Tarps and Bivies

[Jason Griffin]

My buddy and I use an MSR Hubba Hubba when hiking together and we're contemplating lightening the load a bit by going to our own tarp and bivy setups. I was looking at the MSR E-wing and MLD monk tarp (5.9' x 9'). The monk is 11 sq. ft. larger and 2 ounces heavier. Then I was looking at the Rab ultra bivy; it's more of a sleeping bag cover made of pertex endurance that weighs 6.7 ounces. I just have a few questions.

Do you think the e-wing at 42 square feet is too small to give me full coverage?

Would I still be able to fit my gear under the tarp with me?

How does pertex endurance hold up to rain and the ground? Condensation?

Will I want a ground sheet?

What would your suggestions be for a so see-um option to accompany this set up. I'd like to keep it super light and more of a drape/bivy type enclosure so I can move in the summer when I'm not wrapped up tight in my bag.

Will I hate myself for not getting a bivy that closes over my face?

Will I hate myself the first time it rains?

Will this be appropriate for winter backpacking; I plan to use a marmot lithium bag.

Last but not least how do tarps hold up in the wind?

Sorry for the multitude of questions; I've done a lot of searching. Thanks for responses.

[John Sixbey]

I can't answer some of your specific questions, but I've used bivies for a few years now and have a few thoughts. My setup is a bivy with no tarp, one that has a hoop to give more room over the face. Having something that covers the face is the best way to keep off the bugs IMHO, but it's very annoying if the fabric drapes directly on the face. I forgo a footprint and use my closed foam mat directly on the ground instead, but this only works well if I stake down my bivy around it to keep things from shifting around.

Rain can be an issue with a bivy; since I opt for no tarp, I have to pay attention to which way the wind blows, etc., and rig up my ventilation to compensate. You don't want to completely close up a bivy for fear of suffocation – even ones made of breatheable fabrics don't get the kind of ventilation that tents do. I usually keep at least 6 inches opened up somewhere near the head. My bivy is made mostly of gortex, and it hasn't had any of the condensation issues that other people have talked about. Only the taped seams get moist in the mornings.

I'd say bivies add about 10 degrees F to a bag rating, so they do alright in cold weather. Along with having the head hoop I also place my boots in the foot of the bivy to create some air space in there, and this seems to provide more heat for the toes.

I don't think any tarp will hold up to wind the way a bivy will, at least not with the Alaskan hikes I go on every year. Bivies are generally rated for 4-season use. A tarp would be a nice-to-have item used to give me a place to store gear and change out of rain gear before climbing in the bivy. (You *can* change clothes in a bivy, but you have to be a limber, slender guy.) Six Moon Designs makes a tarp I've been tempted to buy; it pitches with one pole and has some insect netting that drapes all around the ground level.

[Jason Brinkman]

Interesting that Rab describes the ultra bivy as made from "Pertex Quantum Endurance" fabric. There is no such thing. It's either Pertex Quantum, or it's Pertex Endurance. PQ is very breathable, but not very waterproof. PE is not claimed waterproof, but it has a membrane and will withstand a > 1000mm water column, so it's a lot closer. Would be nice if someone could verify exactly what Rab is using. My guess is that it's actually Endurance.

[Edit: There may be such a thing as "Pertex Quantum Endurance" after all (see below), but there is no mention of PQE on the Pertex website at http://www.pertex.com ]

The E-wing is a great looking tarp, but too short to provide full coverage in my opinion. It's ridgeline is less than 7.5 feet long from point to point when pitched as a A-frame, and it's sides slope in from there. You could fit your gear in alongside you though. You might be okay with your feet sticking out in light rain if the Rab Ultra Bivy is made from Pertex Endurance, but you'd have better coverage with the MLD monk tarp.

Q: How does pertex endurance hold up to rain and the ground? Condensation? Will I want a ground sheet?

A: No personal experience with PE, but it would seem borderline without a tarp overhead and a groundsheet underneath because of the relatively low water column rating. Condensation will be more than with PQ, less than most other membrane fabrics. Some condensation is unavoidable in a bivy under the worst conditions.

Q: What would your suggestions be for a so see-um option to accompany this set up. I'd like to keep it super light and more of a drape/bivy type enclosure so I can move in the summer when I'm not wrapped up tight in my bag.

A: It's possible to sew a piece of no-see-um netting into a bivy. I prefer to attach it along the top of the opening and leave the rest loose. When you need it, simply pull it down across your face and tuck it in. This will leave the netting draped on your face, but you can tie it up with a short piece of cord if this bothers you.

