Northern Ireland Outdoors Forum - Hiking, camping and more

General => Gear Questions, Information, Reviews and Competitions => Topic started by: andy1984 on January 24, 2011

Title: Bivvy Condensation
Post by: andy1984 on January 24, 2011
Hi All,

Managed to get a very last minute night out in the bivvy ( first time!) on saturday night. Camped up just at the end of lough shannagh!! was a great night, i'll write up a review a bit later when i get pics on the computer.

I was ok all night in general, warm enough for most of the night although a few cold spots just before morning and i noticed in the morning my sleeping bag was quite wet with condensation.

I was in a hunka xl bivvy and my bro was in a army gortex one, we both had the same problem. we both had the bivvy done up with about a 4 inch hole for breathing out of for most of the night. I dont think i'd have liked to have been out a 2nd night with the damp down sleeping bag, i have a feeling thats why i felt more cold towards morning ( as the bag got wetter).

Does anyone else have this problem when in the bivvy?
Title: Re: Bivvy Condensation
Post by: twentyclicks on January 24, 2011
Hi Andy,

The hole will allow some ventilation, but unless you are breathing directly out through it, any moisture in your breath will quickly condense on the cold surface of the bivi. Even if it is directly over your mouth, but say 6 inches away, breath will still seep into the bag.

Personally, unless it is raining, I leave the bivi quite open around the head area. When it is worse I usually only close it to 'face size' and tuck it in around my chin to protect the sleeping bag: as a side sleeper, I can turn out of the wind and sort of 'peak' the bivi over the top of my face/head to keep it out of my eyes. I guess if spindrift was about the same would apply.
Title: Re: Bivvy Condensation
Post by: RedLeader on January 24, 2011
Sounds like you needed a bit more ventilation. I've never noticed much condensation but I've never had mine pulled that tight round my face.
Title: Re: Bivvy Condensation
Post by: andy1984 on January 24, 2011
cheers guys,

interesting that you havent had the same problems, it must be a ventilation problem.

I lay with my head out from below the tarp to look up at the stars etc, and in the morning everything was covered in dew / frost so i would have thought that if i had of left the bivvy open then the bag would have just got wet with dew?  :-\
Title: Re: Bivvy Condensation
Post by: RedLeader on January 24, 2011
I always lie with my head under the tarp and the bag not pulled tight at all. There are some hardy types on here who scoff at tarps and just sleep in the bag, they'll be able to shed some light.
Title: Re: Bivvy Condensation
Post by: Tim on January 24, 2011
On my summit camp on Doan i was using the Rab storm bivvy, which has a sort of half-circle zip at one end. I had this unzipped all night with the top section that would be covering my face folded down onto my chest, just so I could look up at the stars all night. I woke up in the morning completely covered in frost from head-to-toe on the outside of the bivvy bag and the top of the hood on the sleeping bag that hadn't been in the bivvy bag, but the sleeping bag was bone dry in the morning. This was on a very clear night with no wind so luckily I didn't have to zip up at all, but no matter what bivvy bag you use you will inevitably get some condensation on the inside if any of your breath has the chance to get between the bivvy bag and sleeping bag. Unfortunately it can be pretty unpleasant leaving any sort of a breathing gap in nastier weather, which is a big problem with bivvying.