Deep Diving 108 feet w/ a single AL 80 (Air.) No redundancy.

[boulderjohn]

We also did the anchor wall which puts you out in the blue at 110 or slightly more feet. We were told that a couple minutes of your computer beeping about exceeding MOD was acceptable. Not saying this was a PADI instructor saying this or not.

I am not sure exactly what you mean here, but I think you are saying that people allowed you to dive to 110 feet (or a tad deeper) on EANx 32 and told you that it was OK to go a bit beyond the 110 MOD briefly. I thought I would comment on that.

The MOD for EANx 32 using a PPO2 of 1.4 is 111 feet, usually rounded off to 110. The MOD for EANx 32 using a PPO2 of 1.6 is 132 feet, usually rounded off to 130. In typical nitrox training, divers are told to use the 1.4 standard for most of their diving. They are told that 1.6 is the "contingency" MOD, and it is OK to go to that limit briefly.

In any case, neither of those MODs is a barrier where you immediately go into oxygen toxicity upon passing it. It takes some time. How much? No one can say with any certainty.

 

[Josh the diver]

yeah I would do it. As long as I follow my rock bottom gas plan and not to exceed NDL.

 

[tursiops]

yeah I would do it. As long as I follow my rock bottom gas plan and no NDL.

You mean, "not exceed NDL"?

 

[Josh the diver]

You mean, "not exceed NDL"?

yeah, I will fix that.

 

[Dan]

The MOD for EANx 32 using a PPO2 of 1.4 is 111 feet, usually rounded off to 110. The MOD for EANx 32 using a PPO2 of 1.6 is 132 feet, usually rounded off to 130. In typical nitrox training, divers are told to use the 1.4 standard for most of their diving. They are told that 1.6 is the "contingency" MOD, and it is OK to go to that limit briefly.

The over 1.6 PPO2 briefly was about a couple of minutes for me. Before the dive DM asked me what I would like to see. I told him that I have never seen Zebra shark, yet. He then said that it’s around here, probably sleeping in the sand since it’s a nocturnal animal. So we were cruising around 100’ deep for a few minutes in search of it. Then DM turned around and put his hand on top of his head as a sign of a shark and pointed the little stick that looked like a shark laying on the bottom. I pointed to my camera and to the shark as a sign of “can I descend to it for a picture?”. He looked at my SPG and saw that I still had 1200 psi (of EAN32 in AL80). He then gave me 2 fingers (which meant 2 minutes) to get down there, take the dang picture and get back up to where we were. I went down to the bottom & took some pictures of the Zebra shark & started hearing tank banging up above. Didn’t realize my 2 minutes was up so soon. We started to ascend when I was back to the group. Later I check the bottom was at 144’.

 

[Dan]

Dove with an AL80 & EAN27 to 141’ for Mola Mola in Crystal Bay, Nusa Penida, Bali, Indonesia.

 

[Dan]

The last Mola Mola dive was in Sep 20, 2019 with AL80 & air. Saw them at 137’ depth.

 

[Steelyeyes]

I am not sure exactly what you mean here, but I think you are saying that people allowed you to dive to 110 feet (or a tad deeper) on EANx 32 and told you that it was OK to go a bit beyond the 110 MOD briefly. I thought I would comment on that.

The MOD for EANx 32 using a PPO2 of 1.4 is 111 feet, usually rounded off to 110. The MOD for EANx 32 using a PPO2 of 1.6 is 132 feet, usually rounded off to 130. In typical nitrox training, divers are told to use the 1.4 standard for most of their diving. They are told that 1.6 is the "contingency" MOD, and it is OK to go to that limit briefly.

In any case, neither of those MODs is a barrier where you immediately go into oxygen toxicity upon passing it. It takes some time. How much? No one can say with any certainty.

That's why my computer is set to 1.6 for PPO2 and I limit my time anywhere near a dangerous depth for that mix. I just find it odd that a person would teach you to a standard and immediately push the boundary.

 

[Blackcrusader]

I've done a number of dives to 130' with an AL80. 8 minutes at depth and return to 20' for 20 minutes, still come out of the water with at least 500 psi.

I don't understand why someone would call a dive to 110 feet or 32m insane on a single AL 80. Even for divers who are not as good on air as I am I would get them to buddy up with me and make sure they would be back to shallower depths with plenty of air. Pretty much most of the dive centers I dive with ask the DM to have the diver with the least air back doing their safety stop with 50 bar. There are only a handful of experienced divers I know who could do this 93 minute dive and finish with 50 bar 750 psi The diver center owner is a friend of mine and the same dive he would be at 65 mins with 50 bar which is still a good dive time. Of course I am in nice 28c warm ocean water.

 

[boulderjohn]

That's why my computer is set to 1.6 for PPO2 and I limit my time anywhere near a dangerous depth for that mix. I just find it odd that a person would teach you to a standard and immediately push the boundary.

I don't think it is much of a boundary push to spend some time in the 1.4 to 1.6 range on an NDL dive. As I said, agencies like PADI teaching nitrox say it is within boundaries.

Although I do not advocate ignoring the nitrox boundaries, those limits for recreational (NDL) diving are pretty safe, with a good buffer. I honestly doubt that anyone has ever suffered a toxicity event on an NDL dive, even if they violated those limits. The few cases people cite are very iffy. (As in, "well, maybe it was toxicity. Could be, I guess.") The sure toxicity cases I know of came on technical dives, with longer exposures to high PPO2s, usually because of the diver breathing the wrong gas for that depth.