Brett, the myth is making feet warm by wearing a hat. There would be no frostbite of the feet if wearing a hat prevented it. That saying is an oversimplification to get people to understand the importance of wearing a hat in the right conditions, but it has no significant physiologic accuracy.

You could go climb Everest with a -20 F sleeping bag on your head, but if you don't properly insulate your feets too, you gonna lose them toes.

Sincerely,

The Easter Bunny

Edited by jshann on 04/02/2007 12:20:36 MDT.

Thank you Easter Bunnny.. I will avoid wearing a sleeping bag on my head while walking barefoot in the snow.. from now on I mean.. ;)

I'm hoping to through-hike the PCT next year, so am trying to figure out my gear this year --- this article series is a great basis for thinking through the Sierras stretch.

I was able to do a morning hike yesterday starting out at 22 degree F in snow, wearing a mesh watershoe (Columbia Aquatooth) and Rocky Gore-tex socks over a wicking sock and a wool sock. It took a bit to get over my visceral reaction of "this is crazy" (this article gave me the confidence to try it), but it worked just great. My feet got mildly cold at times, but never painfully so, and after 3 hours of hiking fairly steeply up and then back down I was amazed at how dry my liner and wool socks were.

What particularly sells me on this system is the idea that I don't have to care if my shoes get wet --- they'll get wet, but they'll dry much faster than supposedly waterproof shoes or boots that I wouldn't want to be committed to on a many-day trip in snow.

The one caveat I have is in getting the sizing right. In "normal life" I wear a size 10 shoe. I got size 11's in the mesh shoes, for obvious reasons. So I ordered a size 11 gore-tex sock. Barely fits me. Yesterday afternoon I found I was developing blisters on the outsides of my second-to-smallest toes (both of them); I suspect this is due to the size of the Gore-tex sock, so I'll probably buy a pair of size 12's (!). If that doesn't work, then a bigger shoe. Getting the sizing right is likely to take some iterations, and expense. And once I get it right for "now", I'll have to factor in the odds that my feet will be larger by the time I hit the Sierras ...

Thanks, BPL, for such a detailed (and for me, timely) article series.


Brian Lewis

"Replacing that heat with a hot beverage is a good way to maintain core temperature and stay hydrated, while drinking ice cold water puts more demand on your body’s metabolism to produce heat."

My experience agrees with this--if I drink a liter of hot tea (by the way, that's quite a bit for one sitting), as I do just about every morning, I feel very warm. But that doesn't make much sense! A liter of water at 50C (I don't know the actual number, but that's close to scalding) contains 50 more Calories than a liter of ice water. That's utterly dwarfed by the Calories taken in by an energy bar.

Is it that while the energy bar's energy takes a while to make it into the system, that liter is applied over 20 minutes? 50C/12min (gulp!) is 4C/min; the article says you should be eating 300-400C/hour, which is 5C/min. So the liter of hot drink maybe doubles your caloric intake for a few minutes--is that what's going on? Is it enough to explain the heating?

If I eat two power bars, will my skin feel warm? No. Is this just a situation in which one kind of energy can be regulated but the other can't?

Or am I missing something else?

The case of hot food is far more extreme. Here, you can expect to take in 800C in a meal, maybe 20C of which is thermal. But I do love a hot meal :)

Riveting article. A most read.

Excellent work Will and Janet! I reread it this year to brush up.

With all the talk lately about poor article quality of late, this is a fine example of the good ol' days.

Thanks!

I'm STILL waiting to read about how important VBLs are to keep boots dry (and thus warm).

Any article on winter footwear without a discussion of this AND having warm boots or boot liners to don in the morning is very incomplete, especially when we're talking about winter camping.

OK, I'll "write it" i.e. the part about using VBLs & overnight camping.

To wit:
I agree with Will that above 25 degrees F. you are likely not to need a VBL, but a WB menbrane boot instead. In these and +32 F. conditions keeping water & bsnowmelt out is essential.

BELOW 25 F. you must have 2 conditions for your footwear to be safe.
1. Enough DRY insulation
2. a VBL to keep that insulation dry

>A thin poly-pro sock is a necessary liner

>A neoprene VBL sock (like a eam-sealed divers sock) is one of the best types but a fabric VBL works fine.

OUTER boot waterprofing is essential to keep the insulation layer dry from the outside in case you step in water. (it happens!)

Felt pacs are a standard winter boot for very cols weather so let's take a look at them and insulated Gore-Tex boots.

