Hot rocks?

RoyalM

RoyalM

Joined
Dec 10, 2007
Messages
2,150
With all the talk of Jeremiah Johnson and with the time of year it is I wanted to ask has anyone tried using the hot rocks under your bedding to keep you warm technique?

I watched the film and from what I can figure I would do the following:
1) Dig a pit long enough for my body and as wide, effectively a shallow grave.
2) Light a decent fire in the hole
3) Put rocks on fire
4) Allow fire to burn down and cover with the soil I dug out making the pit
5) Pack the earth down firmly then cover with a thick blanket
6) Lie on the blanket and cover up as normal then go to sleep

So who fancies trying this out?
 
I used hot rocks in my arm pits, the small of my back and between my legs for heat on my last campout in late November...It worked well for about 3-4 hours....It was my intention to build a bed as you mentioned. But I didn't have much day light left by the time I had selected my sight...Just don't select rocks from a river bed or moist area, as they can trap moisture inside and burst when heated.
 
This works but can be a pain in the ass depending on the soil. If you are in a frozen environment and put soil on top of your hot rock bed that is mostly frozen, you will wake up in a muddy mess. I've used this technique a few times and one time I had a bad experience. You won't be covered in mud as if you were 4 wheelin' but you will know if the ground was damp or not when you're home cleaning off your gear.

Also, as RescueRiley pointed out, rocks with moisture trapped in them will explode. This happened on the Primitive Winter Survival course I took with the MPSS a few years ago. Makes you sit by the fire with a hand in front of your face to protect it from flying shards.
 
My (limited) experience is that you are best served by spending that time gathering brouse and making the best loft base for your sleeping area. The body is the heat generator in your sleeping area, insulate IT, and you'll be happier.


YMMV
 
There are certain caveats with a firebed, which is what you describe. As has been pointed out, you can end up taking a steam bath if moisture laden soil thaws during the night (This is one instance where a couple large contractor trash bags between you and the firebed are worth their weight in gold as a waterproof barrier). However, even in the most frozen conditions you can still successfully make one of these. I recommend just doing a "torso-length" one at most, since you'll expend less calories, and really the key is to keep your core body temp going. Plus, you use less fuel to build the fire. But for true luxury, a full body length firebed is an amazing wilderness experience.

I use the 2-4-8 rule as taught to me by my friend Ron Hood. You build and maintain a strongly burning 2 hour fire, in a pit dug 8" deep, with the bed of coals sitting at 4" deep once the fire has died down. Line the bottom of the pit FIRST with rocks (make sure they are not moisture filled rocks from a stream bed or drainage area - the moisture can expand with heat and explode, causing serious shrapnel wounds). Leave a 1/4" or so of airspace between the rocks for some airflow so that the fire can draw the oxygen...plus, the heated rocks will radiate heat throughout the night in addition to the coals on top of them.

Once you have that bed of coals ready after two hours, then bury them with dirt. After about 45 minutes, the heat should start to radiate through, and should, if done right, last about 6-8 hours. Your mileage may vary depending on conditions.

I just demonstrated this to a group of kids that a friend of mine teaches/counsels in a wilderness therapy program about 3 weeks ago, with great success. Everyone had a great time and great success with it, and the kids were hungry for more survival-related ideas. They could not believe how luxurious a primitive camping experience could be in the bitter cold! However, you have to experiment, like any other skill, to get this technique down and be able to use it efficiently.

If the ground is frozen, you can still make a firebed, but it will not be as effective. You have to burn the fire on the ground to thaw it first. As long as you use the fire for cooking and other purposes (multitask use of the fire) you can do the firebed technique effectively. And, it can save your life when other alternatives are not as readily available!
 
OK, I've wanted to try this, but never did because of the amount of digging and the potential to destroy some fragile spots in my favorite hiking areas. In the Adirondacks, the ground is often too rocky and root-laden and if you get higher up, it's a bit fragile to go pulling away the topsoil and pulling out the plants that keep the soil together. There's a lot of erosion caused by hikers going around puddles and I've seen some areas trashed down to the bare rock. It's not going to get back to its original condition any time soon.

Forget what I've said if the spots you hike in are more remote or made up of different kinds of soil or are on your own private land. It's just that I really try to leave no trace and place as little impact on the area if even for the next person so they can believe that they've found a pristine spot to spend the night. I'm not trying to be judgemental, but just putting this out there.
 
As an alternative to this type of technique...

I have used Nalgene bottles filled with hot water to warm my bed, and that works quite well.

M
 
The thing that worries me is that moisture laden rocks may explode.

If you're doing this in the snow, what have those rocks been doing ever since it snowed? Sitting in the snow right...wouldn't they be just as moisture laden as rocks sitting in a creek?

I think before I tried this method ( even though I know enough people have tried it that it works) I would go with building a fire on the ground to dry out and warm up the spot I wanted to sleep. Then drag the coals over and sleep next to them. I believe Siguy did this ( or something similar) on one of his excursions for the winter challenge giveaway at Christmas time.

That being said, the Jeremiah Johnson pit bed does have one advantage that I have never seen anyone use...When I was a kid we used to cook hogs and calfs in a pit like this over night. So, if you were hunting ( or had killed something in a survival situation) this would also be a good chance to pit roast your kill while you slept.

David
 
i have used hot rocks a couple of times now winter camping and i would say they make the single largest difference in me being warm at night.

i used rocks a little smaller than my fist, heat them up to just below glowing red hot, and wrap up in a towel, bandanna, etc. i took one and put it with my feet to keep my toes warm, and another i held against my sternum all night.

the rocks stayed warmer than my water bottle, and the rock that was wrapped up stayed warmer for longer.

even so, the rocks i was using cooled enough to be ineffective in about 3-4 hours.
 
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