I have been pondering ways to cut my pack weight down (as always) and shelter is one big area I can cut down. I currently use a Duomid. I have been experimenting with smaller tarps (5'X7') and they just don't provide the coverage I feel I need in a decent storm. Too much rain splatter. So, in order to use a small tarp or conventional poncho tarp I would need to add a bivy. Let's figure 3 ounces for a small tarp (in cuben). Add 6 ounces for an average light bivy and you're at 9 ounces. Alternatively, I look at a larger tarp. Let's just figure on the CubicTwinn (cuben tarp compared to a cuben tarp) (5.5 ounces). Since you can forego the bivy with a larger tarp you need a ground cloth. Figure on the large polycro at 2.7 ounces. That's 8.2 ounces. So it seems you're better off to just ditch the bivy and go with a tarp with more coverage unless you are using the bivy for extra warmth or wind protection. Seems like that's weight better spent on insulation. Am I missing something to the equation?

No you are not missing anything. It is a matter of assembling the kit that works best for you.

If using a poncho/tarp, which is also your rain gear, then you need a bivy. A larger tarp and you can dispense with the bivy, but then you need rain gear. Sometimes I use a water proof pad instead of a ground sheet.

Some people use bivys for other reasons too.

No you pretty much have it. A bigger tarp with ground sheet will be approximately same weight as bivy with small tarp. The extras you get with bivy are warmer...extra layer around you to trap warm air, blocks wind, provides bug protection, can be used on its own, keeps mice off you, and provides sense of security. Being wrapped inside a bivy when a big storm blows through is just fun for me. Lastly a smaller tarp/bivy requires less space to setup.

I'd say the advantage of a larger tarp is flat out more living space. There is more room to cook, more room for gear, easier to sit up, etc. Since I don't spend much time under my tarp this doesn't do a lot for me. If I did then a larger tarp would indeed be a nice advantage. You might also consider that condensation management is easier since you aren't dealing with the trapped moisture in a bivy.

I think both techniques are valid approaches.

Jamie

Edited by jshortt on 07/31/2011 16:49:19 MDT.

I think Jamie did a good job of pointing out advantages of bivies that often go overlooked- built in ground sheet, bug protection, protection from spray- with the right kind of conditions- even a big tarp leaves you susceptible and maybe the most overlooked is the added warmth to your sleep system-especially when adding in a little wind to the mix

I like using a bivy when cowboy camping (weaher permitting), an unexpected light shower usually gets beaded up pretty well

also correctly pointed out, when using a small poncho/tarp you eliminate the need for raingear

there is no one right way for shelter, lots of options and worth experimenting on your own to see what works best for you

If wind cuts right through your insulation, then more insulation doesn't necessarily help. A bivy and a 30 degree bag can be warmer than a 20 degree bag in windy conditions, while weighing less. A bivy also provides bug protection.

Edited by lindahlb on 08/01/2011 10:51:02 MDT.

I use an ultralight bivy even under an 8x10 tarp because:
1) bugs
2) extra warmth
3) ground protection - I squirm a lot in my sleep and often wake with my sleeping bag off of the ground cloth and on the wet and/or muddy ground.
4) spray/spindrift protection
5) Allows for cowboy camping even if heavy dew and light sprinkles could be an issue

I've never used a traditional bivy, but I do use a Bear Paw Pyra Net 1 bug bivy. I had mine made with a 70D silnylon floor, which allows me to skip a ground sheet. With the 70D floor it weighs 12 oz; standard version with a 30D floor weighs 8 oz. There are lighter options, but I was using a Tyvek floor weighing 4-6 oz before this. I've only had the Pyra Net 1 since November, but bought it so that I could skip the rest of the shelter and sleep under the stars during the summer. Happy so far!

if weather is forecasted to be high pressure, so risk or rain or storm is nil, and its a day hike out if the weather unexpectedly turns on you, then why bring a bivy or tent at all? why not sleep under the stars?

my concern is bear country - what "protection" does the tent serve for a wandering inquisitive griz? and does it make sense to get to high ground on a ridge to lessen the likelihood of a griz encounter... or do the bears go to the highest part of high country at night in search of yummy food items..

