Why do you get dry suit squeeze and not wet suit squeeze?

[markr]

GAAAAAAH!

Do you disagree with what I was trying to explain in post 77, or do you not understand it? There needn't be a space/time anomaly -- the fact that the material gets taken up by the ridges is elementary and trivially observable.

If some of the material gets taken up in the ridges, the effective "size" of the suit is indeed reduced.

I'm not disagreeing with anything you said in post 77. I like your description of what's happening, including the "constrictor-style" squeeze description in post 107.

 

[SteveC]

Actually, reefhound summed it up nicely way back at the beginning.

These explanations make no sense to me. Air is compressible but it will only compress to the same psi as the water. Law of equilibrium. What does it matter if you have 50psi water or 50psi air adjacent to your skin?

 

[markr]

I am aware of that. My post and your statement are not mutually exclusive.

I never said magic was involved. The inverse relationship between pressure and volume that you evidently understand (from the first part of your post) is what's responsible. We are not inside a vaccum. Air doesn't just compress and that's that. Something else moves into the space the air used to occupy. As I said, this something is water, suit material and skin/tissue. It is the pinching/stretching of your skin, componded by the concentrated, irregular tug on it by suit material that does this.

If I understand you're statement along with your earlier post, your theory is the water pressure causes the air inside of the suit to compress. This compression causes the air to displace less volume. This results in your skin being sucked into the space vacated by the reduced volume of the air.

If that's what your saying then magic must be involved because it's certainly not physics. For the air to be compressed it needs to have pressure applied from all sides or else it won't compress it will just move. As you descend the water pressure pushes the air in the suit inward until the pressure on all sides of the individual molecules is the same. The air molecules move closer to your body as this happens, as opposed to your body being sucked into a void being created by the compressed air.

 

[rakkis]

You are forgetting one important factor, hydrostatic pressure acting on your body.

Your body tissues (being composed of water for the sake of this argument) are under the same pressure as the water surrounding them. So yes... as you descend, your skin pushes outwards towards air pockets inside your dry suit with the same pressure as the water outside the suit pushes inwards.

 

[markr]

You are forgetting one important factor, hydrostatic pressure acting on your body.

Your body tissues (being composed of water for the sake of this argument) are under the same pressure as the water surrounding them. So yes... as you descend, your skin pushes outwards towards air pockets inside your dry suit with the same pressure as the water outside the suit pushes inwards.

Hydrostatic pressure is what we have been talking about all along. It's the pressure exerted by the weight of the water above you. It increases by one atmosphere for every 33 feet of depth. The rest of us are just leaving the "hydrostatic" part off.

 

[TeddyDiver]

I didn't read the whole thread throw, but here's my sincere view for the subject.

There's three kinds of squeeze with a dry suit
1. Hydrostatic pressure difference between the lowest and upmost parts of the suit. In the suit is air and the pressure is equivalent inside the suit, but the water pressure outside is different in different parts of the suit
2. Undergarments (the actual fabrics) have a certain resistance against pressure (lets say it Pt) Water pressure Pw=Pt+Pa (Pa is the air pressure of the suit) When feeling sqeeze adding air increases Pa, and Pt decreases. So the squuze is -Pt.
3 Trapped airspace in some part of the suit. Appears most commonly when trying to use DS without any undersuit.

 

[rakkis]

Hydrostatic pressure is what we have been talking about all along. It's the pressure exerted by the weight of the water above you. It increases by one atmosphere for every 33 feet of depth. The rest of us are just leaving the "hydrostatic" part off.

The point of my previous post was to address yours regarding an air space "being pushed around". It isn't - force is being exerted on it from all directions; including your body.

 

[rakkis]

We are not inside a vaccum. Air doesn't just compress and that's that. Something else moves into the space the air used to occupy. As I said, this something is water, suit material and skin/tissue. It is the pinching/stretching of your skin, componded by the concentrated, irregular tug on it by suit material that does this.

If I understand you're statement along with your earlier post ... This results in your skin being sucked into the space vacated by the reduced volume of the air. .... as opposed to your body being sucked into a void being created by the compressed air.

Actually, you are misunderstanding my post. Like I said, there is no vaccum anywhere on this system - hence no "sucking". What you have is your tissue moving into the space by virtue of it essentially acting as a fluid under pressure.

 

[ReefHound]

Actually, reefhound summed it up nicely way back at the beginning.

Two points.

You seem to be saying that you don't believe squeeze is for real. I know it's for real. I've dived dry and felt it. I, like many others here, am simply questioning the physical explanation for it.

The fact that something doesn't make sense to me doesn't mean it isn't so.

 

[Xman]

ARGGGGHHHHHHHHHHHHHHHHHHHHHHHHH
Give up this thread already. Its really not that complicated. My estimation for the savy of our forum members is nosediving.