BC Failure

[Charlie99]

I'm glad that I dive mostly tropical waters, with 5mm or less.

I had a similar failure of a BCD on a 130' wall dive. I discovered the problem around 65' or 70' during the descent. I was wearing only 5mm wetsuit and had just 6 pounds of gas (80 cubic feet) so loss of ability to hold air in the BCD was a non issue and I finished the dive normally, although finning around at a 45 degree angle.

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It's easy for a diver to check his ability to cope with total loss of BCD or wing buoyancy. Just go to the max depth of the dive site, near the beginning of a dive when you have full weight of air, and see what happens when you completely empty the BCD of air.

There's nothing you can do about the loss of buoyancy of wetsuits caused by compression, but getting your weighting right means you are not fighting unnecessary negative buoyancy.

Charlie

 

[Mr Carcharodon]

This seems like a case where a pause at 10 fsw to adjust buoyancy and check for leaks would have been really helpful. It would have been a chance to know there was a problem before there was a significant loss of buoyancy due to wetsuit compression.

 

[dumpsterDiver]

Hi, John...!

Those are good points, and while I am a medical moderator, my diving experience is nowhere near that of the OP or yourself, so I hesitate to argue diving specifics. It is true that a well balanced rig should be swimmable up from depths (is that grammatically correct?), and that people clearly were diving long before the modern BC was available. Please understand that I am not doubting either your or the OP's skills or ability to deal with the situation safely. I also totally agree with you about the difference between being overweighted at depth and on the surface.

However, I do stand by my comments in the context of this forum, where less experienced divers may take away a potentially dangerous message from this approach.

The OP stated that he added air to his BC at depth, and found it to not hold air. Thus, we must assume that he felt the need to add air. Also, he said that he made an "uncontrolled descent", enough to stress his Eustachian tubes, and that he was "pretty darn heavy".

Sure, in optimal circumstances, a diver should be able to swim his rig to the surface even if there is failure of his only buoyancy device. And the OP could probably handle a wide variety of mishaps due to experience and training… But the point is that this diver was overweighted at least at the start of the dive (i.e. he needed to add air to the BC), and as Vladimir pointed out, it is good to have a gas reserve in case plan A turns out to be flawed, due to unforeseen circumstances. There can always be unforeseen circumstances (cramping, entanglement, loss of a fin, etc&#8230. Once you have lost one of your redundant devices for getting you safely to the surface, it seems that it would have been more prudent to call the dive.

I guess it comes down to the intended audience of these posts. If I determined that there was a malfunction of my BC when I was overweighted, solo diving with no ascent line, and 50 miles from shore in cold water, I would thumb the dive immediately and deal with the problem on the surface. I think that the majority of recreational divers would feel the same way…

You seem like a nice guy, but kinda lost??? I was not over weighted!!!!! I was carrying the exact amount I needed to perform a safety stop at 15 feet, without floating up and being able to breath normally, with an empty tank.

Anyone wearing a thick (7mm) suit is going to experience considerable suit compression (even the magic G-231) below 60 feet or so. The fact that I needed to add air to the BC to establish neutral bouyancy at depth is NORMAL,, CORRECT and necessary if someone uses this type of gear. To me, over weighted means the diver is carrying more lead or ballast than he needs to function for all portions of the dive. Possibly it is simply an issue of terminology.

As for "balanced rig" I think you may not understand that idea as well.. To me, a balanced rig is a rig that a diver can swim up without too much difficulty AFTER ditching all or a portion of their lead (if necessary).

This is a VERY important concept, because people that dive with gear setups that have insufficeint ditchable ballast and they are too weak to swim up after a BC failure, are putting themselves in a potentially "vulnerable" if not dangerous situation. My rig WAS balanced as far as I'm concerned.

As people have tried to explain, for a recreational diver, I was really in no danger without the use of the BC. I could have dropped the belt and ascended slow enough, especially if done immediately at the start of the dive (when nitrogen loading was minimal). Which is what you suggested and I do not dispute.

My only reason for the post was to remind people that the BC has multiple failure points and that it is nice to have some contingencies... kick like hell, ditch the belt, use an SMB with a dump valve (and sit on it) or use a reel and SMB combo to reel yourself up. That last option was simplest for me and it was a non issue for a simple dive like this.

Also, I should correct something I said earlier with respect to the weight belt. I could have cut it in half with a knife and retained either 6 or 8 lbs and probably pretty easily modulated my ascent from depth. Of course I had lots more dives to do that day (with a borrowed BC), so I was not ditching my weight belt without a good reason.

If I were doing a deco dive and did not have an SMB (or it failed), i suppose I would ditch a portion of the lead and then try to do my deco stop as deep as practical to keep the suit compressed and me close to neutral with maybe half a weightbelt.

