What's the point in Goretex bivis?

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Gotte

Nomad
Oct 9, 2010
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Here and there
As I understood bivis, they were for sleeping out without a tent. Obviously, a Goretex bivi seemed ideal. Then I read you should use them under a basha, because rain water on a goretex bivi will tend to pool and stop it breathing. But surely, if you're using a basha, other than for water ingress from the ground, a goretex bivi becomes pointless, and a normal sleeping bag is better, as there's less to hump around.

Are they really only for emergency or for sleeping out on clear nights when you may get a heavy dew (though surely a basha would do for that, as well)?
 

Mesquite

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Mar 5, 2008
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Even with a tarp you still get a certain amount of 'dampness' in the air so it protects the sleeping bag from this.

The bivi bags also add an extra degree of warmth to your sleeping bag besides protecting it from the elements.
 

Nonsuch

Full Member
Sep 19, 2008
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Scotland, looking at mountains
You don't have to use a tarp with a bivi bag, but in wind and rain it's a much more pleasant experience, not just for sleeping but for cooking / hanging around etc. Also the tarp keeps your other stuff dry.

Ultra-light back-packers tend to have a bivi bag and no tarp - although some have an ultra light sil-nylon small tarp supported by walking poles

Sleeping under a tarp with just a sleeping bag on a mat and no bivi bag can get your sleeping bag wet if you get wind-driven rain, or a wind direction change, or you roll off your mat in your sleep, especially with a down bag. However many do.

NS
 
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Lithril

Administrator
Admin
Jan 23, 2004
2,576
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Southampton, UK
Wind chill in a bivi is also worth taking into account even just using the tarp as a windbreak will give you a much warmer nights sleep in your bivvi.
 

John Fenna

Lifetime Member & Maker
Oct 7, 2006
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Goretex bivvis help keep out anything that blows in under the basha, help keep your sleeping bags clean, and add a little insulation.
Gore-tex on its own is (IMHO) not much fun if it is realy raining hard. Water seems to find its way unerringly to the opening and flood inside or pool in patches, reducing breathability and helping you find any micro holes you were un-aware of until then.
A tarp along with your bivvi helps keep MOST of the rain off, gives you somewhere dry to get dressed and organise your kit in the dry.
The bivvi will certainly help keep "atmosphric damp" out of your bag. A good lightweight groundsheet such as an IPK, under a tarp is almost as useful as a bivvi in a lot of circumstances - and I often use tarp, bivvi and IPK ...but then I live in Wales where rain is an almost constant companion.
I have used bivvis on their own but prefer to have a tarp over it just for the extra convenience and comfort.
For most of what I do I have to admit that a quality polycotton sleeping bag cover would be almost as good as a goretex bivvi as it is mainly there to keep my bag clean and keep off the dap that gets around my tarp.
Using a bivvi on its own in the rain is not for me - I find that I need a little more convenience and comfort these days!
 

Gotte

Nomad
Oct 9, 2010
395
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Here and there
Thanks for that. I'm thinking about getting an ex-army one off ebay, though I have a small one person tent, so not sure if there is any great point. I used to like the idea of them as a lightweight alternative to hauling a tent around, but the idea of having a bivi bag, and a bigish one at that - I seem to remember the ex-army ones are about 9 foot - and a tarp etc lead me to wonder whether the tent alone isn't as good an option.

Thanks for the input

Phil
 

John Fenna

Lifetime Member & Maker
Oct 7, 2006
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Thanks for that. I'm thinking about getting an ex-army one off ebay, though I have a small one person tent, so not sure if there is any great point. I used to like the idea of them as a lightweight alternative to hauling a tent around, but the idea of having a bivi bag, and a bigish one at that - I seem to remember the ex-army ones are about 9 foot - and a tarp etc lead me to wonder whether the tent alone isn't as good an option.

Thanks for the input
My smallest 2 skin tent weighs less than a bivvi-bag ay 1 kg dead and has more room and is still claustrophobic.
For light weight I take a tent for comfort and versitility I take tarp, bivvi and ground sheet :)
 

Gotte

Nomad
Oct 9, 2010
395
0
Here and there
Thanks for that. I'm thinking about getting an ex-army one off ebay, though I have a small one person tent, so not sure if there is any great point. I used to like the idea of them as a lightweight alternative to hauling a tent around, but the idea of having a bivi bag, and a bigish one at that - I seem to remember the ex-army ones are about 9 foot - and a tarp etc lead me to wonder whether the tent alone isn't as good an option.

