Free-Flow --> silt out --> confusion

[mstroeck]

Shortly after experiencing an avoidable equipment failure (see thread "A recall is a recall" ) I had another educational experience last weekend. As part of my on-going quest to make my feats of cluelessness known to a wider public, I'm offering this write-up for your edification.

We were diving as a team of three in a mountain lake in Upper Austria. Two friends of mine (William, a DM with ca. 170 dives and Florian, ca. 20 dives) plus yours truly, with a whopping 20 dives to his credit.

The vistas at that particular lake range from beautiful to breathtaking, depending on where you jump in. However, guides describe the lake's underwater appeal as "limited", so we took our time kitting up, taking pictures and checking equipment very thoroughly. I wasn't really looking forward to the dive, since I had to use an awkward, loaned, jacket-style BCD due to the equipment recall discussed in abovementioned thread. But I tried it out in shallow water and found no problems, so we began the rather long swim to the dive site. After reaching our destination we made sure everybody was OK and dropped down to 20 meters.

Down there, it was unusually dark, uncomfortably cold and mind-boggingly boring. But after 5 minutes of being totally underwhelmed, Mr. Murphy decided to give us a break: Florian's regulator quite suddenly started to free-flow.

William was closer to him, and within 10 seconds Flo was breathing from his octopus and William had shut his valve. In the process, the two of them lost their bouyancy control for a few moments and unceremoniously hit the bottom, resulting in a silt-out of thermo-nuclear proportions.

Now, I did 2 of my OW checkout-dives in all-but-zero vis, and standard low visibilty doesn't bother me at all. But hovering in giant cloud of silt that is swirling around you in trippy patterns, at 20m and in an air-share situation is a rather disorienting experience.

We moved closer together and put William's SPG where everybody could see it. I've never had a problem with stating the obvious, so I gave the thumbs up, which my buddies acknowledged. So William and I blew some air into our jackets, and Florian additionally started to fin up... Needless to say, the cloud of silt quickly got big enough to be seen from space.

After some of this (close to a minute) I looked at my computer and noticed that we were still at exactly the same depth as before. We hadn't noticed due to the mother of all silt clouds we had been busy kicking up.

I indicated this to my buddies. We added a little more air to our jackets and finally started to ascend. The rest of the ascent went fine, more or less, but with hindsight I think that our communication didn't really work. At one point, our computers indicated different depths, so we had an argument about where to do a safety stop. Also, bouyancy control was really hard for some reason, the dive profile looks rather strange ...

In this case, everything turned out fine, and none of us went beyond extreme alertness. Collectively, we were easily able to handle the situation and I didn't even breathe more than usually. But now I can really appreciate it when people talk about cascading failures. One more problem, and things might have gone awry.

Also, I'm not sure what would have happend if it had been William who had a problem. Would we two far less experienced divers have been able to facilitate a safe ascent? I believe so, but it definitely got me thinking ...

 

[Rick Inman]

Been there done that. A lot of divers are neutral in the water as long as they're swimming and getting a bit of lift from their slightly angled profiles. Then once they stop dead, they are heavy and hit bottom. I found that the frog kick helped me discover this and correct my trim.

One of the flaws in a three-man team is that once there is an issue (air sharing, for example), the third guy is basically a solo observer. If diver #3 suddenly has an issue, he's on his own.

Another benefit of the long hose is the ability to share air and do safety stops somewhat independently.

Sounds like everything went well and all survived the excitement. Thanks for sharing the story!

Oh, BTW, did you ever turn his air back on to see if the FF had stopped and you could all continue independently?

 

[Snowbear]

Oh, BTW, did you ever turn his air back on to see if the FF had stopped and you could all continue independently?

I was wondering the same thing..... So did you?

 

[mstroeck]

Been there done that. A lot of divers are neutral in the water as long as they're swimming and getting a bit of lift from their slightly angled profiles. Then once they stop dead, they are heavy and hit bottom. I found that the frog kick helped me discover this and correct my trim.

Yes, I started out with frog-kicking right from OW class and generally kick up no silt at all. That's the one thing I have on some more experienced divers, who for some reason mess up my visibilty all the time ;-)

One of the flaws in a three-man team is that once there is an issue (air sharing, for example), the third guy is basically a solo observer. If diver #3 suddenly has an issue, he's on his own.

That's true, but I had not considered that before this dive. Actually, I don't think that I will do that kind of diving again without some kind of redundancy on my back. At least a bottle with two independent valves. Unfortunately, I don't own a bottle yet and only single-valve ones can be rented at my LDS (which is kind of irresponsible, I think. Nearly all the diving with their equipment is done in extremely cold water.) In the long run, I'm afraid, this might even have an impact on the amount of dives I do. As a caver and mountaineer almost since childhood, I'm really anal about security. The more I learn about diving, the fewer of the practices I see all the time seem acceptable to me.

Another benefit of the long hose is the ability to share air and do safety stops somewhat independently.

I dive with a long hose, but since William was the first one to respond, it didn't do us any good. I didn't want to complicate matters any further by taking my regulator out of my mouth and offering it to Florian. It was our first dive together with me in that configuration, and while I did explain what I was going to do in event of an air-share, it might still have startled either of them.

I'm really looking forward to DIR-F, which I will be taking in two weeks. I think I will benefit a lot from the drills an practices taught there.

Oh, BTW, did you ever turn his air back on to see if the FF had stopped and you could all continue independently?

Sorry, I forgot to mention that! Yes, we successfully did so at 12 meters, but decided not to let go of him. He was breathing a lot, so we were concerned the regulator might free flow again.