I think these types of discussions can be very useful if they simply get people to investigate and formulate their own responses to potential problems, well before they happen.

In my opinion, most divers could probably kick up being 10 lbs too heavy, but this is a gross generalization that is abot as useful as saying most divers SAC is 0.8 cu-ft/min.

 

[dumpsterDiver]

This seems like a case where a pause at 10 fsw to adjust buoyancy and check for leaks would have been really helpful. It would have been a chance to know there was a problem before there was a significant loss of buoyancy due to wetsuit compression.

ABSOLUTELY! that would be good practice for the PADI diver. However, I was solo diving in a current with 10-15 ft visibility, 6 ft seas and whitecaps, no visual reference and had never dove this area before. It was essential that I descend ASAP to the bottom before getting blown off. I was not going to be "checking for bubbles" while solo in a washing machine.

A better more practical solution is to simply inflate the BC fully on the boat (then vent) before the dive and assume that it will not fail in the 30 seconds it takes to get to the water. I ddin't do this and it is possible that it would have entirely prevented the problem.

 

[doctormike]

You seem like a nice guy, but kinda lost??? I was not over weighted!!!!! I was carrying the exact amount I needed to perform a safety stop at 15 feet, without floating up and being able to breath normally, with an empty tank.

Sorry, that's what I though you were implying from your description. You used the terms "quite heavy", "pretty darned heavy", and said that you had an uncontrolled descent, and landed with a thud.

Anyone wearing a thick (7mm) suit is going to experience considerable suit compression (even the magic G-231) below 60 feet or so. The fact that I needed to add air to the BC to establish neutral bouyancy at depth is NORMAL,, CORRECT and necessary if someone uses this type of gear. To me, over weighted means the diver is carrying more lead or ballast than he needs to function for all portions of the dive. Possibly it is simply an issue of terminology.

Yeah, I think so. Terminology. I didn't say that you were not diving correctly, or that you were weighted incorrectly. I said that you stated that you needed to add air to your BC to establish neutral buoyancy, which is true, and as you point out, an example of proper diving technique. So the BC failure did impact on your dive plan. Whether or not it is something that would cause you to thumb the dive is up for discussion. You did not feel that it was necessary to call the dive under the circumstances, and I defer to your experience. I would have called the dive at that point, and I posted my thinking so that another inexperienced diver might consider doing so under similar circumstances, when reading the comment thread.

I think these types of discussions can be very useful if they simply get people to investigate and formulate their own responses to potential problems, well before they happen.

Absolutely.

 

[Crush]

Anyone wearing a thick (7mm) suit is going to experience considerable suit compression (even the magic G-231) below 60 feet or so. The fact that I needed to add air to the BC to establish neutral bouyancy at depth is NORMAL,, CORRECT and necessary if someone uses this type of gear. To me, over weighted means the diver is carrying more lead or ballast than he needs to function for all portions of the dive. Possibly it is simply an issue of terminology.

...

Also, I should correct something I said earlier with respect to the weight belt. I could have cut it in half with a knife and retained either 6 or 8 lbs and probably pretty easily modulated my ascent from depth. Of course I had lots more dives to do that day (with a borrowed BC), so I was not ditching my weight belt without a good reason.

dumpsterDiver, doctormike states (below your post quoted above) that you would not have been overweighted if your BC had not failed and recognizes that wetsuits do compress. Given that, I personally would have used the term "negatively buoyant" rather than "overweighted." However, like you, I get frustrated when warm water divers (doctormike may well dive cold water, don't know) claim that you should always be able to swim your rig to the surface, and that if you are carrying more than 10# in lead you are probably overweighted.

One additional method of self-rescue did occur to me - you could have secured your spool to your belt, dropped it, and allowed yourself to rise up, using the belt and spool as a sort of anchor line. This could be dangerous in a drysuit, but you would probably have been OK if you had had a drysuit.

 

[jkaterenchuk]

Obviously Dumpster Diver has a perspective on continuing the dive and feel it is justified and without significant risk.

On the other side of the table are the numerous DAN results and analysis from past accidents that clearly indicates that many fatalities are not a result of a single failure but rather a combination or chain of failures or issues during a dive. So I think DAN would say that Dumpster Diver had a lucky dive since no other unforeseen failures or issues occurred to continue the downward spiral to a fatality. Had that not been the case we might have been reading a posting here from DandyDon about a lost diver in which the body was never recovered and no one would ever know that it all started with an otherwise simple equipment failure.

IMO that is the message readers should be taking away from the valuable posting of this event by DumpsterDiver.

An additional side point might include an complete and evolving equipment pre-dive check list, diving with redundant buoyancy when using a wetsuit on a solo dive.

