Originally Posted by
MinnMan
If you are talking about the insulating effect of a layer of water inhibiting the cooling to your skin ,then it would have to be a rather thick layer. The thermal diffusivity of water (D) is around 0.2 mm/sec^2, which means that for a layer (x) 1-2 mm thick (that's a thick layer, think about it), the thermal equilibration time (x^2/D) is just a few seconds.
BTW, a uniform layer 1 mm thick on your entire body would be almost 2 liters of water (average male body has a surface area of 1.9 m^2, etc.).
Yes, that pretty much was the point I was trying to make. I certainly can't prove you wrong and you do now seem to be addressing what I was saying instead of dismissing it.
On my ride yesterday, I weighed before and after riding with cycling shorts and jersey on. I weighed the same after the ride. I drank 67 ounces of water on the ride and pee'd just about 10 of those ounces immediately after weighing. So surprisingly, your 2 litres of water 1 mil thick has merit for being a great example. If I hadn't run out of water, I would have road the full three hours and probably made that 2 litres of sweat.
So I understand a little better where you disagree about the negligible benefit to the body being able to cool itself by ridding itself of excess sweat. There are other factors though, one of them being that sweat doesn't pool evenly over all your body. Most all my upper body sweat runs down to my shorts. Where after the saddle I don't know.
I still don't want it on me, so in the heat, I want to lose any excess that isn't going to disappear through evaporation. Even if it doesn't help with letting the body cool itself, it does help keep my clothes fitting snug enough not to rub me. The wetter places on my skin always were the places where I felt abrasion starting. Though I can honestly say I haven't had a saddle sore in the past 15 years. Came close, but close only counts in horse shoes and hand grenades.
Maybe in winter we can re-visit this topic. I'll be wanting a base layer and several other layers then. <grin>