 

[Mark Vlahos]

Sounds a little like my full cave class, but of course those "failures" were intentional and while a surprise to me were all planned.

Cudos to all 3 of you for handeling the problems. Dealing with problems well will separate an adequate diver from a good diver. When it hits the fan just deal with the most important problem first, so long as you are breathing you are alright. Other problems are more likely to arise when you are distracted, so multiple problems are more common than you might think, take your time and work the problem without making things worse.

You all made it safely to the surface, but you indicated that there was some problem on the depth of the safety stop. Remember, a safety stop is optional, if you really had problems you could always make a direct ascent to the surface. Or if the only issue is depth then close is fine, you could be a meter or two off and still be fine.

 

[Snowbear]

One of the flaws in a three-man team is that once there is an issue (air sharing, for example), the third guy is basically a solo observer. If diver #3 suddenly has an issue, he's on his own....

Gotta disagree with you on this one. If the 3 are a true team, then each team member looks out for the other 2 no matter what's happening. While multiple failures are not common, they can happen and can be dealt with. We did lots of that in my Tech 1 class last year. Even in the DIRf class last weekend, the instructor introduced multiple problems to the teams... i.e. ... while one guy was air sharing with another, the 3rd guy "lost" his mask. It was dealt with. Just 'cause you're helping one person on your team doesn't mean you ignore the 3rd member

 

[mstroeck]

You all made it safely to the surface, but you indicated that there was some problem on the depth of the safety stop. Remember, a safety stop is optional, if you really had problems you could always make a direct ascent to the surface. Or if the only issue is depth then close is fine, you could be a meter or two off and still be fine.

It was not really a problem, but confusing none the less. I did not describe it exactly in the original post for fear of it getting to long (edit: actually, I described it badly, sorry for that), but it went somewhat like this:

We had been at 20m for some time. William (who, as the most experienced hat taken the lead) had been ascending to slow for my taste, with occasional dips of a few meters towards the bottom. So I figured the profile was rather unhealthy. Additionally, that lake is at altitude. I would have prefered to go straight up to a safer depth of 5 to 4 meters to see if problems persisted. If so -- fin up straight to the surface in a controlled manner. If not: hang around for a few minutes and then slowly fin up.

For some reason, William decided to go up extremely slow. He later said that he didn't feel that it was slow, but I think was. If it hadn't been slow, we wouldn't have had time to create such an up-down profile. His computer was showing a longish (deco)stop at 10 meters. I don't know where it got that idea from, perhaps it could not deal with the profile? That's where the "argument" arose. I would just have prefered to go up closer to the surface where air consumption and even an emergency ascent would not have been much of an issue ...

In the end I waited till his computer let him continue the ascent. We had enough air left, otherwise I might have objected strongly.

 

[Rick Inman]

Gotta disagree with you on this one. If the 3 are a true team, then each team member looks out for the other 2 no matter what's happening. While multiple failures are not common, they can happen and can be dealt with. We did lots of that in my Tech 1 class last year. Even in the DIRf class last weekend, the instructor introduced multiple problems to the teams... i.e. ... while one guy was air sharing with another, the 3rd guy "lost" his mask. It was dealt with. Just 'cause you're helping one person on your team doesn't mean you ignore the 3rd member

You are, of course, right. Yes, you, Ms. Bear - who have taken DRIF & Tech 1 - and your three-person-team, I'm sure can deal with multiple issues. But most 3 person, short hosed, PADI-trained teams are not trained on what to do when there is a silt-out and diver A is sharing air with diver B, locked together while one is sucking on his Air2, and then diver C gets entangled in a cable...

I guess what I should have said was, One of the flaws in most three-man teams is that once there is an issue (air sharing, for example), the third guy is basically a solo observer. If diver #3 suddenly has an issue, he's on his own, because of lack of training on how to be a good buddy in a three man team.

BTW, yes, now that you ask, I am jealous of your training and availability to similarly trained buddys.

 

[mstroeck]

Gotta disagree with you on this one. If the 3 are a true team, then each team member looks out for the other 2 no matter what's happening.

What Rick said. Having now witnessed a PADI-style air-sharing situation, I'm really happy I chose to buy a regulator on a long hose. I would also like to add that nothing in my diving education (OW & AOW) prepared me for something like this. I never heard anything about three-buddy teams, I never heard anything about managing silt-outs. I also obviously was never taught adequate gas planning. Had this dive been any longer and had we followed common "come up with 30 bar left" advice, this might have been even less fun, with tiny margins for mistakes ...

I don't subscribe to that particular piece of "wisdom", but that's certainly not because I was taught any better. I had to read up on all the really useful info on the internet, which is kind of insane. I would not want to continue diving with only the training I got from my diving courses so far, which is why I will be taking a GUE DIR-F now and probably at least GUE Tech-1 sixty to a hundred dives later.

 

[Snowbear]

BTW, yes, now that you ask, I am jealous of your training and availability to similarly trained buddys.

My training was great.

For now, the availability of similarly trained buddies pretty much only happens when I head south. Which any more is rare if at all :frown:

Anyhow, since my communication skills suck and you apparently didn't get the point of my post.... What I was trying to show was that the 3rd team member doesn't have to be solo just 'cause one member has a little trouble. Just like all the battles on ScubaBoard about rotten buddy teams of 2, I was just trying to say teams of 3 don't have to be rotten any more than teams of 2 do. It's all a matter of situational awareness and attitude, not what classes you have taken.