Condensation in Single Walled Tents


What a dripWhat a drip
I don't know about you but when I'm sleeping I find it slightly irritating having water splashed in my face. Because of this little foible, I've decided to offer up a few handy tips on how to keep the waters at bay.

Firstly, I'm going to assume you are sleeping in a tent and not a bath with your head tap side. Secondly, I'm going to assume it's a single walled tent since single walled tents are where you can expect a bit of nightime dripping.
Condensation
As you know, the drips are usually not because your tent is leaking, but are due to condensation forming on the walls of the tent. When the condensation gets too bad the water drips off. A brief description of how condensation forms is probably a good idea.

Condensation is when water vapour drifting around in the air converts into liquid form. This happens when the air temperature drops below the dew point. According to the easiest place to get a unreliable definition, Wikipedia, the dew point is 'the temperature to which a given parcel of air must be cooled, at constant barometric pressure, for water vapour to condense into water.' Which means when the air becomes saturated with water, the water vapour condenses to water usually on a cold surface (your tent wall). Temperature is a factor in this process because the air can hold less moisture at lower temperatures which is why condensation forms more easily at night. Obviously I have made a mockery of the scientific process by simplifying it so much, but as a camper who wants to avoid drips and doesn't like physics this is all you need to know.
Condensation image
So you're there in your tent….
You've finally got your bag toggle from sticking in your eye and your thermarest is feeling like a four poster. You're snoozing. Throughout the night your open slavery mouth will be filling up your tent with about one litre of water vapour. Not only that, but there will be some evapouration from the ground. If you've stored wet clothing in the tent then that will definitely not help and that stunning lake lapping up against your guy ropes will certainly by adding to the moisture. You've zipped up the tent good and proper because of the midges, it's raining anyway, the dropping temperatures are causing the air to become very poor at holding on to moisture… dear, oh dear… in these conditions I suggest you sleeping in your armbands and emergency snorkel.

Conditions where condensation is inevitableConditions where condensation is inevitable
Sometimes there is nothing you can do. If the day has been warm and humid it won't take much nighttime cooling to produce condensation. Since 'warm' is rarely a problem in the UK, probably the two worst scenarios for our climate is firstly just good old solid rain. Rain all day, rain all night. The only good thing about this is that the cloud cover will reduce the temperature drop at night, but then again it won't take much of a drop in those conditions to produce condensation.
Secondly, it rains in the afternoon, and then you have a clear night so you can cook your noodles in comfort. With no cloud cover the temperature plummets and the substantial amount of moisture left in the air turns to water on your tent wall. On days like these all you can do is keep wiping your tent walls and follow these general guidelines.

General Condensation Stopping Guidelines
Air Flow
Condensation hates air flow. Your breath is nicely filling up your tent with moisture, the tent wall is lovely and cool, saturation point is close and then in comes a silly breeze and clears out all the moisture and you have to start all over again. Damn that mesh vent at the foot of your tent.

In your battle (let's make it sound heroic) against condensation, the breeze is your army and mesh vents are your ramparts. Which means tent design is important and so is where you put up your tent.
Tent Design and pitchingTent Design and pitching
Single skin tents should have mesh and vents to help your army get inside the tent. You're right, I will drop the army thing because we're talking about drips and not incoming nuclear warheads. Mesh sides are brilliant, especially when used with high vents in the main body of the tent. Pitch the foot of your tent into the breeze, so air flows through the mesh vents and through the high vents or the front door. Leave the door open as much as weather or midges will allow. Mesh is good but even a mesh door greatly reduces air flow through the tent. Also, pitching the tent off the ground leaving a large air gap along the tent sides is a good idea.
Tents with steep walls
Tents with steep walls are also good. If condensation does form it will just roll off. As with everything there is good and bad, a steep walled tent is great for condensation but bad in very windy conditions because it might blow down. A compromise has to be reached or else you will have to carry a tent for every weather condition. Whatever you do pitching the tent so the tent walls are taut is a must. If the tent is saggy, condensation will puddle and then drip in your eye.
Campsite selection
Sleeping near a river, a bog (by that I mean marsh not toilet), a lake, a tributary, a brook, a puddle, basically anything that's damp will increase the prospect of condensation. Sleep away from these evil places. If you want the romance of moonlight on a silver lake that's fine but pitch your tent a few hundred yards up the hill and walk back down you lazy git. Harsh but I'm just thinking of you. Even a few hundred yards makes a difference. An open area on higher ground will get more breeze.
Sleeping with a friend
We all know sleeping with a friend can get hot and sweaty. In a single skinned tent this is definitely the case. The more slavery breaths filling up the tent the more you have to ensure you get some air in there. If you must sleep with a friend because it's too scary for you alone on the hill, make sure you pick a tent with lots of venting options, leave the door open if you can, and make sure it is big enough for two people comfortably.
Wet Gear
If you store your moist socks (yuk…) and your sodden waterproof inside the tent this will add to the dampness and raise the humidity inside the tent. If it's stopped raining, leave your wet stuff outside, or even better throughout the day whenever there is a ray of sunshine get the wet stuff out and hang it up.

This is especially true with your tent. If you're up and hiking early, I'll bet, all you do is give your tent a shake and stuff it into your bag. It will still be wet. Even if you're lazing around the campsite for a few hours before you set off, morning is never a good drying time. Sometime in the afternoon get your tent out and let it flap around in the lovely breeze and the beautiful sunshine for a while. Do the same for your horrible socks.
Cooking in the tent door
Cooking produces a load of water vapour from the combustion of the fuel and steam during cooking, so if you possibly can, do it away from the tent. Cooking inside the tent is never a good idea anyway, but for the purposes of condensation it's a definite no.
Conclusion
For those who couldn't be bothered reading the rest of this brilliantly crafted piece and have skipped to the end, the only way to beat condensation is to sleep in a chicken suit and cluck all night. The frequency of the clucking causes a harmonic resonance in the drips...

Alright here's the basics to avoid condensation in single-skinned tents:

Get a breeze blowing through your tent.
Choose a single-skinned tent with lots of venting options.
Don't camp near water, marshes etc.
Dry out your gear and especially your tent during the day, if possible.
Cook away from your tent
Hope it doesn't rain.


Thanks for reading.

Ian Young
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