I believe the point is - gas monitoring should not be blamed for any amount of gas - because if you are looking you know how much you have or don't have and you must tailor your dive to your gas...
Unless you are trying to make some kind of obscure link - you must agree - you must watch your gas consumption on the dive regardless of tank size or fill.
Right?
Sure, we agree that you have to watch your gas consumption on every dive. It's vital.
The point I'm trying to make is that accidents/incidents nearly always have more than one cause --- and this one certainly does. Accident analysis is about addressing all the causes and putting safe equipment, procedures, and attitudes in place to ameliorate as many of them as is practicable. The rip in the mask (or whatever the problem may have been with it) was part of the cause because the incident would not have occurred
but for the fact that the mask leaked. The short filled cylinder was part of the cause because the incident would not have occurred
but for the short filled cylinder. Failure to monitor the SPG was part of the cause because the incident would not have occurred
but for the short filled cylinder.
Failure to monitor the SPG is perhaps the most basic and critical mistake, and most immediately in control of the diver. But let's not overlook the other causes.
Gear problems are in practice a matter of judgment but a mask that will not work as it should is a reason to call the dive. In like fashion, diving a short-filled cylinder, while not inherently dangerous, is not as safe a practice as insisting on a full cylinder for every dive.
One of the problems some people encounter with HP tanks is not getting them filled to their capacity.
I dive HP120s and find that this is an ongoing problem. The dive shops I use for fills won't adjust their fill pressure above 3442 to compensate for temperature, so I have to leave cylinders with them for a day so that they can fill them, allow them to cool for several hours, and then top them off. I check every one of them before leaving the shop and occasionally find one that is a few hundred PSI short.
Several years ago I was diving with an operator that routinely supplies HP 120s to its customers. It is well known for doing that, and I had done many dives with them. One day we did the first dive of a two tank dive and then had a surface interval at a restaurant on the beach while the DM and skipper stayed on the boat. We returned and were surprised to find our tanks were only filled to 3000 PSI--everyone of us. We mentioned it, and the DM gave us a surprised look and said that tanks are always filled to 3000. This was not the first rodeo for any of us, so we called BS on that. He insisted. What were we do do? We did the dive, and after it, the DMs actions confirmed what we suspected--he was in such a hurry to get the boat back and get us off of it that it was obvious he had dumped air to cut our dives short.
Now, you were on a liveaboard, so it was a different story, but it could be related. If the liveaboard is trying to keep to a schedule, it might have been intentionally underfilling your big tanks in order to make sure you finished the dives in time for them to hold to their schedule.
Wow. That's maybe not quite as bad as the guy who dumped gravel on the road in front of his house so that the motorcycles won't go around the corner as fast, but close.