John

 

[dumpsterDiver]

dumpsterDiver, doctormike states (below your post quoted above) that you would not have been overweighted if your BC had not failed and recognizes that wetsuits do compress. Given that, I personally would have used the term "negatively buoyant" rather than "overweighted." However, like you, I get frustrated when warm water divers (doctormike may well dive cold water, don't know) claim that you should always be able to swim your rig to the surface, and that if you are carrying more than 10# in lead you are probably overweighted.

One additional method of self-rescue did occur to me - you could have secured your spool to your belt, dropped it, and allowed yourself to rise up, using the belt and spool as a sort of anchor line. This could be dangerous in a drysuit, but you would probably have been OK if you had had a drysuit.

Yeah I guess it is terminology.. "over weighted" diver sounds bad... negatively bouyant diver doesn't necessarily have the same "negative" connotation.


Dropping the belt and reeling up from it could work as well, as long as there are negligible currents.

 

[John C. Ratliff]

Obviously Dumpster Diver has a perspective on continuing the dive and feel it is justified and without significant risk.

On the other side of the table are the numerous DAN results and analysis from past accidents that clearly indicates that many fatalities are not a result of a single failure but rather a combination or chain of failures or issues during a dive. So I think DAN would say that Dumpster Diver had a lucky dive since no other unforeseen failures or issues occurred to continue the downward spiral to a fatality. Had that not been the case we might have been reading a posting here from DandyDon about a lost diver in which the body was never recovered and no one would ever know that it all started with an otherwise simple equipment failure.

IMO that is the message readers should be taking away from the valuable posting of this event by DumpsterDiver.

An additional side point might include an complete and evolving equipment pre-dive check list, diving with redundant buoyancy when using a wetsuit on a solo dive.

John

John and all,

There is a lot of good discussion here.

Concerning this "downward spiral to a fatality," I think he was a long ways from that type of situation. I have very few dives where nothing goes wrong. To call a dive is something rather minor goes wrong would be to call a majority of dives. You could look at this a bit differently from an accident prevention standpoint, and that is that divers who are what we used to call "equipment dependent," or "pushbutton" divers are setting themselves up for this kind of accident that would evolve into a fatality. To be so totally dependent upon the functioning of a BC that it makes this spiral says something about the diver him- or herself, the training, the planning and the abilities. Concerning redundancy, there was a lot of that in this situation:

--Swimming ascent
--use of the spool to ascend
--dropping the weight belt, and a free ascent (probably buoyant).

So there were still viable options for him to use to deal with the situation, which he did.

There is also the concept of "immediate emergencies" verses "delayed emergencies." If a diver runs out of air (OOA), that is an immediate emergency. That did not happen. An BC equipment failure could be construed as a "delayed emergency" if the diver was dependent upon the BC. For instance, if this diver were diving in blue water, and experienced the same thing, then it could be an "immediate emergency" for which action was required--dropping weights, swimming up or otherwise establishing control of the descent. But in this situation, there was not that need. He had time to ascertain that nothing bad was likely to happen, enjoy his dive, and make his ascent.

SeaRat

 

[Gombessa]

Concerning this "downward spiral to a fatality," I think he was a long ways from that type of situation. I have very few dives where nothing goes wrong. To call a dive is something rather minor goes wrong would be to call a majority of dives.

One of the things that is often stressed regarding the downward spiral or incident pit is that it rarely starts with a "major" failure. Instead, it's exactly the minor failures which by themselves seem insignificant or ignorable that lead to complications if something else goes wrong (either independently or as a result of the first failure). It's not having a busted BC that completes the spiral, it's just the first step down. The way I was told, the idea isn't that any small thing going wrong immediately necessitates a thumbing of the dive, it's that such small problems should be fixed and not ignored, because they can come back to bite you if something else goes wrong down the road. Presumably, many minor issues can be fixed underwater, while on the dive. This particular one, not so much I'd think.

That said, I wouldn't personally consider a complete loss of a wing in a wetsuit at depth with a large steel tank at the beginning of the dive a "minor" inconvenience, even if it can be handled calmly and without rushing. If anything, I'd think that being quite so negative would really impact the quality of my dive. Perhaps I'll think differently when I have thousands of dives, but from my comfortable armchair here, I think I'd have taken the chicken way out and just called the dive.

--dropping the weight belt, and a free ascent (probably buoyant).

It's been a while since I've dived a thick wetsuit, but I'm not convinced this would have resulted in a buoyant ascent, especially if done when the problem was first discovered. 16lb belt, ~10lb gas (assuming nitrox), a compressed wetsuit at depth. Had DD just dropped his weights, he probably would have been close to neutral or even still slightly negative by safety stop depth, if he even felt he needed to make the stop.