Ginnie Springs diver missing - Florida

[CptTightPants21]

Based on your arguments, perhaps we should have a HUD or vibration alert on SPGs? Maybe when you reach 700psi?

That is a weak argument and a deflection.

1. Gas doesn't magically disappear-any escaping gas can be heard and seen. PO2 dropping can only be accurately observed looking at a monitoring system--controller/HUD
2. Time--The time it takes to breathe down a tank is a much longer duration than breathing down a loop to the point it can kill you.
3. Redundancy--Much of technical diving is based on the philosophy of 'Two is One and One is None'. Why wouldn't you have two methods of monitoring PO2? You have two tanks, two regs, and a buddy for additional gas.

 

[Dsix36]

As much as I hated the hammerhead electronics on my Optima, I still believe kevins
DIVA should be an industry standard on all rebreathers. It just needs to be powered by a Shearwater so it is reliable. when it vibrated and made your teeth rattle, you noticed - end of story!

 

[tbone1004]

That is a weak argument and a deflection.

1. Gas doesn't magically disappear-any escaping gas can be heard and seen. PO2 dropping can only be accurately observed looking at a monitoring system--controller/HUD
2. Time--The time it takes to breathe down a tank is a much longer duration than breathing down a loop to the point it can kill you.
3. Redundancy--Much of technical diving is based on the philosophy of 'Two is One and One is None'. Why wouldn't you have two methods of monitoring PO2? You have two tanks, two regs, and a buddy for additional gas.

on point 3. Very few rebreathers actually have any real redundancy in ppO2 monitoring. Liberty is one of the only ones. All of the others have may have redundant components, but the parts that actually monitor ppO2 are not. A standard rebreather uses 3 cells that are shared between the two monitors. Even worse is on the Canbus systems where the O2 cells all plug into the same O2 board that does the Analog-Digital conversion so if that one component fails the whole system is done. The Liberty is the only eCCR I am aware of that offers true redundancy where no sensors are shared and either set of them can run the unit. I am not aware of any mCCR's that are still made that do not have shared sensors either.
Not saying it is a bad thing, but using the redundancy argument for ppO2 monitoring is not a good one IMO and assuming the facts presented are true, redundant ppO2 monitoring alone would not have changed the outcome of this dive. This is especially true if the redundant ppO2 monitor was a handset instead of a HUD, but even a HUD can easily get knocked out of place. Like I said earlier and @Dsix36 just said above, if that handset vibrated, I can almost guarantee he'd still be here. If he had a HUD that vibrated, I'm almost certain of it.

 

[jale]

You won't notice it on a scooter.

yes that is why you don't do it scootering. We cannot get everything, choices have to be made...we want to be spoiled

 

[sunnyboy]

on point 3. Very few rebreathers actually have any real redundancy in ppO2 monitoring. Liberty is one of the only ones. All of the others have may have redundant components, but the parts that actually monitor ppO2 are not. A standard rebreather uses 3 cells that are shared between the two monitors. Even worse is on the Canbus systems where the O2 cells all plug into the same O2 board that does the Analog-Digital conversion so if that one component fails the whole system is done. The Liberty is the only eCCR I am aware of that offers true redundancy where no sensors are shared and either set of them can run the unit. I am not aware of any mCCR's that are still made that do not have shared sensors either.
Not saying it is a bad thing, but using the redundancy argument for ppO2 monitoring is not a good one IMO and assuming the facts presented are true, redundant ppO2 monitoring alone would not have changed the outcome of this dive. This is especially true if the redundant ppO2 monitor was a handset instead of a HUD, but even a HUD can easily get knocked out of place. Like I said earlier and @Dsix36 just said above, if that handset vibrated, I can almost guarantee he'd still be here. If he had a HUD that vibrated, I'm almost certain of it.

Prism Topaz. The 3 cells directly drive the analog secondary meter and can be scrolled at any time to confirm the PO2 of any sensor.

 

[tbone1004]

Prism Topaz. The 3 cells directly drive the analog secondary meter and can be scrolled at any time to confirm the PO2 of any sensor.

nope. The 3 cells still share a common ground wire going back to the handsets. That one wire goes and the whole thing is done

 

[telemonster]

. Even worse is on the Canbus systems where the O2 cells all plug into the same O2 board that does the Analog-Digital conversion so if that one component fails the whole system is done. The Liberty is the only eCCR I am aware of that offers true redundancy where no sensors are shared and either set of them can run the unit. I am not aware of any mCCR's that are still made that do not have shared sensors either.

I took mine (Prism2) apart a while ago when I couldn't really get info on the architecture of the system. As I recall (I posted pics on here actually), the o2 cells feed two separate PCBs. One has the ADC for the HUD, the other has the ADC/solenoid driver for the handset if I recall??? I'd have to look back at the pics. Sure one board malfunctioning could drag the sensors down but they were mostly independent outside of sharing reading the same cells.

I do agree I never understood why Shearwater skipped vibrators on their CCR controllers.

 

[sunnyboy]

nope. The 3 cells still share a common ground wire going back to the handsets. That one wire goes and the whole thing is done

I don't disagree, but if the display goes down, then I consider that an "abort dive" situation.

 

[The Chairman]

I don't disagree, but if the display goes down, then I consider that an "abort dive" situation.

A mile back in the cave? Yeah, that's gonna work out great.

Most divers, including cavers, plan for a great dive. They seldom plan for the caca a dive might engender. Sure, we cavers have some redundancies built in, but for the most part, we often don't think in terms of us dying on a dive.

 

[ofg-1]

we often don't think in terms of us dying on a dive.

Kinda depends on who you are diving with, don't it?