Bivy with or without groundsheet?

2:08 a.m. on September 6, 2014 (EDT)
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This is less a conversation and more a poll, but am transitioning into tarp camping and plan on supplementing it with a bivy.

The bivy is a bug bivy, with a silny bottom and bug netting top.

Additionally, I plan on placing my inflatable sleeping pad inside the bivy.

Do those of y'all out there using bivy sacks bother with a groundsheet? Swear by it? Never bother?

My short term goal for fall is to fit my base weight into a 25L daypack. Being able to ditch the groundsheet frees up some interior real estate and drops the pack weight by a few ounces.

Ultimately this is less about saving weight and space and more about determining whether or not this is an unnecessary redundancy.

Curious to hear what y'all have to say!

10:37 a.m. on September 6, 2014 (EDT)
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I use a ground sheet with a tarp, but have never owned a bivy. I don't use a ground sheet under a tent.

4:14 p.m. on September 6, 2014 (EDT)
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No need for a ground sheet IMO. If you happen to wear a hole in your bivy its nothing a little diluted silicon cauk cant fix.

4:21 p.m. on September 6, 2014 (EDT)
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Eric...I use my bivy (1.7 oz coated-nylon bottom) in the same ways as you suggested above...and I don't use a ground-sheet. I find that for moisture and puncture resistence a raised-bed of nearby leaves + sand + etc. works really well...takes almost no time to construct (often pushing it together with my shoe)...and weighs nothing. For the same reasons I do not use ground-sheets with my bivy I do not use them with my tent either...but if tent camping in really wet conditions I sometimes bring my bivy.

FYI...if you use your pad inside your bivy I would make sure to get a bivy with a bit of extra space to keep everything lofty and provide additional dry-storage for electronics and the like. I also use the trash-compactor bag in my pack for additonal dry-storage and work-space.

8:02 p.m. on September 6, 2014 (EDT)
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Glad to hear the groundsheet is more an added redundancy than a required necessity, guys.

Ken - I always keep a partial roll of Tenacious Tape in my pack for field repairs. Stuff works great for silny. Already used it thrice to repair holes on my Thermoball jacket and it holds up really well over time.

Mine has a 30D silny bottom, Joseph. Think I should be alright.

You're talking about building a small "retaining wall" around the perimeter, like you did down at Forest Glen, right?

The size of the one I've got is good: doesn't constrain the loft of my bag when the pad is also inside the bivy. Interesting thing is that it relies upon the user being inside it to raise the silny bottom up, creating a bathtub floor. If I had too much room with this design, I couldn't achieve the tension needed to create the bathtub.

Actually have used my compactor bag liner for work space, a sit pad, etc. Glad you lent me one down at Shawnee and got me hooked on using the things. One of the most versatile things in my pack, easily.

12:22 p.m. on September 7, 2014 (EDT)
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A bivy has always seemed too confining and steamy as a place to sleep. The tarp keeps the dew off if sleeping in the open. In a blow I lower the tarp close to the ground. If there is some blowing snow or rain I use the ground sheet as the last line of defense.

1:17 p.m. on September 7, 2014 (EDT)
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The bivy I've purchased is more than anything aimed to combat the buggier months here in IL, with an emphasis on breathability - the entire top half is mesh.

While the close quarters are less than ideal, the larger tarp allows me more room than I had in my Lightheart Gear tent. No matter how I positioned myself in that tent, my head and/or feet always came in contact with the walls. Last thing I'd want is to wake up in the morning with a wet foot box on my down bag.

Once the weather cools off, I think a generously-cut groundsheet would work well, folding back whatever excess was unneeded, while at the same time having spare material to wrap myself in or push against an exposed side for more weather protection and coverage.

12:42 a.m. on September 8, 2014 (EDT)
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I used bivy sacks in my climbing days. Both the totally unbreathable type and later a breathable I made using Goretex on the top and waterproof on the bottom. I put my pad outside. On my tents,  I use a groundsheet on the outside. Some advocate on the inside. Either way will work, and I have done both. It is sort of, do you add your cream first or your sugar?

6:58 a.m. on September 8, 2014 (EDT)
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Or do you just drink it black? =P

9:24 a.m. on September 8, 2014 (EDT)
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I use a groundsheet with everything. The reason is that I wild camp... up in the hills/mountains, off any paths or camp grounds. You rarely ever find truly good ground so in an effort to protect my tent, as well as have a dry porch area, I prefer to carry a groundsheet.

9:53 a.m. on September 8, 2014 (EDT)
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Wild Camp? Is there some other kind?

10:31 a.m. on September 8, 2014 (EDT)
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TJ brings up a good point. The ground sheet on the outside will protect the floor of your tent from wear.

11:11 a.m. on September 8, 2014 (EDT)
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ppine said:

Wild Camp? Is there some other kind?

Well a lot of people go to designated or sheltered areas either on or just off trail..... usually fairly well suited for pitching. While thats still in the wild, its a bit more friendly.


Finding some borderline flat terrain half-way up the side of a mountain or a passably dry spot in the middle of a boggy plateau has different challenges altogether.

5:51 p.m. on September 8, 2014 (EDT)
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Eric...what you saw me doing around the perimeter of my tarp was keeping drafts down by closing off the small gap on the windward sides of my tarp. Where I intend to place my bivy I push together a good pile of leaves (soft ground debris) to create a raised bed...which helps prevent punctures and helps insulate me from ground moisture and prevents some heat loss. I have been doing this for years...and I have found it very effective and convenient in Eastern Woodland areas where leaves and other soft debris is always abundant.

When I made my bivy I intentionally made the top smaller than the bottom...this allows for a larger overall volume while still providing the bathtub effect you mentioned. However...if your bivy is not compressing your bag then it sounds like the size is appropriate...just thought I'd mention it to prevent you from losing some of the effectiveness of your bag.

Eric...unless you sleep like the dead I would caution against using just a ground-sheet in the cooler months. Where you and I play moisture (often hard to see) is trapped on everything in the form of ice during the cooler months...and everything you and your gear touches will get wet. A bivy provides both a high degree of assurance against moisture/ice as well as additional warmth...ground-sheets just don't measure up IMO.

3:16 p.m. on September 9, 2014 (EDT)
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What do you do when everything is really wet and muddy?  Wouldn't a not too big mylar or tyvek ground cloth or even a space blanket as a ground cloth be nice then?  How do you keep the mud out of the inside of your sleeping bag/bivy if you don't have a dry place to change before turning in?   Even when the ground is fairly dry, moisture will come up under you.  My ground cloth is always wet on the bottom.

8:11 p.m. on September 12, 2014 (EDT)
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I would presume that most bivy bags have a waterproof bottom (mine also has a WPB top). With the addition of a thick bed of leaves as my base...I have never had issue with moisture coming up from the bottom....though I have had water completely surround the bed of leaves like a moat.

I cannot speak for others...but I take my wet clothes off outside of my bivy...hang them up from the ridge-line under my tarp...and then put dry clothes on inside my bivy (note that I prefer an over-sized bivy).

2:08 a.m. on September 16, 2014 (EDT)
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Eric:

Keep the ground sheet, ditch the bivi sack since it appears you use it mostly for the big netting, and go with one of those mini tent bug nets that protect your head from bugs while you otherwise sleep under the stars.  this system will be lighter and less bulky still than the bivi system you describe.

Ed

 

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