bivvy sack

12:26 a.m. on May 7, 2007 (EDT)
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Most or even all bivvy sacks are about 15% too small. There's no excuse for this. They all want to save weight.

I've used a one-pound non-waterproof bivvy sack about 20 nights a year for four years. It nicely protects my two very light sleeping bags, adds warmth, and sometimes I just use warm underwear.. with sack... I use tarp shelters, and have mostly now given up groundsheets and also stuff sack due to bivvy sack's usefulness, and/or my chronic forgetfulness........

The top part of sack is water repellant and I haven't found condensation much of a problem. OR discontinued this model, and now all I can see are Goretex or similar. Don't know if they breath as good. I may need a new one in a couple of years.

12:54 p.m. on May 7, 2007 (EDT)
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I'm not sure how you want to use your bivy sack. But you might want to look at Integral Designs' line of bivies. They use a proprietary material they call "Tegraltex" (very similar to "Toddtex" that Todd Bibler used in his tents and bivies and Black Diamond still uses in the Bibler line of tents and bivies since they took over Bibler). It breathes pretty well and is waterproof. The bivy I use most is one of IDs. I also have one of ID's bivie/VLB liner that I use a lot for winter and polar trips. It is not breathable, since it is made of silcoat, but is useful as an half-pound emergency bivy that stuffs into a fist-sized stuff sack. It isn't a substitute for a tent, of course.

I am guessing that what you are looking for is more like a small 1-person tent. The original intention of a bivy sack was exactly that - a waterproof, windproof sack that you carried on a climb in case of a planned or forced bivuoac. Therefore, they are all designed to be basically just a sack into which you could climb to provide shelter from rain, wind, and snow, and would thus provide a bit of warmth while tied into a ledge somewhere on a climb. They are a step up from the cagoule+footsack (as someone noted here a while back, cagoules are hard to find anymore). My old Cairn climbing rucksack has a fold-out inner liner that works well as a footsack, coming up to my waist, while a cagoule would come down to my knees, providing a reasonable overlap. Insulation was provided by a down parka and down-filled elephant foot (a half-bag). The only extra weight you were carrying was the elephant foot, since you carried the down parka for belay stances, gear in the pack, and the cagoule for rain and wind protection.

So bivy sacks really are intended for just you and your sleeping bag, and maybe a narrow 3/4 length ensolite pad, basically just a sleeping bag cover. They aren't intended as a tent substitute. There are small 1-person tents like my SierraWest tent that aren't a lot bigger than a bivy. I can take my boots inside the SierraWest and some of the other gear. But the main pack stays outside.

Since bivies are intended only for a bivouac, they are only big enough for a person, with the pack staying outside. You don't sit up or stand inside one, but sit up wearing it like your sleeping bag. One bivy I have, a heavy one that REI sold for a while called the Cyclops, has arm holes for you to sit up while you cook (problem is it lets the mosquitoes in at the face and arm holes, plus it is way too heavy). Maybe what you are looking for is one of the Integral Designs guide shelters. These are larger than the SierraWest 1-person "tent/bivy", but still small and light.

2:17 p.m. on May 7, 2007 (EDT)
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I have (or had - not sure where it is) a Gerry sleeping bag cover - it was an uncoated nylon bag with a half length zipper and a drawstring at the top - it was not a bivy sack per-se - but rather just a cover for your sleeping bag.

I doubt that they've been made for 35 years - mine is the only one I can recall seeing - but it did serve well on the Appalachian trail in summer time (kept the bugs off and provided some level of modesty in trail shelters) - it would have been really nice with a light fleece bag inside it ...

If you're looking for either an uncoated one or fully coated one I cannot imagine an easier sewing project - then you could control the size, the material, the zipper location (if any) - mosquito netting (again, if any) -

5:46 p.m. on May 7, 2007 (EDT)
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I have four different Integral Designs bivies after using two Early Winters versions plus a Black's one and a Gerry tarptent for many years. I will not go a step from my vehicle without a bivy and I.D. and Bibler are the best available, IMHO.

I use a yellow I.D. eVent Bugaboo plus Exped PL Wallcreeper plus a yellow I.D. Sylshelter for ALL my day hikes here on the B.C. coast, this with an original yellow Thermarest 3/4 length and a Ridgerest. This is for emergencies due to getting lost, injured or delayed by weather which happens here within sight of Vancouver and kills hikers every year, even in high summer.

I use a dull green I.D. eVent South Col with an ID green Sylwing as my ultralight emerg. shelter for dayhunts in the early season and with a Ridgrest cut to fit. This is light and just an excellent camp for overnights when I get delayed by hiking too far on old mining trails to hunt Grouse and Deer.

