Question How to behave after uncontrolled ascent

[azstinger11]

I don't think we should even try to address that demographic. I sure won't. Those people are going to show up to the boat, put on whatever weight the crew tells them, bounce around and break coral for 45 minutes give or take, and then get back on the boat. Do it again at the next dive site.

And there's not a thing anyone can do about that. It is what it is.

But there in lies the problem right? As potentially the largest group of divers doing dives on any given day, for a variety of issues them having issues represents the largest threat or issue in the dive community. They are the most likely to have an issue underwater and the least likely to be able to deal with it ( poor/rusty skills, unfamiliar gear, poor weighting, etc). Not saying I have an answer. Unfortunately too few instructors take the time to work with students in OW to dial in bouyancy/trim (like is quite apparent you do) and set them up for success and too many operators are more interested in quick turning their boats (and overly weighted divers are an "easier" problem to deal with than under-weighted). One of the more systemic issues I've observed in the sport.

For divers and instructors that care, there are a whole host of ways to help and your blog does an excellent job of highlighting them. I think we in full agreement about what should be taught both in course, and done by individual divers post-course.

 

[loosenit2]

just enough weight to hold you at your shallowest stop with cylinder(s) near near empty (500 psi) with empty BCD/wing and for you to ascend in a controlled manner due to possible neoprene expansion (relevant to thick wetsuits and neoprene dry suits).

The reason I bring this up is if you are already overweighted, then you have extra gas in your BCD (and possibly dry suit). We all know that gas expands. So that excess gas will make you even more buoyant. It is bad enough that you have a jammed power inflator. You were already taught (an assumption here) to deal with that by disconnecting the low pressure hose from your inflator.

TL;DR: the point is to reduce the amount of additional buoyancy force you experience when you start to ascend.

We completely agree on definition of good weighting....I would take it a step further and argue for a neutral rig that is no more than 10lbs negative so you can swim it up in the event of a BCD failure. (with some exceptions to that for specific types of diving and with specific redundancies).

I can see your point more clearly now and how you came to your conclusion, it was not readily apparent to me from your one line comment. In practice I don't think it would make a practical difference in the case of a run-away inflator but I at least understand your logic path. It would be interesting to test the difference to get to quantifiable results, using dummies of course...risk of embolism and lung overexpansion with live subjects would be far too high to justify for experiments.

 

[johndiver999]

The issue of weighting is entirely (or almost completely) irrelevant to the problem. That whole argument is silly, irrelevant and misses the point of the problem and how to handle it.

In reality, now that I think about it more, if you are diving with excess lead, then you start with the BC more full, so that when it starts to inflate autonomously, the total potential swing in excess buoyancy is LESS than if you were diving with less lead and therefore would have had less air in the BC at the start of the problem. That is all bologna anyway.

The OP did not handle it well. As s/he mentioned they should have just disconnected the inflator and vented. and definitely shouldn't waste time shutting down the tank. If there was time to shut the tank down on ascent, there was more than enough time to ignore the valve and just vent the BC - even if you fail to disconnect. I think it would be much MORE difficult to shut off a valve for most people, compared to venting and/or disconnecting the inflator hose.

But lesson learned, an inflator can start filling and the response is vent and disconnect. That might be one situation where a pull dump is superior because you can pull down and work on disconnecting all at once.

As for getting just 10 minutes of the dive.. I definitely would not have paid for the dive trip, but generally you pay before the dive. I don't think it would go well on shore if they refused a full refund, but that is just me.

 

[wetb4igetinthewater]

The issue of weighting is entirely (or almost completely) irrelevant to the problem. That whole argument is silly, irrelevant and misses the point of the problem and how to handle it.

In reality, now that I think about it more, if you are diving with excess lead, then you start with the BC more full, so that when it starts to inflate autonomously, the total potential swing in excess buoyancy is LESS than if you were diving with less lead and therefore would have had less air in the BC at the start of the problem. That is all bologna anyway.

The OP did not handle it well. As s/he mentioned they should have just disconnected the inflator and vented. and definitely shouldn't waste time shutting down the tank. If there was time to shut the tank down on ascent, there was more than enough time to ignore the valve and just vent the BC - even if you fail to disconnect. I think it would be much MORE difficult to shut off a valve for most people, compared to venting and/or disconnecting the inflator hose.

But lesson learned, an inflator can start filling and the response is vent and disconnect. That might be one situation where a pull dump is superior because you can pull down and work on disconnecting all at once.

As for getting just 10 minutes of the dive.. I definitely would not have paid for the dive trip, but generally you pay before the dive. I don't think it would go well on shore if they refused a full refund, but that is just me.

Are you mad? If a BCD gets completely filled, the diver is shooting to the surface. Most jammed inflators are much slower than that, but a sudden 10 lbs of lift is going to lift a diver towards the surface. And that whatever gas is in the BCD is going to expand. You want to minimize that amount of expanding gas. Like me or not, it is science.

Don't believe me? Have someone surprise you by jamming on your inflator button and let us know how that works out.

 

[admikar]

Are you mad? If a BCD gets completely filled, the diver is shooting to the surface. Most jammed inflators are much slower than that, but a sudden 10 lbs of lift is going to lift a diver towards the surface. And that whatever gas is in the BCD is going to expand. You want to minimize that amount of expanding gas. Like me or not, it is science.

Don't believe me? Have someone surprise you by jamming on your inflator button and let us know how that works out.

He does have a point. Let's say you dive so much overweighted that you need 100% full BCD to keep you neutral. How much buoyancy will runaway inflator add?
Now consider diving properly weighted and consider how much buoyancy can be added to empty BCD.
This is all irelevant in this situation.

