Instructor bent after running out of air at 40m

[tursiops]

In the early 90s many divers regularly went down to 50-60m+ on air and a single tank. Most other divers would not even bat an eyelid. Times sure have changed.

Nostalgia is just not what it used to be.

 

[ijdod]

According to their own record, they used 12L tanks. That may not mean much, but IME the standard 12L in southern Europe is a 12x200, which carries about 9% more gas than an Al80 (which, IIRC, is 11L 209 bar). A 15x200, a 12x232 or a 10x300 is about 100 cu.ft, a 15x232 or a 12x300 is in the 120 cu.ft range

It's also not uncommon for an AL80 to be, incorrectly, called a 12L. I suspect the AL80 to be the default tank in the Mediterranean.

 

[Storker]

I suspect the AL80 to be the default tank in the Mediterranean.

I've dived in southern France, southern Italy and the Canary Islands. At least two of those are in the Med. Still haven't encountered an Al80 (with the exception of stages I've seen carried by tech divers back home). Only metric steels, typically 12x200s with the occasional 15x200 available on request

 

[ijdod]

I've dived in southern France, southern Italy and the Canary Islands. At least two of those are in the Med. Still haven't encountered an Al80 (with the exception of stages I've seen carried by tech divers back home). Only metric steels, typically 12x200s with the occasional 15x200 available on request

I've only ever seen AL80s in Greece, Italy and Turkey; steel tanks will likely be actual metric sizes. Now that I think about it; I have seen a 12L short (which is steel) in a magazine article about diving in Sardinia.

 

[AfterDark]

In the early 90s many divers regularly went down to 50-60m+ on air and a single tank. Most other divers would not even bat an eyelid. Times sure have changed.

Back in the early 90's one would need to be face to face with the offending diver, today we can hide behind the keyboard.

 

[Kay Dee]

Narcosis................can also mean a diver or divers lose track time, forgets to check SPG, get so overly focused on something simple that it becomes THE most important thing you've ever tried to do to the exclusion of everything else.

I have to say I have found myself, while involved in photography at depth on gas on (an 'e')CCR - a Mk15.5 - getting so 'involved' in the photo taking / making process that I 'forgot'- for want of a better word - to check my PPo2 more times than I ever 'forgot' to check my SPG whilst doing same - i.e. making photos - while at say 60m on air. I checked that SPG like a hawk while deep on air, which I usually did my PPo2 on CCR, but...........at times..................Just saying.

You can plan your dive and dive your plan, if you can remember what it was..

I have found that if one is disciplined enough, and back in the day many deep air divers were - they HAD to be to survive (as some of those that weren't didn't) - and regularly dived to say 60 / 65m on air, you had a plan and you followed it rigorously. And while many folks will say you can't build up a tolerance to narcosis, you can adapt - again for want of a better word - to it / recognise it, and be aware of its insidious effects. But, and there is always a 'but', when / if the s**t hits the fan (deep on air) then things can turn nasty real real fast, and at moments like that you really really wished you were on gas!

By the same token, in my opinion, and it is just my opinion from my experiences after all, as big a problem as narcosis - especially for 'experienced' deep air divers - was the fast build-up of the PPo2 clock on the bottom at 60-65m (or a bit beyond in some cases), i.e. when at almost (or slightly above) 1.6ata, for say 30mins or more, and then when back up on deco from 6m on up breathing pure o2, and then (or there) overloading / passing the supposed CNS clock limit (as per NOAA tables) and then taking an o2 hit (and often then drowning). Yes, I and many others have way way over-ran the CNS clock on very deep (say 'expeditionary' type) gas dives, so its not like 45 mins at 1.6ata is set in stone but.............................there seemed to be more o2 hits shallow back in the day then there ever was on the bottom. Again, just saying.

EDIT; For the record, I wasn't real crazy back then; the deepest air dives I did were to 70 / 72m, and I didn't stray / stay below say 65/66m for very long at that. Just long enough for a few pics, or to take a survey measurement (on wrecks, not caves, as although I am cave trained I rarely ventured below 40m in caves unless on gas).

 

[AfterDark]

Could not agree more @Kay Dee. Having done deep diving on air back in the 1970's I've experienced and/or seen all of what you posted.

 

[Kay Dee]

Could not agree more @Kay Dee. Having done deep diving on air back in the 1970's I've experienced and/or seen all of what you posted.

Man, then you know what I am talking about, as you's still here! But in the the 70's!, my God, I was still just surfing the waves back then, and hadn't even looked at, let alone touched, a regulator (although had done a little free diving)!

 

[EireDiver606]

When I did the deep dive as part of AOW we did a timed puzzle first. Then on the dive, at only about 70 ft., I did the puzzle again. I remember thinking wow I did it a lot quicker then on land. All the way to shore I was thinking I was special. Until during the debriefing the instructor pointed out that I had taken considerably longer at depth.

A slow computer processes things slower. It take the same number of cycles to do a problem but each cycle takes longer. The computer cannot tell because its clock has slowed down.

Most of my dives at the coast are 70-100 ft. At 70-80 I am a little narced. At 100 I have to make a conscious effort to keep checking the spg and the NDL.

How did the instructor know that you took longer? Nitrox? Trimix?

 

[Steve_C]

How did the instructor know that you took longer? Nitrox? Trimix?

The instructor timed me on land. He timed me again when I did it at depth timing me with the same timing device. Think it may have been a dive watch but not sure. He is also a tech instructor and had a number of different kinds of timers he could have used.