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.