Archaeological dive incident

[rs86]

Hi everyone,

I would like to get your opinion on an incident that happened to me last week while diving in Mauritius. I'm an archaeologist regularly working out there, and this time several members of the local dive club asked me to take a look at some anchors in order to determine their age and origin. Several days before the dive, I told one of the guys I would like to dive on nitrox, as they were located quite deep and it takes quite some time to record them properly. On the day of the dive we all arrived at our meeting point. The guy I had asked for the nitrox gave me the tank, and I asked if I could check the content; turned out he didn't have an analyzer, but he asssured me it had been double checked and it was fine. I told him I was not going to dive with a tank that was not checked by myself, so eventually we found another guy willing to trade his air tank for my nitrox. I could tell some of the guys were getting a little annoyed with me, but I didn't care as I knew it was their fault not supplying an analyzer and they should've known better...
Anyway, all was fine and we headed out. When we arrived on the site we were given an extensive briefing by my buddy (who was the dive leader and also an instructor). Then we went down. The conditions were quite bad; only a few meters visibility (and for Mauritius that's bad!) and quite a strong current. On the bottom we found 3 anchors, but not the very large one they were keen to document. After swimming around for a while, it dawned upon them we were heading in the wrong direction, and turned around. At this point, we were down at 34 meters, and my Zoop showed a no-deco time of 5 minutes. I told my buddy I should be ascending to a shallower depth soon (the rest were all on nitrox so still plenty of time left for them). Four minutes went by, and nothing happened; we kept on swimming back, fighting the current, and I was slowly getting out of breath. I told my buddy again to ascend, as I was running out of time. Again, nothing happened; he kept swimming back against the current trying to find that damn anchor. After a minute, my computer showed ascend time, while at the same time I saw my air supply was down to 100 bar. Also, I was getting more out of breath by the minute, which I told my buddy. I wanted to ascend, but not knowing the dive site that well, combined with the strong current, low visibility, and no SMB or other way of attracting the boat's attention, I opted to stay with the group. After a few minutes though, I realised I had to go up, or I would run out of air during my ascend and deco stop. I told my buddy I was going up, and I didn't even care if he or anyone else would come with me; I knew I had to do something, and getting back to the surface in good health was the first thing. So I took off, with no one following me at first. After a while though, my buddy followed me and we made a long stop together, until my computer was happy again. I analyzed the situation afterwards, and though about it for a long time thinking if I should've done things differently. Obviously these guys were quite reckless, especially seeing as how they ignored my no-deco time completely. I think in the end I did the right thing, what are your opinions: should I have stayed with them, or should I have ascended earlier?
Thanks for any opinions you can give on this situation.

 

[Heath Sapp]

Take care of yourself first then your buddy, if your buddy does not surface with you he should in couple mins if he can not find you. Then you know not to dive with that person again. I am picky about who I dive with. There are many more people on this board that have more exp. than I so that is my 2 cents worth. The ultimate respon. is to know what to do not depend on someone else to do it for you.

 

[jar546]

Poor planning.

If you were the only guy on 21% O2, this should have been discussed and put into the dive plan.

I would have left them behind and surfaced as needed. Your buddy should have followed no matter what.

 

[Jim Lapenta]

After the first up signal is ignored you signal with the middle finger and go up. You have also learned to carry your own SMB and reel or spool. And to not dive with azzclowns like them again. Good on ya for not trusting the mix. Whoever took that tank on the word of someone else is a diver to stay away from as he will get you killed. Also charge the hell out of em and get the money up front!

 

[Heath Sapp]

Whoever took that tank on the word of someone else is a diver to stay away from as he will get you killed. Also charge the hell out of em and get the money up front!

Charge about 1000 dollars an hour then they will not ask you to go again

 

[rx7diver]

Several days before the dive, I told one of the guys I would like to dive on nitrox, as they were located quite deep and it takes quite some time to record them properly. On the day of the dive we all arrived at our meeting point. The guy I had asked for the nitrox gave me the tank, and I asked if I could check the content; turned out he didn't have an analyzer, but he asssured me it had been double checked and it was fine. I told him I was not going to dive with a tank that was not checked by myself, so eventually we found another guy willing to trade his air tank for my nitrox. I could tell some of the guys were getting a little annoyed with me, but I didn't care as I knew it was their fault not supplying an analyzer and they should've known better...

rs86,

Not what you asked about, but a quick comment: My understanding is that no one is obligated to supply you with an oxygen analyzer with which to check your nitrox (although many nitrox vendors will allow you to use theirs). If you dive nitrox, you ought to have your own analyzer.

Safe Diving,

Ronald

 

[lowtech]

rs86,

Not what you asked about, but a quick comment: My understanding is that no one is obligated to supply you with an oxygen analyzer with which to check your nitrox (although many nitrox vendors will allow you to use theirs). If you dive nitrox, you ought to have your own analyzer.

Safe Diving,

Ronald

If it's a new shop I'll ask if I need to bring an analyzer, but I've never had to with my limited experience.
I don't have my own analyzer, but if I can't check it, I don't dive it.

I'll second the good on you, for not trusting the mix.
I don't remember who said this but it stuck with me. "The wrong gas kills good divers".

It doesn't sound like the dive was planned out or executed very well,
and if it had been a lot of the problems you experienced could have been avoided.
As for surfacing or staying with the team, I'm with Jim thumb, then bird,
things generally don't get better in stressful under water situations.

 

[TSandM]

It was a revelation to me, the first time we went to MX and I discovered that the fill station had no analyzer. I had always analyzed with the shop's device, and I had none with me. I was able to make do with borrowing one from one of my buddies, but I learned a lesson -- if you are going to dive Nitrox, either have your own analyzer, or inquire ahead of time whether one is available. I think it was good that you didn't dive the tank, but how did you know the air tank was air, if it came from the same place?

As far as the problem at the end of the dive goes, it was a failure to communicate, perhaps; a definitely failure of the buddy system, and a failure on your part to take control. Did your buddy realize WHY you wanted to get shallower? Did you show him your gauge, or indicate you had deco? The second time, did you communicate your gas? Now, of course, a thumb is a thumb, and not to be argued with or dismissed; if you actually thumbed the dive and he ignored you, I would either have begun an ascent alone, or I would have swum up, grabbed him and shaken his arm, and stuck the thumb obnoxiously in his face. If he blew you off then, you were committed to a solo ascent.

And there's the final lesson -- emergency equipment is just that. I don't ever dive off a boat, any kind of boat, without an SMB and spool in my pocket. To me, that's a safety device, and very important in exactly the conditions in which you found yourself -- low viz and high current.

These guys were doing a goal-driven dive, and they're dangerous. The drive to achieve the goal can make people ignore all kinds of safety considerations.

 

[fisheater]

I, too, ALWAYS dive with a SMB and spool.

Here's an account of me having to use it in a similar situation. Www.alertdiver.com/636




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[dumpsterDiver]

I would have taken the nitrox. You seem to trust your life to buddies you don't know while underwater, but do not trust them with something simple (on land) like checking the mix on a tank?

Either you trust your life to some strangers or you bring your own analyzer AND you configure your gear with sufficient redundancy and emergency gear (like a SMB) if you are planning on doing a deep, challenging dive.

To expect these guys to supply you with tanks (that they trust their llife with) and then put up stink because they didn't bring an analyzer for YOU is not cool. I borrow tanks on the boat from guys who I trust to have analyzed the tank all the time (but of course I know them).