Q: Will I hate myself for not getting a bivy that closes over my face?

A: You will not need it to close over your face if you use a tarp. Closing a bivy over your face is a miserable exercise anyway, as the humidity and condensation become unbearable quickly that way.

Q: Will I hate myself the first time it rains?

A: Maybe. A bivy without a tarp is possible, but not much fun. Without a tarp there is no where to get out of the rain, dry things out, and hang out.

Q: Will this be appropriate for winter backpacking; I plan to use a marmot lithium bag.

A: Yes, very appropriate, assuming the temperature is within the temp rating of you bag, plus clothing worn, and with a minor contribution from the bivy.

Q: Last but not least how do tarps hold up in the wind?

A: Depends. Catenary cuts are made to shed wind. Judicious staking also helps. Tarp material matters too.

[Diplomatic Mike]

I have a Rab Quantum Endurance 250 sleeping bag and the fabric is not totally waterproof. It is excellent at reppelling moisture from condensation and splashes but not direct rainfall. The foot end of mine was soaked once after lying in a pool of groundwater overnight. The Endurance coating will degrade over time IMO. In cold/wet conditions, i use a bombproof Integral Designs All E-vent bivvy under a tarp, and for milder conditions, a TiGoat Ptarmigan bivvy or MLD Bug bivvy depending on how bad the bugs are.

[Roger B]

Hi Jason Welcome to the joys of tarps and bivies.

There has been a number of excellent articles written on BPL about tarps and bivies the links to some are here (though you may need to be a member.)

Poncho Tarp Inclement Weather

Inclement Weather and Tarps

As well as many excellent forum threads

Enjoy

[Christopher Holden]

Jason Brinkman wrote:
"Interesting that Rab describes the ultra bivy as made from "Pertex Quantum Endurance" fabric. There is no such thing. It's either Pertex Quantum, or it's Pertex Endurance."

Jason,
I never really thought about it until you mentioned it, but BMW/BPL does too. Check out the specs for a Cocoon PRO90 quilt. It includes "Shell Fabric: Pertex Quantum Endurance Ripstop (1.3 oz./sq. yd.)"

[Diplomatic Mike]

If you check the Rab website, under Fabrics, it gives the following info. Pertex Quantum 30g/s/m, Pertex Quantum Endurance 50g/s/m 1500 mm Hydrostatic Head, Pertex Endurance 66g/s/m 1500 mm Hydrostatic Head. As Endurance is a coating, i believe it can be applied to any Pertex fabric. P.Q.E. is the lightest.

[Gordon Green]

Hi Jason,

I too am fairly new to the pleasures of tarps and bivies. To me they make the perfect combination. I may be fortunate, but, I've never felt claustrophobic in a bivy bag. The idea of using a tarp never entered my head until a few years ago. Than I started a few trips with a bombproof bivy and a simple flat tarp; to my delight I loved it. Here in the UK we have blood sucking mini-vampires which go under the name of midges. What I found was that they entered my tents when I did, but, stayed when I got out. The first 10 minutes in tents were spent trying to find and deal with the unwelcome visitors! I thought this was no fun, so I experimented. With a bivy, with a net, (I too have the Ti Goat Ptarmigan bivy), they have a very small chance of joining me for the night. So, no time spent trying to find the last two or three that end up spending the night with me. Plus, get the right location and the tarp stands up all night. I've had the experience of a tent being blown down and it taught me to be extra careful in where I pitched.
The use of tarps in the UK is still hocus pocus, but I love it. I can't wait for an MLD cuben tarp to arrive from the USA, to start to enjoy the experiences it will give me. I do use a light groundsheet (spinntex) if only to keep the bivy bag from being covered in mud etc., The other great advantage is that, being tall, 6'2", tents tend to be very confining. A tarp is space plus…. Even when I do use a more conventional set up I'll just use a flysheet with a bivy bag.

[Jason Brinkman]

Thanks Mike, I was apparently incorrect in my prior post. I did not find any mention of Pertex Quantum Endurance (PQE) on the Pertex website (only PQ or PE), but the circumstantial evidence clearly points to its existance. It would be rare for BMW/BPL to get it wrong. Makes since if in fact the "Endurance" is a coating. A membrane perhaps? Can anyone verify?

[Stumphges]

Here's a discussion wherein a Feathered Friends rep talks about Endurance as coating on the interior of the fabric (and discusses durability issues when used with synthetic insulation):

http://tiny.cc/k97IA

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