Orange Grove fatality?

[cerich]

Oh no, I'd definitely try! Not keen on drowning But I think the idea is oversold and not all that realistic in a cave environment. I also think that holding your breath while solving a potentially complex problem while stressed, in the dark, on the line, etc is much easier to type than to do.

Keep it simple.

never said it was easy, then again the other option is harder

 

[seanmeboy]

My money is on that he did not have a formal side mount class. If it was a roll off then he was staging doubles not side mount. Complacency or panic indicates he was unfamiliar with his gear and no muscle memory since the regulator that he was breathing on was right there around his neck! Good point made in this thread - he probably did the intro in back mount!

 

[rjack321]

If it was a roll off then he was staging doubles not side mount.

More than one person has rolled off a sidemount tank. Either in a small passage (not applicable here) or as the bicep rubs on the valve.

The deceased was diving sidemount and his right tank was off with 22-2300psi remaining when he was recovered. He probably didn't start with a tank at the pressure so he either turned in off at some point or it rolled off. We don't know which or why.

 

[seanmeboy]

It would be nice to know if he intentionally shut it off do you know if the equipment was functioning properly?

 

[tursiops]

unlike this swap regs thing which is literally part of the curriculum in some SM courses.

That's why I taught TDI Sidemount recently instead of PADI Tec Sidemount, after discussion with the student.

 

[DA Aquamaster]

A manifold gives you access to *all your gas* when you shut down a post due to a failure like this:

With independents you cannot access that tank's gas. You're down to whatever left in the other tank. Fingers crossed its enough to get out.

There are risks in back mount as well, but there's no need to cross your fingers at all in side mount.

Assuming I have 260 cu ft of gas to start and 173 cu ft at turn pressure, and I need half that (86 cu ft) to exit, I haven't got a lot of time to identify the failure and turn off the correct valve.
A Mk 25 (or the Halcyon branded version) will flow 300 cubic feet per minute out of the end port - that's 5 cubic feet per second. That leaves me just 17 seconds to correctly identify and shut down the failed reg. Any longer, and I'm going to be dependent on my team mate(s) reserve to get out. I have to take a positive action and accomplish it quickly to preserve sufficient gas to exit.

In contrast, in side mount starting with the same 260 cu ft split between two tanks and having the same failure at max p, I'd identify the failure immediately as it's either on my right or left, so the odds are I'll still close the valve in time to save some of the gas - although it's a moot point as I'd need to swap regs to use it, and I agree with you that it's a non starter of an idea.

However, on the way in (assuming I started with 3600 psi in both tanks) I will have breathed one tank down 1200 psi, then switched to the other, and breathed another 1200 from it, using 2400 psi total for penetration gas. But this also means I have 2400 psi in each tank at max penetration. So when the failure occurs and I lose access to all the gas in one tank, I still have exit gas in the other that is equal to my penetration gas - even of I do absolutely nothing other than turn the dive.

Now, I'm also not a real believer in thirds in a two man team as it's not an adequate amount of gas in real world scenarios and was in fact designed for a 3 man team. But since more often than not I am in a two man team I plan the gas differently to ensure some extra margin for real world delays in turning the dive, depending on the dive, the conditions, tight passage, restrictions, etc.

Even on an easy dive, I still use a 1200 psi "third" with pressures over 3600 psi. Given that the average fill in cave country is now in the 3800-4000 psi neighborhood, this leaves an extra pad of 200 to 400 psi per side - about 13 cu ft extra with a pair of LP 85s at 3800 psi, and 26 cu ft with LP 85s at 4000 psi.

The same extra gas margin would apply in doubles as well, but 13 and 26 cu ft respectively only provides another 3 to 5 seconds to resolve the above mentioned problem.

 

[PfcAJ]

I always find those "300cuft per minute" figured from sp to be unrealistic. It takes more than 16 seconds (300cuft/min) to empty an al80 with the valve all the way open an no reg at all.

 

[Jack Hammer]

I don't recall a fatality at EN with a closed isolator, can you send me info? The Wayne's World one for sure though (amongst other things).

I think a lot of isolator related problems occur from poor management on the surface rather than in the water. The manifold can certainly cook your goose idiots not managed right, but it gives you options that just don't exist with independents.

I'm going off memory and it's been a few years. I wouldnt swear to it in court, im pretty sure i recall a second incident. I gave a quick "poking it with a stick" kinda search, found nothing.

 

[karstdvr]

I think thats more viable than switching regs while holding your breath. But still no ones teaching that and it hasn't been mentioned with any seriousness since the early 2000s, .

Thanks, for the clarification. I really liked the WKPPs attitude on emergency procedures,but I sure hated that one method.

 

[karstdvr]

My money is on that he did not have a formal side mount class. If it was a roll off then he was staging doubles not side mount. Complacency or panic indicates he was unfamiliar with his gear and no muscle memory since the regulator that he was breathing on was right there around his neck! Good point made in this thread - he probably did the intro in back mount!

Your suppositions may be right,and it is easy to dismiss this as an inexperienced intro to cave diver with unfamiliar gear that exceeded their limits. Conversely, I have dived with a couple intro divers that had hundreds of deep wreck dives with quite a few on the 'Doria,but had taken a cave class to learn more about cave techniques. Knowing more information, such as experience can help solve the puzzle. Then again there have been very experienced cave divers that got stressed, breathing goes up, CO2 retention, and severe narrow focus, who have made similar mistakes