Do you think computers encourage risky diving in new/ young divers?

[EFX]

But still, it completely boggles my mind that the concept of NDL isn't understood by newer divers.

There's always exceptions to every thing. I think the vast majority of new divers understand the concept of NDL. I remember back to my OW training with PADI that this concept was drummed into our heads. The entire arm of sport diving we call "recreational diving" depends on the NDL concept. Now, with that said there are probably instructors who fail to teach this concept in a meaningful way to their students. I think the problem is not so much not understanding the concept but complacency in monitoring their NDL, and this is more of a problem for more experienced divers who are not gas-limited and cross over into deco. As has already been mentioned, not being trained adequately in the use of their PDC or tables is also a problem for new (or any?) diver.

 

[wetb4igetinthewater]

I wish min gas was taught in open water. Haven't read all the other comments.

 

[Scraps]

I think for many new divers, NDL is primarily thought of as the dark square at the bottom of each column of table one of the dive table.

 

[boulderjohn]

I wish min gas was taught in open water. Haven't read all the other comments.

Why? Is there any evidence it is a superior ascent strategy?

 

[100days-a-year]

Yes. But so do a lot of other pieces of gear that are great safety features in the right hands.

 

[boulderjohn]

I find it interesting that there is discussion about whether or not NDL is taught enough at the OW level. There have been discussions in the past that NDL is in fact overly emphasized, to the point that divers are more afraid of it than other dangers of diving,including especially AGE, which is a far more common cause of death than DCS. Here is a story that illustrates this.

I was diving in the Galapagos with a buddy I had never met before the trip--we were the only unaccompanied divers on the trip. He was certified at the DM level, although he was not active. We were diving at maybe 85 feet when suddenly he started to bolt to the surface. I was right next to him when he started and was able to catch him after about 20 feet. I grabbed him and gave a WTF look. He shoved his computer in my face, his eyes wide with terror. I knew the model well, and I didn't see any cause for alarm. I was about to ask when he pushed me away and started another panicked sprint to the surface. I didn't catch him until he was past 20 feet, and he again shoved the computer in my face, his eyes still wide with terror. The computer was doing a safety stop countdown. I turned it to him and gave a WTF gesture. He calmed down. We completed that safety stop and went to the surface.

On the surface he said that he had looked at the computer and seen that he had only a couple minutes of NDL left. He knew at that depth it would take him at least that long to get to the surface, so he had to go as fast as he could to get there before he ran out of NDL. At that point we were picked up by the panga, and as the panga picked up the other divers in our group, he told each one how he had narrowly escaped death by exceeding NDL. I tried to explain to him that as soon as he had gotten up those first 20 feet or so, the computer had changed to give more NDL time. He dismissed that idea out of hand--I was foolish to think that. I was trying to explain it yet again when the diver sitting next to me on the panga whispered, "Forget it--he's never going to get it."

The point is that the diver was so panicked about going over NDLs that he risked death via AGE. A study by DAN a few years ago found that other than medical conditions, the most common cause of diver death was AGE caused by a panicked ascent to the surface. It was usually preceded by OOA, but if it had happened in this case, it would have been caused by fear of NDL.

 

[wetb4igetinthewater]

Why? Is there any evidence it is a superior ascent strategy?

I'm surprised you would ask that. It is basic safety. Divers should always have enough gas to ascend to the surface at a proper rate. How is that controversial?

We all know that far too many students are insufficiently trained.

I find it interesting that there is discussion about whether or not NDL is taught enough at the OW level. There have been discussions in the past that NDL is in fact overly emphasized, to the point that divers are more afraid of it than other dangers of diving,including especially AGE, which is a far more common cause of death than DCS. Here is a story that illustrates this.

