How common are problems?

[SkipperJohn]

OK, I can see the OW course was all about coping with problems as much as learning skills, but as I read these boards, as I read into some of the comments, and even with my limited experience I see lots of problems that can be more serious than losing a mask or a fin.
For instance, on my 4 OW dives, I saw 3 tanks blow the o-rings as the valves were opened on the boat. I thought the first was a fluke, the second a curiosity. On the third I asked: "does this ever happen under water?" I got no answer (would love one here).
A week later I was telling a few colleagues at work that I went diving. One told me of a friend that dove, fell ill afterwards then past a few days later. An autopsy back home determined it was "bad air".
My own personal experience, on my first dive after a few minutes cruising the bottom in around 45 feet of water I suddenly began to rise. I immediately grabbed my BD and began dumping air. But, as I later learned I was improperly weighted and with the little air I consumed with each foot up I became more positively buoyant and could not stop my assent. My instructor chased me all the way and stuck a few pounds in my BC pocket then all was well, but the thought of ascending too rapidly or form too deep or into a boat propeller... And this not being theoretical, it happened to me. Well, I think it's important to understand the larger issues as I prepare for my first dive tomorrow after receiving my card.
What else is there and how common are these problems?

 

[Doc]

How common?

It is very uncommon for an o-ring to blow out of a tank nipple any time after it has survived being initially pressurized. In the rare instances of this occurring, I can assure you it is quite a spectacular (and memorable) sight for the other divers underwater nearby. The diver it happens to may not be attuned enough to notice or diagnose the problem and others might have to assist him, without his understanding why~ or, he might need a change of underwear. After pressurizing your tank- do not attempt to initiate a stress failure in a weak o-ring by gorilla wrenching your first stage to and fro. You will likely bust a toe when the tank falls off the bench and will cause un-needed stress to the reg's hoses... if you're going to worry about something having a catastrophic failure, hoses would be higher on my list than tank o-rings. That~ and jilted ex-girlfriends (Pam Anderson has still not forgiven you) cutting your hose with their large pointy dive knives. You may have seen this in Sea Hunt.

Bad air is bad bongos. It is also rarer than an honest politician. There are all sorts of gauges and meters available to test for CO, but suffice to say if you can smell your air, it's no good. Possibly, when the speaker referenced "bad air", it was the literal translation of Malaria (Mal Aire), which is also bad bongos but equally uncommon~ and most travellers no longer die from it.

A sudden uncontrolled ascent is more common in noob divers. As you get more experienced, you will quickly notice minor variations in your depth- even when they are not intentional. Is it common to ascend into a boat propellor? No- most divers either hit the bottom of the hull (mathematically more probable as the size ratio of the two objects on a 200 Ton Vessel is about 1250:1) or they just simply pop into the sky and out of the ocean like a nuclear submarine or a breaching Whale. This outcome is much more likely as the sky is... well... quite big as compared to any propellor. Also, quite spectacular and if someone snaps a pic- it gives rise to stories in the Weekly World News about heretofore unknown monsters lurking from the depths.

You worry a lot. Relax. Pay attention, ask questions. You'll be fine, just like the rest of us.

 

[ClayJar]

For instance, on my 4 OW dives, I saw 3 tanks blow the o-rings as the valves were opened on the boat. I thought the first was a fluke, the second a curiosity. On the third I asked: "does this ever happen under water?" I got no answer (would love one here).

For all the divers I've been around in over 250 personal dives and countless pool excursions, I've seen three O-rings blow while I was in the water. One was at the end of a pool dive, and the other two were right at the beginning of pool dives. I know of one person whose buddy had an O-ring blow on an actual dive. So, although my experience is only anecdotal, that's less than one hand's fingers of O-rings blowing in the water over several thousand dives witnessed.

If it ever happens, just start ascending with your buddy, and if your tank runs dry on the way to the surface, share air with them. There's no need to immediately reject your reg just because your air is rapidly escaping, but your tank can be exhausted in very short order (possibly under a minute if it's a full-on blow late in the dive, possibly long enough to make it all the way back to the surface), so starting an ascent and having air ready to share is called for.