Thanks for the input
My smallest 2 skin tent weighs less than a bivvi-bag ay 1 kg dead and has more room and is still claustrophobic.
For light weight I take a tent for comfort and versitility I take tarp, bivvi and ground sheet :)

Thanks for that. I can see your point re comfort.
 

rik_uk3

Banned
Jun 10, 2006
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IPK
http://www.surplusandadventure.com/...ource=google&utm_medium=base&utm_campaign=S&A

Bivvy bags are very useful under a tarp, remember wind and rain can change direction and the odds of getting wet under a tarp are higher than tent camping. My two man Hex 3 tent weighs less that a bivvy and a tarp setup to be honest. Just my opinion, I don't sleep under tarps they are for cooking under or chatting with chums, I sleep in various tents (and chat with chums).
 

johnboy

New Member
Oct 2, 2003
2,258
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Hamilton NZ
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What's an IPK ?

An IPK is an Individual Protection Kit. A bit of Army surplus. You get a plastic pouch with a plastic OG waterproof sheet. A selection of Aluminium pegs and a decent length of white nylon cord.

They were designed to be used to provide overhead cover to trenches / foxholes to protect against indirect fire and NBC agents. The idea being you dug the trench made a supporting lattice from the white cord and pegs placed the sheet on top and then covered that with the spoil dug from the trench. Fine in theory... Possibly not so in practice.

Bushcrafters like them because you get a sort of useful: waterproof sheet, pegs and cord for a extremely cheap price... Therefore ticking some of the Bushcraft mental check boxes.

Army Surplus. Check.
Low Cost. Check.

HTH

John
 

Shewie

Mod
Mod
Dec 15, 2005
24,259
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Yorkshire
IPKs make a nice sized mat for putting under the hammock in bad weather, give s you some to stand and sort yourself out for two minutes.

As for bivvys, if you use one on the deck with a tarp then you can take in what's going on around you, unlike a tent where you're shot off from the outside. The idea with the goretex is like Rik says, if you have a tarp in a lean-to configuration then the wind and rain switches in the night, the goretex keeps your doss bag dry.

I wouldn't worry about a pool of water affecting the breathability, your're not sealed up unless you get a hooped model, but even then a pool of water somewhere won't affect the rest of the fabric.
 
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RAPPLEBY2000

Bushcrafter (boy, I've got a lot to say!)
Dec 2, 2003
3,195
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England
Why Bivibags and tarps?
it reminds me of 2 occasions that might go some way to explain why both is a good idea:

1: on a British Army TA exercise the whole platoon had made a Base camp known as a "harbour" with around 30 men paired up in "shell-scrapes" (holes about the dimensions of a flat poncho and 2ft deep) the base looks a sort of triangle spider web from above.oh and...it was a wet exercise.
Constant heavy rain, every shell-scrape had a 58" poncho or self bought tarp(if you could get hold of one) as a roof.
nearly everyone was using the issue 58" sleeping bag a down bag with a waterproof base (4 seasons when dry, 0 when wet!).
I used a cheap Goretex copy (Hydroram) and by the end of the day my sleeping bag was one of the only ones that was dry, and not covered in mud!
Everyone was trying to beg or borrow the last 3 or 4 dry sleeping bags!
so in that situation every person had a tarp(of sorts) but the sleeping bags all got wet!

I remember a previous exercise again the "shell-scrapes" and again poncho roofs, exept that time i didn't have a bivibag and water ran down the shell-scrape side, into my sleeping bag, the waterproof base had limited use as i could feel the cold water running down the base....yeah...nasty!
after several attempts in the early hours to move onto the dry part or keep warm I gave up, got up put my Issue PVC waterproofs and got bag into the sleeping bag! uuugh! the down side...to down!
ugh, a pun, I didn't mean to! :eek:
apparently some Army exercises in the past had been called off in the past, due to wet 58" sleeping bags!

2. on a Civilian Mountain leadership course, we all bivied overnight on the side of a Welsh mountain (Cadair Idris).
it was wet that sort of "fine misty rain" that soaks everything, this time most people used bivibags, some were military.
nearly everyone including myself got soaked, due to the small gap you leave to breath through.
out of 20 people 3 people stayed totally dry, they used sleeping bags under a tarp. they'd built a sort of "C" shaped wall from rocks and placed the tarp over it.

to be fair using both Bivi bag and tarp is a "belt and Braces" approach, but even the military use both as you can hold a meeting read maps etc in Bivibags!
I tend to use both.


:sigh: The IPK sheet :(

uuuugh:sigh:... Everyone seems to think the IPK sheet is amazing....it isn't! it's just cheap!

An IPK is an Individual Protection Kit. A bit of Army surplus. You get a plastic pouch with a plastic OG waterproof sheet. A selection of Aluminium pegs and a decent length of white nylon cord.

They were designed to be used to provide overhead cover to trenches / foxholes to protect against indirect fire and NBC agents. The idea being you dug the trench made a supporting lattice from the white cord and pegs placed the sheet on top and then covered that with the spoil dug from the trench. Fine in theory... Possibly not so in practice.

Bushcrafters like them because you get a sort of useful: waterproof sheet, pegs and cord for a extremely cheap price... Therefore ticking some of the Bushcraft mental check boxes.

