


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Not a Meg instructor, just Inspo and more recently the Poseidon unit. He's been around for donkeys years so has a lot of experience, and a few dead friends over the years.

 

[gianaameri]

While I like to think I am good at thinking things thru, my bet is on either 02 off or controller off, not a failed ADV. That's just a statistical guess. It's the simplest possibility.

Do we know if he did a pre-breathe (properly)?

Does the JJ Controller turn itself off after a certain amount of time that it has not been submerged beyond a certain depth (i.e. depth sensor not triggered)?

I take some time to hook up bottles in the water and to do in-water checks and I find my dive computers (not the Meg APECS) usually turn off on their own before I submerge.

 

[gianaameri]

The JJ uses Shearwater controller as I understand rather than own electronics.

Is there a time-out on that Controller (i.e. after being turned ON it shuts itself down if not submerged say for xx minutes)?

I found on some Dive Computers/pPO2 Monitors that I'd turn them ON, do the pre-breathe (10 min. for me, 5 min. on eCCR anf 5 more min. on eCCR + Pelagian Needle Valve combined), then I walk in the water and start putting the side-mount and under-mount tanks on, then I do in-water checks on everything (all LP buttons, each OC 2nd stage, BOV...), and by the time I am ready to go, the Dive Computers/pPO2 Monitor has turned itself off (I no longer use them now).

 

[mike]

Following the procedure of a 5 minute "all systems running" on deck pre-breathe with the solenoid bringing up the loop from 0.21 to 0.70 would reduce the number of RB mishaps by a huge percentage.

I completely agree with the idea of checking to makesure your solenoid is firing and the unit will hold setpoint before jumping in. But I'd like to suggest a modification to your procedure.

I really DO NOT agree with the idea of ever having the loop contents down at .21 ever. (unless the unit is in pieces, or you are sitting on the couch).

I've fallen in backwards from a RIB while getting geared up with the DSV in doing a pre-breathe. I was very glad I had mostly O2 in the loop as I sorted the rest of my shit out... including adjusting the unit sothe lungs were properly attached and I could reach the manual adds.

There is no functional difference in testing between letting the loop drop from 0.7 to 0.69 and having the solenoid fire, and having the solenoid bring the loop up from 0.21. There is a huge safety difference between having 0.69 and 0.21 in the loop. Having 0.69 means that you will run out of breathable volume before you go hypoxic.

Stay safe and keep well away from every having less than PPO2 of 0.5 in your loop.

Mike
(My procedure is to turn the unit on and flush O2 up to .8 or so, before I even start getting geared up. Then while I'm getting geared up you can monitor counterlung pressure, listen for the solenoid, dump water over the unit to look for leaks etc. Then once I've put it on, I breathe until the solenoid fires and brings the unit up to 0.7. Often I'll tap the ADV (MEG adv in my prism) to check it's working and drop the PPO2 if I've had too close to 100% in the loop. But that's all just detail, the principle is that if there is enough volume in the loop to breath, you must be sure PPO2 is high)

 

[Blomman]

Do we know if he did a pre-breathe (properly)?

Does the JJ Controller turn itself off after a certain amount of time that it has not been submerged beyond a certain depth (i.e. depth sensor not triggered)?

I take some time to hook up bottles in the water and to do in-water checks and I find my dive computers (not the Meg APECS) usually turn off on their own before I submerge.

The handset on the JJ is a Predator hardwired to the head. All Predators have wet sensors and shall not power off while still wet.

 

[mike]

Bit tricky on a Sentinel (and possibly Poseidon Mk6) as the surface set-point is 0.4. It only raises to 0.7 once below the "splash" zone.

FYI - I was led to understand that pre-breathing on a lower set-point meant you where more likely to feel any CO2 effects (that's masked by higher set-points)

I can only repeat "stay away".:nono:
(Never seen either unit, but neither sounds like anything I'd consider buying)
I like as close to 100% O2 in the loop is is possible anywhere shallow. I''ve always run deco manually and splashed with ~100%.

Hitting PPO2 of ~2 for a short period will not kill you. Dropping below ~.1 will.
Hyperoxia has killed one or two. Hypoxia has killed hundreds.

I'm not an expert on physiology, but I have sat breathing on a scrubberless unit with just O2 in the loop while a hyperbaric doc watched and laughed at me. The effects of CO2 kicked in as expected... it takes a while. A mate on a prism managed to jump in without a working scrubber at all - after a pre breathe - and made it to the down line and descended a ways before he felt a bit crap and floated back to the surface.

O2 might mask the body's reaction to carbolic acid slightly, but I suspect it's noise in the variable response of different people on different days. I trust correct prep and a long duration scrubber way more than a pre breathe for preventing CO2 hits.

Mike

 

[gianaameri]

The handset on the JJ is a Predator hardwired to the head. All Predators have wet sensors and shall not power off while still wet.

