Camping in a hammock has many advantages (including compared to the tent), the main ones being surely the practicality of setting up and the lightness of the equipment.
But anyone who has ever slept in a hammock in mid-season or winter must also have noticed: there is a big disadvantage, which is the cold!
And yes… the hammock is not the best way to isolate yourself and take shelter from the “fresh” temperatures of the very end of the night.
Fortunately, there are a lot of solutions that will allow you to stay warm, in your airy cosy nest…
Why does your back get cold in a hammock?
Because yes, it’s usually always in the back that the cold comes to bite you.
There are two main reasons for this…
Thermodynamics and air currents!…
We’re going to save ourselves the physics lesson and we’ll just remember the fact that, because the hammock is high up, there is necessarily air circulating underneath.
This cold air cools whatever it comes into contact with.
Here, your back…
The colder and more moving the air, the colder you will feel.
Add to that the fact that at night, the body naturally loses heat… and you risk spending a few unpleasant and not very restorative hours, waiting for the first rays of the sun to warm you up.
To prevent, or at least reduce, this feeling: it is essential to choose the location where you are going to camp (in addition to properly hanging your hammock).
Opt for the mid-heights of mountains and hills to protect yourself from the prevailing winds. Also, stay away from waterways.
Also use a tarp, properly positioned, to break up winds (including drafts under your hammock).
Finally, protect your back: I’ll talk about it below.
Logic, you will tell me…
The more it curdles, the more it curdles.
Going to bivouac at the beginning of autumn in the plain, or in the middle of the winter season in the mountains, will not offer you the same “comfort”.
The feeling of cold is very personal, but it is generally said that below 10-15°C in a hammock, the first discomfort appears.
For my part, I consider myself a chilly person and I am indeed in this range.
So, there is no question of going for a bivouac in a hammock in very low temperatures, even negative, without appropriate equipment.
My advice is to make camping in a hammock pleasant, even in winter
To guard against seasonal coolness, rain and winds, it is important to choose the right equipment.
Rule N°1 – Protect yourself with a Tarp
The tarp is the essential cover that will protect you from rain, snow, wind and tree leaves.
Stretch its fabric and bring it as close as possible to your hammock, taking care to lower it below the level of the bedding and check the prevailing winds.
This will aim to prevent the wind and the ambient freshness from infiltrating your bedding.
Bonus: you are in a pleasant cocoon, protected from prying eyes…
Rule N°2 – Opt for bedding that optimizes warmth
If I had to trivially sum up how a sleeping bag works, I would say that it is an envelope whose function is to trap as much static air as possible.
It is not the fibres of the sleeping bag that insulate, but it is the static air that the fibres manage to trap.
Concern: when you lie down, the fibres of the bag, under your body, are crushed… and therefore cannot trap the air.
In short, a sleeping bag insulates you on top and sides, but never (or very little) below.
Hence the floor mats.
To reduce this phenomenon, it is advisable to opt for a synthetic and non-down sleeping bag.
Indeed, the feathers of the down bag will be more likely to be crushed than synthetic fibres, which are more compact and less sensitive to pressure.
They, therefore, retain more of their insulating capital.
You can also equip yourself with a tube duvet, made with the same materials as the sleeping bag.
Finally, if you are camping with someone you are quite intimate with (or plan to be!), and you have a double hammock, you can opt for a two-seater in a tube.
It has the same advantages as the single duvet, but in addition, you will enjoy the human warmth emanating from your two bodies.
Last tip: to avoid any loss of heat inside your bedding, don’t hesitate to keep some of your clothes/stuff inside so as not to leave any air gaps.
Rule N°3 – Use a mattress (or a sub-hammock) to improve back insulation
We have seen it previously: there is a loss of insulation in the sleeping bag at the level of the back.
The mattress is therefore there to compensate.
Several possibilities :
- the inflatable or self-inflating mattress (quite a hassle to fit in a hammock)
- the foam mattress (easier to hold, and the possibility to “cut” it to size)
- a large woollen blanket or a sheepskin (atmosphere bushcraft but not too “light walking”)
- … or a simple car or truck sun visor.
