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Bivy vs larger tarp
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John G
(JohnG10) - F

Locale: Mid-Atlantic via Upstate NY
Bivy vs larger tarp on 11/22/2009 09:26:39 MST Print View

I'm thinking of moving to a tarp, and need some advice.

My understanding is that most people use a bivy with a tarp for the following reasons:
1. Cuts down on wind blowing through the sleeping bag/quilt fabric
2. Eliminates the need to tuck/strap the quilt to prevent heat loss when you move in your sleep
3. Eliminates problems with rain splatter

But using the Bivy has the following disadvantages:
A. Much harder to get in/out of than a quilt alone
B. Lot's of condensation in a humid environment

So, I'm wondering if the following strategy would serve the same puposes with less weight, and more convenience:
i. Use a slightly larger tarp, and stake the windward side to the ground
ii. Use a slightly wider quilt so the edges don't lift off the ground and allow heat to escape when you move in your sleep

Is there something I'm missing ?

Thanks.

Edited by JohnG10 on 11/22/2009 09:27:27 MST.

Doug I.
(idester) - MLife

Locale: MidAtlantic
Re: Bivy vs larger tarp on 11/22/2009 09:46:44 MST Print View

For hotter, more humid climes, MLD makes a bug bivy. All mesh, hooks up into your MLD tarp (or any tarp with hooks along the underside of the bivy). So more solid bivy for cooler temps, bug bivy for hotter temps.

I have both as I'm one of the people who can't get past the "creepy crawlie" thing. Others can, and would do like you suggest.

Daniel Benthal
(DBthal)

Locale: Mid-Coast Maine
Tarp & Bivy on 11/22/2009 09:50:28 MST Print View

This forum is wonderful because of the great insights we get from experienced backpackers from all over the world. However, one potential downfall is the conditions we actually backpack in don't always match the conditions (and "best" equipment) behind all posts.

In an Alpine environment in the western U.S. a small tarp and bivy is perfect since there is less rain and it can get very cool at night.

For East coast backpackers, there can be copious rain, high humidity, warm nights, and a lot of bug pressure.

For these conditions I prefer a larger tarp and bug bivy / shelter. If bug pressure is low, leave the netting behind.

Dan

Edited by DBthal on 11/22/2009 09:51:43 MST.

Adam Frizzell
(adamf) - MLife

Locale: Mid-Atlantic
Re: Bivy vs larger tarp on 11/22/2009 09:55:26 MST Print View

Hi John,

I think you're right on... a large tarp and no bivy vs. a small tarp and a bivy are pretty much 2 great options. I don't think you could go wrong with either.

A couple months ago, I started using a tarp exclusively and went with a solo-sized tarp and bivy combo. I believe this is going to offer me a handful of options in the long run:

Cool night with no precip: ditch the tarp
Light precip with no heavy winds: ditch the bivy
Heavy precip with directional rain coming at you: use both

I'm in Maryland too, so I know about our humid summers and how gross it can get. For this, you could bring the tarp and a bug bivy or MLD Serenity Shelter. You'll have the bug protection and great airflow.

I did a hike with some guys last weekend, and I had an MLD solo tarp and TiGoat bivy and another guy had an 8'x10' ID sil tarp. He pitched his tarp to the ground on the sides and it was palatial! Even if it had poured all night, he would have stayed dry. But, he did experience some condensation under that big old tarp.
I've taken my solo tarp and bivy into downpours and had no issues with condensation (even in warmer showers) or rain getting in the bivy. The highly water resistant and highly breathable fabric of my bivy (TiGoat uses Intrepid, which, as I understand it, is just a rip stop version of Momentum) kept all of it at bay.

I think if you went with a larger tarp without a bivy, a flat tarp (i.e. an 8x10 tarp) would be the way to go. Lots of pitching options to keep weather at bay. But, Maryland's (and the surrounding areas) mosquitoes in the summer are pretty nasty. I would want the bug protection.

But, again, I don't think you can go wrong with either option. Tarp camping is awesome, and I love the simplicity, the views and the connection to the place around me. Don't think I'll ever go back to a full on tent.

Best of luck!

Regards,
Adam

John G
(JohnG10) - F

Locale: Mid-Atlantic via Upstate NY
Condensation in Bivy on 11/22/2009 12:37:26 MST Print View

Is condensation inside the bivy as much of an issue in the mid-atlantic as in the mid west ? (Not as cold, but more humid).

Lucas Boyer
(jhawkwx) - MLife

Locale: 38.97˚N, 95.26˚W
re: condensation on 11/22/2009 13:06:51 MST Print View

As a midwesterner, the humidity is near and dear to my heart. Well actually, it's near, but I don't know how heartfelt it is when sleeping. Keep in mind a light breeze will move a lot of water vapor away from your bivy, but a still night will create havoc. I recently used my DWR Top/Sil Bottom'ed MYOG bivy on its inaugural run here in the midwest for 6 cool fall nights. While there was no precip any night, I utilized the bivy 5 of the 6 nights to get a better feel of the conditions it would perform well in. The best performance was the nights a nice breeze was present. However, the coldest night was also the calmest night. I cowboy camped in the bivy. I wetted out my WM Ultralite by daybreak and was having cold spots from the collapse of the insulation. Some of this was probably due to my keeping my head inside the bag and breathing in to the bag, rather than outside. The top 24 inches or so of my bivy is no see um mesh and vents rather well. I have not used a quilt in the bivy, but I have used my bag like a quilt in the bivy and didn't have condensation issues. However, I wasn't breathing into the bag and light breeze stayed through the night. I would caution anyone using a bivy/tarp combo to keep the tarp "up" and not staked to the ground, unless of course a gale force wind is coming through, then you will still have adequate ventilation. Moral of the story: your experience may vary with conditions present. Calm nights in humid environs = wetness potential. I would like to hear from anyone that has comparisons of DWR ripstop against Momentum. I may construct another MYOG like mine with Momentum instead.

