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DanO

Bivy Sack as Overbag?

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I have been reading lately that a thin synthetic sleeping bag over a down sleeping bag will keep the down bag dry. I have not tried this system yet to date but sounds good.

 

I have Salathe bivy sack, I wonder if this would do the same thing or not?

 

I wonder if it would work well to have a down bag then synthetic overbag then a bivy sack over everything?

 

Of course the lightest option is to have a down bag then the bivy sack. That is for total shelter.

 

I saw one writer who said that a synthetic sleeping bag over a down sleeping bag was weather proof, I can't imagine that is

true in a rain, it would have to soak through, also wet snow.

 

I have a synthetic bivy coat, I could put that over my down sleeping bag as a sort of synthetic overbag while in the bivy sack. Is that a good option as well?

 

Dan

Edited by DanO

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i think for anyone to help you out here, you gotta lay out what it is you are planning on doing.

 

i don't even know where to begin with this post, there's a lot of false assumptions, misunderstanding of the information, and incorrect information.

 

A synthetic bag over a down bag will slow down your inner bag from getting wet but the point of adding another bag would be for increased warmth with a bonus of adding weather resistance, not to keep you dry. If you're concerned about water from the outside, a bivy sack is better, but by no means the lightest option or is it total shelter.

 

my advice based off the info provided (it sounds like you are doing an open bivy in the snow or rain on a route by yourself) - wait for a better forcast and try not to bivy on the route. Bring a tent for the base.

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if a lightweight tent (firstlight for example) weighs the same as a synthetic overbag, then why go with a overbag? I would rather be bagless in a tent than tentless with a bag if the weather was bad.

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In SAR,

 

So don't have the luxury to choose a good spot to camp every time... Or when on a mountain. Trying to be light as possible. Most times don't have to bivy, but good to have that option, without the chattering shakes when it arises without excessive weight.

 

Seems like the best option is a mountaineering bivy sack(one where you can sit on a ledge if need be), a belay coat and a super light 30 degree down sleeping bag with a pad. May throw in a synthetic overbag or a change up to a 20 degree sleeping bag with extra weight if colder and or more likely to bivy.

 

Being a gear junky I wonder how the synthetic overbag over a down sleeping bag would work out.

 

 

Thanks all

 

Dan

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If you are bivying on a ledge, then you are on some technical ground. I would not want to carry the bivy, 30 deg down, synth overbag and a belay coat. (in addition to all the other stuff one needs) especially if it is on 5.8's and such.

 

My bivy kit would be a ultra light bivy (epic material no zipper) really LW down bag liner (40 degree) 3/4 foam pad and a light puffy coat. sleep in all climbing clothes and it will be OK. have done it with only the epic sack and a flaked rope. (too tired to care)

 

a good headlamp is lighter than all that gear. Like what Drew was saying, just keep going till 3am, pass out on some flat boulder, shudder for a couple hours, and keep going. That is how I got married. :)

 

If you really want to learn about lightweight bivy gear, give promountain sports website a look. Jim Nelson can talk your ears off about LW gear. Maybe pose your question to him personally.

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You have to bivy en route for search and rescue? If you're in charge of finding and helping people stranded in the mountains then i have three questions:

 

1.)why are you bivying on route?

2.)why don't you already know what to bring?

3.)do you also plan on getting rescued?

 

nothing about your questions or intended use makes any sense. I applaud your noble intentions for helping others, but I sure hope I don't need SAR where you work.

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for an overbag that mitigates internal and some external moisture you need to have some synthetic filling ... a plain bivy wouldnt do the trick

 

for a WPB bivy, you need WPB fabric, a synthetic bag without such wouldnt do the trick

 

why not just use a synthetic bag if you are worried about moisture ... pair that up with a UL tarp that you can wrap the subject/yourself in if you need

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An overbag plus a light down bag will be much heavier than just bringing a warmer down bag. I don't know anyone who uses an overbag for much in this State. As mentioned above an overbag can help mitigate the wetting out of a down bag on extended trips where you have difficulty drying things out (high altitude, bad weather).

 

Not sure what SAR you are with, but I'd go with a synthetic bag and a simple bivy sack. You are a lot more likely to be trekking through wet brush than in the middle of a technical route. A wet down bag in your bivy sack still sucks, use that for climbing in good weather, not searching in crappy weather.

 

Good luck!

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Western Mountaineering Ultra lite bag 20 deg rateing 1#13z

Black Diamond Winter bivy 9z Epic fiber

stay warm, stay dry, wind proof.

better protection Same bag, B.D. first light tent 2#13z

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Thanks for the tips. Thinking about all of them.

 

I think it too heavy for most missions to have a overbag

with a down bag.

 

Good day.

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With due respect, this is a bizarre question coming from someone who is tasked with going into the mountains to "save" people. Maybe I have missed the point or misunderstood the original question but it would seem to indicate a basic lack of understanding of mountain knowledge.

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Just because I belong to SAR does not mean I don't walk around on earth like everyone else. I have a lot of experience but no experience with synthetic over bags used over goose down sleeping bags. Hence the question. How many here have this experience. I just wanted to hear about others experiences, etc.

