drysuit squeeze cause

[stas]

What causes drysuit squeeze exactly? I mean I know the standard answer that there is air in the suit and as you go down the pressure compresses that air but at the end you are exposed to ambient pressure just like in a wetsuit and no more.

I think I know the answer but want to make sure. I believe a vacuum forms inside the suit and it pulls your skin into the suit where ridges form and that's where the discomfort comes from. Is that the case or is it something else?

 

[dave4868]

Not a vacuum, just a positive pressure differential from the outside causing the suit material to fold up and crease just like it would if exposed to a negative pressure differential from the inside (vacuum).

The folds cause the pinching and stiffness of the suit and can actually hurt at times.

It just feels like a vacuum because it "sucks"....

Dave C

 

[Mark Michaud SELAUSAR]

I am not a scientist or engineer, but, here goes.................your body is made of water, a wetsuit gets permeated with water as do clothes. The pressure, to reasonable depths, does not crush or squeeze your body. Your air spaces do squeeze until you add gas to equalize the pressure that is being exerted from the water pressure. When pressure is exerted at depth, in non water filled spaces, you have to alleviate that pressure by adding gas to equalize that pressure. A tank is a rigid container and can sustain the outside pressure. A plastic water bottle (empty) is non-rigid and will collapse under the pressure. The same bottle, full, will stay the same at depth, or at least, to a reasonable depth. A drysuit is also a non-rigid closed container. If you flood your drysuit it will no longer squeeze your body as the inside and outside pressure are the same, or very close. Obviously each point can be streched for arguement but this is just a simple answer. Hope this basic answer helps.

 

[snowflake4727]

I have had squeeze from my gold core semi dry. It does not feel good in my man areas.

 

[TSandM]

If you think about it, when you put on your dry suit, there is air inside it. The air between your body and the suit is like a lubricant -- it allows you to move inside the suit, and with respect to the suit. If you sat on the surface and sucked all the air out of the suit, it would "shrink wrap" around you, and make your mobility difficult.

What happens underwater is that, as you descent, the air that was in the suit on the surface is compressed. At 30 feet, you have half the volume of air you had before, although you have the same number of air molecules. It's not a vacuum, because a vacuum is pressure LOWER than what's around you. The pressure in the suit is the SAME as the pressure around you, but the volume of air has been cut in two. It's the same effect as sucking half of the air out of the suit on the surface. It reduces the gas "lubrication", and reduces your mobility.

You don't experience the same thing in a wetsuit, because the gas molecules trapped in the neoprene compress where they are. They don't provide "lubrication" between you and the suit. They DO provide insulation, which is why wetsuits aren't as effective against the cold at depth as they are in shallow water. At depth, the suit gets thinner, but not tighter around you. A dry suit gets tighter around you.