wetsuits and wool

[simonk999]

well, I knew those arguments were coming about the 2mm of trapped water.

I'm actually more interested in the answer to the first part of my previous posting, the question of whether or not the hollow wool fibers (or even to confirm that they're hollow) can get equalized to underwater pressure, and thus keep some actual non-waterlogged space for insulation. I suppose that even if they were not equalized, compression shouldn't result in 100% lost volume, much like the neoprene doesn't become completely compressed, so I would think that the wool must keep some air space and therefore insulate even underwater.

But getting back to the 2mm question, 1st, the suit in question is a semi-dry, so isn't expected to shift a lot of water around in the 1st place, and from other postings on other threads, it appears that indeed not that much water is actually absorbed by the lining.

Anyway, I don't own one, so no idea of practice vs theory.

-Simon

 

[jonnythan]

The fibers are semi-hollow, but not watertight. When the wool is saturated, there are no trapped air spaces. If there were we wouldn't need closed-cell neoprene Hence, there is no "equalization" or anything like that.

There's no volume loss. The wool soaks up the surrounding water, and you have a totally waterlogged space of a wool and water mixture (with no air) between yourself and the actual insualation (the air spaces in the neoprene). The wool fibers do absolutely nothing to insulate when they're soaking wet. It would provide the same amount of underwater insulation as a cotton layer... zero. Out of the water, the wool will dry significantly faster, and should add slightly to surface insulation, but underwater it's highly counterproductive.

 

[Stirling]

I wear woolen hiking socks inside my boots because (a) they make it easier to slide the boots on and off, (b) they take up room inside the boot and improve the fit marginally, while also (c) keeping water from moving around inside the boot, (d) because wet wool is better for avoiding blisters than wet cotton (although blisters are not really a concern, reduced friction and comfort are), and (e) because - when I get OUT of the water, the wool retains some insulation value, while cotton has none. IN the water, a wet foot is a wet foot. The *only* thermal benefit of the wool socks in the water is to firm up the fit and retard the movement of water over my skin and in and out of the boot.

Wet wool retains insulation value because the extremely thin outer layer of the wool fiber (the epicuticle membrane) forms little bubbles (Allworden bubbles) *on the surface of the fiber* when it gets wet, and because the surface of the epicuticle is also covered by an extraordinarily thin layer of fatty acid that helps to repel water (drying the surface of the fiber quickly). Those little surface bubbles are present only in such a small part of the wool fiber that they cannot possibly compare to the insulation qualities of embedded air in neoprene, and - because they are not embedded *in* the fiber - there is nothing to keep them from being carried off when the fiber is submerged and work is applied to the fiber (from swimming, compression of the suit around it, etc.). And that skinny little layer of fatty acid isn't going to fight off the ocean when it's submerged - it was designed for sheep who had to stay out in the rain.

Submerged wool does not retain air worth a damn. If there is any theoretical thermal benefit ("Look! There's a microbubble trapped in the fibers!"), I am certain it would be too small to measure.

And I was just astounded at some of the things said on the website linked to at the top of the thread:

"Wetsuit manufacturers have been making the most of this basic physics principle for decades. It’s not your wetsuit that keeps you warm, it’s the thin layer of water trapped between your skin and the wetsuit that you can thank for keeping you toasty and snug 90 feet deep off Vancouver Island."

Anybody who has actually been in the water with a wetsuit for an extended period of time can figure out that "thin layer of water" is still colder than you are, and is draining the heat out of your body very efficiently. If you can keep that thin layer of water from moving around (with a snug suit, and maybe the wool could make it easier to get into a tighter suit), and being replaced with even colder water against your skin, that's all to the good.

But there is no other way that a thin lining of wool is going to provide any thermal benefit that the same (additional) thickness of neoprene wouldn't do a whole lot better.

 

[jviehe]

What about the whole exothermic claim, that wool gives off heat when wet?

 

[jonnythan]

It's bull.. wool warms slightly when absorbing water vapor. Any heat given off when absorbing as much water as it takes to fill that wetsuit wouldn't even warm up the water itself more than a couple of degrees, if anything.. much less impart any warmth to you.

There's no way around it, a fully wet layer of wool provides 0 insulation and is probably counterproductive

 

[jviehe]

It's bull.. wool warms slightly when absorbing water vapor. Any heat given off when absorbing as much water as it takes to fill that wetsuit wouldn't even warm up the water itself more than a couple of degrees, if anything.. much less impart any warmth to you.

There's no way around it, a fully wet layer of wool provides 0 insulation and is probably counterproductive

Ok, now present the science to back it up. We are not in the "basic scuba discussions" section.

 

[garyfotodiver]

We arnt in the regular forums here, we are in the physics forum. If you have something to contribute related to the physics of this, please do. Otherwise, keep your negative comments to yourself.

Physics - Will the extra weight of the water-soaked wool affect the diver's bouyancy?

 

[jonnythan]

Physics - Will the extra weight of the water-soaked wool affect the diver's bouyancy?

No.

 

[garyfotodiver]

Or, to put it another way, a sodden sheep in a thunderstorm is not much different than a diver underwater. :11:

Baaahhhhh!!

The sodden sheep's wool has lanolin on it, which provides the water-proofing. My Army blanket sure weighs more when it is wet than when it is dry.

Humbug.

 

[garyfotodiver]

No.

Why not?