Too heavy after a certain depth ?

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The Monty Halls' programme was complete and utter crap. He has admitted off camera he was told so say certain thins and massively over dramatise for the cameras.

Ultimately if you're wearing a really really thick wetsuit and diving a wing which is nowhere near big enough for the dive then yeah you'll get heavier and heavier as you go down as the suit compresses. Whether its so much that a sensibly weighted diver simply cannot become buoyant i seriously doubt.

Possibly if you were *TRYING* to do it you could wear a single tank travel BCD with 10kg lift, hang 4 or 5 tanks off it, stick on a 7mm+7mm wetsuit and do a 100m dive. It might be an issue then but then you are actively planning to kill yourself.

With proper equipment, planning and training it simply cannot happen.

The whole programme was crap. Mythical curses and all that. Simple fact is the blue hole is a very simple technical dive site. The 55m arch is a 20m long tunnel and a very very simply normoxic trimix dive (or even an ER dive). The 100m bottom is a very simple advanced trimix dive. Good conditions, good visibility, little or no current.
Nearly all the deaths there are by people without the current training, equipment and attitude. A lot of the bodies down there are wearing single tanks for example.
Trying to dive very deep on air is idiotic, doing it on singles takes it to a whole new level of stupidity and that's what goes on all the time there. Ive been coming up through 80m there before now (hypoxic trimix OC) and was passed by an Egyptian guide and 2 russians going DOWN past me each wearing a single 12l of air and 1 gecko computer between them. You see it all the time.
Yuri Lipsky who accidentally filmed his own death there was doing an 80m+ dive on air. He toxed. It happens. That's why people shouldnt do it. No curse there, just stupidity mixed with bravado.
Blue Hole has fewer incidents from *properly trained and equipped* technical divers then a lot of open sea tech sites the same depth - its benign.

Quite simply, use the correct exposure suit (id say dry over really thick wetsuits but ive dived it before in a 7mm+5mm shortie without issue) and use the correct size wing for the tanks required. Dual bladder if its diving wet and you have a couple of stages. Then the too-negative situation simply cannot happen.
 
In theory the suit will continue to compress the deeper you go so you will continue to accelerate and your speed increase to some extent. The rate at which you accelerate (called a jerk) will decrease with depth.
 
In theory the suit will continue to compress the deeper you go so you will continue to accelerate and your speed increase to some extent. The rate at which you accelerate (called a jerk) will decrease with depth.

When Bob DBF mentioned terminal velocity, this is what he was referring to. So no, neither in theory nor in reality "you will continue to accelerate and your speed increase". We are all subject to the same physics.


Terminal velocity - Wikipedia, the free encyclopedia
The terminal velocity of a falling object is the velocity of the object when the sum of the drag force (Fd) and buoyancy equals the downward force of gravity (FG) acting on the object. Since the net force on the object is zero, the object has zero acceleration.[1]
In fluid dynamics, an object is moving at its terminal velocity if its speed is constant due to the restraining force exerted by the fluid through which it is moving.
 
It would be more correct to say that you will continue to accelerate to a velocity that approaches terminal velocity asymptotically. Terminal velocity will be achieved once your suit will not compress any further. Mathematically the volume of a bubble approaches zero as your depth approaches infinity.

All this is just a theoretical abstraction as far as an OW scuba diver is concerned. If you need 6 lb and you put 20 lb of lead on your belt, while your BCD may support you on the surface, if you go deep enough and your suit compresses enough you may not be able to ascend without dumping weight.
 
It would be more correct to say that you will continue to accelerate to a velocity that approaches terminal velocity asymptotically. Terminal velocity will be achieved once your suit will not compress any further. Mathematically the volume of a bubble approaches zero as your depth approaches infinity.

All this is just a theoretical abstraction as far as an OW scuba diver is concerned. If you need 6 lb and you put 20 lb of lead on your belt, while your BCD may support you on the surface, if you go deep enough and your suit compresses enough you may not be able to ascend without dumping weight.

