Wet Cotton Insulation

[ManSteak]

Howdy scuba-boarders, I have a technical proposal on the insulating ability of cotton that I’d like some feedback on. You see, I was diving in northern florida last year when I realized, much to my chagrin, that the water was far from the 85 degree turquoise paradise I was expecting. In fact the gulf was colder than the glare I received from my boss yesterday when I suggested that she had nice legs. So, having only a 7 mm wetsuit to my name I decided to improvise with a couple extra layers. All I had on me was a long sleeved cotton tee shirt, and while we all know that cotton “doesn’t insulate when wet” I hold that that only applies to dry land situations. Under the water where the environment is totally uniform, i.e. water everywhere, it shouldn’t matter and the cotton should insulate just like it would on a normal dry day. Well, the dive master, and everyone on the boat agreed that I was dumb (I mentally told them to bite me) and hopped in anyway. While I was still cold, I have nothing to compare my experience to, so I don’t know if I’m correct. From all that I gather, wet cotton is only cold because it is hydrophilic and therefore allows water to remove heat from your body while evaporating. Anyone care to comment?

 

[JimC]

While it might trap some water next to your skin.. its not traping any air. Water is one very bad insulator, so I would sugest you achived a nice placebo effect.

Wet cotton has no insulation properties because it can't trap any air when its wet. It actualy removes body heat for the reason you stated.

I would suggest fleece for your next outing, there would be more placebo effect in action since it "works while wet"...

Not that this would work ether... not even magical fleece can trap air when submerged.


P.S. Why is this on the tech forum?

 

[Soggy]

I suspect the reason why the t-shirt helped underwater had nothing to do with it's material. It probably had the effect of slowing the movement of cold water over your skin but taking up space between you and your wetsuit.

 

[ManSteak]

yup soggy, I agree. And thereby, it acted just as it would on land (though of course on land it would be blocking the movement of air.) Jim, I think you're getting hung up on the need for air to be present in order to keep yourself warm. Though air is certainly a better insulator than water, I think that cotton does a fine job insulating you under the water, provided that you're not sitting on the surface where the water could evaporate off of you.