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Bivvy Bags...worth it?

Discussion in 'Carrying' started by Bushcraftsman, Jan 26, 2011.

  1. Woody girl

    Woody girl Full Member

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    I don't know which bivvy I've got. It's got a a cammo pattern so it's a good chance it's an army one. I do have a tarp and will make a tarp tent if weather looks iffy, otherwise it will be a plow point shelter. I'm using a 3 season bag. I should be ok. My buddy has a tent if things don't go well so I'm pretty confident. ...may squeeze in my trusty plastic sheet aswell. I know that works. Nothing like a plan b and c!
     
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  2. Tiley

    Tiley Full Member

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    I think that, ultimately, the art of successful, dry bivvying is, as Scoman points out, keeping everything well ventilated. This does rather fly in the face of the perception of what a bivvy bag can do (keep you dry in wet or humid conditions) but, when you think about your average 'waterproof-but-breathable' jackets and trousers, one almost always experiences condensation on the inside, so why should a bivvy bag be any different? Add into the mix the fact that, while sleeping, a lot of folk will end up breathing into their bags and you have a fairly ready explanation about why the condensation appears. So, sleep with your head outside, wearing a hat, and keep yourself and your bag well ventilated!
     
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  3. Woody girl

    Woody girl Full Member

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    Well a bit of research has identified my bivvi. Yes as I thought British army goretex. 2006 manufacture date. Should be fine if I remember not to breath into the bag. !
     
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  4. Barney Rubble

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    I wouldn't worry about it. I've used my British army bivvy many many times and seldom had issue with condensation. This is primarily down to the gore-tex fabric which is more breathable than others. As per my previous post, the one time I noticed condensation as being a problem was when I failed to put clean/dry socks on before bed, this also happened to be on a still and humid night (there was lots of mist about in the morning!). One of the things that I think works well when using the issue bivvy with a tarp is to leave the bivvy open. With the tarp over head, there's really no need to be cinching it up around your face. This means that you get plenty of waterpoof protection for your sleeping bag and still get plenty of air flowing around you as you snooze.

    Of course if the weather is good with no rain likely then ditch the tarp and still leave the head end of the bivvy open. I've done this as well and have been absolutely fine!

    My set-up from a beach camp last year:
    [​IMG]
     
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  5. Madriverrob

    Madriverrob Native

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    Simple and effective !
     
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  6. Duggie Bravo

    Duggie Bravo Nomad

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    When I was in the forces, I always slept with the issue bag upside down, that way the flap covered my upper body and kept the rain off me. I’m normally a side sleeper.


    Sent from my iPhone using Tapatalk
     
  7. Feurio

    Feurio Member

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    I never had any real issues with condensation in a bivvy bag under a tarp (or without it in dry conditions) either. Only a damp climate inside.

    It gets „uncomfortable“ when used directly in rain.

    But then again what do you need the „waterproofness“ for (with its associated weight...) if you have to use a tarp anyway.
    While the (GB/NL/D) issue bivvy bags weigh round about 1000 g, the MSR E-Bivy weighs 180 g. Too bad that it only comes in bright orange.
     
    #47 Feurio, Sep 4, 2019
    Last edited: Sep 5, 2019
  8. EdS

    EdS Bushcrafter (boy, I've got a lot to say!)

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    Definitely worth it.

    Use my Outdoors Designs alpine bag a lot.

    So much easier and lighter than tent.....especially when you've a walk in and a load of climbing kit as well
     
  9. Van-Wild

    Van-Wild Forager

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    I always carry a bivvy bag. I have two kinds. The first being a green army issued one and the second is a snugpak SF in black. Thoughts for both.......?

    I've never had condensation issues with either bag. The army issued one is totally bomb proof and I've slept out in it under a tarp and on its own. If it rains during the night I just roll on my side and pull the top over like a kind of roof. I never do the bivvy bag up tight as I don't like to feel restricted inside it. So I guess it's always well ventilated. I've used all sorts of sleeping bags inside it, from snugpak softie 2 (?) to brit army issue ones. The snugpak SF bivvy is a tad tight but I'd say that's the only negative in using it.

    I always slide a 3/4 sleeping pad inside the bivvy. Stops me rolling off it and keeps it clean.