With felt pacs you must keep the felting layer of insulation dry at all costs. Wealing the rubber/leather joint with something like Shoe GOO is important, as is treating the leather wit NikWax or Sno Seal wax.

An good VBL in felt pacs is rwquires to avoid a felt bootie having a lengthly dry-out period befoe a carefully tended fire.

Insulated Gore-Tex boots range from light Thinsulate insulation to very thick Thinsulate but it always seems to be Thinsulate that's used as insulation. Here again you must keep the Thermolite dry from perspiration. The Gore-Tex keeps out exterior moisture.

BEDDY-BYE Story:
FELT PACS>
At night I'd prefer felt Pacs because the removed liners (Yeah, they must be removed every night) can be worn to bed or just stuffed in the bottom of your bag. Any moisture they get will be negligible but to be SURE of keeping them dry on long trips put them in a WP stuff sack overnight.
Place the feltpac overboots outside in your vestibule TELESCOPED over each other to keep out spindrift snow.

Thinsulate Insulated boots>
These boots must be placed in TWO waterproof stuff sacks to lay on either side of your feet at the foot of the bag.

With the felt liners and/or boots in your bag you will have warm feet in the morning. The alternative is too painful and too dangerous to contemplate.

VBLs AT NIGHT:
Take 'em off before bedtime and turn them inside out. Let them dry a while before putting them in your bag. stow poly liner socks in a small stuff sack for dirty clothes. try to take a pair of thin liner socks for each day.

Don your thick wool sleeping socks or down socks for bedtime.

In the morning on go the new poly liner socks and the VBLs
and then the boots or felt liner & overboots.
Now you'll have warm feet all day long. Your feet won't be dry but they WILL be warm as long as the insulation is dry.

This was what I was referring to regarding the use of VBLs for overnight camping overnight. It's not complicated and you may as well learn it here as through hard and cold experience.

Edited by Danepacker on 09/26/2010 22:16:36 MDT.

So...write it.

> My experience agrees with this--if I drink a liter of hot tea (by the way, that's
> quite a bit for one sitting), as I do just about every morning, I feel very warm.
> But that doesn't make much sense!
Oh yes it does. You are confusing energy content with physiology. To explain:

When you eat an energy bar the food goes into your stomach and intestines to be processed into energy. Some immediate heat is generated while this goes on, but not much. The energy is available to your muscles, but is used up slowly.

When you drink a litre of hot tea at 50 C your stomach and internal organs see their temperature go up by a significant amount above your normal core temperature. Uncontrolled this could lead to thermal breakdown and collapse. It won't in this case of course, but your body has no way of knowing that. So to compensate your body immediately shunts a lot of blood flow to your extremities to dissipate the excess heat. Your skin senses the increased heat flow and feels warm - immediately.

Cheers

"Your skin senses the increased heat flow and feels warm - immediately."

So, if you are wearing a puffy jacket, a lot of that warmth will be captured as it leaves your skin, and you will stay warm a long time. If you are not wearing the puffy jacket, then most of that warmth will be lost into the air, and the warm feeling is very temporary.

Mountaineers drink hot tea!

--B.G.--

Will, as a long time Nordic Patroller and well versed in The National Ski Patrol's Outdoor Emergency Care training I must absolutely disagree wtih your statement about heat loss from the head.

TO WIT:

1. Neck and head veins do NOT vaso-constrict in cold temperature exposure as they do in the rest of the body.

2.The physiological reason for statement #1 is because the brain is the most important organ of the human body and must be kept warm at the sacrifice of other body parts.

3. the blood supply to the head is very good, thus the reason for profuse bleeding of relatively minor head wounds.

4. In light of the above information the head and neck are the most efficient RADIATOR of heat and must be kept warm in cold temps.

BELOW 25 F. you must have 2 conditions for your footwear to be safe.
1. Enough DRY insulation
2. a VBL to keep that insulation dry


I don't like the use of "must" here. I've spent plenty of days and nights below 25 and have never used a VBL of any sort.

I found that the chemical toe warmers didn't work very well because they couldn't get air inside the boot. I love using hand ones in a pocket, but the toe ones didn't keep warm more than 5-10 minutes before I had to take my boot off to get them warm again.

I know I am probably reviving a very old thread but I was just wondering: could you use a wool sick as the liner layer? Or does it have to be a man-made material (ie polyester)? In other words, could you wear a thin wool sock as a liner and a thicker wool sock on top for warmth?

Yes. The main disadvantage to very thin wool socks is poor durability.