When to use a bivy bag

jonnno

Forager
Mar 19, 2009
223
0
50
Belfast
I'm off for a weekend under a tarp (probably in a forest) and I have a Alpkit Hunka. I'm wondering if I'm under the tarp and no rain is getting in do I actually need to get into the bivy bag? It has no zips and seems like it might feel quite restrictive so I don't want to use it unless I have to.
 

Pierr

Forager
Sep 15, 2008
190
0
France
Hi,

you certainly don't need the bivvy if under a tarp + having wood cover + not raining.

You only need to combine protection of tarp and bivvy if sleeping out in the open under rain and windy conditions.
 

calibanzwei

Settler
Jan 7, 2009
885
0
45
Warrington, UK
I'd take it. Unless the ground beneath you is bone dry (which at this time of year I suspect not), its a dry barrier between the ground and your sleeping bag - you could insead take another tarp for this job, but getting inside a bivvi both protects you from the elements and you'll be warmer for it (I believe they can add another 5 degrees)

EDIT: I'll be taking mine this weekend!
 

jonnno

Forager
Mar 19, 2009
223
0
50
Belfast
Should have mentioned, I'll be using a self inflating mat with an orange survival bag underneath it. I figure the orange bag will be wider than the mat and help keep the crap off my sleeping bag.
 

gregorach

Bushcrafter (boy, I've got a lot to say!)
Sep 15, 2005
3,723
29
51
Edinburgh
Are you willing to bet that it won't start raining / blowing a gale during the night?
 

Pierr

Forager
Sep 15, 2008
190
0
France
I still stand that if under wood cover and with a tarp, thebivvy is not a necessity. Of course you need some ground cloth and a mat.

A side benefit, but very important for me, of the bivvy is that is keeps all your stuff together. If sleeping on non flat ground it can be very annoying and detrimental to sleep to have your layers sliding under you.

I also use a Hunka and put the mat inside it. In woods I use the bivvy and a poncho, no tarp. If not raining I sleep the head out. If it starts raining I crawl back under the poncho.
 

jonnno

Forager
Mar 19, 2009
223
0
50
Belfast
I still stand that if under wood cover and with a tarp, thebivvy is not a necessity. Of course you need some ground cloth and a mat.

A side benefit, but very important for me, of the bivvy is that is keeps all your stuff together. If sleeping on non flat ground it can be very annoying and detrimental to sleep to have your layers sliding under you.

I also use a Hunka and put the mat inside it. In woods I use the bivvy and a poncho, no tarp. If not raining I sleep the head out. If it starts raining I crawl back under the poncho.

I've not used it yet - is it easy to get in and out of?
 

Pierr

Forager
Sep 15, 2008
190
0
France
I've not used it yet - is it easy to get in and out of?

Depends on your size I guess. Not as bad as I thought. I sit on the hood part and can just slide in with bent knees.

It is a bit restrictive. I use a very think closed cell foam mat and a Carinthia Tropen (or an Exped poncho liner) and there is no much room left. For a winter sleeping bag it would be too small and would reduce the loft I think. A zip would be a big plus.

The hood is another minor annoyance. It is hard to get a snug fit and, if sleeping with a blanket/liner you have to carefully wrap yourself to avoid draft.

On the positive side it stands rain very well and I never had condensation issues, which is a surprise given it is not the most breathable fabric (condensation is a mysterious thing).

All in all I really like it. Light, cheap and quite strong. I slide my mat in it, then myself and I can sleep anywhere. I might by the XL version. It is only 140gr heavier.
 

JohnC

Full Member
Jun 28, 2005
2,624
82
62
Edinburgh
I put the mat and the bag inside my bivy, the orange bag on the ground might be a bit slippy.
I found it useful to practice getting in and out of the bag in a hurry at home.
I'd also echo Dunc's thought of it starting to rain overnight...it's happened to me, and I was glad I was in the bivi.
 

coln18

Native
Aug 10, 2009
1,125
3
Loch Lomond, Scotland
lately i have started to put my mat under the bivi bag, that way you get a little bit more room in the bivi bag.

Once you have slept in the bivi 5 or 6 times, you will get used to it and not feel so closed in, and still have the guarantee of staying dry if it rains.

Col....
 

calibanzwei

Settler
Jan 7, 2009
885
0
45
Warrington, UK
I have one of those wide entrance ex-Army bivi's in OD - entrance/exit is a doddle with both self inflating mat and sleeping bag inside.
Getting the hood of the bivi in line with the sleeping bags' to get a snug fit round your head can be a bit of a wrestle, but achievable.
 

Andy2112

On a new journey
Jan 4, 2007
1,874
0
West Midlands
Should have mentioned, I'll be using a self inflating mat with an orange survival bag underneath it. I figure the orange bag will be wider than the mat and help keep the crap off my sleeping bag.

Jonno, if your mat is small enough put it in your bivvi with your sleeping bag, this is what i would do if my mat was smaller. Because my mat is massive i tend to put the sleeping bag in the bivvi then sleep on top of the mat, i also put a ground sheet on the floor as a bit more protection. Saying that i did sleep out under a tarp this weekend but without the bivvi an i was perectly warm although it was mild. hth :D
 

Broch

Life Member
Jan 18, 2009
8,464
8,344
Mid Wales
www.mont-hmg.co.uk
The problem with this time of year in the UK is that all nights are damp rain or not. If you're spending a few nights out and don't use your bivi your sleeping bag will end up damp if not wet.

I don't use the bivi under a tarp in the dryer months but from September onwards tend to use both.

Broch
 

Kerne

Maker
Dec 16, 2007
1,766
21
Gloucestershire
I'd take it 'cos it WILL rain - especially if you think it won't. It doesn't weigh much or take up much space and It helps to keep your sleeping bag clean. You can always have it ready in case the rain comes. It also adds a bit of warmth.
 

ocean1975

Full Member
Jan 10, 2009
676
82
rochester, kent
This is one of my set ups,survival bag and bivi bag with thermarest in the bivi and my sleeping bag and tarp above ideal for all weathers ,and the survival bag doesn't make it slippery.Just thought i would share that.
bivysetup.jpg
 

Scots_Charles_River

Bushcrafter (boy, I've got a lot to say!)
Dec 12, 2006
3,278
42
paddling a loch
www.flickr.com
You need to use it if it is not raining as it may rain and you will get drafts, cold air sinking, or winds. If room is available you can stand into the bag and then bivvy. Your much better being warm and dry than risk it.

You can practice getting into the setup in yer hoose !

Nick
 

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