My own personal experience, on my first dive after a few minutes cruising the bottom in around 45 feet of water I suddenly began to rise. I immediately grabbed my BD and began dumping air. But, as I later learned I was improperly weighted and with the little air I consumed with each foot up I became more positively buoyant and could not stop my assent. My instructor chased me all the way and stuck a few pounds in my BC pocket then all was well, but the thought of ascending too rapidly or form too deep or into a boat propeller... And this not being theoretical, it happened to me. Well, I think it's important to understand the larger issues as I prepare for my first dive tomorrow after receiving my card.

You responded to the situation precisely as you would have been taught in many of the classes with which I've assisted. There's one bit that's often left out, however, that would likely have helped you in that situation: If you feel your buoyancy getting away from you, the *first* thing you should do is start swimming.

As you found out, the more you rise, the more the air expands, the more you accelerate, the harder it is to get under control just by dumping air. The trick is to cut off the vicious cycle before it gets out of control. When you notice yourself start floating up, *first* swim downward to stop your ascent and get back to the right depth. *Then* dump some air from your BC. If you're still floaty, repeat the process.

Of course, if you're underweighted, you'll never be able to get to neutral. Still, by swimming down against your buoyancy, you can keep yourself from shooting to the surface. It may not be the most relaxing dive, but it's much safer than an uncontrolled ascent.

I had one unintentionally underweighted drysuit dive in a quarry. I was fine until near the safety stop, by which point I'd used about five pounds of air from my tank. I ended up having to "swim down" the entire safety stop to keep myself from floating to the surface -- it was like being on a treadmill. Even though I was underweighted, however, I never lost control and floated to the surface. It was certainly more effort to maintain control (by swimming, instead of by buoyancy), but it works in a pinch.

If you *take control* of yourself when you're losing buoyancy by swimming first and then adjusting buoyancy (if possible), you should *never* need to find yourself uncontrolled and heading toward the surface. I guess I'd say that's one of those "common" things for new divers that ought not be common at all.

 

[Scuba Ken]

I think small issues are pretty common. For example less then 15 dives on my gear and my buddies we both had things happen. First dive his SPG starts to leak. Second Dive I extruded an o ring out of my power inflator on decent to a wreck. The key is to start every dive with a good buddy check. We have added a few extra things to ours beyond the basics PAdi describes. On decent, once you are down a few feet, take a second to check each other for bubbles or leaks. Once you hit the bottom keep not only an eye on your buddy, but also on their gear. If anything doesn't feel right abort the dive immediately. Safety first.

If you take a few extra moments to check over gear before the dive, I think lots of issues like you mentioned can be avoided. One quick example, If I dive a rental tank the first thing I do is replace the o-ring. It cosst 10 cents and it definitely doesn't hurt.

 

[vondo]

But, as I later learned I was improperly weighted and with the little air I consumed with each foot up I became more positively buoyant and could not stop my assent. My instructor chased me all the way and stuck a few pounds in my BC pocket then all was well,

This worries me a little bit. Being underweighted is not going to cause a run-away ascent, but a gradual drift up. If you are underweighted you should have no air in your BC so nothing to expand as you rise. On the other hand, being overweighted will make you more likely to have a runaway ascent because all the air in your BC will expand as you go up a little bit.

Of course, you want to be properly weighted. But make sure you're not "solving" the problem by taking on more and more weight.

As others have said, the more you dive, the less likely this particular problem will be because you will weight yourself better and be more in-tune with what's going on with your buoyancy.

As for how common problems are, in 140 dives I've experienced two minor issues: First, buddy's valve leaking air faster than it should have (probably twice as fast as he was breathing). I wasn't looking and didn't notice. He aborted the dive, I came up after him as quickly as I felt comfortable. He wouldn't take my octo, surfaced with 300 psi, probably. Second problem, snagged my octo on a wreck and it broke so it would breathe very wet. I aborted the dive.

I learned something from both of these incidents.

 

[DeputyDan]

I have seen masks knocked off "for various reasons" multiple times

Only seen one O-Ring failure on an actual dive and that was as the descent was starting - not at depth.

Have never seen anyone with a significant equipment issue during a dive but most of the folks I dive with dive alot and their gear is maintained.

I think the single biggest safety issue is exiting the boat and boarding the boat - or the slickness of the steps on shore dives.