    The bivvy bag offers another windproof layer to your sleeping bag, keeps yr sleeping bag clean and is a ready made waterproof stuff sack. For tarp shelters it is, in my humble opinion, an essential and like I said I would never be without it. How do I choose which I will carry? Weight. If I'm trying to scrape an oz here and there, I'll take the snugpak SF.

    Condensation inside a bivvy bag can come from perspiration off the person inside it. If you've been working hard all day and haven't dried the sweat off before getting in, you will rapidly warm up the air inside of your sleeping system it will evaporate inside the bivvy and then condense on the inside of the bivvy bag. (And that's science!). Same goes for having damp or wet clothes. Socks and under garments being the main culprits. This can be avoided by stripping off all your day clothes (before getting inside) and drying off before donning your sleep clothes. My routine involves a 'wet and dry' system. ALL of my day wear is removed before bedding down and I don dry thermal underwear including socks before getting inside my bag.

    Sent from my SM-G903F using Tapatalk
     
  10. Woody girl

    Woody girl Full Member

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    Well I have just got back from my weekend camp on the north Devon coast with my pal Pete ( or totaly frustrating nutcase as I call him :) ) He had a Fjallraven tent. I had an ultra light tarp and my bivvi bag... (thanks van wild). I don't normaly use a bivvi bag but my gosh I'm converted! This morning there was a very very heavy dew and I'm sure I may have got very damp without it. I had no condensation problems at all. I had a 3 season bag and had a set of thermals to sleep in. It worked very well both nights. I had a great time, cooked some great food and will be doing this again.. but I'm still a hammocker at heart. I'm unusually stiff and sore from sleeping on the ground despite three different mats rangeing from a foam mat, self inflating, and the alpkit dumo. I like my comfort! The great thing was I was packed and ready to go half an hour before my pal. I did flip the bivvi over to cover my head as my wooly hat wouldn't stay on my head, and made sure I was in clean dry clothes to go to bed. So thanks for the tips guys. They realy work.
     
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  11. Feurio

    Feurio Member

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    Hi everybody! I have some news to share with you!
    After @Erbswurst brought up the idea of a production fault in my Snugpak bivvy again, I thought I might give it a try and ordered a new one.

    Here's my findings!
    The old one:
    - labeled "coyote", was sort of mint-greenish
    - weighed 430 g instead of the claimed 340 g
    - was cut 20 cm shorter than the SF 1 sleeping bag
    - and, most importantly, left me damp even in dry nights.

    The new one:
    - labeled "coyote", too, is simply brown
    - weighs only 325 g. The fabric does feel thinner, too
    - is cut 10 cm shorter; still not perfect, but it works for me
    - and, most importantly, the climate inside is excellent. Dry outside, dry inside! Significantly better than the Alpkit Hunka, and on par with the heavier and more expensive Gore-Tex (issue) or eVent bags.

    Why those differences? I guess the former was different line of production?

    Last night, I tested the bivvy bag without a tarp in fog and medium dew - and unfortunately I was slightly damp inside in the morning. This only shows what I have found to be true throughout my testing: the membrane's efficiency is highly dependent on a dry surface and will soon decrease, once the outside starts to be coated with water. This does not pose a problem for overnighters, nor for trips with sufficient dry weather, where you can regularly air and dry your sleeping bag. For prolonged trips in bad weather, however, a tarp is crucial to protect your bivvy bag.

    My conclusion after all: worth it, but only in conjunction with a (poncho-) tarp. Yet in contrast to what I argued beforehand, I would now always choose my Snugpak bivvy over a lighter but only waterresistant bivvy, like the MSR E-Bivy. The Snugpak bivvy weighs only 100 g more and is just as breatheable under dry conditions (as under a tarp!), yet in an emergency situation or if you cannot pitch your tarp, you can safely spend a rainy night inside it. You will be relatively uncomfortable and experience relatively heavy condensation, but that is just way better than being completely soaked and therefore cold as in a non-waterproof bivvy.
     
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  12. Erbswurst

    Erbswurst Settler

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    Did you realise, that the SF System is offered in 220 cm and 250cm?

    My SF1 (220cm) fits well in the SF bivvy bag.
     
  13. Feurio

    Feurio Member

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    Yes I did. My sleeping bag and my two bivvy bags were all the "regular" lenghts. The first bivvy was way too short, the second one now is o.k. but still a bit shorter than the sleeping bag. Anyway, strange how the production seems to vary so much.
     

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