Army Surplus. Check.
Low Cost. Check.
HTH
John

I totally agree with Johnboy
It is....
a sort of usefulwaterproof sheet
:cool: that's the best description I've seen!:35:

Can I add...
IPK sheets are OK for a short term solution because that's what they are designed for, to be buried, provide some basic protection and then it's forgotten!


I've had bad experiences with IPK sheets!
They aren't laterally very strong, (if torn will rip)and it's difficult to add suitable hanging points without weakening it further.
I've tried glue, Duct/Duck tape, rivets, sewing, Big brass Grommets, all of which failed, I also tried joining 3 together, which just made the strength problem worse. I'm yet to be convinced you can make a re usable shelter from it!

not as strong as a "basha" or "poncho" by a long way.
also I bought one that was sealed but every fold you could see light through so barely waterproof!
ground sheet? check.
shelter?...if you're careful, but you'll need to make sure you can tie cords somehow.
windy stormy weather?...forget it!
WARNING, as the saying goes "you get what you pay for",

don't expect big things from something that costs £5!
don't believe the advertising hype...if you only have £5 to spend, by a builders tarpaulin, string, and a few 6" nails....hey presto a much better shelter!
or save towards a 2nd hand poncho!


The pegs and cord are worth it!
best for making an underground shelter with.....it even comes with instructions how to!:lmao:
 
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Andy T

Full Member
Sep 8, 2010
899
27
Stoke on Trent.
ive seen goretex surplus bivi bags for as little as £15 on the net, worth investing in at that price and as was said in a previous post they definitely keep you warmer and dryer especially when the wind changes direction. i wouldnt go without mine even in summer
 
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R.Lewis

Full Member
Aug 23, 2009
1,098
20
Cambs
So going by many of the comments above, a Belgian bivi would be ideal? They are a canvas top with waterproof base and massive hood for kit storage. Been toying with buying one just not sure as to practicality of a canvas bivi. No worries about breath-ability and will act a great groundsheet/bag protection. They roll up and strap like a bedroll too...

http://cgi.ebay.co.uk/Military-Bivv...Collectables_Militaria_LE&hash=item45f71302c5
 

RAPPLEBY2000

Bushcrafter (boy, I've got a lot to say!)
Dec 2, 2003
3,195
13
48
England
Sounds a bit like the German "Sniper" sleeping bag design :confused:

the top is canvas to allow it to breath...which means the bottom is not breathable probably PVC...OK.

so if you decide to sleep under the stars without a tarp and it rains, no doubt you will get wet

I'd find out as much as you can has it got taped seams for example.
 

Ray Britton

Nomad
Jun 2, 2010
320
0
Bristol
Just a quick few things to add/ask.

I am shocked that anyone pays a fiver for an IPK! I used to sell them in bulk to surplus dealers, who then made a VERY good profit selling them on for a pound each!

to the O.P. when you talk about gore tex, are you also referring to ALL MVP fabrics, or just gore tex? This has to be asked, especially as many of the MOD issue bivi's are not made of gore tex.
The water pooling you refer to is not a huge issue with gore tex as an MVP fabric, and will affect you more of less, depending on whether you have the bivi fully closed up. MVP's like gore tex work on the micro climate principle, and will only transmit vapour to the outside of the fabric efficiently it there is higher pressure ont he inside of the the bag, so if it is fully open then this cannot happen. Other MVP's work more on a wicking principle, and are better suited to bivi's.

Gore tex is an odd material, in that it is now very old in design, and although it is affected by surface water on its outside, it is heavily affected by being muddy (more so than other MVP's), which your bivi is likely to become!.

So, although it will keep some mud off the outside of your bivi, it won't do anything for the inside (obviously). It will not transfer vapour very well unless closed up. It will be lighter than the 1kg tent mentioned above (at 700g), but will not be lighter if you add a tarp on top of that. It will provide very marginal insulation in the opened up position, as it will still readily lose heat from the 'pumping' phenomenon.

If you consider an MOD type bivi to be a water and dirt protective cover for a sleeping bag (but not necessarily the users face) will be be about right :)
At least the MOD bivis are MVP on their tops and bases, which at least allows you to turn them upside down for use, which then gives you a small rain cowl, which you could support on two sticks/pegs for ventilation.

The introduction of the military bivi was prompted by the Falklands conflict, as during that period it was common to use sleeping bags by themselves with no bashas overhead (and often there was nothing to attach the basha too), so the bags often became soaked and thus very very cold. If you are looking to use a bivi to save weight, then ignore ALL military bivis as they are very heavy, and simply pick up a nice lightweight one, which will also roll up much smaller.

Just a few thoughts :)
 

Andy T

Full Member
Sep 8, 2010
899
27
Stoke on Trent.
i went down the cheaper road to begin with , i bought a kestrel bivi, small, light and very compact when rolled up, it lasted one meet, it's now become waterproof bags for some of my kit , i know its waterproof because of all the condensation on the inside when i woke up,..... i had to do the front crawl to get out the damn thing
 

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