Bivvy Bag Problem

[tom.moran]

i may have some input on this, i too was out hammocking last night AND friday night. friday night no problems everything was as it should be, last night however my hammock was wet under my sleeping bag. i just put i down to changing weather or an unusually high moisture count

 

[ex-member BareThrills]

i may have some input on this, i too was out hammocking last night AND friday night. friday night no problems everything was as it should be, last night however my hammock was wet under my sleeping bag. i just put i down to changing weather or an unusually high moisture count

which hammock is it Tom?

 

[tom.moran]

erm a cheap one http://www.gooutdoors.co.uk/trekmates-expedition-camping-hammock-p110711

the sleeping bag was a jura 2.

also had an expanding sleep mat in the hammock layers, but like i said it was fine friday night but not saturday

 

[ex-member BareThrills]

interesting. sleep mats in the layers will promote condensation as they dont breath but it will be worse depending on temperature differentials / dew point.

It all an education with condensation. sometimes it makes no sense

 

[SJStuart]

I just switched to an e-vent bivvy and so far no condensation at all.

Out of interest, what bivvy are you using?

 

[ex-member BareThrills]

Bugaboo II mate. Got it on offer from needlesports

http://www.needlesports.com/Catalogue/Camping-Equipment/Bivi/Bivi-Bags/Bugaboo-II-Bivy#.UpuxnkDLegk

 

[Tracker NTS-054]

Personally I use a trekmates bivvy, and I've never had any problems with it, I would go as far as arguing that it was one of the best £15 I've ever spent. Just learn from your mishaps and in future have a system where you choose between hammock/bivvy
All the best!
Also, the fact that it's mil-tec can't help! They make good cheap water bottles that do the job but otherwise, just go elsewhere.. All the best!

 

[Bucephalas]

Been there, done that.
I also had problems wearing softies inside a synthetic bag and put it down to the DDTravel hammock. The base is waterproof and doesn't allow air through it so condensation can be a big problem.
Idles your hammock have a breathable bottom?

 

[benp1]

NO bivvy bag will leave you condensation free 100% of the time, its physically impossible in some conditions

Humidity, temperature, dew point etc all play a part. In an ideal world it'll be warm inside and cold outside, and very low humidity.

If your sleeping bag is keeping all the warmth inside and against you, then there won't be enough heat between your sleeping bag and bivvy bag, so the bivvy bag itself is cold (as its 'touching' the outside air), so the water condenses against it (think condensation against the windows inside your car or house). The warmer the bivvy bag is

A cheapish bivvy bag clearly won't help, you want to give it as much help as possible to remain condensation free.

 

[boatman]

NO bivvy bag will leave you condensation free 100% of the time, its physically impossible in some conditions

Humidity, temperature, dew point etc all play a part. In an ideal world it'll be warm inside and cold outside, and very low humidity.

If your sleeping bag is keeping all the warmth inside and against you, then there won't be enough heat between your sleeping bag and bivvy bag, so the bivvy bag itself is cold (as its 'touching' the outside air), so the water condenses against it (think condensation against the windows inside your car or house). The warmer the bivvy bag is

A cheapish bivvy bag clearly won't help, you want to give it as much help as possible to remain condensation free.

Have you tried a TrekMate or is this your theory?

 

[SJStuart]

Been there, done that.
I also had problems wearing softies inside a synthetic bag and put it down to the DDTravel hammock. The base is waterproof and doesn't allow air through it so condensation can be a big problem.
Idles your hammock have a breathable bottom?

It's the Warbonnet Blackbird 1.1 XLC... so, yes, I believe the bottom is breathable.

 

[ebt.]

NO bivvy bag will leave you condensation free 100% of the time, its physically impossible in some conditions

Humidity, temperature, dew point etc all play a part. In an ideal world it'll be warm inside and cold outside, and very low humidity.

If your sleeping bag is keeping all the warmth inside and against you, then there won't be enough heat between your sleeping bag and bivvy bag, so the bivvy bag itself is cold (as its 'touching' the outside air), so the water condenses against it (think condensation against the windows inside your car or house). The warmer the bivvy bag is

A cheapish bivvy bag clearly won't help, you want to give it as much help as possible to remain condensation free.

