hey all
i was just wondering about your opinions on the best bivy set up. i was considering making one with a sil nylon floor and an epic top, however ayce at thru-hiker said that this is not recommended for full rain conditions and only as a "splash bivy" for use in conjunction with a tarp. if that is the case i would just use pertex or momentum for that application however i noticed that black diamond is using epic on their bivys and tents. would this material withstand a light rain by itself and if not why is black diamond making tents out of the stuff. and finally if i do want to make a bivy that will withstand a light rain and epic is not that fabric i want what is. it seems that in the end i might have to make two more sepecialized bivy instead of one that has a greater range of use, but if i can avoid this that would be great.
thanks guys
will

Edited by okuncool on 01/24/2007 19:01:56 MST.

William (sorry I used your wrong name previously), funny you should start this discussion today; just yesterday I ordered a Black Diamond First Light (BDFL)for use as a Bivy (minus the poles) and for use as a mountaineering tent (with the poles). Several hours of reading online reviews, including the FirstLight review here at BPL have me convinced that Epic is an acceptable fabric for my intended use. Although, I have no experience with it personally.
Going LightWeight is of course very important to me, but recently, looking at my piles of light weight gear, I feel the need to reduce the NUMBER of items as well. The BDFL will do the job (and thus replace) the following items;
1. A Montbell zelt (500 gram 'pup' tent is lighter but not free-standing as the BDFL is)
2. Goretex sleeping bag cover (just use the pole-less BDFL)
3. REI QuarterDome tent (BDFL is almost as big, and 500g lighter)
4. Sierra Designs Lighting (complete BDFL is almost as light as the SDL in Fly/Footprint configuration, which is the only reason I have the SDL)

At least, my high hope is that these can all be eliminated from my gear room.

Are you considering a BD tent as a Bivy? Anyway, I will post a review of the FL after Ive tested it. Let us know what you decide as well?

Heres an objective discussion of Epic for mountaineering
http://www.promountainsports.com/tents.shtml?http://www.promountainsports.com/tents-bivy.shtml

Edited by Brett1234 on 01/24/2007 22:41:57 MST.

let me go ahead and explain my usage. i currently have a golite cave 1 tarp with no bivy. i was considering making a bivy for my upcomming thru hike of the pct. the bivy would serve a couple of purposes. i was considering ditching the cave for a poncho/tarp in which case i wanted more protection.

i was also planning in southern and central california to just use the bivy without the tarp as it will be mostly dry. that way if i get a little rain no worries.

the bivy could also be used to add warm to my sleeping bag in the colder climates.

and finally if i have a particularly rainy season i can use the bivy as extra protection with my larger tarp.

so in the opinion of all you pros out there

what is my best option.
do i really need to make two bivys or will epic be my best option out there.

thanks again
will

I'm currently at the beginning of a personal bivy project. I really didn't like the traditional bivy designs I've seen because I like the comforts of a tent, but I don't like the weight, so I'm trying for more of a hybrid, without the poles. I got the Wal-Mart killer deal on silnylon and so I have tons to play around with. My plans are to have a treated silnylon floor with an untreated top. Since breathability is a factor, I'm going to put 4 side vents in with noseeum mesh around my calves and hips, and to protect those from water, they'll have a loose backing of silnylon on the inside with the air opening on the top so water won't get in. For the top 1/3 of the bivy, it's going to be what looks like from a side view to be a triangle, and from the head of the bivy, a dome, with silnylon for one half, and mesh for the other half. There will be a silnylon cover that will completely cover the mesh to make it watertight if it rains. That structure will be supported with an inflatable tube encased in its own silnylon, which unlike the balloon supports I've seen on this site, will use a thermarest valve so it can be blown up and deflated with ease. The head structure will open up completely when the mesh isn't zippered to the inflatable tube structure, and there will be a side zipper for ease of getting in and out. I know it sounds complicated, and I should really get you a picture if you're interested. I'm hoping for a lowball estimate of 12 oz, but if it's more like 16 I'll be okay with that. Most of my backpacking trips are in the desert so I want something where air can circulate easily, but I also head into the mountains, so I want something water tight as well. If this doesn't work out, then all I've wasted is time and a little money, but gained plenty of experience for the next design.

Edited by mroy79 on 01/24/2007 21:55:58 MST.

I've been using am old breathable bivy (DWR but not at all waterproof) for about 8 years. It's great under a tarp, or out under the stars, or in a trail shelter. It keeps me on my sleeping pad, keeps the bugs and mice out of my face, and adds some wind protection and warmth. On very hot nights I can just sleep on top of my bag inside the bivy. The bivy is an old Moutain Hardware Micro Mesh, which sold like hotcakes on the AT about ten years ago, then was discontinued. The major flaw is the weight of 15 oz.

My lovely wife has offered to help me make its replacement, so I just ordered the materials from AYCE at thru-hiker.com. I went with the Momentum 90 top fabric b/c I wanted the most breathable fabric with a good DWR. I don't want anything waterproof, since I will pitch my tarp if it's raining or snowing. In my mind, Epic may be the worst of both worlds -- not waterproof enough to be a stand-alone bivy, and not breathable enough to use without some condensation. (I know, lots of people LOVE their Epic tents and bivies. The vast weight of public opinion is against me. I can take it.) If you do decide to try the Epic bivy on its own, you'll need to seal the seams or have a zipper flap, etc.

