Northern Ireland Outdoors Forum - Hiking, camping and more
General => Gear Questions, Information, Reviews and Competitions => Topic started by: whoRya on December 24, 2010
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What is your normal layer system for a walk in the hills in winter?
I was out for a walk the other night around the town and had a normal 'stay dry' base layer (top and leggings) on with a microfleece, heavier fleece and water/windproof shell on top, just a pair of jeans below. Gloves and a hat also, and two pairs of socks. I felt ok whilst walking, it wasn't a high tempo walk though. When I got home I didn't bother taking the base layer on. Strangely whilst sitting in the lounge my legs felt a little cold. I'm not sure if I was just imagining it or is there anything to suggest that a base layer would take heat away from you? As I type that it sounds daft.
The next night I went for a moonlit tramp through the snow up Big Collin (http://mountainviews.ie/mv/index.php?mtnindex=898)and wore thermal leggings and a thermal vest, all the rest of the gear was the same. This was a more aerobic walk and I started to get quite hot, I had to open the front of the jacket and pit zips. The inner of the jacket was damp, as was the outside of the heavier fleece. Microfleece and thermals were dry, obviously doing their job of wicking moisture away.
What do you find to be the right combination? Do you wear a thermal base layer of a 'stay dry' base layer?
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Base layers all share similar properties, but are tweaked for effect. They wick moisture away from the skin which keeps you dry, and the dry air trapped offers insulation. Layers designed for say, summer running, will be thin and highly wicking, with a large surface area of fibres to promote evaporation (which causes cooling). Because this cooling occurs close to the skin (tight fit/ thin material), there is a sharp temperature gradient which cools the body. The benefit over bare skin is that the sweat can be spread out through the fabric - being more effective at cooling, but also drying quicker once activity has ceased (UV protection also).
A 'thermal baselayer' may be physically thicker to trap more air, or have hollow fibres to hold air - which offers a little more insulation. It will still wick in summer but the cooling effect will be less. As shown by the moisture being out on the top of your fleece, any evaporation is now happening further from your body: the conductance temperature gradient is more shallow so you cool at a lower rate, and the extra dry air in those layers provides more insulation from convection cooling (and probably radiant cooling too).
I suspect that although the 'light' base leggings started to feel cool, perhaps you would still have felt even cooler without them? Remember that denim is a rather cold material...it will hold on to that wicked moisture and conduct heat away from you.
The 'thermal' leggings would actually cause more perspiration, but due to their emphasised insulating properties they could better protect you from conductive (to the denim) cooling even at rest... perhaps retaining more moisture themselves, so less in the denim and increased 'wet suit' effect. You would not be aware of the levels of moisture but it could still have an effect. Wear different trousers :D
These days I just wear wind-proof, fast drying trousers. Unless I'm on the bicycle I don't need the base-leggings (I'm not sitting around outside these days). All my base layers get rotation on the top, mostly 150 or 200 merino, with a wool sweater on top. This seems to work well indoors or out (with a wind-top or jacket).
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Thanks again for such a detailed response. The advice is always welcome as I'm sure you are well aware ;)