I was diving in the Galapagos with a buddy I had never met before the trip--we were the only unaccompanied divers on the trip. He was certified at the DM level, although he was not active. We were diving at maybe 85 feet when suddenly he started to bolt to the surface. I was right next to him when he started and was able to catch him after about 20 feet. I grabbed him and gave a WTF look. He shoved his computer in my face, his eyes wide with terror. I knew the model well, and I didn't see any cause for alarm. I was about to ask when he pushed me away and started another panicked sprint to the surface. I didn't catch him until he was past 20 feet, and he again shoved the computer in my face, his eyes still wide with terror. The computer was doing a safety stop countdown. I turned it to him and gave a WTF gesture. He calmed down. We completed that safety stop and went to the surface.

On the surface he said that he had looked at the computer and seen that he had only a couple minutes of NDL left. He knew at that depth it would take him at least that long to get to the surface, so he had to go as fast as he could to get there before he ran out of NDL. At that point we were picked up by the panga, and as the panga picked up the other divers in our group, he told each one how he had narrowly escaped death by exceeding NDL. I tried to explain to him that as soon as he had gotten up those first 20 feet or so, the computer had changed to give more NDL time. He dismissed that idea out of hand--I was foolish to think that. I was trying to explain it yet again when the diver sitting next to me on the panga whispered, "Forget it--he's never going to get it."

The point is that the diver was so panicked about going over NDLs that he risked death via AGE. A study by DAN a few years ago found that other than medical conditions, the most common cause of diver death was AGE caused by a panicked ascent to the surface. It was usually preceded by OOA, but if it had happened in this case, it would have been caused by fear of NDL.

For the part that I emphasized in bold, if people kept track of their cylinder pressure and depth, maintained min gas, why would they panic?

Do you want to get into the inadequate training that exists at the open water level? It isn't limited to just that. But my guess is that there will be a lot of bickering and convergence to a set of ideas will never be achieved.

 

[EFX]

I find it interesting that there is discussion about whether or not NDL is taught enough at the OW level. There have been discussions in the past that NDL is in fact overly emphasized, to the point that divers are more afraid of it than other dangers of diving,including especially AGE, which is a far more common cause of death than DCS. Here is a story that illustrates this.

I was diving in the Galapagos with a buddy I had never met before the trip--we were the only unaccompanied divers on the trip. He was certified at the DM level, although he was not active. We were diving at maybe 85 feet when suddenly he started to bolt to the surface.

On the surface he said that he had looked at the computer and seen that he had only a couple minutes of NDL left. He knew at that depth it would take him at least that long to get to the surface, so he had to go as fast as he could to get there before he ran out of NDL.

The point is that the diver was so panicked about going over NDLs that he risked death via AGE.

Being a DM his lack of knowledge regarding NDL is shocking. To illustrate why this is so shocking I ran my spreadsheet for an 85 ft dive on air for 24 minutes with DSAT tables and a GF of 95/95 using descent and ascent speeds of 60 fpm and 30 fpm respectively. After 24 minutes the NDL remaining is 1 minute. Oops! Time to ascend immediately! Ascending to 65 ft, just 20 ft shallower, after spending 1 minute at that depth the NDL becomes 5 minutes. Five minutes is plenty of time to sort things out and decide where to go for the rest of the dive. Ascending to 50 ft after 10 minutes the NDL goes up to 15 minutes!

I remember in my OW training that it was taught that after running out of NDL, especially under 5 minutes, the remedy was just to get shallower and recheck the NDL. No big deal. What I wish I got in my training was how quickly the NDL changes on ascents. I suspect if your DM knew this he wouldn't have bolted to the surface but would have signaled to you to go shallower.

 

[boulderjohn]

I'm surprised you would ask that. It is basic safety. Divers should always have enough gas to ascend to the surface at a proper rate. How is that controversial?

We all know that far too many students are insufficiently trained.

Ooops! My bad. I misread your post. I thought you wrote min deco. Carry on!

 

[formernuke]

A DM wow.

Especially since this one of the big pluses of computers over tables, multi level diving.