Bivy inside shelter?

[William Hanson (live2hunt)]

I used a bivy this year and likely won't go without one again. It keep everything clean and dry and contained. I used to use a piece of tyvek and it worked ok but the bivy is better.

 

[WV Mountaineer]

Tyvek works as a ground sheet but it does let moisture through. I use a custom cut piece of Silpoly with a very high waterproof rating. Yeah, its slippery but not after applying lines of thinned silicone sealer....My pad doesn't slide.

I used 2nd quality silnylon that was categorized as such due to being way over coated, for just this reason. Nothing slides around on it

 

[gdog]

I use in my Cimarron during cold weather:

Helinox Lite Cot (the is new-only used on one trip so far)
Borah Lightweight Bivey
Big Agnes Q Core SLX
EE 10 degree quilt
piece of Tyvek under cot to give me something clean to stand on

 

[corylee4870]

No bivy in my Redcliff

If I am below treeline 3 to 4 inches of pine boughs / ground cloth / Big Agnes Q-Core / Bag
Above Treeline - Thermosrest Ridge Rest SoLite / Big Agnes Q-Core / Bag

Why do you change ground pads depending on elevation/treeline?


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[corylee4870]

I use a TiGoat Bug Bivy - keeps everything together, bottom dry, doesn't retain moisture.

TiGoat Ptarmigan Bivy

I really like this idea. Keeps the bottom dry and everything together with no worries about condensation inside the Bivy.

It doesn’t protect my bag from any condensation in the tent, but if I elevate the sides and keep the top open a few inches I don’t think I’ll have that problem.

It also cannot be used as a stand-alone shelter.


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[Akicita]

Why do you change ground pads depending on elevation/treeline?


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In cold weather below treeline I can cut Pine boughs for added ground insulation - above tree line I can't do that so I pack my Solite for the added insulation. These combos are for any time of year the ground if frozen or snow covered.

 

[ellsworb]

Looks like I'm in the unpopular camp of NO bivy. Floorless or Tarp doesn't matter to me. I'm on a polycryo groundsheet, thermarest neo and quilt on top. Like others , I too am a warm sleeper and the (relatively few) times I have used a bivy the interior condensation was not acceptable.

Plus, with my quilt, I'll often throw a leg out to vent. I felt like the bivy artificially restricted the liberty of using the quilt!

 

[mtwarden]

with a smaller tarp I see no way around not having at least a bivy with decent DWR, much too easy for moisture to blow in; a larger tarp or mid- agree that a bivy is definitely optional

 

[Odell]

That’s the only way I’ve ever done it, until this year and using a Helinox cot for the first time, but I still used my 6 oz. bivy to keep everything contained.

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This is exactly what I did this year, a 6oz bivy from Jimmy tarps on a helix cot with a quilt. Kept me slightly warmer, dry in a very wet condensation and snow scenario, stopped a few drafts and it also kept my arms in place. The cot is only as wide as my torso and super annoying to have your arms drop to the ground when I end up on my back. Even adding a cot, my whole system is still much lighter and packs smaller than my bag/tent combo and way more comfortable.

 

[Tim in Wa.]

I'm not familiar with all of Ti goat or Borah gears bivy offerings but could it be that your using one that is not very breathable?

Obviously not breathable enough but they were both supposed to be

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[corylee4870]

What Bivy and pad combo are you guys using? A standard pad wouldn’t fit inside the Bivy.


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[mtwarden]

I'm using an Xtherm pad (regular size- 20" wide) with a MLD eVENT bivy- size large

 

[mrbillbrown]

I’m running a large mummy shaped Xtherm pad, Kifaru Slick bag, and an oversized Borah Gear SnowySide eVent Bivy with a custom center zip to match my Slick bag inside my Tut or under a tarp.

 

[AK Troutbum]

What Bivy and pad combo are you guys using? A standard pad wouldn’t fit inside the Bivy.


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I use several different bivy/pad combos depending on the circumstances, but the largest pad I use is a regular size Xtherm and it fits in both of my bivy’s (Ti Goat and Borah Gear), with plenty of room to spare.


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[Ten Bears]

Instead of a bivy fo any of you guys run lightweight nests ? Mountain Laurel Designs has one at 10oz. I have been contemplating this over the bivy options.

 

[AK Troutbum]

I have a two person nest that I bought from Seek Outside when I bought my tipi and I’ve used it a few times but I determined that I don’t really need it. It’s a lot more comfortable sleeping on a cot and bugs are never an issue during the times that I use the tipi. I’ve kept it for those “just in case“ times, but I haven’t used it in years.


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[Owenst7]

I would say the need for a bivy in a tarp shelter really depends on too many variables to narrow it down to a generic explanation. Temperature, humidity, wind, how well you seal up the bottom, if you vent the top, etc.

I recently had three of us sleeping in my 2 man Mountainsmith tarp for close to a week. Temps were about 35-40 during the day and about 15-25 at night. We got hammered with nonstop squalls for a day. It was very windy and we piled deadfall/snow up the perimeter to seal the bottom to the ground and closed the vents to keep spindrifts out. Two of the three bags (all down) were goretex with worn out DWR. One bag (that we placed in the center to protect it) had no protection for the feathers and was only a 20 lower EN rating, so he used a sol "breathable" bivy. I use a sheet of 2 mil LDPE painters plastic under my pad. The condensation was freezing to the inside of the tarp quickly due to the cold, so we did not have much drippage, but everyone was brushing the tarp all night due to the cramped conditions, and we had frost all over our bags all night. The day after the squalls subsided, I made clotheslines and hung ALL our gear up immediately. The goretex bags were damp on the surface due to the DWR being worn out, but obviously the teflon underneath protected the feathers just fine from frost (liquid water may have made it through the baffle stitching at a very slow rate). The non-protected bag's exterior that was inside a bivy was saturated inside from breath/perspiration over the last three days. The untreated nylon exterior had wetted out, but the feathers were not clumpy at all. I hung the bags in the breeze and turned them inside out after a bit, and the non-protected bag was totally dry in a half hour. The goretex bags probably didn't need to be hung, just brushed off and left in the tarp with the door open.

In the summer when I use a different bag or a quilt that is not water resistant, I usually lay a sheet of plastic over part of my insulation if it is conditions where I will experience significant condensation inside the shelter (it has to do with temp/wet bulb/dew point). I prefer a sheet of plastic that still gets airflow to a bivy because a bivy can trap moisture. On the other hand, plastic can get blown away/slide off. It really depends on how you sleep, your shelter's shape, your weather, etc. The big thing is you need to understand the advantages and limitations of your equipment and plan how you'll use it effectively in the weather your will experience. If you're in a tiny sheep tarp in a chinook, a bivy is probably going to be more practical, but you need to pack your bag away in a waterproof sack and wipe out the inside of your bivy every morning. If you're using a sheet of plastic, you need to pile rocks around the perimeter to keep the wind from blowing it off the bag and letting it get wet. If you're in a big tarp with a lot of protection, you're probably best off to use a non-goretex bag that breaths better and use the large interior air space to your advantage and vent the shelter strategically to keep the inside humidity to a minimum.