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

[Soggy]

The balloon is not squeezing you, the pressure outside the balloon is squeezing you.

Good lord, this is such a simple concept. The fabric is what is causing you to FEEL squeezed because it is shrinking due to the forces of pressure outside.

The suit doesn't become to small, it is being pushed in by the external pressure or are you claiming that the suit is subject to some form of space/time anomoly which causes an extra large to become a medium at depth?

The volume within the drysuit is shrinking because it folds up. There is no space time anomaly.

As far as the black hole, it's an entirely inaccurate analogy. The force involved in a black hole is gravity not pressure. The gravitational force works on the individual atoms of your body with a force inversly proportional to the square of the distance from the black hole, pressure is applied to the surface area of your body. All of which has nothing to do with the discussion at hand.

It was something of a joke, but the analogy is there and accurate with a little bit of abstract thought. The event horizon is the point where nothing can escape the black hole. The edge of your body is the point at which the shrinking volume of the drysuit starts to squish you.

 

[ClayJar]

To an observer falling into the black hole, the event horizon is a non-event. In fact, for a large enough black hole, the tidal forces at the event horizon might not amount to much at all. To an observer outside the black hole, things appear otherwise. Either way, I'd have to agree that it would be exceedingly forced to apply it to a diver, at least if you think of it with more than the utmost superficiality.

Anyway, this thread has become long on analogy and very weak on reality. Although some of it continues to entertain, perhaps we should go with the concrete and stop debating the merits of analogies, forced or otherwise?

 

[Soggy]

Are we really at the point where a joke requiring a little abstract thought is being taken that seriously?

 

[ClayJar]

Are we really at the point where a joke requiring a little abstract thought is being taken that seriously?

Well, I'm certainly not, but it seems to be terminally confusing some people here.

Incidentally, just out of curiosity, I know I dive dry, and unless I'm mistaken, Soggy does too. Do we all, or is some of the confusion due to never having felt what we're talking about? (I know I learned a bit when I started diving dry that I couldn't have easily absorbed from reading, and I'm a physics nut.)

 

[Soggy]

Incidentally, just out of curiosity, I know I dive dry, and unless I'm mistaken, Soggy does too. Do we all, or is some of the confusion due to never having felt what we're talking about? (I know I learned a bit when I started diving dry that I couldn't have easily absorbed from reading, and I'm a physics nut.)

I did my open water course in a drysuit. Aside from 3 short warm water trips, every dive I have ever done has been in a drysuit. I do technical dives year round in New England, which means water temperatures in the mid 30s during the winter and early spring.

I too am an armchair physicist.

 

[do it easy]

I too am an armchair physicist.

I never knew the physics of armchairs could be so fascinating

Are we really at the point where a joke requiring a little abstract thought is being taken that seriously?

I guess my PB n J analogy didn't cut the mustard.

This thread is too abstract- maybe we should just imagine that we sealed up the drysuit, with nothing but cooties in it, and dropped it into the ocean. At depth, it would shrivel up like a grape left in the sun. Now, imagine trying to stuff a diver back into the suit. Not only would it be a tight fit, it would be a tight squeeze.

 

[Tigerman]

Well, I'm certainly not, but it seems to be terminally confusing some people here.

Incidentally, just out of curiosity, I know I dive dry, and unless I'm mistaken, Soggy does too. Do we all, or is some of the confusion due to never having felt what we're talking about? (I know I learned a bit when I started diving dry that I couldn't have easily absorbed from reading, and I'm a physics nut.)

I do dive dry. And its certainly squeezing me if I dont put air into it..

 

[Soggy]

This thread is too abstract- maybe we should just imagine that we sealed up the drysuit, with nothing but cooties in it, and dropped it into the ocean. At depth, it would shrivel up like a grape left in the sun. Now, imagine trying to stuff a diver back into the suit. Not only would it be a tight fit, it would be a tight squeeze.

Maybe sort of like this?
http://www.scubaboard.com/showpost.php?p=2740967&postcount=56

 

[rakkis]

The air is decreasing in volume because it is being compressed due to being at a higher pressure.

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

The decreasing volume doesn't magically create a low pressure area against your skin, it creates a pressure against your skin equal to the pressure of the compressed air.

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.

Let's try this:

Put on a latex glove. Now pull on it to try to tighten the latex around a finger. Do you feel:

a) ONLY the force of the surrounding medium(the atmosphere)? or

b) The force of the atmosphere PLUS the inward force excerted by the material trying to destretch (yay new word) PLUS the radial force of the material as it tugs on your skin "sideways"?

This isn't as simple as being under the water column. As others have said, a full understanding of the concept must also include the stretchability and rigidity of the suit material, how much extra material/space for air pockets that can shrink there is, the dampening effect of the underwear, etc.

 

[rakkis]

it's the feeling of someone grabbing the back of your shirt and twisting it into a ball until the shirt fabric starts constricting you.

This is perfect. This is very close to what happens in a dry suit. Except that in this example, the volume in your shirt gets smaller because you are in essense squeezing the air out from the portion of shirt you twist instead of air shrinking.

Now imagine this or my latex glove example happening in random directions towards every little flap of extra material. That, is dry suit squeeze.