...However, that neglects the fact the air is a poor conductor, so the energy transfer is still dominated* by energy conducted from the body, by the fabric, and by the water itself.
* Body and air will both be radiating to the water, so it would be interesting to compare the radiated energy transfer against conducted energy transfer. My gut feel is that conduction dominates at those temperatures.
This is hideously complicated... Yes, I'd thought that as they were roughly the same contributions given their respective temperatures. That means radiation will be the same, but I'm not sure of the relative contributions of radiation and conduction here. The conduction from air would indeed be lower than through the fabric, but then this starts to depend on how wet the fabric is too...
I am sure our paths will cross at some point and we can put the world of baselayers to rights over a beer or two!
Sorry for completely derailing your thread, Wayne. I think a meco baselayer would be a good investment and that you'd notice the benefit.
Tenohfive, I think I agree with much of what you say, though I am cautious about calling merino 'warm when wet'. I actually wrote a blog post about that too (sorry! https://gearandmountains.wordpress.com/2014/05/23/warm-when-wet/) and though that was geared towards down versus synthetic, some of it still applies. I think merino is certainly a lot better than cotton, but because it absorbs that much more water than synthetics I don't think it's that warm when wet, just because it takes ages to dry. However, its wicking means it might certainly be better than something like a soaking wet Helly Hansen. The thicker baselayer is certainly worthwhile if you don't think you've much chance of overheating, as then the extra insulation is worth it. I suppose I'm writing from my own experience where I don't think there's many days I've been out in the UK and haven't got a bit too hot at some point: if your baselayer is thinner there's less chance of this happening than if it's thick.
Captain, the point regarding 'indirect evaporation' - good term, or at least follows my back-of-a-fag-packet term(!) - is a good one, and something I hadn't really thought all that much about to be honest. It's worth noting that the evaporative effect is less than 'direct evaporation' because some of the thermal energy will now come from the environment, rather than the skin: if it's 30 °C, about half of the energy for evaporative heat loss will come from the air, not the body. In colder weather, however, the body's will contribution will obviously be far greater.
I knew this baselayer thing would be a can of worms, but it's a good debate.
Thanks Pete. I actually discussed your first point in some detail with a couple of guys a year or so ago. The discussion went round and round and we even debated over whether the creation of sweat (ie it coming out of your sweat glands) cooled you down. We decided that it didn't. However, the wet skin thing was really hard to work out, and it was way more complex than we first realised. I think we eventually decided that wet skin makes very little difference to your overall heat loss because it comes out of you at body temperature and the limiting factor on conduction is more the surface it conducts to (the fabric) than the skin/water. Radiation is actually marginally hindered by wet skin, too.
I'd not thought of Paramo reversible shirts when I wrote it, nor had I thought of including the idea of changing baselayers halfway through a day, as I often do. Might have some edits to make... Cheers.
If you're keen to hit the science of baselayers, I wrote a blog post about it last night (here https://gearandmountains.wordpress.com/) . In short, though, I'd get something that fits that is as thin as possible.
I'd argue with that many glove layers you'd loose dexterity and probably overheat too. I've never worn more than a pair of all-leather Wilkos gardening gloves on the summit of a 4000 m peak (something like 15 separate days over 6 different years), but have always had a pair of warm climbing gloves ready in my bag. I know that if it's much colder than I expect, if I drop a glove, or if I get into difficulty, that I can tie knots, climb, and generally be effective with those warm gloves on. Some people really get on with Dachsteins, and I agree that they are possibly the best value-for-money mitt out there if it's dry, but doing your laces in them takes some practice!
If looking at 'climbing' gloves, Black Diamond are the best bet if you've got stubby fingers. Mountain Equipment and Rab also make excellent gloves, but they don't really fit me.