Bivvy Sack: It’s that much better than an Emergency Blanket

Just about every outdoor pack has an Emergency Blanket or two.  Mostly because they are small, cheap, and light.  But are they really that useful? Here’s why I think you should go for an Emergency Bivvy Sack instead.

The Bivvy Sack

A Bivvy Sack (or Bivouac Sack, Bivy Sack, or Bivi) is usually a slip on cover for your sleeping bag to make it warmer or waterproof.  An emergency bivvy sack is made so that it can be used by itself.  Usually out of synthetic materials that are designed to reflect and hold body heat.

Obviously it’s something great to throw in your Bug Out Bag, but I am thinking it might be most useful for an Urban Survival Bag.  It would be a great warmth and weather protection option for an urban survival pack that is usually smaller and might not be made for out right camping, in which case you don’t have a full sleeping bag.

1. Its Reusable

I don’t know about you but I am never going to be able to refold a .79 cent emergency blanket back into that tiny little square. An emergency Bivvy Sack comes with a stuff sack and is made to be reused.

2. Sleeping Bag Style

Bivvy SackEmergency blankets are nice but they are awkward in a situation where you need warmth around your whole body. Square blankets are great for laying on the couch in the winter, but when you need full protection from the elements a sleeping bag style is really the best way to go.

Not to mention you could just slip it over your full sleeping bag anytime you need to for added warmth or water protection.

3. Help Other People

Not that any Survival Cache readers would be caught unprepared, but you could use an emergency bivvy sack as a sleeping bag if you had to. Assuming all our great readers are prepared, you could use it for helping out someone else who isn’t prepared.

AMK Heatsheet Emergency BivvyAMK Heatsheet Emergency Bivvy

AMK (Adventure Medical Kits) makes a great one called the Heatsheets Emergency Bivvy. It only weights 3.8 ounces and comes with a stuff sack. It costs more than a survival blanket, but since it is much more substantial and reusable that’s not a big deal.  They also make an updated version of the bivvy sack called the Emergency Thermal Bivvy II.

Photo by: Javasport

25 thoughts on “Bivvy Sack: It’s that much better than an Emergency Blanket”

    • Yes, it is definitely more useful than a space blanket for a full nights shelter.

      However, if at all possible you should try to find something else to put over you if you plan to use if for the whole night, to keep the dew off.

      A space blanket is good, but like you mentioned a tarp is probably better for long term. Long term being a couple of days, before you can put together something more substantial.

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      • my down filled cold weather sleeping bag has a older style canvas bivi on it if you treat that with some water repelant it is a great bivi I like it because of the OD green it blends in well with the foliage around my area so i just slip into it and role under a bush and walla no one can find you unless they are looking for you that is.

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  1. I was at FT Irwin in the winter one time and had my seeping bag stolen. I could have used a bivy sack ,but they didn't make them back in the 80's as far as I know. Having one in my pocket would have help get trough a freezing cold night.. I tried to wrap my shelter half around me but it didn't help much. I managed to cozy up to next a heater in one of the tents. long night.

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  2. There is not much worse than spending the night freezing. Glad you got through that night alright.

    These little bivvy sacks are so useful for an emergency shelter, or a sleeping bag cover for added protection.

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  3. I'm using a fleece sleeping bag, and in all practice runs it has been fine up to 0 degrees F when used with a tarp. If you leave an extra layer on it would probably do better. Also it weight is less than a pound, but its disadvantage is it is a little bulky when you strap it in to a rack, and it isn't waterproof by itself.

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  4. This may be a little off subject but I read on another survival site to have a carpenter garbage bag (55 gallon). They weigh practically nothing nor take up space but that of a garbage bag. You fill them with leaves etc. and you have a pretty soft, dry way to sleep instead of the cold, hard ground. I bought a carton of 18 bags at Wal-Mart for around $20.00. I put 1 in my bag and 2 in my husband’s bag. It is a light bed roll in our grab bags. Love this site! Thanks Lucas.

