OOA with a faulty SPG

[TSandM]

I'm glad you stayed calm, and that the DM was nearby, and that the air-sharing ascent went smoothly.

But I'd like to take this opportunity to put in a plug for learning gas management. If you know this material and use it, you'll essentially use your SPG as a backup for the processing in your brain. I know, for example, that at 60 feet, I'll use not quite 150 psi every five minutes. So if the dive is averaging about 60 feet in depth, I should see the SPG decrement that much every five minutes, and if it doesn't, something's wrong. I also know that I can expect a certain length of dive off the tank, and if I'm coming up on that time, it's time to be preparing to get out of the water. I wouldn't say I could safely execute a dive to 500 psi without any gauge at all, but I definitely have a double-check on what my gauge is reading.

You can find an excellent article on gas management HERE.

 

[denniscloutier]

Me too, me too. I had more or less exactly the same thing happen to me in Roatan a few years ago. In may case, my wife and I got back to the boat ahead of everyone else, as usual and we were noodling around under it when the DM got back. When he saw that I, the air hog in his group, was still under he realized that something was wrong. He swam over and worked my tank valve back and forth and the needle went to zero and stayed there. He gave me his alternate and the three of us ascended together.

What I learned from it is:
1 Buy my own gear, which we did when we got back.
2 As TS&M says, be aware of the fact that if my air seems to be lasting much longer than normal, then there is probably something wrong, DOH!

By the way, Kudos to the DM, who was clearly paying more attention than I was, and no kudos to the dive shop for the gear they were renting.

 

[stefo2]

Interesting to hear the DM donated his primary.

What I find more interesting is that he only donated it after checking the diver's SPG, whacking it and thus establishing that the diver really WAS out of air.

I think if a diver gave me the OOA signal, even if they seemed very calm and we were at safety stop depth, I would make sure that they have something to breathe first before fiddling with their gear.

What if the needle had not gone to zero - would he then have told the diver, no sorry, you are not out of air, just keep breathing?

 

[Peter_C]

It happened again on another dive but this time the boat crew curiously looked at me and the tank, then gave the SPG a thwack. The needle popped back up to 3000 psi...

What I find more interesting is that he only donated it after checking the diver's SPG, whacking it and thus establishing that the diver really WAS out of air.

I would assume (OP correct me if I am wrong) that the DM was part of the boat crew, so we already established they were a major part of the problem to begin with.

Doubtful anyone here would argue with you that the first thing should have been to donate air, then proceed with checking things over. Of course the OP should have never been put in that predicament in the first place.

 

[Beiji]

Paradise, I'm glad you posted your story. You did a brilliant job staying calm and keeping safe.

 

[RAWalker]

Glad everything went well and the incident didn't turn into an accident.
One thing that I feel should be stated is this is a case where a B&G SPG had a misleading catastrophic failure. Unfortunately there are many B&G SPG that are equally as dangerous to divers simply because they are not accurate. A SPG that is considered accurate is one that is +-150psi but that is only at 2 points on the scale. So in theory a good SPG could read 500psi when actually only 350 is left. Failures on SPG are nearly always simple out of range inaccuracy and can go unnoticed. AI computers on the other hand either wireless or not use pressure transducers that are accurate +-50psi across the entire scale. Also when the transducer fails (which is rarely after manufacturers burn in periods) it is near always a obvious total failure.
Knowing these facts I need to chuckle when I hear divers state they wouldn't dive without a B&G SPG. Don't get me wrong I believe in redundancy even simply in pressure monitoring but simple a pressure tranducer and AI computer is more accurate and the way it fails doesn't lead to a false sense of security. I use 2 AI computers when diving and a failure of the pressure transmitter would cause me to abort a dive. I could then take steps to repair or replace the transmitter and return to diving.
As for air management it is very difficult to accurately predict how differing equipment and conditions will effect air consumption for the average diver vacation diving with rental gear.
Divers that dive more regularly will have a better idea of consumption based on dive history in similar conditions. Since they dive regulary their conditioning will also be more stable and they will probably have their own gear.
For average vacation divers a AI computer will give you real time consumption and air time remaining numbers in addition to the more accurate tank pressure.
For this reason in addition to knowing the condition of the equipment the first piece of gear I suggest to any diver to purchase is a regulator set with AI computer. Simple it is worth the investment.

 

[paradise]

What operator rented you the gear? And, what - if anything - did they do when you reported the problem?

I rented my reg from Scuba Club Cozumel. They exchanged my reg for another. Back on the boat, the DM did several checks to ensure that the SPG wasn't acting funny.

What I find more interesting is that he only donated it after checking the diver's SPG, whacking it and thus establishing that the diver really WAS out of air.

Hi Stefo, I should have been more clear about this. When I got the DM's attention, I gave the OOA signal then showed him my SPG with a . I'm sure that if I gave him the OOA sign w/o all the extra gestures, he would have donated his reg immediately.

I would assume (OP correct me if I am wrong) that the DM was part of the boat crew, so we already established they were a major part of the problem to begin with.

The DM was not aware that my SPG was acting funny prior to the incident. It was a different boat crew member who I went to when I told him the tank only had 2500 psi.

Thanks Beiji for encouraging me to post this story. I met Beiji at SCC when she helped me get my fins back on shore/dock after a shore dive. We have a lot in common.

Thanks everyone for your insight, support, and recommendations.

 

[Beiji]

I met Beiji at SCC when she helped me get my fins back on shore/dock after a shore dive. We have a lot in common.

One of the things we have in common are bad rental SPGs! The one I own flooded, so I rented one. The first rental SPG had a hose that broke - lucky it happened while on the boat and not in the water. The second one had a slow leak. I'm not sure I will ever rent equipment again.

 

[TSandM]

As for air management it is very difficult to accurately predict how differing equipment and conditions will effect air consumption for the average diver vacation diving with rental gear.
Divers that dive more regularly will have a better idea of consumption based on dive history in similar conditions. Since they dive regulary their conditioning will also be more stable and they will probably have their own gear.

This is certainly true, but even a resort diver should have an idea, after a few dives, of how long an Al80 will last at a given depth. I don't think it's responsible to tell people that it's fine not to learn any more about gas management because an AI computer will do it for you. Not everyone has an AI computer; not everybody wants a console computer, and wrist-mounted AI computers are both significantly more expensive, and much more temperamental.

I would also be interested in where the information about the transducers in digital pressure gauges being more accurate came from . . . the last discussion of this I remember reading said that both analog and digital gauges are inaccurate at the far ends of their ranges.

 

[cgvmer]

I decided early on to purchase my own gear, since I could not find any BC's that fit comfortably and never saw a rented reg setup that wasn't banged up (and appeared un maintained). This summer my 2 sons, daughter and myself all with our own gear got on a boat. While diving I noticed my sons tank valve leaking from the threads, then my daughter pointed out the same to me of my tank. So even though I have my own gear, I can't travel with tanks, I am still dependent, so we must be diligent whenever we go.