Sleeping bag footbox condensation

replace the bottom panels of pertex with Goretex material, any thoughts? 
I think you will still get condensation forming.
Realistically, your shelter is too short for YOU. Get a longer shelter.

Cheers

put the fleece or synth poofay over the footbox

itll prevent internal and external moisture

slick fabrics such as rain shells and windshirts dont work as well for that

Problem solved …. Thats all therr is to it

;)

I’m tall, too, and agree with Roger–you gotta get a longer tent. It’s a simple, but not easy, solution. There are very few tents that accommodate tall hikers.

I think we should step back and look at the bigger picture: why are you getting so much condensation and why are you touching the end of your tent?

With the duo-mid the issue of hitting heads and feet and getting too much condensation is usually a result of pitching it too low so you loose the space and it can’t ventilate. I have lots of friends that pitch too low trying to get some warmth out of single layer tents only to get massive condensation and loose space.  My Zpacks Altaplex (which is basically a ‘mid) has the same issue for me at 6’1″ where if I pitch it low I get feet touching but if I pitch it properly at about 6-8″ off the ground I have plenty of space. When pitched low it also fills with condensation (even if I leave the door open) but when pitched properly it hardly gets any. The MLD duomid at 9’ it seems like you should have plenty of space even if you are 6’6″ if you are pitching it high. I haven’t used the Hile but specs say it’s about 7.5 feet long so I can’t imagine why you are hitting the end of that unless you are a NBA player?

Unless there’s some other bit of info we are missing (like that you are 7 feet tall and backpack in ultra humid swamps all the time) I’m hopeful that a change of your pitch on the duo will be the simple solution you are looking for.

im not quite sure where james is from … but if hes a from the UK (rab bag user) … then my understanding is that there can be quite a bit of wind blown rain in the UK …

where there is such conditions, you basically need to pitch low or youll get quite a bit of rain blow through …. or you can use a solid inner

you can read about a BPLers issues with it in a duomid here …

https://backpackinglight.com/forums/topic/mld-duomid-condensation/

honestly for just plain jane “condensation” … with a pertex endurance shell and rab DWR down n good condition … i wouldnt worry one bit about it especially if you put yr fleece/puffy over the foot end

in cold wet enviroments, youll often get condensation no matter what … ventilation or no

;)

I am indeed from the UK but I am using this gear on a world bike/hike/packraft trip, currently in northern Sweden (i.e cold and condensation central). Both shelters are actually very good for venting, but if you camp out in those temperatures every night you will get some moisture. I’m 6’1 but have to account for a large, lofty bag and I lie with my feet straight (most comfortable after a while). I might try a superlight bivvy, my puffy works well enough unless I move too much.

Zip up your WPB parka and cinch the hood down. Pull it over the foot of your sleeping bag and you will be fine.

I came across this thread and wondered: To prevent a wet sleeping bag footbox in case it’s touching the sidewalls of your tent. Is it better to cover it with a fleece (good enough to avoid direct contact), or a rain jacket (might block internal moisture)?

I’m using my Duomid all the time now except for in high mountains. I think the length thing is down to using a thick pad, due to the angle of the walls it decreases the length a fair bit. I’ve been using an MLD superlight bivvy, it does the job if you brush against the walls and is breathable, but will still wet through if you leave feet pressed against the tent wall all night. In the mountains I put my belay jacket at the foot end, against my sleeping bag dry bag, it does the job.

Have you tried two poles to set up the Duomid and sleep on the diagonal?
It works for me.

I had the same exact problem with several of my Hilleberg tents as they are too short and allow the footbox of my down bag to touch the inner tent end wall.

And as mentioned when on top of the sleeping pad and counting the high loft of my down bag the angle of the end wall is more pronounced and therefore the tent is shorter (due to the height of my sleeping system).

Since condensation is an inevitable fact of life with tent living, esp in the winter—all efforts should be made to find a shelter that does not touch any part of the down bag’s shell.  Finding a tent with vertical head and foot ends solves this problem unless you’re 6’5″.

Hilleberg’s recommendation to compensate for their short tents is to place a rain jacket over the footbox of your bag.  This does not work because a layer of frost/wetness can form between the shell and the bag.

So when sitting up in our tent in the morning after a cold night in the snow, I have to be very careful not to let my head brush against the inner tent.
Or there is a shower of ice crystals down the back of my neck just as I am waking up.

