Livable Bivy

[R]

Just mulling over an idea here.

Consider a WPB ‘flat’ bivy (no box corners) with typical head and food widths, expanding to 4′ wide in the middle.

That provides enough space to:

• sit up and change your clothes in
• keep your pack in
• pitch the thing as a half-mid tarp and eat under

That last one being the reason to skip the box corners.  Also makes it simpler to construct with fewer seams to seal.  Sitting up in it would be a lot like a bothy.  If you have to crawl in to it in wet rain gear, the added space would make it much easier to wipe down the interior.

This adds a half square yard to the foot print.  Using RSBTR’s WPB and .61 Dyneema, that’s one ounce.

Would anyone (that’s spent a rainy night in a bivy) care to comment?

[Edward John M]

Well I’ve spent a few wet nights in a bivvy bag and none of them were pleasant, they were however lifesavers which was the original place for their use.

I’d suggest reading Andy Kirkpatricks thoughts on bivvy bags and then come back because I tend to agree with most of what he says, one of them being most are too small

In rain even a very small tarp makes all the difference

 

[R]

Just took a look at Kirkpatrick on bivies.  Maybe I should point out that my intended use is backpacking, not mountaineering.

What size tarp are you talking about and what do you feel is the most important function it serves?

[Mark Fowler]

I have always believed that a “livable bivy” was actually a tent. :)

[Edward John M]

What Mark said and also what Andy alluded to in his ramble

A small tent will be lighter than a proper bivvy sac

[R]

Now I’m curious about your notion of a proper bivy sack.

[Geoff Caplan]

I suspect that Edward is referring to a sack made with a breathable material like eVENT or Gore-Tex. For example a very simple bag like the Rab Ascent bag in the the eVENT Exchange Lite fabric is 650g, which is about as light as you are going to get. Hooped bags or heavy-duty bags might be 1k or more.

The MLD SoloMid weighs 354 – 440 g depending on the fabric, plus a few grams for a ground-cloth. It’s still a pretty basic shelter, but a palace compared to a bivy. The footprint isn’t that much bigger, and it will stand up to most weather.

I know where I’d rather spend the night, particularly if I’m going to be out for more than a couple of days…

[Edward John M]

I come from a climbing background so my idea of a bivvy is indeed in a WPB fabric, anything else is just a sleeping bag cover and for my uses all of the bag needs to be in WPB fabric.

I’ve made a few WPB sleeping bag covers and bivvy sacs over the decades and those with shaped foot boxes work better

A sleeping bag cover should be just bigger than the sleeping bag but a bivvy bag should be much bigger, you need to be able to wriggle around inside it to get clothes off / boots off and when talking about that much fabric a small tent becomes a no-brainer for me

[Michael F]

This is why I’d like to see a small dome tent for cooking in rain, changing clothes, bathing, sitting out a rain shower etc. it would be super lite but more private than a tarp, you could then sleep in a bivy or a hammock for sleeping. In certain areas you want walls sometimes even if its just chilling under a small tent for short periods of time it comes in handy

[R]

Comparing my design to the Rab Ascent, they use similarly breathable fabric (20-30 kg/m2 MVTR), mine is a 10d instead of a 40d, and I use a waterproof floor.

The lightest tents are a pound, my design is half a pound. I don’t hike w/ trekking poles, so on solo trips I can’t discount the pole weight of a tart/tent.

I’m well aware that a tent is more comfortable than a bivy – that’s not what I’m asking.  I want to hear if anyone w/ bivy/rain experience thinks this design would make the experience any more bearable than a traditional design – does it seem worth doing?

Edit: Edward, you posted while I was typing.  Thanks for the clarifications.  To your point about wiggle room, how does an 8′ girth at the waist sound?

[Edward John M]

No is the short answer

 

My current bivvy sac is about the same size as the biggest Bugaboo offer at 970mm wide

8 foot girth is huge, that is big enough for 2 climbers and it you read Andys post and looked at the photo that is the size he is using in one of the pictures.

However a tent makes better use of fabric and is more comfortable

My own feeling is that a small hooped tunnel in WPB similar to the cheap monkey coffins from Eureka and Coleman work better

Such tents were common when Goretex first hit the market but they do have limitations

[Edward John M]

I should explain my reasoning.

The major limitation with bivvy bags is in being unable to cook or brew-up, even the smallest tent can offer some room under cover to  boil water during a blow/rain storm For winter safety I carry a small SB cover and a tarp, the tarp is so I can dig a trench and cover it with the tarp specifically so I can brew up

I consider the ability to boil water and make coffee essential to survival; I need caffeine but also it’s a comfort thing

[R]

8′ is indeed just enough for me to sit up in, hence the design decision. Given that I’m backpacking in bear country, cooking in my shelter is out of the question. Keep in mind, however, that the girth allows the bivy to be pitched as a small tarp for cooking.

Andy does ramble. I searched his articles and blog on ‘bivy’ and didn’t see what you’re referring to.

I’ve thought a fair bit about the slippery slope between a hooped bivy and a tent. Stakes are part of the equation.  The fewer in my life, the happier I am. But now you’ve got me wondering what this would look like (on the scale) if it could take a center hoop. Vents are also part of the equation.

