Bahamas: Missing Female Diver

[Cave Diver]

Let me make sure I undetrstand what you are saying, are you saying that a diver should put some air in thier BC when decending at or near 140 ft because they might not be able to get enough air in the BC, due to ambient water pressure, to lift them faster enough if they need to ascend quickly? This is the first I'm hearing of this?

No.

Because the air in the bladder compresses at depth and reduces the volume of the BC, you need to add more air in while descending so that you don't have to add it all in when you get to your target depth. The more you have to add at depth, the longer it will take to achieve neutral/positive bouyancy again.

Failure to keep up with this decreasing volume is the reason why you see so many divers post here about ending up 10' + deeper than they intended.

The LP hoses deliver air at about 140 psi over ambient, so it's no problem to inflate at depth, the problem is it takes time to achieve the volume necessary to maintain neutral bouyancy.

 

[miketsp]

If your inflator can't keep up with your descent rate, it's either broken, incorrectly designed or you're massively overweighted.

I fully agree. However as far as I'm concerned there are many BCs on the market with design deficiencies. My rear inflate fills extremely slowly while my jacket BC fills really quickly. The former is not broken, I've stripped it all down and rebuilt it, it's designed like that. Fill rate is not important until you start pushing the recreational limits and beyond and very few people pay attention to this when purchasing a BC.

However in any case, that was not the problem here, since the DM went down, had some sort of contact with the diver, then ascended. This indicates that the DM's equipment was working properly.

If the DM had the problem you describe, this would have been a double fatality.

Terry

She came up alone. If she'd stayed holding on to the victim it might have turned out differently.

 

[Thalassamania]

A malfunctioning BC inflator is about the most bizarre, reaching at straws, ex post facto BS, made up out of the whole cloth with no evidence what-so-ever explanation that I can imagine. Intervention by aliens is more likely (and more believable).

 

[DennisS]

A malfunctioning BC inflator is about the most bizarre, reaching at straws, ex post facto BS, made up out of the whole cloth with no evidence what-so-ever explanation that I can imagine. Intervention by aliens is more likely (and more believable).

Gotta think outside the box on these speculation threads When it comes to speculation, it's all good

 

[Thalassamania]

That's out of the box, down the street, around the corner, onto the interstate, into the next state, then somewhere in Mexico.

 

[Web Monkey]

I'm just not buying into the idea that the victim somehow prevented her own rescue.

Maybe I'm just expecting too much, but it's my opinion that anybody with a professional card should be able to get their buddy (especially an elderly woman) to the surface, even from 140'.

And even more important, anybody with a professional card should be able to keep their buddy from ever getting to 140' if it wasn't part of the dive plan.

A profession certification means by definition that there's a good chance that at some point you're going to need to save someone's butt. This means the DM should have been trained, equipped and ready to do this, especially if she accepted the task of being the buddy for a single diver.

Terry

 

[LeadTurn_SD]

Regarding uncontrolled descents... I've never dove the area where this accident occured, and so I'm guessing at water temps... but if we are talking about the tropics with thin wetsuits (that have less bouyancy to lose) and less ballast weight.... assuming neither diver was grossly overweighted, stopping the descent should not have been that big of an issue. You are going to be negative to be sure, but just how negative?

It might have been a factor, but my feeling is that in the tropics it should not be that big an issue (compared to if we were talking cold water, thick wetsuits, lots of ballast weight).

As a point of reference, I've been to these depths in (probably) thicker wetsuits here in Hawaii, steel 72, 10-12 lbs on a weightbelt without a BC.

Best wishes.

 

[stevejaz]

I'm just not buying into the idea that the victim somehow prevented her own rescue.

Maybe I'm just expecting too much, but it's my opinion that anybody with a professional card should be able to get their buddy (especially an elderly woman) to the surface, even from 140'.

And even more important, anybody with a professional card should be able to keep their buddy from ever getting to 140' if it wasn't part of the dive plan.

A profession certification means by definition that there's a good chance that at some point you're going to need to save someone's butt. This means the DM should have been trained, equipped and ready to do this, especially if she accepted the task of being the buddy for a single diver.

Terry

I can't remember for sure, but didn't the DM notice the diver at 80' and she was at 60'? If that's the case, I'm assuming the DM would have reached her pretty quickly, let's say between 90 and 100' if the diver had a pretty fast rate of decent. Then, they interact on one level or another for the next 40' with the diver reportedly resisting. Now they've both dumped there air at one point or another. The DM to decend quickly and the diver in a defiant reaction to rescue or assistance. I'd imagine this could make for a very difficult recovery in a potentially hostile situation especially if the DM is 1. overweighted as they often do 2. had a small BC. Granted there is always the DM's weight belt but as I understand it, that is a last ditch effort and if there is a fight of sorts going on, that may be a bit difficult to get to on the other diver. I could certainly understand the DM not ditching hers at it sounds like that goes against training and is understandably not an action they'd want to resort to, especially with a diver that is fighting you and may get away from you.

Now, as for the petite DM, I'm the one that brought that up as one of there DM's is very petite, but we don't know if that was the DM.

Steve

 

[stevejaz]

Regarding uncontrolled descents... I've never dove the area where this accident occured, and so I'm guessing at water temps... but if we are talking about the tropics with thin wetsuits (that have less bouyancy to lose) and less ballast weight.... assuming neither diver was grossly overweighted, stopping the descent should not have been that big of an issue. You are going to be negative to be sure, but just how negative?

It might have been a factor, but my feeling is that in the tropics it should not be that big an issue (compared to if we were talking cold water, thick wetsuits, lots of ballast weight).

As a point of reference, I've been to these depths in (probably) thicker wetsuits here in Hawaii, steel 72, 10-12 lbs on a weightbelt without a BC.

Best wishes.

I just returned from Maui and was in the Bahamas in November. In Maui, all of our DM's wore full wetsuits and most had hoods, unsure of the thickness. Water temps in the low to mid 70's. Bahamas, all wore fulls and again some with hoods with water temps being about the same.

 

[mikemath]

A malfunctioning BC inflator is about the most bizarre, reaching at straws, ex post facto BS, made up out of the whole cloth with no evidence what-so-ever explanation that I can imagine. Intervention by aliens is more likely (and more believable).

Hmm, intervention by aliens...does seem plausible In seriousness, it takes a volume of air in a BC to compensate for a given level of negative buoyancy. An inflator hose provides the air to change the volume by a set rate at a given depth. However, the volume of the air already in the BC decreases with depth. Depending on the rate of descent and the amount of volume needed to establish neutral buoyancy, it seems at least theoretically possible to descend so fast that the increased volume of air provided by the BC inflator is completely offset by the decreased volume from additional pressure. I do not think that is what happened here. However, in a situation where time is critical, couldn't a fast descent rate have slowed the rate at which neutral buoyancy could be achieved?

I haven't ever tried inflating as fast as I could while in a rapid descent at 140' (and I don't intend to). Does anyone have any related experience about whether the rate of descent could have compounded the problems in the situation?