Pretty much spot on.

I was out the other night, snugpak travelpak3, thermals, army gore bag. Woke up a bit too warm, with frost on the outside of the bivi and condensation on the inside. I guess the campfire burrito the night before was more than enough fuel (nothing to do with 1L of westons finest)

 

[benp1]

Never finished my post for some reason.

What I meant to say was the warmer the bivvy bag is then technically the more gradient you’ll have either side of the bivvy bag and so the less condensation you’ll have, but then you’ll also be losing heat by warming that bit of space, rather than warming the space right next to you, so its probably more inefficient

I haven’t tried the trekmates bivvys, based on the few things I’ve had from trekmates I suspect its at the cheaper end of the scale. I’m sure its perfectly functional in the right conditions, but it’ll be harder pushed as conditions aren’t as favourable.

I’ve had a few bivvies, the only two I currently have are the army camo MVP one which has been a lender and very robust for mucky use, and a custom made PHD one. My problem with bivvies is I’m tall so unless they’re long enough its either uncomfortable or just doesn’t let my bag loft

 

[ged]

I can't speak for the Mil-Tec products and I don't know what the problem is here, but it's a little surprising to me.

I have two breathable bivvy bags, the standard issue one and a Terra Nove Jupiter which I bought about fifteen years ago from a place in Bath.

Neither gives me any trouble with condensation, and believe me when I say that if anyone is going to get condensation problems, it's me.

Occasionally I use the issue one in a cheap non-breathable DD hammock, and even then it keeps me dry as a bone.

I find that a hot water bottle is really effective at driving away moisture, especially near the feet which tends to be the coolest part of me when bivvying, but it's just moisture which collects on the outside of the bivvy bag, not in the bag with me.

 

[ozzy1977]

I guess it partly boils down to quality of materials, the issue ones whether its the us one which the mil-tec is a copy of or the UK army one are made out of the real deal Gore-Tex, where as the mil-tec one is not.

 

[SJStuart]

Here's a thought... if I wrap a wool blanket around my sleeping bag inside the bivvy bag... would that eliminate (or at least reduce) the condensing air layer between the sleeping bag and the bivvy?

If it didn't take so damned long to dry the sleeping bag out, I'd spend a few nights out there testing various things to reduce (or if possible eliminate) the condensation problem.

I'm testing out the bivvy bag for a "shelterless winter weekend" challenge.

 

[ex-member BareThrills]

Here's a thought... if I wrap a wool blanket around my sleeping bag inside the bivvy bag... would that eliminate (or at least reduce) the condensing air layer between the sleeping bag and the bivvy?

If it didn't take so damned long to dry the sleeping bag out, I'd spend a few nights out there testing various things to reduce (or if possible eliminate) the condensation problem.

I'm testing out the bivvy bag for a "shelterless winter weekend" challenge.

I think you are trying to solve a problem that doesnt exist. Just leave the bivvy bag at home. ive never needed a bivy bag in a hammock and cant see any conditions where that would change

 

[SJStuart]

I think you are trying to solve a problem that doesnt exist. Just leave the bivvy bag at home. ive never needed a bivy bag in a hammock and cant see any conditions where that would change

I'm not intending to use the bivvy bag inside the hammock again (I only did that because I was hammocking anyway and wanted to try out the bivvy at the same time).

 

[ex-member BareThrills]

Ah sorry, my bad.

my guess is you would trap condensation between the bag and the blanket but obviously its dependent of so many factors. I try to keep it simple. a sleeping bag rated to the temps im likely to face and thats it. over gunning the insulation will make you hotter and produce more problems. My guess is your bivvy just doesnt breath anywhere near enough and no amount of tinkering on the inside will change it.

 

[SJStuart]

Ah sorry, my bad.

my guess is you would trap condensation between the bag and the blanket but obviously its dependent of so many factors. I try to keep it simple. a sleeping bag rated to the temps im likely to face and thats it. over gunning the insulation will make you hotter and produce more problems. My guess is your bivvy just doesnt breath anywhere near enough and no amount of tinkering on the inside will change it.

I'm thinking you're right there. Time to consign that bag to a return and get something that breathes better.