2ering

This year was to be my entry into the world of bicycle touring. Bought all the gear but the double-whammy of the destroyed housing market and my daughter's decision to attend a pricey out-of-state college limited me to only a couple of long weekend forays. Well maybe next year, or in 4.

Anyway my question concerns waking up in my double-walled tunnel-style tent with the top of my sleeping bag quite damp & wondering if it is a result of poor tent design or an unavoidable occurrence given the conditions. I didn't find any dampness on the tent floor (even under my mattress), sides or ceiling. Nor were there puddles anywhere. The tent's exterior, grass & cars in the KOA were all covered with heavy dew. Some nights I kept the doors open with just the netting covering the doors while other nights I buttoned up the doors, but every morning found the sleeping bag damp. The dampness wasn't a problem with my tours earlier in the year, or at least I didn't notice it, nor did I notice any dew formation. I assume it is unavoidable given the heavy dew formation, but if anyone should know the answer it would be people in this forum. Thanks for your help.

FlowerBlossom

Don't take it personally, but, the problem is likely you. Your breathe is moist, your body leaks moisture from pores. The moisture accumulates in a small space pretty fast, especially if there's no air circulation. Can you open a zipper or window to let some of this moist air out? Not sure where you are touring; mosquitoes and other biting insects might make this an unreasonable suggestion.

DuckFat

Yeah, try opening an upper flap a bit more to let out the moisture and excess heat.

Camel

Happened in my single wall (Eureka Zeus EXO 2 classic), untill I figured out how to properly ventilate it. Play around with your vents, in mine I used a small stick to keep the upper vent open.

I sprayed the outside of my down bag with tectron water-repellent. It's not a water proof, but makes water bead up & roll off. I use a vapor barrier liner inside my bag, so I wasn't worried about my condesation building up inside the down (as much). I did dry/air out my bag when the sun came up.

Losligato

I absolutely love Hilleberg tents... but this is the one negative thing I have heard about them. We camped next to a guy in a Hilleberg Keron 2 for two nights. Both mornings he woke up and had to dry his sleeping bag in the sun while we had little or no condensation at all.

Is your tent a Hilleberg?

CardiacKid

You might try and find a small piece of Tyvek house wrap to put on top of your sleeping bag. It should keep your sleeping bag from getting wet. You can just shake the water off it in the morning.

fthomas

Venting - that is the key. I have four tents and one bivy bag. What you are describing is a result of not getting a good flow of fresh air. Try and vent at the bottom of the door and the top of the other door or tent walls themselves. A Goretex bivy can be really bad about this particularly in very cold weather where your respiration turns into condensation. I have even had a layer of frost inside tents and the bivy bag from improper venting.

What are the night time temperatures and humidity. The Dew Point can also tell you a lot. The closer it gets to the temperature the more condensation you may have and when it gets even with the them you've got fog.

2ering

Thanks for the responses. My tent is a 2 man Hilleberg Kaitum and I too had heard about condensation issues with 4 season tents but how much more can I improve ventilation than having both ends, including the vestibule doors, open--which I tried. Not sure of the nighttime temps/humidity/dew points but when we started riding around 8am it was 53 deg F with daytime highs in the low 80's and we were riding in northern Indiana. There was a fairly heavy rain one evening for an hour or so. Now that I'm thinking about it what about the grass which should have as good ventilation as possible yet it was dew covered. Taking a piece of Tyvek/plastic sounds like a good idea otherwise I would have to dry my bag out each morning, too.

fantom1 

It depends. I had a Big Agnes Seedhouse SL1, supposively one of the best ventilated tents out there, and the only times on tour I didn't have condensation was in the high desert.

If there is enough moisture in the air and the dewpoint is right, you will get condensation on the cold surfaces regardless of ventilation.

NoReg

I'd say the tyvek is a bad idea. It's noisy stuff in most cases, and it will just trap moisture in your slepping bag, It might stop your breath from condensing onto your bag but that should be solveable. I would work on the ventilation and also on the realization that while most nights in a tent shouldn't be as bad as you have experienced, it ain't the Waldorf either, and temperature control, condensation etc... is a problem. It can be "so bad" in winter you need a dew absorbing liner, though I confess to never have needed one myself.

It's all pretty basic stuff, if it's a hot and sweaty night, it doesn't get better living in a plastic bag with poor air circulation. You may wish to bone up on tarps, but where I live, not so far from you the bugs are a big problem and one can only ventilate through midge netting so much. Also keep in mind that one doesn't need a bag at all times, that can get you over hot to start with. 53 deg should be pretty nice sleeping weather, really.