 

99% in SAR are volunteers, unpaid, buy own personal gear, etc.

 

My experience, done a fair amount of climbing, a average climber. Can do up to 5.8 trad these days. Can lead around WI 3 on ice.

 

Never been lost in the mountains. Done some decent climbs, plan to do some more.

 

SAR is always looking for good climbers and ground pounders to help out. Often enough only a few guys are all that show up on missions, especially at first. Of course sometimes many show up.

 

Maybe someday in the future one of u posters will show up at a mission? That would be nice, welcome it, I mean that.

 

Good Day

 

Fin

 

 

Edited by DanO

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hopefully english isn't your 1st language, if so, I apologize for sounding harsh. If not...i don't even know where to begin. good luck on your biving.

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I have a lot of experience but no experience with synthetic over bags used over goose down sleeping bags. Hence the question. How many here have this experience. I just wanted to hear about others experiences, etc.

 

Basically, they are two different things, and they work just like jackets do.

If you put a synthetic jacket on over a down jacket it makes you warmer - assuming the down isn't squashed flat because the overjacket is too tight.

 

If you put a Goretex jacket on over down it keeps the down dry.

 

It's the same thing with sleeping bags. An overbag is like putting another puffy on. A bivy sack is like putting an uninsulated hardshell on.

 

If you have a down sleeping bag, do you want to make it warmer or do you want to make it waterproof?

 

If warmer, use an overbag.

If waterproof, use a synthetic overbag.

If both, use both.

 

You can dry out a slightly damp down bag in otherwise dry conditions by putting an overbag over it because the warmth of your body and the way you move the dew point outwards will make some of the moisture move outwards away from the down bag into the synth. You can't do this just with a bivi sack.

 

On the other hand a synth overbag by itself over down in wet conditions (dripping wet snow cave, rain, or even sleeping directly on snow) is not waterproof enough to prevent your down bag from getting wet and becoming useless. First the synth will get wet, then it will make the down wet, then you will be screwed.

 

I hope this answers some of your questions.

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You have to bivy en route for search and rescue? If you're in charge of finding and helping people stranded in the mountains then i have three questions:

 

1.)why are you bivying on route?

2.)why don't you already know what to bring?

3.)do you also plan on getting rescued?

 

nothing about your questions or intended use makes any sense. I applaud your noble intentions for helping others, but I sure hope I don't need SAR where you work.

 

Layton, I think you're kind of being a dick. When I was doing SAR stuff, I can't remember how many times doing grid searches my team (I don't mean MY team, I wasn't a leader or anything) would just stop and lay (lie?) down right where we stood until the sun came up and we could resume searching. Granted, it wasn't "on route" or anything.

 

Even after joining mountain rescue and being on more "technical" missions, there were many times we would bivy in awkward places. Granted, they were also not "on route" but they were often in awkward locations (people tend to get hurt in awkward locations) and almost always in bad weather. For example, spending a cold night on a shelf at the Mt. Pugh saddle, above a subject who was stuck below, or a night in an awkward boulder field on Three Fingers while we waited to see if weather would improve enough to get a helicopter in.

 

Regarding the OP, instead of using a synthetic overbag, I would prefer a down bag that was warm enough (no overbag needed), and a lightweight bivy sack to protect against weather. If it was going to be an extended stay (rare in my limited experience with rescue), I would opt for a synthetic bag instead, and still use the bivvy sack. If you wanted to go lightweight, you might consider a down bag with an eVent shell -- I think Feathered Friends will make you one. Then, if it gets wetter, throw the bivvy sack on.

 

I have a mtn-hardwear bivvy sack that I really enjoyed, it has a see-through plastic window on the face (great for when you're in it and sitting up; you can see the weather or if it's daylight yet) and has openings for your line when sleeping anchored in your harness or just for venting.

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Thanks Rob,

 

I think even a very experienced climber doesn't really understand the differences of situations that a SAR person may get into on a trip out. So far I have not gone on very technical ground on a SAR trip. Even so you can't just pick your spot and may end up on ground that it is not easy to set up a tent. You may be with others as well and this further narrows the spots that are available. Like you say on Pugh, it is a long stretch on third class with very few good spots to camp. When you get to the injured party, most often that is where you are at, good spot to camp or not.

 

I sort of focus on the possibility of a bivy on my trips out, even though a unplanned bivy has been rare for me so far.

 

I think to be light is just carry the bivy sack, some extra clothes and like you say maybe a light sleeping bag. Most likely a 30 degree down bag as this is the lightest I have in my kit. As you say extended trips out in SAR are fairly rare for me so far. Of course if it is dumping rain when I start out I may opt for my synthetic half bag in my kit.

 

I didn't mean to stir up pot when I posted, I had no idea this would have happened.

 

 

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Lots of vadid points made. I believe the key is being as educated about the enviroment in which you'll be traveling as possible. Personally I carry a B.D. winter bivy and a light tent when ever I go out in winter or out alpineing alone. It's insurance when you leave your tent and gear behind at camp. Only weighs 9 oz. and impervious. I have used this bivy sack on very cold ridges inside a tent to trap more of my body heat. So it works kind of like an overbag in itself. BONUS !!!!

 

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