My Wing Incident

[O2BBubbleFree]

Never mind. Post deletded. On reading your post for the third time, I answered my own question.

 

[dougaldiver]

One additional thought here. Presumably the air trapped in the wing was the air that you had fed in during your descent. As the air was trapped on the side away from the dump (and therefore away from the inflator) the wing must have been open across the top at the start of the dive. It would seem then that, whatever the cause, the 'blockage' occured during the dive.

 

[radinator]

On the DSS wing there is no "side away from the inflator". The inflator hose is in the center of the top of the wing.

 

[PacketSniffer]

One additional thought here. Presumably the air trapped in the wing was the air that you had fed in during your descent. As the air was trapped on the side away from the dump (and therefore away from the inflator) the wing must have been open across the top at the start of the dive. It would seem then that, whatever the cause, the 'blockage' occured during the dive.

No. Actually, from my pre-dive check, the wing was still inflated. What I don't know is if both sides of the wing were inflated during the check. I would typically check the power inflator first and then finish the test orally to max fill. The force of the oral check would indicate the wing was inflated and holding air. I'd also listen for leaks. Then, we finned out a bit on the surface and then dropped down. I purged air on the way down. I usually don't need to add much air at all once at depth. That's a luxury of being properly weighted.

I'm thinking the problem probably existed before I went down (don't know for sure though). I just didn't know it because my pre-dive procedure didn't have me actually feeling both sides of the wing to verify 100% proper inflation. You can bet I'll be doing this going forward. It only takes a second. Probability points at the root cause being a dirty bladder. I'll never know for sure.


Richard

 

[dougaldiver]

OK, I'm a bit confused by that. I assume you mean you purged at the surface to start the descent? If you are properly weighted then the only air that should be left in your wing at that point is what you would need to compensate for the weight of the gas that you will use during the dive (making you neutrally bouyant at the end to carry out any stops). In my experience, unless diving with large doubles then the wing is normally emptied completely at the surface in order to start the descent.

If there was a significant amount of air trapped in the wing at the surface then you wouldn't have been able to descend normally unless you either

a. overweighted yourself or
b. duck dived and finned down against the excess bouyancy

Therefore we should be able to assume that the wing was either empty on leaving the surface or had only a very small amount of air left in it representing the weight difference of the gas. To be honest I would have thought this was negligable and, unless you are diving with very large tank(s) with a considerable gas difference between the start end end of the dive, I doubt you would even notice it until the last 2-3 metres (7-10 feet)

The only other air in the wing would be what you added during the dive to offset compression of any exposure protection. This would enter via the Low Pressure inflator in through the corrugated hose connection and into the wing.

The normal mechanism for dumping from the wing would be either the rear pull dump (OPV) or by using the purge button on the LP inflator. If you used the purge button on the LP inflator then the air in the wing would vent through the corrugated hose, in exactly the same way that it went in. In fact this is the way that the air would have gone in when you orally inflated on the surface so if there was significant air trapped in the wing at depth the the failure must have occured sometime after the oral inflation, and probably sometime after the dive actually started.

As a matter of interest were you able to dump any air from the wing (i.e some came out but some got stuck)?

Sorry if this sounds like a bit of a lecture, it's not intended to be. I just like to get to the bottom of things. Hopefully I can help you, or indeed help myself. I dive with a wing and although I've never had a problem like this Ithat doesn't mean to say I never will. If there's a lesson to the learnt I am always keen to learn it.

 

[PacketSniffer]

OK, I'm a bit confused by that. I assume you mean you purged at the surface to start the descent? If you are properly weighted then the only air that should be left in your wing at that point is what you would need to compensate for the weight of the gas that you will use during the dive (making you neutrally bouyant at the end to carry out any stops). In my experience, unless diving with large doubles then the wing is normally emptied completely at the surface in order to start the descent.

If there was a significant amount of air trapped in the wing at the surface then you wouldn't have been able to descend normally unless you either

a. overweighted yourself or
b. duck dived and finned down against the excess bouyancy

It's a just a little bit of (b). I wouldn't say that it requires a "duck dive" and would say "slight excess bouyancy". I purged most but not all. I didn't need that much air in the wing at depth. I'm stingy when it comes to my gas supply. More is always better and I try not to "give it away" at depth. So, I leave a little in as I'm descending. Yes, I realize the amount needed to compensate is negligible but I can be anal sometimes. It keeps me entertained.