I saw one of those single pole, single wall mountaineering tents once at a gear swap in the late 90’s. Always wondered what it’d be like in use.

 

[John Smith]

I like bivys for ease of use. Small footprint. Simple set up. Weight can be lighter but not typically compared to single wall CF tents

The simplicity is what I like best. I am looking at the following bivy for my next purchase:

http://www.milesgear.com/UberBivy.html

[R]

East of the Cascades – do you see much rain?

I notice the girth at the pole is 101″, or 8′ 5″.  Suggests my 8′ isn’t so bonkers :)

[Bob Moulder]

UberBivy 24 inch height and 26 oz weight would instantly rule it out for me.

Zpacks Splash bivy and Hexamid tarp together weigh about 14 oz and offer actual “livability” and flexibility for weather/bugs/space.

Changing out of wet clothes and into a dry layer in a bivy? Maybe a 4’10” contortionist could do it.

[Eric Blumensaadt]

“LIVABLE BIVY” -> yet another oxymoron. (IMHO)

To me a bivy should be made of eVent on top and only be used inside another shelter, particularly snow cave, trenches and quinzhees or a tarp.

But then if using it under a tarp why not just forget the bivy and use a single or double wall silnylon solo tent like a SMD Skyscape? I’ve seen bivy users deeply regret bringing them when the sky opens and they can’t change clothes inside their bivy and get wet entering and exiting the bivy.

[Bob Moulder]

Bivy + tarp offers flexibility that a tent-only does not.

Bivy alone when there’s no chance of rain but bugs are a problem.

Bivy alone when it’s windy and cool but no threat of rain, although a few more degrees  of warmth are welcome.

Sleep cowboy camp-style on top of bivy used as a simple ground sheet.

Tarp + bivy when rain/cool and possible wind-blown rain.

Warm, gentle rain with no bugs, use the tarp but sleep on top of the bivy as ground sheet, as above.

It’s really nice to just quickly roll out the bivy and sleep almost anywhere. A couple of weeks ago I slept on a very small slab of rock where pitching a tarp or tent would’ve been nigh impossible.

 

[AG]

yes and i would add the best reason of all: tarp+bivy is the lightest (and smallest packing) full protection shelter. at least that i know of.

even the lightest single wall enclosed shelter (ex Solplex, Altaplex) will be in the 15-18oz range.

whereas a tarp+bivy could easily be in the 10oz range.

but i agree with others above about how much of a PITA it is to change clothes, escape the rain and bugs, etc. with a bivy. those are the breaks.

[Jerry Adams]

what Bob said – bivy when it’s not raining.  Never cover your face and breath into it because then you’ll have condensation.  I really like just sleeping out in the open – you can see all around, stars, listen,…

when it’s raining add a pyramid tent.  You don’t need a floor since you have a bivy.  If it’s windy and air blows in under the sides the bivy will protect you.  Leave the pyramid door open as much as any rain/wind will allow you to to get better ventilation and minimize condensation on inside of pyramid.

[Edward John M]

I would argue that the tarp plus bivvy combination is not lighter than a small double skin tent with a maximised mesh inner if the bivvy is a full sized one made with a good WPB that is truly waterproof [ 10k] and truly breathable [ 10k+] because a good bivvy for winter will use the same fabric top and bottom and WPB is heavier than silnylon. Summer not so much of a problem but you may be able to afford both a winter bivvy and a 3-season SB cover

[Jerry Adams]

yeah, bivy plus tarp is going to be heavier than just tarp

except if you like to sleep without tarp when not raining, then you need a bivy, and then the lightest possible tarp for when it rains

if you always sleep in a tent (like most people?) then better to have a tent with a floor, and no bivy.  The tent also has to protect from wind.

[Franco Darioli]

From Rene :
“Consider a WPB ‘flat’ bivy (no box corners) with typical head and food widths, expanding to 4′ wide in the middle”.

If I understand that correctly the middle when flat would be 8′ wide if opened up as one layer.

At 5’8″ I would need to slouch a bit , the top of the bivy would be pressing against my head and would have very little elbow room.

Have you made a mock up of that set up ?

[R]

Franco,

Exactly – *just* enough room to sit up and do what ya gotta do.  4′ width, top and bottom laying flat, 8′ girth. Yes, it will be resting on your head when sitting – just like a bothy.  It’s entirely possible I’ll change the dimensions if I get to a mock up.

I re-visited my calcs on weight and think this will come in closer to 6oz.  It’s 2.5 sq yd made with 1.4osy WPB upper, 0.61osy DCF lower (both from RSBTR) (that’s 5oz), a little grosgrain at the corners so it can be pitched as a tarp (1/8oz?), maybe 1yd waterproof zipper (half oz) and some bug mesh for venting.  I guess seam sealing might take it to 7oz?

 

[Dale Wambaugh]

Bivy + poncho works. If your bivy is waterproof, you can pitch the poncho as a “porch roof” over your head and trunk, making it liveable and you can cook off to the side.

[Author]

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