Wednesday, December 30, 2009

Thermal Regulation

I've been thinking about thermal regulation while hiking this winter. During a hike your need for insulation can change quite quickly depending on outside temperature, wind speed, humidity, and exertion. Being too cold is no fun of course but being too warm can be a problem as well because perspiration can quickly chill you once you stop hiking.

Conventional wisdom says that the right thing to do is to dress in layers and remove layers as you get warmer or put them on as you get cold. However this is a lot of trouble because it involves stopping and taking off your backpack to put away or take out a layer. To avoid this nuisance most hikers don't vary their insulation enough.

I've discovered a better solution. It turns out that most heat lost you experience is through your head and your hands. I used to take my hat and gloves off when I got warm but I ended up having to try and shove them in the pockets of my pants (which were already full from my GPS and snacks). For the past few hikes I've instead worn my Sugoi Speedster 2 hoodie. I originally bought it for winter running and biking but now I'm finding it very useful for winter hiking as well. The fabric is a full stretch, wicking, midweight base layer with fleeced inner side so it's comfortable and warm. But the best features are the hood and cuff gloves. If I'm warm I can keep the hood off and my hands bare.

When I begin to feel cold I can pull the hood up and tuck my hands inside the cuff gloves. They aren't really gloves, just a fold of fabric that encases your hands. It doesn't allow for any dexterity but this is a feature I use while hiking, not while setting up camp or cooking.

I've really been loving how easy this makes it to adjust to my changing needs for insulation while hiking. In previous posts I've sung the praises of merino wool and of course this top is synthetic. The tradeoff is that the synthetic tops have a problem with odor while wool seems impervious to body odors.

On my most recent trip to hike the Trace Creek section of the OT I made a mistake when it comes to nighttime thermal regulation. I went to bed with little insulation on my legs. When I went to Sam A Baker state park a few weeks before I had worn very good lower body insulation to bed and found that it was too much and so removed it. I had brought that same insulation with me on this trip but left it in my pack. Once I realized I was a bit cold in the night it was snowing and blowing quite hard and I didn't feel like getting out of my quilt to rummage through my pack to change so I just settled for being uncomfortable.

The lesson is that you should always wear you warmest clothes to bed. It's easy to take things off in the night but it's hard to add insulation that you didn't take to bed with you. Oh well. Lesson learned.


Jacqueline said...

I like your idea for the top, plus you look a little like "bad spiderman" with the hood up, so that's got to have some kind of psychological boost...maybe.

Anyway, it is great to read about what you've learned about hiking so that I will not have to freeze my feetsies (not to be confused with "feces") next time I try to sleep outside in a sleeping bag.

P.S. This is Lybi

Maz said...

Also, bear in mind that it is much harder to warm up when already cold than it is to cool down when too warm. Thus, go to bed too warm and take a layer off at night if necessary rather than wake up freezing and hope to get warm by adding layers.