Have fun -- making gear is almost as good as using it.

Will,

I have no experience with Epic material as a bivy, but i can answer one question for you.

"would this material withstand a light rain by itself and if not why is black diamond making tents out of the stuff"

In a tent the fly doesn't have to be really waterproof. It should be highly water repellant. Just think of tents made out of cotton. Cotton isn't waterproof at all, still you're perfectly fine in a cotton tent when the rain is coming down. Water should bead up on the surface of the tentfly and roll of. The fact tht this doesn't work in a bivi comes from the differnt angles of the material.

In a tent the walls have a big incline: water rolls off. In a bivi the material is horizontal and water will pool there and will eventually work it's way through unless the material is waterproof.

Eins

Definitely look here:

State of the Market on Bivy Sacks.

William- I recently made a 'splash' bivy from materials purchased from Ayce at Thru-Hiker.com. I typically sleep under a sil-nylon tarp. I have been caught in 1hr long downpours with just the bivy and have stayed warm and dry. I must admit that with more than a summer/fall squall I will usually be under my tarp. In the Sierra, Anything less breathable than Momentum or Pertex is a problem. Condensation wets my down bag out and repeated days of this reduces my loft. I hope this helps with your decision.

Nice work, David!!
-Mark

Nice Bivy! I had been using Momentum on bivy tops for a little while and have received similar reports from users about the water resistance in light rain, splash and snow. I recently went through a lot of fabric testing looking for the very best (1.1 oz/sq/yd final weight or lighter) DWR bivy top fabric regardless of cost. I must have tested a few dozen over the last few yeears. I even tested two new Pertex Quantums in the past few months (costing me over $30 per yd for the samples after duty/shipping from Japan- I was on THE HUNT! Of course a large shipment would cost out a bit less than Momentum) and the Momentum was clearly better. I found that Momentum was closer to the water resistance of the Epic (1.7 0z/sq/yd) but more breathable and much lighter. Even though I have a boat load (literally-from Jakarta) of Epic in stock, I've stopped offering it for bivys and instead will now only offer the Momentum or if fully WP is required, two layer eVENT 2.0 (oz/sq/yd).
At 1.05 oz sq/yd finished weight, the Momentum is exactly the same as the lightest Pertex Quantum's I tested, equally breathable in a bivy/bag top and more water resistant and even bit more snag resistant.

My old bug-bivy design had a 30" long foot panel of Momentum, to protect from rain spray from the back of my tarp, with no-see-um netting elsewhere, and a silnylon bottom. I used this about 100 nights last season. Whether the Momentum is highly water-resitant or not, I can't say, because at the last minute I added a back panel to my tarp and that provided plenty of rain protection. But I did find that all the condensation that wasn't trapped in the foot area of my sleep-quilt ended up being trapped in the Momentum of the bivy, so that this foot panel was consistently moist in the morning. By contrast, the no-see-um netting, which is made of polyester, traps zero moistures and the silnylon was usually dry, unless the ground happened to be wet when I was setting up the night before. Because the rest of the bivy was dry, I sometimes got lazy and didn't bother to sun dry the momentum each day, and every time I did this, the result was mildew in the Momentum. My current bivy design eliminates this foot panel, in favor of pure no-see-um netting on the top.

Obviously, the bivies discussed here are not bug-bivies, and so replacing Momentum or whatever with no-see-um netting is not an option. But you should be aware that you will have to sun dry these Momentum bivies every day to keep mildew away. Because Momentum is nylon, it absorbs quite a bit of moisture, regardless of how well the DWR finish repels liquid water, and so drying takes longer than with something like EPIC, which is silicone-coated polyester and hence absorbs essentially no water. On a sunny day, drying will be instantaneous if the color is black. But if you hike in an area with logs of fog and overcast skies, then drying won't be so easy and you better learn to like the smell of mildew.

Devils advocate here, but getting back to your 2nd post I'd be inclined to ditch the bivy and just use the tarp rather than Just having the bivy. Bivys serve a purpose but if its actually raining... well, life sucks and everything gets wet.

David E, cool setup!

Edited by EricP on 01/29/2007 13:51:18 MST.

I guess this as good a place to post this question as any.

I'm new to the tarp/bivy combo, and I'm thinking about making my own bivy. It's obvious from all the posts about breathable tops that condensation can be a big problem (I'll be using a down bag too).

Question: Would incorporating a sizable panel of no-seeum mesh with a breathable nylon top (we're talking cheap, lightweight, dwr ripstop of questionable breathability) be an issue in the rain?

I'm thinking of adding a 5-4" strip running down from chest to the knee area. I think it will be fairly simple to sew, but I would like to hear from folks with tarp/bivy miles under their belt. Will I get soaked? Will this make any noticable difference with breathability?

Edited by ling_jd on 02/27/2007 09:43:07 MST.