 

[don Francisco]

Prroblems are about as common as dive practices allow. There will always be some minor snafus that must be coped with, but with decent dive habits, serious problems are amazingly rare. So rare in fact that most divers have to practice emergency proceedures from time to time lest they forget, and are unprepared when something critical eventually happens.

As far as bad tank o-rings are concerned, most blow off immediately, though a few ocasionally do so after a few minutes. Usually a bad o-ring will simply fail to seal anouncing the problem with a steady hiss. When they blow off it's usually because the o-ring or reg was not properly seated, or because the yoke was loose when the valve was opened. A properly seated reg doesn't allow enough space for the o-ring to extrude through and blow out.

One way I prevent nasty surprises is visually inspecting that the o-ring is seated before installing my regs and by leaving my tank valve open after the initial pressurization. This gives the o-ring plenty of time in case it might blow out, and it also prevents me from forgeting to turn the air before jumping in.

While the risk of bad air is real, it's exceedingly rare these days, and you can cut the risk even lower by diving with reliable operators. In simplest terms, you cannot control all the ways a sloppy operator can screw you up, bad air being one of the least likely. You have to choose operators carefully and dive with a degree of trust based on instinct and experience.

In the final analysis, diving is more than reasonably safe, but don't get complacent. Avoid problems as much as possible with good practices, but stay prepared to manage problems as they arise. As the old saying goes "Luck favors the prepared"

 

[SkipperJohn]

for the record, my runaway ascent was probably caused by my not being horizontal. So my kicks were moving me upwards as well as latterally. Once my instructors pointed this out I was fin even though underweighted again on my next dive (they just refused to believe how much weight I said I needed until they saw for themselves).
And yes, I did have a bit of air in my BC mostly because I thought there was supposed to be some. I'm learning...

 

[Roko]

A week later I was telling a few colleagues at work that I went diving. One told me of a friend that dove, fell ill afterwards then past a few days later. An autopsy back home determined it was "bad air".

I once had a friend who was big into diving. One day he went diving, and nothing happened. In fact, nothings happened to him yet... Guess that doesn't make as good of a story...

It's just that we hear about all the bad things happening way more than we hear about the good dives... And there are WAY more good dives than dives where things go horribly wrong, just the nature of what people like to talk about. Best bet is to just learn from the bad dives, and work out and practice an action plan of what to do in the event of such a failure. Then in the small chance that you do have a problem underwater, you'll be better prepared to deal with it.

Good diving!

 

[TSandM]

And yes, I did have a bit of air in my BC mostly because I thought there was supposed to be some.

Well, at the beginning of the dive, you are right! The reason a BC is called a buoyancy COMPENSATOR is because you need to compensate for the gas you are carrying at the beginning of the dive, but intend to use up by the end. Since you have to weight yourself to have enough ballast to be able to hold a stop with a near-empty tank, you will by necessity be somewhat negative at the beginning of the dive. How negative depends on how big a tank you are carrying! So at the beginning of the dive, you should require some gas somewhere (in BC or drysuit, if you are using one) to be neutral.

In addition, as you descend and if you are wearing a wetsuit, the wetsuit compresses and has less lift than it did shallower. Since you weight yourself at the surface, you have to have something to compensate for that loss of buoyancy, or you would just keep heading down! So, if you are wearing a thick wetsuit and carrying a big tank, you may have quite a bit of gas in the BC at the beginning of the dive, and progressively less as the dive goes on, until you should have little to none at your safety stop.

Back to the original question: Between me and my husband, we have over 1000 dives. We've had a variety of minor problems -- connections backing off and leaking, inflators slowly leaking, a leaking burst disc, a variety of light failures -- and one major issue, which was a freeflow. Diving is pretty equipment-intensive, and if you use a lot of equipment, from time to time there will be glitches. Good pre-dive checks will pick up many of them, and good buddy awareness will spot most of the rest before they create a major problem. Doing a bubble check on the surface or shortly after beginning the dive will find a lot of small problems before they become big ones.

The biggest reason for practicing emergency procedures is not because you expect to encounter that particular emergency, but so that you will retain your composure and your buoyancy control when you encounter issues, whatever they may be.