You are such a pedant - and wrong.

You are neglecting to factor in increasing water density and its impact on the drag force.

Is all of this a theoretical abstraction? Yes. That is not a free pass for incorrect information. No, you will not continue to accelerate.
 
For the context we're talking about, up to say 100 m depth, what would be the variation in water density?
 
They may have enough suit compression that they have no reserve bouyancy left. Hard to imagine a suit that big or a wing that small.
 
The Monty Halls' programme was complete and utter crap. He has admitted off camera he was told so say certain thins and massively over dramatise for the cameras.

Ultimately if you're wearing a really really thick wetsuit and diving a wing which is nowhere near big enough for the dive then yeah you'll get heavier and heavier as you go down as the suit compresses. Whether its so much that a sensibly weighted diver simply cannot become buoyant i seriously doubt.

Possibly if you were *TRYING* to do it you could wear a single tank travel BCD with 10kg lift, hang 4 or 5 tanks off it, stick on a 7mm+7mm wetsuit and do a 100m dive. It might be an issue then but then you are actively planning to kill yourself.

With proper equipment, planning and training it simply cannot happen.

The whole programme was crap. Mythical curses and all that. Simple fact is the blue hole is a very simple technical dive site. The 55m arch is a 20m long tunnel and a very very simply normoxic trimix dive (or even an ER dive). The 100m bottom is a very simple advanced trimix dive. Good conditions, good visibility, little or no current.
Nearly all the deaths there are by people without the current training, equipment and attitude. A lot of the bodies down there are wearing single tanks for example.
Trying to dive very deep on air is idiotic, doing it on singles takes it to a whole new level of stupidity and that's what goes on all the time there. Ive been coming up through 80m there before now (hypoxic trimix OC) and was passed by an Egyptian guide and 2 russians going DOWN past me each wearing a single 12l of air and 1 gecko computer between them. You see it all the time.
Yuri Lipsky who accidentally filmed his own death there was doing an 80m+ dive on air. He toxed. It happens. That's why people shouldnt do it. No curse there, just stupidity mixed with bravado.
Blue Hole has fewer incidents from *properly trained and equipped* technical divers then a lot of open sea tech sites the same depth - its benign.

Quite simply, use the correct exposure suit (id say dry over really thick wetsuits but ive dived it before in a 7mm+5mm shortie without issue) and use the correct size wing for the tanks required. Dual bladder if its diving wet and you have a couple of stages. Then the too-negative situation simply cannot happen.

Yeah I agree with you.
Peoples ego sometimes is the worst enemy ! Of course stupidity is another factor as well !!!

---------- Post added February 11th, 2014 at 10:31 AM ----------

This is a bit of a myth (second time posted in this thread) your wetsuit isn't an ideal gas and so won't be half the volume at twice the pressure. There is a fair amount of non compressible rubber in there rather than bubble and those bits won't shrink as much. You do loose buoyancy from your wetsuit but it isn't a balloon full of air that you take down.

I think thats why it says that the "change is not linear" !
 
They may have enough suit compression that they have no reserve bouyancy left. Hard to imagine a suit that big or a wing that small.

Maybe not that hard to imagine. I've seen people diving with two piece suits 7 + 7, so lets say an average of 10mm over 2 m2 of body area.
That's 20kg of water displacement.
Let's just suppose that the suit is well used and the neoprene is soft and they go deep enough for the 10mm to become 4mm, they just lost 12kg of lift. The average medium sized BC only lifts 12 or at the most 14 kg depending on the model/brand.
If they started overweight by a few kg, not hard when you're trying to sink a 7 + 7 suit, they can easily end up negative at depth even with the BC generating full lift.
But then there are a lot of divers out there that don't always pull the right dump valve and let a lot of water into their BC during the dive. So that theoretical 12 or 14 kg of BC lift is now 10 or 12 kg.
 
I want to see a wetsuit explode!
 
https://www.shearwater.com/products/perdix-ai/

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