Hilleberg Nammatj 2 Condensation

[Willy P]

Hey,
I've got a Hilleberg Nammatj 2 and I can't control the condensation. I mainly use it in the Sierra for ski mountaineering / touring above tree line. I open both the vents all the way the moment i get in. By morning the inner tent is coated in frost and condensation.

I've read a lot here and on Hilleberg's site about condensation in their tents. They are vague on one front, should I be using a ground cloth in snow? When I decamp the snow beneath the sleepers is melted out and the platform is lower. Does that mean moisture from melted snow is rising between the inner and outer walls? I own a ground cloth but I like to dig a foot ditch in the vestibule and it would get in the way. I suppose I could cover the vestibule portion when I go to bed.

Generally speaking, does the ground cloth prevent moisture from rising from the ground and getting between the inner and outer tents? If so could I cut out the center of a ground cloth to make it lighter? So all it did was block the thin space between the inner and outer walls and the vestibule?

Appreciate the help…

[Joshua Billings]

I have trouble with condensation sometimes also. Does this happen even when it is windy? I use mine only in the winter so bugs aren't a problem. I leave the fly partly open under the vent unless spin drift is flying in. I also leave the door of the inner tent open all the way or open at the top. The tent I have has a lower vent also at the back that I leave open for more air flow.Like you, I also like to dig a foot trench at the vestibule.I extend this trench beyond the end of the fly by a foot or so for more lower air flow. If there is no wind, condensation can still be a problem and for this reason I bring a bandanna to wipe the inner tent if need be. As far as a ground cloth I actual use it inside the inner tent. Not sure about your question if the ground cloth would help with condensation.These tents are awesome in the snow and wind and in my opinion that is when they should be used.

[Willy P]

It's funny, I always have either insane wind where I am glad to make it through a night, or no wind. The no wind nights are bad for condensation. I've done similar tricks where I radically opened up the tent and it helps, as long as the weather allows for it. But honestly, what's the point of spending all this money on a tent if I'm going to get wet anyways or I have to leave it open to the point where I might as well use a tarp :)

I'm going to try the ground cloth. But from reading around, it seems like condensation is unavoidable in 4 season tents. I'm fine w/ that, as long as it's not on the inner tent.

Thanks for your help.

[Charles Jennings]

You may want to consider bringing along a UCO Candle. I have done that to help dry up the condensation.

[David Ure]

Yes – try the ground cloth in the vestibule – I found that did make a difference in the Akto.

[F. Thomas Matica]

A just have a few windless nights in an Akto. Lots of condensation. I haven't tried every combination or solution to this phenomenon, but I can readily identify with this issue.

My breath condensed on the inner tent near my face. The outer had plenty of condensation which dripped onto the top of the inner tent. It was above freezing. I dropped the inner tent and wiped this outer down with a towel and then picked up any drips and water that was on the inner tent. This is a hassle. This was with the doors zipped and all of the vents open, trying it out in the backyard.

I'm not sure that I need two walls for the cold camping that I might be doing. I have a Shires Rainbow and the condensation is easily handled since I can wipe down just about the entire inner side of the canopy while still inside the tent. Lots of room to do this. I also can wipe down during the night if the water has built up too much. It would be nice if the single wall Tarptents had storm flaps or wind blockers for cold or windy conditions to shut out the built in breezes that accompany that design. I guess adding them could be done.

I've been studying Roger Caffin's tent designs. It looks like some that he describes have a pretty closed up design with good vents built in. They look like double-walled tents without the inner tent. I see a few of this type of design from other manufacturers, but nothing as nice as Roger's, in my opinion.

Any rumors about upcoming designs from Shires or Caffin going into production would be interesting???????

[Roger Caffin]

It's a bit more tricky than that.

The windward end vent at the top on the single-skin summer tent can be closed up in bad weather, yes. But there is also a 50 mm gap between the roof and the ground all around the edge of the tent. The idea, which does work, is that cold air can come in at ground level and pass out at the top vent, driven by the heat from two bodies. The down-wind vent is always open for this. Any breeze through the top vent just helps.

The double-skin winter snow tent has a sod cloth around the sides and windward end. This cuts off any circulation from ground level, which is sad but utterly essential in a howling storm. (See 'When Things Go Wrong' for pictures.) The windward end vent can be sealed up as well. Of course, there is that much 'pumping' of the tent shape in a storm that you don't need to worry about air movements anyhow!

However, should the night be fine and mild the sod cloth can be rolled back/up and a gap left at ground level. Then it works like the summer tent.

Production – I wish! Still searching.

Cheers

[Tim Heckel]

Certainly there will be moisture from the ground/snow. I can never find the condensation article from a couple years ago on BPL by Will Rietveld, but I have a copy on my desktop. It is excellent, if you can find it. From that article "Water vapor from the ground or vegetation exposed within the tent can be trapped within the shelter and significantly raise the relative humidity level."
I use a ground cloth under the vestibule in my Akto.

[Willy P]

@Tim
Do you have a ground cloth that -only- covers the vestibule or a total ground cloth?

@everyone
Thanks for all the insight. I'm going to go sleep outside a few nights this week and test the ground cloth / candle theory.

Also, do the hilleberg's with vents on the top, like the Jannu or the Allak vent better than the tunnel style tents?

[Roger Caffin]

> do the hilleberg's with vents on the top, like the Jannu or the Allak vent
> better than the tunnel style tents?

Imho – the question is a bit too generalised to get a definite answer. I know my tunnels vent very well; I have seen others that don't.

Cheers

[Willy P]

@roger
Excuse me, would the Allak deal w/ condensation better than the Nammatj?
Thanks…

[Roger Caffin]

Hi Willy

> would the Allak deal w/ condensation better than the Nammatj?

(Drawings from Hilleberg web site.)

Well, both have vents up near the top, so both should handle ventilation moderately well under mild conditions.

However, these are seriously different tents! Comparing them is not easy.

The Nam is a tunnel tent suitable for extreme weather conditions, including wind and flying snow. When the wind howls you shut the vent to the windward, and leave the downwind vent (or door) open a bit. Air will move … :-)

But what can you do with the Allak? Can you seal those top vents against flying spindrift? I don't know, but if you can it looks as though you would be left with no ventilation. That might mean a sauna bath – or a frost chamber. If you can't, the Allak may fill up with spindrift.

Cheers

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