An accident waiting for a place to happen

[Kim]

Today I heard a story that has shocked me very deeply. I thought of posting this in the accidents forum - but it hasn't happened yet. I have a friend who is Japanese and an OW Scuba Instructor with the Japanese Scuba organization (don't know it's name). The guy is a good instructor with new divers from what I've observed - but on his own he is another story.
I was at his house this evening and he asked me what was the deepest dive I had ever done. I told him 38 meters (124ft) and asked him why he wanted to know. He told me that he had just broken his personal record and done a dive to 65 meters (213ft). Shocked - I asked him if he had done this on air. Yes, he replied, and so I asked him if he was aware how dangerous it had been. He seemed to think that the only problem that he could have had was narcosis - so I asked him if he knew about oxygen toxicity - he didn't (he has never done a Nitrox class and knew nothing about it). I explained partial pressures to him quickly, and he was interested - but not overly concerned about what he'd done. I tried to tell him that there can be no warnings to sudden convulsions and at that depth it's almost certain death. I don't think he believed me.
The guy did this dive on a single tank with another diver (also on a single tank) - they had no stage or pony at all - they had no idea what they were really doing.
Now I'm just waiting to hear one day that he's been killed - possibly with someone else.
I don't really know what to say to him now - 'goodbye' doesn't seem that constructive.

(If the mods feel this post is in the wrong forum - please move it)

 

[DORSETBOY]

Unfortunatley not everyone practices what they preach and I include myself in that, we've all done things we shouldn't do. When instructors teach they often get bored of repetitive dives and in their own time may 'push the limit', this can apply to non-diving circumstances too. Yes it is hypocritical for someone to teach one thing and dive breaking 'the rules' but then people used to dive to 70 m on air with no redundancy in the past it's just that we now know of safer ways of diving to these depths.

Does it shock me that an instructor has done such a dive? It should but in reality this is very common.

 

[Kim]

I just wish that he could speak and read English. Then I could introduce him to SB and broaden his horizens a bit!

 

[captain]

A lot of spearfisherman do 200 foot dives on air every week here on the Louisiana oil rigs. Acording to what is said on this board the local newspapers should be fill with stories of dead divers but they aren't. Every few years there is a fatality usually because the diver speared a fish he couldn't handle and didn't know when to give up and let the fish go.

Captain

 

[Kim]

A lot of spearfisherman do 200 foot dives on air every week here on the Louisiana oil rigs. Acording to what is said on this board the local newspapers should be fill with stories of dead divers but they aren't. Every few years there is a fatality usually because the diver speared a fish he couldn't handle and didn't know when to give up and let the fish go.

Captain

So are you telling me that this is OK and I shouldn't be worried? That a PPO2 of over 1.6 is actually safe? Maybe it's time for me to relearn everything I thought I knew!

 

[Rick Murchison]

You seem to be concerned about oxygen toxicity at 213' on air.
The NOAA limit for a single exposure to air at that depth is 45 minutes - not likely to be a problem on a single tank.
Certainly there are other issues on such a dive - narcosis, DCS, marginal gas supply, marginal redundancy (just a buddy), marginal planning, marginal thinking.
But oxygen toxicity isn't likely to be a problem.
Rick

 

[pipedope]

Diving is not safe.

Diving deep on air is certainly less safe than diving shallow on air.

Diving to deeper and deeper depths is an enhearently dangerous activity that requires major study of ALL of the risk factors if you expect to survive very long.

Many of the risk factors offset each other to 'some' extent making a good understanding of the overall risk difficult at best.
Example, high N2 reduces the likelyhood of O2 tox. Unfortunately it also make you loopy.

Another big problem is going deep without redundant gas supplies and enough gas to handle a problem at depth AND then do the deco required by the extended bottom time.

And this is just a start.

Lots of people have gone deep on air.
Some survived, some didn't.

Few will do it today.

I support the right of each diver do do what he wants AS LONG AS HE (SHE) KNOWS WHAT HE IS DOING!

 

[Rick Murchison]

So are you telling me that this is OK and I shouldn't be worried? That a PPO2 of over 1.6 is actually safe? Maybe it's time for me to relearn everything I thought I knew!

Naw, he's not telling you that...
(213+33)/33=7.45 X .21 = 1.56 PO2
Very short exposure; no worries.
At least not from the oxygen.
Rick

 

[MikeFerrara]

Unfortunatley not everyone practices what they preach and I include myself in that, we've all done things we shouldn't do. When instructors teach they often get bored of repetitive dives and in their own time may 'push the limit', this can apply to non-diving circumstances too. Yes it is hypocritical for someone to teach one thing and dive breaking 'the rules' but then people used to dive to 70 m on air with no redundancy in the past it's just that we now know of safer ways of diving to these depths.

Does it shock me that an instructor has done such a dive? It should but in reality this is very common.

200 ft on air may still be somewhat common but they cut things kind of close as far as reserve gas supply (if they were on Al 80's) and I hope that isn't too common especially for people who should know beter.

I don't think of 200 ft as a very deep dive and while I don't care to go that deep on air lots of divers have and do.

You couldn't get me that deep on a bet without a descent size gas supply and some redundancy though. IMO, that's a stunt not a dive.

 

[Rick Murchison]

200 ft on air may still be somewhat common but they cut things kind of close as far as reserve gas supply (if they were on Al 80's) and I hope that isn't too common especially for people who should know beter.

I don't think of 200 ft as a very deep dive and while I don't care to go that deep on air lots of divers have and do.

You couldn't get me that deep on a bet without a descent size gas supply and some redundancy though. IMO, that's a stunt not a dive.

Well said, Mike. A stunt is an accurate description, I think.
Rick