Neither provides any protection from bears.
It is extremely rare for bears to attack a sleeping person, unless they sleep with their food.
Lightning is by far more dangerous. So heading for high ground is probably more dangerous.

I use a Tarptent Moment for 3 season backpacking. To me the only time I want a bivy is in a snow cave or quinzhee snow shelter. There it provides protection from moisture. And my first choice would be an eVent bivy.

A bug seltered bivy in summer is NOT what you want to use in when its' pouring down rain and your need to exit to pee or get some snacks from your pack. Don't ask...

The thing you might be missing is that with the bivy you might be able to take a lighter sleeping bag and possibly end up with a lower total weight.

I go with a GG twin sized tarp and no bivy on most occasions. I really like the set up. It feels open. No bivy has ever been needed 3 seasons.

No bivy is fine, unless bugs are a problem. Then some kind of netting is recommended by most.
And you'll probably want a ground cloth when you go without a bivy.

it seems you're better off to just ditch the bivy and go with a tarp with more coverage ... Am I missing something to the equation?

Edited by JohnAbela on 01/17/2012 01:07:30 MST.

"lighter than just about any bivy tarp out there and provides enough room that you will never ever get wet"

Tarp-n-bivy users will use a bivy for more than just staying dry. Adding another stagnant air layer helps for warmth. Also, having a smaller tarp can be a benefit in certain cases.

I have gone through the same analysis. It helped me realize that for 2 people who need shelter with bug protection, I could not justify going away from my old 32oz SMD Europa silnylon tent to a tarp + 2 bivies. Even with today's product offerings, a 2-person cuben tarp plus a floored inner bug tent gets darn close to 32oz. Certainly close enough that the extra hundreds of $$$ aren't worth it. If I was starting from scratch, though, I think I would go with a beaked 8x10 cuben tarp plus a 2-person inner bug tent. Very modular.

John, love your info at hikelighter.com, thanks for putting all that together.

when we're talking about small tarps lets remember poncho/tarps- that's my experience w/ small "tarps", not carrying raingear sheds some ounces (and volume- which using an Ion as is almost important) as well

full disclosure :)- I've since gone away from poncho/tarps and moved to a small-ish shelter (solo trailstar) and carry raingear, I'm also now convinced I can get away w/o a bivy w/ this shelter (but adding a ground cloth) so the weight hit isn't too bad

John, love your info at hikelighter.com, thanks for putting all that together

Three years ago I used a bivy (REI Minimalist), and a tarp (Silnylon) that were quite heavy but I enjoyed using them. Not clostrophobic at all.

Since then I have been using a single wall enclosed shelter (GG One) that is quite light compared to the bivy and tarp.

But I feel in the enclosed shelter I cant see out and I miss being outside and seeing the stars. So when the conditions warrent and I do not have to set up the tarp all the better. I also dont mind getting up to move into/under the tarp if neccessary. I get up once or twice any way when nature calls as it is.


Disclaimer: significant rain in forcast, all options are considered, even breaking out the old double wall tent.

I have a SUL bivy. Custom from MLD - .74 cuben, M55 top, sized perfectly to me. It's great when I want protection from bugs and/or a little extra warmth.

If I were looking these days, I'd look instead to the Zpacks Hexanet. Roomier, doesn't get clammy (or add condensation), just as light.

@John

"I can add about 2 additional ounces of material to my tarp and increase the width and length of the tarp by nearly 1/3rd of its existing size. You can get a tarp that is 8.5 x 11 rectangle that is 6 ounces - lighter than just about any bivy tarp out there and provides enough room that you will never ever get wet. Not to mention its a lot cheaper than buying a smaller tarp and a bivy."

How can a tarp keep you dry? If it rains eventually the groundwater wets you from below surely. Does the mat assume to keep you off the wet but what if you move around off the mat? Did you mean you still have a groundsheet? Surely its then comparing large tarp plus groundsheet vs smaller tarp plus bivy?

"I have a SUL bivy. Custom from MLD - .74 cuben, M55 top, sized perfectly to me. It's great when I want protection from bugs and/or a little extra warmth."

Do you find the .74 bottom durable enough? Looking to pick up a bivy soon, but I was thinking of going with a 1.0 or 1.43 floor.