I had a 3mm full suit, gloves, boots, steel tank, 6lb on my belt and a SS plate which is around 5lb. I'm prefectly weighted for my safety stop for this high salt content region. ...not too much nor too little.

Therefore we should be able to assume that the wing was either empty on leaving the surface or had only a very small amount of air left in it representing the weight difference of the gas. To be honest I would have thought this was negligable and, unless you are diving with very large tank(s) with a considerable gas difference between the start end end of the dive, I doubt you would even notice it until the last 2-3 metres (7-10 feet)

I started to notice the listing after we planed out on a set course. I was diving with a steel 120cu.ft. (single) that day.

The normal mechanism for dumping from the wing would be either the rear pull dump (OPV) or by using the purge button on the LP inflator. If you used the purge button on the LP inflator then the air in the wing would vent through the corrugated hose, in exactly the same way that it went in. In fact this is the way that the air would have gone in when you orally inflated on the surface so if there was significant air trapped in the wing at depth the the failure must have occured sometime after the oral inflation, and probably sometime after the dive actually started.

You're missing the part where I have stated that on my wing checks in the past, I would NOT actually feel either side of the wing for proper inflation. Therefore, I can't positively say that there was no blockage before my descent.

As a matter of interest were you able to dump any air from the wing (i.e some came out but some got stuck)?

No air was able to be purged from the wing until at one point (after a few minutes of fiddling once doffing harness) I noticed the air on the same side as the rear dump. Purged all air and then I was on my way.

Sorry if this sounds like a bit of a lecture, it's not intended to be. I just like to get to the bottom of things. Hopefully I can help you, or indeed help myself. I dive with a wing and although I've never had a problem like this Ithat doesn't mean to say I never will. If there's a lesson to the learnt I am always keen to learn it.

No worries. It bothers me a bit that I will not have a solid answer to this incident. I like to correct my mistakes or improve precedures where possible so that I don't encounter them again. Diving can be deadly. I don't intend on becoming fish food any time soon.


Richard

 

[dougaldiver]

You're missing the part where I have stated that on my wing checks in the past, I would NOT actually feel either side of the wing for proper inflation. Therefore, I can't positively say that there was no blockage before my descent.

Actually what I'm saying is that if there had been air trapped in the wing before the dive you shouldn't have been able to descend normally

 

[cool_hardware52]

It still sounds like a contaminated bladder to me.

What we know:

A some point gas would not move from one side of the wing to the other, i.e. stuck in the right half. Only explaination for this is some type of block in the top arc of the bladder. Given that there was no observed external trapping or mechanical compression of the wing, what is left is a bladder stuck together.

The problem apparently spontaneously resolved, this again points to a "Sticky bladder"


The fittings used for both penetrations in the bladder, the OPV and fill hose, consist of a flanged threaded piece that starts inside the bladder, and projects through both the bladder and the outer shell. A large nut secures this piece one the outside of the wing. The OPV or inflator attaches to this outer nut.

The inner flanged piece is about 2" in diameter, with a center hole about .75" in diameter. This leaves a flat flange inside the bladder. It is possible for the opposite side of the bladder to get stuck to this flange, much like flat rubber sheet covering a sink drain.

To prevent this the flanges have raised radial ridges. Even so I can imagine that with a "sticky bladder" the flow of gas out of the bladder could be slowed. Remember when adding gas to the bladder you have greater than ambient pressure, but when venting you have almost no pressure differential. If bladder was stuck together the inlet pressure would need only a small "channel" to fill the wing, and this channel might get pressed shut when trying to vent.

What is apparent to me is the importance of maintaining your gear, whether it be your regs, or your BC.

Tobin

 

[PacketSniffer]

Actually what I'm saying is that if there had been air trapped in the wing before the dive you shouldn't have been able to descend normally

When I hit the deflate hose, it must have purged the left side only. With the amount of air left in the right side, I surprisingly didn't notice it until about 5 minutes into the dive when things calmed down and we planed out for the trip out to the next reef. The amount left in the right side seemed perfect for neutral bouyancy except that it was all on the right side. It's not like I was down 130' and needed lots to compensate. It was ~50'. That's all we got from shore. :-( It beats sitting in the hotel picking my nose though.


Richard

 

[PacketSniffer]

What is apparent to me is the importance of maintaining your gear, whether it be your regs, or your BC.

That's the take-away from this incident. My hope in posting this is that at least one person has learned something from it. I know I have.


Richard