Countermeasures against the cold when sleeping during winter camping.
I considered ways to stay warm with minimal cost and ways to prioritize warmth above all else, regardless of cost.
Futon + Blanket (+ hot water bottle or futon dryer)
This method involves bringing your futon from home to the campsite. Add a winter blanket for extra warmth.
Still, I dislike the coldness when I get into bed, so I warm the futon with a hot water bottle.
If you switch it on a little before bedtime, you'll have a fluffy and warm futon.
Sleeping Bag + Air Mat (+ hot water bottle)
This method involves placing an air mat under a winter sleeping bag.
Air mats have excellent insulation properties, effectively blocking cold air from the ground.
Combining it with a hot water bottle further enhances the warmth!
Sleeping bag + Cot (+ hot water bottle)
Sleeping in a sleeping bag on a cot.
Cots physically separate you from the ground, offering not only comfort but also insulation.
If you lay a blanket between the cot and the sleeping bag and let it hang down to the bottom of the cot, the movement of air under the cot will be suppressed, warming the air and allowing you to sleep more comfortably.
Adding a hot water bottle makes it unbeatable.
Futon + Kotatsu
Finally, here comes the ace in the hole: the kotatsu.
Assuming an AC power source is available, combining a futon with a kotatsu creates a very warm setup. It's almost like a living room at home.
To avoid burns, turn off the power once it's warm.
How to bring a kotatsu to winter camp and utilize a hot carpet
During a relaxing time at a winter camp, bonfires are nice, but how about "kotatsu mikan" (tangerines under a kotatsu) outdoors?
If you adopt the popular low-style camping, introducing it is surprisingly easy.
Making an instant kotatsu with a low table
Low table size (approximate) for number of users
Length cm Width cm Height cm
1~2 people 80~120 50 30~35
4 people 120 80 30~35
5+ people 150 80 30~35
Cover a low table with a blanket, and put about two hot water bottles inside, and voilà, it's warm. An instant kotatsu is ready.
For 1 to 2 people, a low table of about 80-120cm x 50cm is recommended. For a family of 4, 120cm x 80cm, and for 5 or more people, 150cm x 80cm is ideal.
One hot water bottle is not enough to warm the entire table, and three will raise the temperature but take up too much space.
If 3-4 people put their feet in, it gets in the way, and there's a risk of low-temperature burns if their feet touch the hot water bottle, so two is appropriate.
It's even warmer if you lay a napped rug underneath. That's because the more air it holds, the warmer it is.
Choose a rug larger than the low table, and ensure it's large enough for your bottom when you sit down.
Place a blue sheet or leisure sheet under the rug.
Not only does it prevent the rug from getting dirty, but even a thin sheet makes a difference in how cold it feels.
Utilizing hot carpets and heaters
Placing a hot carpet under the instant kotatsu mentioned earlier will boost warmth. If you have access to an AC power outlet at your campsite, make use of it.
The output of powered campsites is often between 700W and 1000W.
The output of a 2-mat size hot carpet is usually around 500W, so it's perfectly usable.
However, if you're using a portable power supply, most products have an output of 400W (even the higher-end ones are 700W), so it would be difficult to use.
Furthermore, portable power supplies cannot perform optimally in low-temperature environments, making them impractical.
There is also a method of bringing warm air from a fan heater into the kotatsu.
For winter camping, a fan heater roughly equivalent to heating a 7 tatami mat wooden room or a 9 tatami mat concrete room is a good size.
Choose one with a tank capacity of around 3.5 liters.
A heater of this size will sufficiently warm the tent without taking up too much space.
Furthermore, even at ignition, when the load is highest, power consumption is around 400W, making it possible to use in conjunction with the hot carpet (around 500W) at most powered campsites.
Attach a thick, corrugated tube to the warm air outlet and pull it into the kotatsu.
This is meant to guide the warm air from the fan heater to specifically warm a spot, rather than heating the entire room.
Since the heater's warmth directly enters, it's cozier than a "hot water bottle kotatsu."
There is a risk of carbon monoxide poisoning, so if you are using a kerosene fan heater, do not get inside the kotatsu.
※The use of heating appliances in a closed room is prohibited. When using, ensure sufficient ventilation and use a carbon monoxide detector.
The heating capacity of a ceramic fan heater's warm air is insufficient to adequately warm the space, and using it in conjunction with a hot carpet could lead to excessive power consumption.