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  5. Glad to see the site back up,missed the great articles. Actually tested one Heatsheet bivy bags on Boy Scout Wilderness Survival merit badge campout this past October,Southeastern region. Temperature approx. 45 degrees, clear skies, wind < 5 mph.Slept uncovered on the ground with just the bivy bag as shelter. Used an Italian wool Blanket as a ground pad (no sleeping bags or foam ground pads were allowed). Bag kept me plenty warm; problem was moisture accumulation inside the bag from my perspiration. Had to keep wiping it off the inside of the bag with my bandana all night. Great piece of kit, just be prepared to deal with moisture if you include it your gear. Could be critical issue in really cold weather.

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  6. Last night my wife and took a group of friends out on a steath bug-out overnighter. It dropped to around +40 and my friends had no sleeping bags, warm clothes, or blankets. I sacrificed my wool blanket, heavy duty reflective blanket, wool vest, and cap to try and help the three of them. I then filled my contractor bag with dry leaves, hung a tarp, and crawled into my down sleeping bag. I slept wonderfully.

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  7. my BOB has several contractor garbage bags in it. They are very multi-functional. They can be used as bedding as stated above, split the seams and they can be used for a tarp, two arm slits and one for the head=poncho, drop BOB into it for water obstical fording, inflate it and and tie it off and “voila” floatation device and on and on.

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  8. Definitely thinking of getting one of these..what is the difference between the two sold on Forge Survival Supply though? I see that the updated one is heavier and mentions a "Thermo-Lite" material, but I'm just wondering how much different it is than the original and if it's the only difference between the two. Thanks!

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  9. Ekrich attributes the change to increases in "street lighting, domestic lighting and a surge in coffee houses," which slowly made nighttime a legitimate time for activity, decreasing the time available for rest.

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  10. Materials used in messenger bags are often more durable and water-resistant than other over-the-shoulder bags. Contemporary bags use thicker gauges of canvas and tarp shielding for the inner waterproof lining.

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  11. Just tried mine out a couple weekends ago as a sleeping bag cover and kept warm and dry even though it was raining most of the time. I would highly recommend bivvies, especially because they pack up so small and can be used multiple times.

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  12. Can't recommend the basic AMK Heatsheets Emergency Bivvy, as its basically an "space blanket" sewn into a bivy.

    Has the same moisture problems as being wrapped in a space blanket. Tested mine indoors on top of the bed at 68F. Woke up soaking wet from condensation.

    Managed to get it folded back up and mostly back into the little pouch. Brand new there's room for a button compass, and matches in a pill pouch in the bottom.

    Have read better reviews for the more expensive emergency bivys which have a vapor barrier.

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    • HI, CAN YOU TELL ME WHAT SITE YOU FOUND THE BIVYS THAT HAVE A VAPOR BARRIER. ARE THERE ANY STORES THAT CARRY THESE? THANKS SO MUCH

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  13. That's truly an amazing review of Bivvy Sack blanket. I agreed with the views about this blanket. For better sleeping comfort such blanket is very effective. I'm using this blanket for quite sometime now and it's good. Thanks.

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  14. I am making a light weight bivy. It is in the planning stage now. It will be a Tyvek shell top and bottom, then an inner ripstop nylon shell top and bottom. I will make the Tyvek outer shell with extra room; that will allow stuffing with leaves above and below the nylon inner sack if necessary for cold. I also will be able to slip a air mattress into between bottom bivy layer instead of leaves. The whole thing will be wider than a rectangular sleeping bag. The inner shell will be big enough to slip inside the bivy a cotton, silk, or fleese sack inside . . . there will be a hold in the bottom to pull the bivy liner inside. I will add a very lightweight bug mesh upper side with enough room for a v shape the height of my torso seat to crown. And I will carry a nylon tarp for extra rain protection. That is the plan . . . I will post how it turns out functionally for cold and wet protection and total weight/compression size and if the Tyvek combined with ripstop nylon are breathable.

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  15. Yes. I agree. People I know have said that a so-called Space Blanket was nearly useless in an unexpected night out while climbing a high peak in the Cascade Mountains. They all now carry a bivvy BAG of some sort and extra warm clothing. If there is no wind and it is not raining or snowing I believe a space blanket might be of some value, but they do not create the envelope you need to keep from loosing the warm are you heat up around your head body. The loss of radiant heat isn't as important as the advertisers would have you believe. Any plastic bag that you can climb into does a remarkable job of keeping the wind and rain off you and your body heat contained.

    Reply

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