BCD vs Wing in adrift situation.

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The trend I'm seeing here is that a properly fired and secured BCD, regardless of style, should float one comfortably at the surface for a long time.
 


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You inflate the wing and then close your dry suit valve and inflate the dry suit. Then you stick your feel out in front of you like you are in a chair. You will float reasonably comfortably that way.
 
You inflate the wing and then close your dry suit valve and inflate the dry suit. Then you stick your feel out in front of you like you are in a chair. You will float reasonably comfortably that way.

In that configuration I imagine my main problem would be staying awake to keep an eye out for potential rescuers. :thumb:
 
Er, ah, well no. It's a common misconception that more lift or more gas in a wing or BC will float the diver higher out of the water.

Any portion of any BC that is above the water's surface provides no buoyancy because it displaces no water. Attempting to use any BC to get belly button high out of the water is an exercise in diminishing returns.
Any object, wholly or partially immersed in a fluid, is buoyed up by a force equal to the weight of the fluid displaced by the object.

It appears in the video, the lost diver is sitting on his BP/W. If he is, would he be more buoyant if he put more air in his wing? If he dropped all his weight would he be more buoyant? What if he is wearing a 6 pound back plate?

If he was wearing a B.C. that supports him under his arms, would he float higher out of the water? By being able to dump all of his weight, would he be more buoyant?
 
..snip..
It appears in the video, the lost diver is sitting on his BP/W. If he is, would he be more buoyant if he put more air in his wing? If he dropped all his weight would he be more buoyant? What if he is wearing a 6 pound back plate?
..snip..

Just curious why you think he's sitting on his BP/W? There are no shoulder straps visible when he's in the water. I get the impression he's dumped all his gear and is just floating there buoyed up by what looks like a 5mm wetsuit.
 
He seems to be sitting higher in the water than just due to a wetsuit. Also it looks like an SMB is floating behind him perhaps attached to the BP/W. If I were in his situation, floating in fairly calm water, then sitting on the BP/W might be an option. If the conditions were rough, then it would be a different situation.
 
If he dropped all his weight would he be more buoyant?
Well, that should be a real no-brainer to anyone with a grain of sense.

There's a reason our national Diving Association refunds dumped weights, no questions asked. Just submit a report of the incident where you felt it necessary to dump weights, and a receipt for the replacement weights, and you'll be reimbursed. And the reason is that way too many dead divers are found still wearing their weight belt, and/or with their weight pockets still firmly attached to their BCD.
 
Any object, wholly or partially immersed in a fluid, is buoyed up by a force equal to the weight of thet. fluid displaced by the object.

It appears in the video, the lost diver is sitting on his BP/W. If he is, would he be more buoyant if he put more air in his wing? If he dropped all his weight would he be more buoyant? What if he is wearing a 6 pound back plate?

If he was wearing a B.C. that supports him under his arms, would he float higher out of the water? By being able to dump all of his weight, would he be more buoyant?

This post will probably be deleted as argumentative by the mods, but I'll take the risk and try to answer your questions. :)

I'll start by noting again that comfort at the surface in a BP&W is a function of being properly weighted and having a correctly adjusted crotch strap.

My definition of properly weighted is just enough ballast to hold a shallow stop with a (near) empty cylinder.

For the typical single tank diver that means they will be negative by the weight of their gas at a maximum, if they are using no exposure suit, up to possibly being slightly positive if they are using a thick suit and modest sized cylinder.

Such a diver will need very little gas in their wing in order to get their chin out of the water. With their chin out of the water very little of their wing will be above the surface. Nearly the entire inflated volume will be *under* the water and therefore displacing water and providing positive buoyancy.

If this same diver wants to be higher out of the water an increasing portion of their wing will also have to be out of the water. Any portion above the surface provides no positive buoyant force, i.e. lift, as it displaces no water.

Obviously dropping ballast while using the same amount of BC inflation will result in more of the diver being out of the water. This is BTW *exactly* my point about comfort at the surface being largely dependent on proper weighting.

In terms of chin height above the water it matters little if the diver is lifted by the armpits or via crotch strap, the net effect is the same. In practice most jackets have to move well up the divers body before they will pick them up by the arm pits. The diver wants to be higher out of the water so they add gas to their BC, the bc rises , but they do not, so they add more gas...... This is how you end up with divers that have their cylinder curled over on top of their head as they thrash underneath.

In a BP&W with a properly adjusted crotch strap when the rig rises so does the diver, very little slack in the crotch strap. Much more effective, and comfortable.

Tobin
 
What I found interesting was that he had removed his equipment and was floating just in his neoprene and I wondered why he'd done this.
I have resisted stepping into the thread until now, but I think beaverdivers is right. If you look at the video, you will see that his upright with his chin is about 8 inches above the water, and he is barely moving his arms, if at all. He is sitting on something, and that is almost certainly his wing. What else could it be?

So, the reason he took is gear off was so he could sit on it and have his head and shoulders totally out of the water.
 
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