Cheers

Thanks for the replies.. it’s an interesting topic. I think a rain jacket would work since it covers only a small part and the humidity would still be able to escape. The difficulty is probably that it won’t stay in place ..

A fleece might work better and should have the same effect as the wetness is usually only at the surface – however, the fleece will get soaked over time and that’s not an option either if you need it the next day.

Possibly wrong on both counts.

The small area of a jacket will not alter the situation when the air temp is so low that the jacket fabric is below the dew point. The humidity will not escape; it will condense.

The fleece might not get soaked as much as you might have expected. For sure, if it is spread over the foot box AND it is pressed up against the tent fabric, there will be condensation.

Really, what you have to do is to get a longer or bigger tent. There are no short cuts at -10 C.

Cheers

The quick, cheap, light solution might be to cover the footbox with a kitchen size trash bag.  It would still breathe since it would be open around your thighs.

As others have said, the long term solution is a new tent.

Extra length of an 1/8”-1/4” foam sit pad would help in this situation.

Basically, you need a higher tent wall to prevent touching it. I have the old Dyad 2 that condenses a LOT at cold temps, but this is also due to the size. Even with the extra length, everything gets a bit damp. But, the extra length also keeps my feet from touching the sidewalls. It doesn’t seem to help a lot though. The small Dyad (not much more than a glorified bivy) just condenses. It is not a cold weather tent. The humidity inside reaches the dew point and condenses all over, including my bag… Not much you can do except 1) Raise the tent off your feet, or, lower your sleeping pad 2) avoid touching the walls with your bag (You knew that) 3) Increase the internal volume to mitigate overall condensation 4) Cover the foot end of the bag 5) Increase overall ventilation.

I do not believe Gortex will help that much. Gortex will pass water vapor but not water. Condensation will still drip down from above, wetting the shell/down.

Raising the Tent:
Often, you can find a small concave area to set up in. While this can trap water from rain, it also has the effect of raising the tent a bit. In cold weather, water is of no big concern, it is snow. This is also against best site selection practice. You can also use a rock under each pole to lift the whole tent up a couple inches. (This also improves ventilation.) I am surprised you have trouble with the Jannu, though. This is a double walled tent that usually keeps the inner/people from touching the outer and commensurate condensation. When using the Duomid, often a 6″ cord on each loop is enough to raise the tent a bit. But, this also leaves a short gap under the edges. Anyway, changing setup location (and/or using a bit of guyline) is perhaps the cheapest option.

Lowering the sleeping pad:
Slightly more expensive, you can switch to a short inflatable and a short CCF pad under your feet. This will give you another inch or two above your feet. This may or may not be a good option for you. In some cases, I have tried a pad UNDER my tent allowing the tent to be raised slightly. It works OK if you also carry a CCF pad for directly under you. But in very cold weather (like -20F or -7C) this may not be an option because of the need for better ground insulation. But, it easy enough to raise the tent, slip your pad under it resulting in a couple inches (5-6CM) more foot room. A reflective IR sheet (emergency blanket) will help, but may already be present in a full Neoair. Two does not help more than one.

Covering your feet:
This will work in most conditions. Sometimes, it may make things worse. The majority of condensation will occur at the first cold/warm interface between them. So moist humid air will condense on the inside also. In cold weather, do NOT expect it to evaporate. Fleece might work better in warmer conditions or if your rain jacket is already wet from the day. Again, depending on temp/humidity, fleece may soak through distributing water along a greater area of the foot end of the bag making things worse.

Increasing the Internal Volume of the Tent:
This is just something that will help. Often, increasing the internal volume is a simple matter of raising the tent. Other times, you will need a larger tent. A larger volume of tent air will allow more humidity in the air without increasing the amount of associated condensation. This means changing the tent, usually, and is the most expensive option. But, you may find that you need a somewhat larger tent anyway. A dome allows the greatest amount of area for the least amount of fabric. This can also be a detriment by concentrating the condensation in the smallest amount of surface area… With a double walled tent, no one usually notices this effect. But, with small solo tents, it is pretty obvious.