Note that there are double-skin hammocks, which have a kind of “pocket” to install the mattress.
If the mattress can suffice in mid-season, you will have to think of something “heavier” for the winter.
This is where the under-hammock, also known as an underquilt or under blanket, comes in.
Underkilts are covers, usually made of synthetic fibre, that allow you to insulate the underside of your hammock.
Combined with a mattress, you can stay warm down to negative temperatures of -5°C to -10°C.
Feedback from Thomas (A loyal reader).
As a loyal reader of Prep4War.Com, Thomas has kindly agreed to present his under blanket to us (photos above and below).
This is a Carinthia HUQ 180 Underquilt.
- The attachment system: he prefers, when possible, to separate the hammock and the under blanket as much as possible. However, it is of course possible to attach the upper attachments of the under blanket to a higher level of the knotted rope for example.
- Once inside, it is possible to “close” the under blanket using the side loops and small elastic ties with a carabiner. In summer, he only uses the under blanket, without down, even if the night is cool (10-15°).
- He has already used it as a floor mat with leaves underneath, the exceptional times when he could not put the hammock. “It’s not as good as a quality floor mat, but it helps out”.
- In general, he is always with him. Summer: alone with the hammock and the tarp (heavier configuration than the duvet + sursac, but more comfortable and adaptable). In mid-season and in winter: it is obviously heavier than a floor mat but you gain a lot in comfort.
- He is also part of his bug-out bag: “if it can help improve the comfort of a picot bed, we’re not going to spit on it! And I also thought of using it as a blanket if one day I have to protect myself from the cold in a car, for example”.
Rule #4 – Put on layers and layers of clothes
Another essential for warm bivouacs is of course your clothes.
The most important of them in my opinion: is cold weather underwear (socks, underpants, long-sleeved t-shirt).
They are thermal, warm and hygienic since they allow moisture to escape.
On top, depending on the outside temperature (and your chilliness), add an under-sweater, fleeces and large wools. Do not hesitate, if necessary, to multiply the layers.
Finally, don’t forget your hood or hat.
Rule N°5 – Put a hot water bottle between your legs
Ahhh, the traditional hot water bottle.
Something old, but something not unpleasant when it’s not hot.
Place an insulated water bottle, filled with hot water, between your legs to create a heat source in your bed.
Indispensable if your body is “cold” when you go to bed. Otherwise, you may have a very hard time warming up.
Bonus – Cunning with Survival Blanket
The survival blanket can also be used to prevent heat loss in your bed.
It can be placed under your hammock, like an underkilt… or some people use it directly under them, like a mattress.
On the noise side when you turn around, I am personally not convinced.
Another option: you can sew it directly inside your hiking poncho, and use it as an under-hammock.
Useful for the bivouac, but also during the day.
Some DIY ideas to protect yourself from the cold…
If you have a limited budget or if you like to get your hands dirty with your equipment, here are some ideas for creating your own hammock or gaining a few degrees in a bivouac!…
Create a hammock with an integrated floor mat
The creation of such a hammock requires a little meticulousness.
However, the idea is very ingenious because this floor mat will both contribute to the insulation and the stability of the sleeping area.
You will need :
- a floor mat
- 10mm polyester ropes
- of nylon fabric, breathable and resistant
- Cut your mat to the following dimensions: 180 cm x 50 cm
- Cut your fabric so as to obtain a square of 200 cm / 200 cm, then fold it in half
- Make about ten reinforced incisions at the level of the two widths of the rectangle
- Lay the carpet in the middle, secure it and sew all the openings.
A hand-made tube duvet
If you want to make a “homemade” tube comforter, there’s a quick and easy way to do it.
All you need is some sewing skills.
- Cut a hole at the end of your sleeping bag and reinforce the edges of the gap so that it does not widen further.
- Then put your hammock in it.
And now, voila!
Make an Underquilt
To create a homemade sub-hammock, you will need no more than two elements.
It will suffice to sew a sun visor (for a car or a truck) inside a hiking poncho, then to attach the latter, during the bivouac, below the hammock.
Setting the device to the correct voltage may be a bit of a hassle, but isolation is guaranteed.