"DiveCAN/rMS: controllers now use wet contacts for auto turn-on." (read here: http://www.shearwaterresearch.com/wp-content/uploads/2012/08/Predator-V46-Release-Notes.pdf )

However, I do not see reference to wet contacts in the manuals/docs. for prior version Controllers.

 

[Blomman]

"DiveCAN/rMS: controllers now use wet contacts for auto turn-on." (read here: http://www.shearwaterresearch.com/wp-content/uploads/2012/08/Predator-V46-Release-Notes.pdf )

However, I do not see reference to wet contacts in the manuals/docs. for prior version Controllers.

My Deep Pursuit have wet connectors, it is from 2010. My stand alone Pursuit computer also have wet connectors.

 

[gianaameri]

My Deep Pursuit have wet connectors, it is from 2010. My stand alone Pursuit computer also have wet connectors.

I guess there is some hardware reason why the wet connectors in your existing system cannot be used to auto-turn ON the Controller (i.e. the software cannot be modified to include the feature).

I do not believe people jump in the water without turning ON their Controller (generally people would look at the screen at some point before leaving the boat), but the auto-turn ON feature would reduce such risk.

What worried me was the auto-turn OFF feature (if any was implemented).

For example, if the wet contacts have failed, even if the diver does turn-on the Controller, any auto-turn OFF feature could shutdown the Controller.

 

[Dave Sutton]

Shearwaters do not have wet CONTACTS.

They might have wet CONNECTORS for adding a rebreather with a Fisher...


Dave

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[drews]

ADV off until 20 feet is taught ab-initio in Meg courses as its the safest procedure in the long term, and builds good habits at the beginning in order to need to make changes in habits as a diver progresses.

Hi Dave
Is this a new rule on a Meg course?.
I did my Mod1 on a Meg last year and was certainly not taught.
I've put a stop on my JJ, recommended by other JJ owners.

 

[erikradstrom]

Shearwaters do not have wet CONTACTS.

They might have wet CONNECTORS for adding a rebreather with a Fisher...


Dave

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Mine is a updated Pursuit and it has wet connectors.
If they get wet it will turn on immediately.

 

[Dave Sutton]

Hi Dave
Is this a new rule on a Meg course?.
I did my Mod1 on a Meg last year and was certainly not taught.
I've put a stop on my JJ, recommended by other JJ owners.

AFAIK It's been Leon's rule since he built the Meg.

In theory it should be taught as standard by every instructor on the Meg.

Of course the difference between theory and practice is that in theory they should be the same, yet in practice they are often different...


Dave

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[Dave Sutton]

Mine is a updated Pursuit and it has wet connectors.
If they get wet it will turn on immediately.

Hmmm..... <scratches head>....... Hmmm.......


Dave

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[gianaameri]

Mine is a updated Pursuit and it has wet connectors.
If they get wet it will turn on immediately.

O.K. yours does, but it is not standard for JJ Controllers.

So, I understand JJ Controllers do not have wet contacts and/or auto-turn ON feature.

I was trying to understand if JJ Controllers have auto-turn OFF features (or they stay ON forever unless Turned-Off manually by pushing buttons).

 

[nickb]

Shearwaters do not have wet CONTACTS

Mine is a updated Pursuit and it has wet connectors.
If they get wet it will turn on immediately.

Hmmm..... <scratches head>....... Hmmm.......

Easy enough to check, rather than argue the toss on the internet.

I just dunked my Predator (also an updated Pursuit) into a small bowl of water and it turned on in about 5 seconds. It did NOT however switch from 0.19 to 0.7 which one might expect.

[EDIT]I tried this with my stand-alone Petrel and it remained switched-off.

 

[nickb]

I was trying to understand if JJ Controllers have auto-turn OFF features (or they stay ON forever unless Turned-Off manually by pushing buttons).

They DO turn-off when in surface mode and no buttons have been pressed for a period of time.

This is a bit of a PITA if you're sat kitted-up waiting to enter the water and the skipper is taking his time getting the shot in or slack is a bit late. One has to remember to press a button every now and then. Another good reason to run the unit with O2, if the lungs bottom-out, add a bit more via the MAV.

 

[RichClark]

Mine is a updated Pursuit and it has wet connectors.
If they get wet it will turn on immediately.

I'm pretty sure that those wet connects have been their since the initial Shearwater GF's

 

[wrench]

Two screws on the right side of the JJ controller are wet contacts.

JJ CCR manual sec 6.3:"At the surface the controller switches off again automatically after 30 minutes"

JJ CCR manual sec 6.1:"Also on the right are the water contact sensors. These switch the controller on automatically as soon as it comes into contact with water"

JJ CCR manual sec 6.2:"Switches on automatically with pressure, depth and water contact"