Al Downie

I overheat in sleeping bags pretty easily, and that certainly exacerbates any underlying condensation problem - that last thing I'd do is add another layer of non-breathable material over the sleeping bag! The best solution (after making sure that the tent ventilation is maxed-out), is to open the bottom zipper on the sleeping bag, from the feet up to about waist level, so every now and then I can stick my legs out into the cold air, and then wheech them back in again if its too cold. I also bought a bigger tent (Nallo GT 3) so two of us aren't squished up against the side walls.

I also make sure that, when I'm setting up the ventilation, I pull/cut/flatten any long grass around the base of the tent which can disrupt any tiny breeze.

fthomas

I adhere to "Leave No Trace". With that said, the dew you describe on the grass is a result of the Outside Air Temperature (OAT) and the Ground Temperature creating Dew. Think of a glass of iced tea sweating on the outside of the glass or the air conditioning in your car, which also acts as a de-humidifier pulling the moisture out of the air - Cold Piping contacting Hot Air with Humidity. Cooler air temp and warm moist ground along with Dew Point temp.

Bivy Bags and Single Wall Tents are notorious for drenching you inside from your respiration. So a bivy can be a real problem if it doesn't provide a way to ventilate your respiration making it useless.

The Clip Flashlight CD is one of my favorite tents with a lot of netting to vent through. It isn't as nice a tent as the Big Agnes nor as roomy. Regardless; It is still important to keep the fly off the ground to allow circulation around and through the tent as well as keeping vents open where available.

I have always wanted to own a Helleberg after seeing a couple of reading the manufactures info and looking at the specs. Of all the tents I can think of the Helleberg should be one of the least likely to have condensation problems.

I have found over the years that most, not all, condensation problems for campers is a result of operator error. As I mentioned above the fly needs to allow for circulation (even in temps as low as -15 degrees Fahrenheit - I wasn't touring) along with keeping vents open in the inner tent walls and doors.

One other small and simple item can help with venting and that is a candle lantern hung from the ceiling. It will heat enough air to get the air flowing.

zoltani

great post tfhomas. I don't really have much to add, just want to give my personal experience with my Big Agnes emerald mountain SL2. When i first camped with this tent i was lazy and did not stake out the guy wires of the fly. This caused the fly to touch the mesh body of the tent, which led to condensation. The second time i went out i made sure to stake out all/most guy wires to make sure the fly was not touching the tent body. When i woke up that second time i was dry, no condensation. The weather/temperature conditions were about the same, mid to upper 40s.

This past weekend i took the tent out for a night in a fog heavy area. The fog collected on the trees and the "rained" down on us all night. The fly was completely soaked on the outside, but since i made sure to stake everything out the inside was dry and we were quite comfortable.
One thing i noticed is that the rain would roll off of the fly and then splash in the puddle. Some drops from this splashing was hitting my face. Any way to take care of that? It wasn't such a big deal, it only happened once per 30 min to hour, but it was just kind of annoying.

Bekologist

despite all venting techniques, the dew point can be triggered soley by body heat and perspiration between the user's temp and the outside air, and it is usually in or near the sleeping bag.

additional perspiration from a human raises the dew point in/on the sleeping bag, which then 'creates' moisture out of water vapor....there's no water vapor transpiring from the tent or tent floor.

tent sounds ventilated well enough if there's no canopy or floor condensation.

don't worry about a little moisture, just air out the sleeping bag. or get a VBL. (stinky!)

ken cummings

Minor techniques: If there is a prevailing breeze aiming the entrance of the tent into the breeze will give more flow through of air. A slightly higher area can often give more breeze and slightly warmer/drier air then a low pocket.

The Smokester

I agree with all the above great advice. In my experience, sleeping in a snow/ice cave is the ultimate high-humidity scenario. I have a down sleeping bag made of Gortex and that has solved the problem even in the most severe cases (except direct exposure to rain).

Juha

I too wouldn't blame the tent. Hillebergs are excellent tents, wish I could justify the cost...

But do try and maximize the ventilation. Besides keeping all the vents open (this you have done already), make sure you pitch the tent up correctly so that the two tent layers don't touch each other anywhere. Depending on your tent design, you may be able to pull the outer layer slightly further apart and off the ground with ground stakes. This will only affect the lowest few cm:s of the layer, and in some terrains it won't be practical or make much of a difference. But it does give more space for air to circulate from beneath the outer layer.

And as mentioned before, sometimes a little moisture is unavoidable. I wouldn't wrap my sleeping bag with anything. That may help in keeping the moisture off the bag surface, but it will increase the moisture inside the bag (where it really counts, and not in a good way).

--J

Bekologist

in winter conditions, a savvy winter traveller has a synthetic overbag for use with their down bag....the dew point moves out into the synth fill of the overbag, preventing 'dewpoint' condensation inside the down if the camper only uses one huge winter bag (where the dew point remains in the down insulation layers).

...just food for thought.... not relevant to bike touring - unless you like to go winter bike camping!

https://www.youtube.com/watch?v=6ORO_nxEba0