Edited by TRAUMAhead on 02/26/2012 23:25:33 MST.

@Christopher: The .74 cuben has treated me well. I make sure the ground is clear of debris, and I'm good to go. With a pad, I'm never putting much pressure on the fabric at any specific point, nor is it rolling around.

Given the choice, the heavier stuff certainly isn't a bad decision. I'm confident in the .74 as a bivy (though would want more for a groundcloth).

In 2009, I thru-hiked the PCT for just under 5 months using a MLD Grace Solo cuben fiber Tarp and a MLD superbivy. I used the tarp maybe 9 times but the bivy 80% of the time since I cowboyed camp almost every night. What I don't like about these threads is someone will eventually talk about their heavy hot gortext bivy which is a completely different thing from a 5-6oz weight water resistant one. The tarp is what provides the water proofness.

What I liked about the bivy:
-I could just stuff my quilt and sleeping pad inside and throw it on the ground. No camp is faster to set up. Packing up was almost as quick.
- In strong winds, you see that often on the PCT, it blocks the wind nicely. I never really had any condensation issues.
-There were a couple of nights when the added warmth was very appreciated near Canada in late Sept exceeding my down quilt rating (or the fact that after 5 months of use and no washing the down insulation was perhaps a little compromised).
-It worked as bug protection until the temps dropped enough for them to leave at night (though 2 nights they never did leave).
-When the temps were too warm for my down quilt, the bivy worked as a lightweight sleeping bag.
-When it would start to drizzle or rain while cowboy camping it help keep me dry (though its only water resistant so it will saturate after awhile) until I could do something about it. Once I was able to move under a large spruce with the bivy sack and stay dry enough to sleep through it without getting the tarp out. Twice it started raining in the early morning, but the bivy sack kept my quilt dry enough until I could pack up and get an early start (not worth setting the tarp up at 5am).
-Though not on my PCT trip, I have been in 30-50mph variable direction wind gusts in bad weather so the extra spray protection under the tarp was good to have.
-No ground cloth needed so some of the bivy's weight penalty isn't there.

Over all, I've been using a small tarp + bivy combo for about 4 years and still love it. As someone who use to use a 8x10 tarp with no bivy, I much prefer a small tarp and a bivy as I find the combination to be more versatile in more situations. Those who prefer to stay in the shelter on days its rains, might want more room. But since I hike sun or rain, I don't mind a small shelter. I hate setting tents or tarps up as I'm a lazy camper which is why I cowboy camp most of the time. For me, the bivy sack works. But to each their own.

Edited by Miner on 02/27/2012 22:39:01 MST.

I'm with Sean for the same reasons.

Maybe we need to use a new term, "bivy" for the standard waterproof bivy that people seem to not like at BPL and use "UL bivy" for the ultralite, water resistant, highly breathable type.

There are lots of comments about bivys being constricting, damp, stuffy, ...

A UL bivy usually doesn't suffer from the comfort issues those old military goretex bivys do.

I usually use my bivy like Sean, as a way to cowboy camp to keep bugs off and any light spray rain, dew and dirt off my bag when I cowboy camp
I can then set up the tarp when it might rain.

Actually, I usually hike in the North East where it always seems to be a 30% chance of precip. So the tarp is usually pitched, but pitched high for ventilation.

I even use the bivy in cold weather. It adds warmth by helping to reduce drafts and having the bug net suspended over my face helps reduce the cold nose issue. It is worth the 7 oz for year round hiking.

Also, my my main bivy, an SMD Meteor, is roomy. I flip flop all night and never feel cramped.
My other tighter, full coverage Oware Drawstring bivy, seems just as comfortable. It is light and moves with my bag when I squirm from side to side.

"Maybe we need to use a new term, "bivy" for the standard waterproof bivy that people seem to not like at BPL and use "UL bivy" for the ultralite, water resistant, highly breathable type."

Good point. I have the Katabatic Gear Bristlecone Bivy. It's a fixture in my ultralight setup for the reasons Sean outlined. Tarp is for bad weather and so only comes out then, otherwise sleeping inside the Bivy is perfect on most nights, provides the views, protects from condensation, bugs/mice, wind. At 7oz it's a perfect shelter for most nights.