Increase overall ventilation:
This has been touched on, but often you can do things that will help ventilation a lot. Raising the tent will help. Increase the size of the vents. Make sure to maximize a natural flow: in is low, out is high. Add a smaller candle lantern to the peak vent. Leave the door(s) open. Open all screening on the vents. Set the tent up in an open area. Some practices may be conflicting, like open doors in a rainstorm, or, setting up in a wind swept area at -10C, but thinking about it should allow better campsite selections, sometimes.

kitchen size trash bag. It would still breathe since it would be open around your thighs.
Wrong.
Sorry, but just wrong.
If the plastic bag reaches the dew point, water vapour WILL condense on it, and transfer to your bag. This is basic physics. And yes, I did try this once when I was a small Boy Scout.

Better (controlled) ventilation through your tent plus a double-skin design are the only things which work. The frost then forms on the inner tent.

And if you are sweating much inside your bag, or trying to dry wet clothing, and the surface of your bag drops to the dew point, the condensation will form INSIDE the outer shell of your bag. Again, this is basic physics.

Cheers

“Better (controlled) ventilation through your tent plus a double-skin design are the only things which work. The frost then forms on the inner tent.”
Uhhhhhh, OK. Confusing….You must mean the inner side of the outer skin. English, what a strange language…

Hi James

Sorry, no. I have often had frost on the inside of the fly when camping in the snow, but that was not what I meant. I meant a layer of frost on the inside of the inner tent. It is all a bit complicated, and depends on the amount of wind and how the inner tent is closed.

We know that the human body gives off water vapour while asleep. That water vapour will condense on any surface which is below the dew point. These are basic physics. But the human body also gives off heat, which warms the air inside the inner tent. The devil is in the detail: how much and where.

If the night is not too cold the inner tent may stay above the dew point. In this case the frost or condensation may form on the inside of the fly or outer tent. Hopefully, any drops falling off the fly will be deflected by the inner tent.

If there is a gentle breeze, that can sweep the water vapour in the layer between inner and outer tents away, with little getting to condense. In this case you wake up in the morning with a dry tent. That’s wonderful.

On the other hand, if the ‘gentle breeze’ is really cold it can chill the inner tent down such that it falls below the dew point and you get condensation forming on the inside of the inner tent. If the inner tent is cold enough, this condensation forms as frost. It depends on the balance between temperature and humidity.

If there is a bit of a storm going on – the same physics applies of course. You might or might not get condensation of frost: it all depends on the balance. This can be unexpected: -5 C and a strong wind can result in a dry tent!

If you have a really still night there are two possibilities. If it is warm enough then the layers of fabric stay above the dew point and all is well. A dead calm summer night fits this. On the other hand, if it is a bit cold and there is a fog outside, your water vapour may linger inside the tent and condense on the inside of the fly. You can wake up ‘slightly damp’, even though the overnight temp was >0 C.

All this is without considering the infra-red energy balance. On a clear night the sky can be effectively at -70 C, and heat loss from the tent fabric to the sky can be significant. Now, how that heat loss balances against the heat flux from your body … complex! What we can say is that a double-skin tent not only traps warm air inside, but it also cuts the IR heat loss significantly.

Cheers

I agree with Roger.  A two wall tent will get frost on the inner tent canopy depending on the weather.  It’s a common occurrence.

Sometimes when I pack up such a frosty tent in the morning all the ice gets dislodged and on set-up later that day at another campsite this ice is on the tent floor and can be swept out.  Sometimes it amounts to a liter or more.

And in the Southeast winters there’s plenty of inner tent condensation to go around—

Well, I can follow all that. Again it depends on outer tent height and ventilation. My old Sirius has looked like the pics Tipi posted, but as far as wet condensation, almost never. I agree the inner tent does get a bit damp though…

I remember one time we packed up at the end of a ski trip and drove 6 hours home. Next morning I hung the tent out to dry – and the ice fell out.

Cheers

In the Duomid, I’m usually using a Zlite, which is a lot thinner than a Neoair Xtherm, giving me just enough length to avoid either end. I just use a single pole set up for convenience.

In the Jannu, it is condensation on the bathtub floor, rather than the inner material, I’m assuming as it is less breathable. On my last mountaineering trip, we left the Jannu set up at 3400m and did not have too many issues with parkas over our feet. We packed down the inner separately and it was dry when we reached the valley. I’m currently planning a long distance ski tour (1500km) and will probably take the Duomid, groundsheet and a heavier duty bivvy bag, so I’m sure the system will be tested.