My basic camping shelter is an early green I.D. Unishelter and it goes everywhere I do and I have used it to sleep just off the highway while traveling and in hunting. It is paired with an elderly US-made Moss Wing tarp and will work well in the worst Canadian weather as it has since 1993.

My latest is a OD Mega Sola by ID, paired with an ID green poncho and, sometimes, an ID green SyltarpIII. This is a pricey rig, but, for high country hunting and in really crapola weather, it absolutely rocks. This is my favourite hunting camp and it is so compact, easy to erect even in high winds and just comfortable, that I wish I had bought one years ago. If, you want "the best", for longer light trips in harsh weather, this is it, IMO.

However, for most bad weather trekking, I would choose the I.D. eVent Unishelter paired with a Syltarp II. Again, this is an expensive piece of kit, but, it is about the finest available and will last as well as keep you warm, dry and even cheerful in bad conditions.

9:54 p.m. on May 7, 2007 (EDT)
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"Most or even all bivvy sacks are about 15% too small."

I have no idea how you arrived at this conclusion. I have a Bibler Winter Bivy, which is really nothing more than a sleeping bag cover and it holds me, my 3 season bag and an overbag just fine. If I was the size of an NFL lineman, then it would probably be too small, but I'm not. After thinking about a bivy as my only shelter, I wouldn't do it. I'd get a Henry Shires Tarptent Rainbow or something like it. There are lot of little one person shelters around that weigh about two pounds and don't look as claustrophobic as a Unishelter or similar designs.

10:20 p.m. on May 7, 2007 (EDT)
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In the case of a sleeping bag, a trim fit results in signficantly more warmth and less weight. But trimmed dimensions for bivvy sack results in much less advantage, and is therefore perhaps needless, and may even result in some compression of winter insulation.

Slightly larger dimensions would also be produce a little storage space, and be more useful as a two-person emergency shelter.

When Thermarest is inside bivvy and I'm lying on my side, it's tough to bend knees and hips. My OR sack only has zipper at top, which is good design, but if it were slightly wider, slithering in would be slightly easier.

But bivvy bags all seem to be about the same size. I use mine as a sleeping bag cover, or by itself, mostly under a separate shelter. Highly recommend the practice with light bags or in snow.

9:32 a.m. on May 8, 2007 (EDT)
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The big difference between a small shelter tarp and a Unishelter is simply weather resistance as well as speed/ease of erection. I can and have, many times, spent 2-3 nights in succession in only my bivy, the ID Unishelter, with NO tarp due to high winds and combined with a good synthetic bag, this is as efficient a system is windy, wet conditions as is available.

I "like"the extra shelter of a tarp and thus carry a Syltarp fo different types due to the low weight and utility, but, a Unishelter, Tripod bivy or Mega Sola is all you really need and far more effective in bad weather than any tarptent I have ever seen.

I got my first bivy in 1969, my first Gore-Tex ones in 1978 and consider these an essential part of my kit, especially for short trips or when hunting/angling in difficult terrain where weight issues are crucial. YMMV.

12:39 a.m. on May 22, 2007 (EDT)
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a.k.a. Steve T

Suggest checking out the bivys made by Ron Bell (mountainlaureldesigns.com). Ron offers bivys with highly breathable dwr coated nylon (what I have) as well as nearly waterproof epic fabric. He will customize to your specs, girth and/or length (I have extra length), also will customize with/without zipper and length.

You may spend a bit more, but will get exactly what you want. Ron has a bit of a backlog and you might wait a couple months to get your order but quality/satisfaction are guaranteed.

Check out his site and give him a call. Steve

2:07 a.m. on May 22, 2007 (EDT)
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a.k.a. tungs, Tony Lynes

Last year I bought a Swiss Gear 2 man bivy/tent from Sam's Club for $39. My son and I have spent weekends in it from 15 below to 95 degrees (Michigan). It's one layer of Syl-nylon, no rainfly (no extra weight-it's not needed) and one aluminum pole. Obviously with one pole it needs to be staked down. I'm 6'2" and 300 lbs., my son is 4'9" and 125 lbs. It serves it's purpose as a 2 man bivy just fine. When I'm alone it's very confortable. My surplus insulated mummy mattress and North Face 3D Goliath zero degree bag fit perfectly. I love the vestibule, it's large enough to put my pack in and cook too (out of the rain). The whole thing is 8'long x 4'wide and weighs 3 lb 3 oz. This bivy goes everywhere with me now. When it dies, I will find one similar to replace it.

September 22, 2014
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