I just hate getting into a sleeping bag that has been sitting at -10 Deg F for the whole day. It is nice to use a Hand Warmer or the MRE Chemical Heater - if you have them. Rocks seemed like something I should try.

I made the normal RING OF ROCKS for the campfire. Several softball sized were placed to ring the fire. Larger rocks on the outside contained the heat.

When the time came, I wrapped the SOFTBALLS in paper towels. I don't like dirt and soot. These I stuffed into small oven bags - turkey bags. Both have an upper temperature limit of ~400F. I stuffed them into the sleeping bag and rolled it up.

That works!

The next test is to use the rocks thru the night for someone who can't stay warm.

When I went trekking in Nepal, I was always given a bottle full of just-boiled water to take into my sleeping bag at night. It really helped with staying warm, and provided safe drinking water for when you woke up.

I don't see why a hot stone wouldn't have the same warming effect, but it probably would not be as thirst quenching!

Anyone know at what temperature the synthetic liners of sleeping bags start to melt?

During winter camping and hiking, a bottle full of hot water is better then heated rocks. We usually will put the hot bottle into a couple of spare socks then into the sleeping bag. These stay warm for many hours and in the morning, you have water that is not frozen and is ready for use.

Thanks for the idea, ponder! i'm going to try that the next time i get a chance!

Per wikipedia, nylon 6.6 melts at nearly 500F. As long as your turkey bag is intact, your bag should be OK.

The rocks provide heat, but also compress the insulation.

I prefer to wear a wicking layer to bed. It helps keep me warm and protects the bag from my grunge.

Or, you can do it the easy way: Hot Water Bottle

Sue

+1. I do this head to toe, including some nice, dry wool socks (or camp booties, even better). The result is an instant toaster effect when I crawl into my sleeping bag. Plus, I have a layer of armour against the 4 a.m. cold should I need to take a short, uh, stroll.

I guess I would try the rock thing on a survival exercise. Probably on the foot end. Seems like a lot of fuss though.

My problem with heating rocks is how to handle them effectively when heated. I've heated both rocks and bricks, and find them extremely awkward to move around. Burns aren't going to increase your comfort or survival rate.

If anyone has any tried-and-true tips on how to maneuver them, please post! It can't be just me!

Sue

Tie two sticks together with a piece of cord and use them like a nutcracker.

The preferred method (when available) is rub two 'campers' together in a double bag. :-) Warms the bag rapidly and the afterglow morphs blissfully into sleep......
Extensive practice is not necessary, but hones the techniques....

lc

Oooo OUCH! I MUCH prefer my method :-), but I expect yours would work...... Anger is also an emotion that raises the temp, and pain likely will also.....:-)

gimpy

Hot rocks under the sleeping bag work well, but the method requires advance preparation. A shallow 6x3 foot trench is dug and the hot rocks are buried a couple of inches down, and covered with dirt and bedding.

Quoting the MFG specs-"Nylon 6.6 Properties:

Structure: Crystalline, Specific Density: 1.14, Water Absorption Rate: 1.3% @ 24 hr., Elongation: 150%, Tensile Strength: 7600 psi, Compression Strength: 8700 psi, Flexural Strength: 5800 psi, Flexural Modulus: 200000 psi, Impact: 2.1 ft. lbs./in. (IZOD), Hardness: R100, Deflection Temperature: 390°F @ 66 psi - 250°F @ 264 psi, Utilization Temperature: -110°F min / 250°F max., Melting Point: 490°F, Coefficient of Expansion: 0.000044, Arc Resistance: 130 sec, Dielectric Strength: 18 kV/mm

Bonding: Good, Ultrasonic Welding: Poor, Machining: Good, Transparency: Transparent, UV Resistance: Good, Chemical Resistance: Acids-Poor / Alkalis-Poor / Solvents-Good

Trade Names:

Capron®, Durethan®, Gelon®, Nylatron®, Rilsan®, Ultramid®, Vydyne®, Zytel®
"
400F seems way too high. I worked in plastics for over 20 years and the glass reinforced nylon polymers we used in structural foam molding were molded in the 500F-600F range. I would not advise putting anythnig like a hot rock inside a synthetic sleeping bag. Boil some water, put it in a Nalgene bottle and wrap it in socks or towels. I can assure you a melted sleeping bag will sleep much colder than an intact one.
YMMV

BTDT.

Camping in the open on the coldest night of the year with a substandard sleeping bag. Sat by the fire all night drinking tea and tucking hot rocks down by my feet. I put them in a canvas bag, but still managed to scorch a few holes in it.

It works, but its hard to tell the difference between hot enought and too hot, especially when numb with cold. I agree that a hot water bottle is probably safer.

i have tried the hot rock trick a couple times by just moving one from the fire to the tent vestibule with a heavy wire cooking grate.i let it warm up the tent,a Timberline,and get some of the damp out of it but even sitting off the dirt on a couple other warm rocks that i could move with leather gloves it went cold within 20 minutes and it was red hot when i moved it.i think this is a overrated camping trick.you would need a big fire and lots of good size rocks to get any effect.the old camping books show a guy sleeping away over nice warm rocks that are buried in the ground under him.ever try and dig a trench at a campsite?.unless you were at a beach it would take hours,and then more to collect the wood and rocks.i have put a candle lamp in a tent to do the same thing with good results and thats why i carry the weight of a small Gaz lamp,with one of those you have a hot tent in minutes.your water bottle filled with hot water in a sox works fine.the problem with the hot rock and other camping "tricks" is that people think they will be able to depend on them if need be and cut back on real gear,and in the end are cold and unhappy..if they survive

These are good techniques to know, but nothing beats an adequate sleeping bag.