 

[napDiver]

I think the dive crew should of been more supportive after the dive, but i think this is more typical. Unless your complaining about pain, they don't tend to pay too much attention after an incident. I'm sure they see something like this often for OW students. Not to say they shouldn't been more caring and monitored you better. I think the industry can do better in respect to that.

Typical rec diving profiles don't usually require a safety stop, so it should be fine. Noting it doesn't assume you have a runaway ascent. And I definitely wouldn't consider going back into the water for the day.

On the flip side, if this was caused by a sticky inflator. You should be able to handle that. It is not uncommon to have inflator issues for rental BCDs. As ****** as this sounds, i feel like your failure to control the situation is on you. So the dive shop/boat don't owe you anything. Now if the BCD had a major malfunction such as a hole or the dump valve broke, etc, then 100% that should be no payment for the trip and apologies.

Lastly, i do not recommend turning off your tank for a runaway ascent. If your inflate sticks, always first just dump. Your can dump as fast as the inflator puts air in. This will buy you time to think and react. You can try this next time at the end of your safety stop. HOLD ON YOUR DUMP AND YOUR INFLATE at the same time.

Hope your feeling better.

 

[wetb4igetinthewater]

He does have a point. Let's say you dive so much overweighted that you need 100% full BCD to keep you neutral. How much buoyancy will runaway inflator add?

Kind of extreme, don't you think?

Now consider diving properly weighted and consider how much buoyancy can be added to empty BCD.
This is all irelevant in this situation.

If your inflator button is jammed and inflating your BCD as if you are mashing on the button, you're basically screwed.
I've actually dealt with this situation before I learned proper weighting. I didn't cork to the surface, but it wasn't a fun ride while it lasted. I also use my observation from my early days as an instructor when I placed students on their knees/overweighted them. They would not realize when they changed depth, and that extra gas they had to add to their BCD made them cork time after time. Once I fixed the weighting, the corking (and cratering) stopped for good for everyone.

Now I won't claim that all jammed inflators won't inflate your BCD in short order, but it is a problem that gets worse if you don't deal with it. I sure hope that the company the OP rented from did something about this and didn't just hand off to the next customer. In most cases, there will be some time delta between when the problem occurs and when a diver disconnects their LPI hose. During that time, they will ascend. They will become more buoyant. I doubt their BCD is going to be full at that point, so John's statement is most likely not applicable. I don't want this to turn into a pissing contest (in case it hasn't already), but if your BCD is completely full, you have to be seriously overweighted for that to not make you cork. And I sure as hell hope most people don't dive like that.

 

[lowwall]

Can we quit the weighting discussion? It's completely irrelevant here. The inflator was filling the bladder. Extra weight would actually mean less lift. But whether the excess lift was 14 or 18 or 22 pounds is immaterial.

Back to what does matter. We all, including the OP, agree the OP should have vented and disconnected the inflator hose. But that's not the question.

The question is what the dive op should have done for the OP given they rented him faulty equipment. IMO it's pretty simple, they should have refunded the dive, offered O2, and monitored for DCS.

 

[Wibble]

What I like about posts like this is it reminds EVERYONE of the procedure to follow if your inflator's leaking: disconnect the hose. MOST people haven't done that in possibly years, so the cause==effect==resolution link isn't strong.

Will run through a complete set of disconnect/shutdown drills next time I'm in the water. Thank you to the OP for this reminder.

 

[SlugLife]

I was diving with a rented equipment, and at around 20 meters after 10-11 mins of diving my BCD started inflating uncontrollable (I checked everything before the dive, it was ok). I tried to get attention of our guide, but he didn’t understand. I closed the tank halfway to the surface (I know I should’ve detached the inflator hose, but everything was to fast and I only thought about closing the tank). So I ascended to the surface in 25-30 seconds, my guide ascended and told me to go back on a boat, so I did. My teeth and ears hurt like s**t. On the boat deckman just gave me a painkiller, said that it’s “a bad luck” and changed the BCD and since that time no one gave me any attention, they only asked me if I’m going for our second dive, which I said no to. When we went back to harbour, I was asked for full payment ( for rental and dives), I argued a bit and payed only for the dive.
So, can anyone help to understand was it normal behaviour of the diving centre or what else could be done. I know that ascending from 20 meters after 10 minutes of diving isn’t lethal, but I was kinda a bit frustrated about the whole situation and the lack of attention I received.

In a perfect world, where you know your inflator-is stuck on, you disconnect the air-hose and start dumping immediately. In a realistic world, it would probably take most scuba-divers some time to figure out why they're suddenly shooting to the surface.

I've done quite a bit of diving at shallow-depths, where bouyancy fluctuates SIGNIFICANTLY. Any time I'm surfacing faster than intended, my response is to go head-down and use my fins FIRST, and then resolve the issue (typically, dumping air). The reason being I can more reliably fin down in a shorter time, than I can reliably purge air.

If you had done the above, chances are it would have slowed your ascent somewhat, perhaps reducing any injury. However, whether you could have realistically known/responded/reacted to a runaway inflator that you completely didn't expect? I'd like to think I would handle such a situation correctly myself, but I'm all too aware that I too probably would have been on the surface well before I figured out my inflator was stuck open.

I'm not a lawyer, but if you were in the mood to sue, this kind of equipment malfunction is EXTREMLEY dangerous and could have even killed you. If I was the business owner, I'd have offered a full refund plus a $500 credit in hopes you wouldn't sue me into bankruptcy and beyond.