Diplomatic Mike
(MikefaeDundee)

Locale: Under a bush in Scotland
Re : Condensation on 11/22/2009 14:10:57 MST Print View

I've been using a TiGoat bivvy in temps from around
+10C to -10C, in mostly humid conditions, and not had any condensation problems.

W/B bivvys are more prone to condensation in my experience. I've used a few different fabrics, and have found Event to be the best. I've had condensation in Goretex bivvys. My ID all Event bivvy has been a fantastic buy. I've never had any condensation in it. I think the fact it is 100% Event is important in its good performance. Most bivvys have a non-breathable waterproof floor.

My winter trips are limited to weekends only, so i can't comment on long term cold weather usage. I also use a quilt nowadays, but don't think that makes any difference.

Ken Bennett
(ken_bennett) - F

Locale: southeastern usa
Re: Bivy vs larger tarp on 11/23/2009 09:06:39 MST Print View

>But using the Bivy has the following disadvantages:
>A. Much harder to get in/out of than a quilt alone
>B. Lot's of condensation in a humid environment


This depends on the bivy design. My homemade bivy uses Momentum .90 top fabric, and has a huge mesh area over the head and chest. I have used it in all kinds of humid conditions and never had any condensation.

This bivy design uses a zipper that runs from the right shoulder to the left hip around the circumference. It is *very* easy to get in and out.

Finally, need to add one more to your "advantage" list: a good bivy keeps the bugs off.

Bob Bankhead
(wandering_bob) - MLife

Locale: Oregon, USA
Re: Re: Bivy vs larger tarp on 11/23/2009 09:55:03 MST Print View

+1 for the larger FLAT tarp. Many pitch options adapts readily to varied weather/humidity conditions. I'm especially fond of the bomber flying diamond. Larger covered area = more protection, plus extra room for you and your gear. Also beneficial should you encounter an attractive and/or distressed member of the opposite gender trying to put up a damaged shelter in nasty weather.

Skip the bivy. Use a microfiber shell on your quilt or sleeping bag. It will provide good protection from both wind, condensation, silnylon overspray, and weather blowing in around the edge of the tarp.

Edited by wandering_bob on 11/23/2009 09:57:08 MST.

David Olsen
(oware)

Locale: Steptoe Butte
Re: Bivy vs larger tarp on 11/23/2009 11:53:51 MST Print View

If you are getting condensation is a bivy, doing away
with the bivy will likely just move the condensation
layer deeper into the insulation of your sleeping bag.
The dew point will just move inward.

In humid climates I like a thin synthetic layer outmost
so the dew point stays in that layer and doesn't effect things so much and is fast to dry.

Acronym Esq
(acronym.esq) - F

Locale: TX
Re: Re: Bivy vs larger tarp on 11/23/2009 14:20:01 MST Print View

"If you are getting condensation i[n] a bivy, doing away
with the bivy will likely just move the condensation
layer deeper into the insulation of your sleeping bag.
The dew point will just move inward."

This has been my (very limited) experience. Sleeping under an 8x10 tarp in very humid cool conditions caused condensation to form directly on the sleeping bag.

I have never heard of a "microfiber shell." What's that?

acronym 11/23/2009 3:19 PM

John Brochu
(JohnnyBgood4) - F

Locale: New Hampshire
Re: Bivy vs larger tarp on 11/23/2009 22:00:26 MST Print View

A couple of points in favor of solo size tarp bivy combo:

* A larger tarp can limit site selection in some areas.

* A solo tarp/bivy combo gives valuable experience if you ever want to move to a poncho tarp. And if you do, you already own the bivy to pair it with.

* Winds can swirl causing drafts to the bivi-less quilt system.

* A half length bivy zipper is well worth the extra ounce or so.

* A bivy offeres bug protection, and can also be used in shelters for bug protection.

Walter Underwood
(wunder) - M

Locale: San Francisco Bay Area
Tarps and Bivys - read the Ryan Jordan book on 12/30/2009 16:11:54 MST Print View

I strongly recommend getting the Ryan Jordan (editor) book and reading the chapters on sleeping (including bivys) and shelter (tarps). Lots of great detail on warmth, condensation, etc.

http://www.backpackinglight.com/cgi-bin/backpackinglight/00070.html

I generally use an 8x10 tarp and a TiGoat Ptarmigan bivy. TiGoat will add a short side zip as a custom option (e-mail them). DJ thinks a side zip is not necessary, but he's glad to accommodate those who disagree.

I'd actually like a longer side zip, but the short one is really nice for getting in and out and for warmer nights.

Condensation happens in a bivy when the outside is cold enough to condense water. A tarp will reduce radiant cooling of the top of the bivy. I have had condensation on cold clear nights when sleeping without a tarp. It was worth it to watch the Perseid meteors in the Sierras this summer.

Condensation is more likely at the foot, because there is less body heat to keep the outside of the bivy warm. A few bivys have a zipper for ventilation at the foot.

I almost always use a bivy because a gentle breeze across my face really bugs me when I'm trying to get to sleep. I rarely zip it all the way closed. I usually tuck my head under the hood of the bivy to get out of the breeze, then drift off to sleep.

Finally, if you want to pitch a flat tarp a lot of ways, you want lots of tie-outs. For that, get a Tundra Tarp from Cooke Custom sewing. They weigh a couple ounces more, but the tie-outs and reinforcing are excellent.