I made some major changes this year to my shelter system, switching to a Mountain Laurel Designs Duomid as my primary go-to backpacking shelter, complemented by MLD’s Superlight Bivy.
While the Duomid has been quite spectacular so far, my favorite piece of new gear in 2010 has been the Superlight Bivy. The Superlight has proven itself as a moisture barrier for my sleeping bag under all sorts of tarps, and even beyond tarp camping.
I originally bought the Superlight for use primarily with flat tarps to help control rain splatter, which is rain that rebounds onto your sleeping bag after it hits the ground. When I ordered the Superlight, I had also decided to use it as a way to protect my sleeping bag from the boggy conditions I expected to find hiking across Scotland during the 2010 TGO Challenge.
But the utility of the Superlight and the customizations that I had made to it by Ron Bell at Mountain Laurel Designs extended its utility beyond just tarp camping: I also use it frequently in shelters as a bug net and to keep mice from running over my face at night, a common hazard of shelter habitation on the Appalachian Trail.
A stock Superlight bivy from MLD has a Momentum DWR top, silnylon bottom, an eVent foot panel, and a right or left side, hip-length zipper. There are also other options available for reducing weight or adding additional functions.
When I ordered my Superlight, I had Ron Bell (the owner) configure it with the larger no-seeum netting option and I got an extra-long so I could stow additional gear in the bivy in wet conditions. The total weight of my customized Superlight is 6.8 oz.
Bivy Sack Experience
I’ve used the Superlight bivy on every backpacking trip I’ve taken this year, which totals to about 30 nights of use. I’ve spent most of those nights under a tarp, but a few have also been inside Appalachian Trail style shelters.
During that time, I’ve only experienced condensation on my sleeping bag once, in Scotland, on top of my bag by the feet, when I was camping next to a stream and a mist clung to the ground the following morning. (I was in the Duomid). I hung my sleeping bag on a tree limb and it was dry before the end of breakfast.
Throughout the year, I’ve slept in the Superlight with a Therm-a-rest NeoAir Pad, split evenly between a torso length pad and a regular length pad. During the day, I store the sleeping pad in the bivy sack and roll the two up together. This expedites set up in the evening and is a very convenient way to carry the two items, while further protecting the NeoAir from puncture.
To my surprise, sleeping on an inflatable pad in a bivy sack has improved the quality of my sleep. I roll around a lot of night and frequently wake up in the middle of the night to find myself off my sleeping pad and cold. Sleeping in a bivy sack (where the pad is in the sack with my sleeping bag), keeps me attached to the pad all night. Nice!
When I ordered the extra large netting option on the Superlight, I got it because I thought it would reduce the risk of internal condensation from my breath. This proved to be correct, but the extra netting has also been great as bug protection throughout the year. There’s a piece shock cord attached to the netting that let’s me attach it to a hook inside my tap or to a cross beam in a shelter, and keeps it off my face, and tented above my head.
Like all ultralight gear, the Superlight requires a little extra vigilance in use because it is not as robust as heavier weight bivy sacks. The only time this has really been an issue for me is when the bivy zipper jams on the top fabric of my sleeping bag, a Western Mountaineering Ultralight 20 MF. This happens a bit more frequently than desirable, but gently pulling the two apart easily clears the jam. These jams can be avoided by being more mindful when opening or closing the bivy sack zipper.
While many bivy sacks don’t have zippers and are immune from zipper jams, I can assure you that having a zipper is a great convenience, particularly as night, when you need to get up and relieve yourself. In fact, it’s such a desirable feature, that I’m on the verge of getting a new winter bivy sack that has one too, because I’ve concluded that it’s an essential feature for long winter nights.
Looking back on 2010, I’d have to say that the Superlight bivy has been the one piece of backpacking gear that has had the biggest impact on my camping experience and comfort. If your main shelter is a tent or you sleep in shelters all of the time, then you probably don’t need a bivy sack. But if you’ve shifted to a floorless tarp and want an ultralight bivy sack to protect your sleeping bag from moisture and provide bug netting instead of a much heavier inner tent system, I strongly recommend you consider the Superlight Bivy from Mountain Laurel Designs. It’s a very flexible piece of ultralight gear than can be used in a variety of situations to increase your sleeping comfort.
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Any ideas on the hydrostatic head for the silnylon bottom – 1200mm as per the Scarp 1 silnylon Tarptents use, or less? I know that the Soul comes with a 70D option for the base – does this have a hydrostatic head rating which is higher – I have not been able to find anything on the MLD site on this…
This was all great information to read! Def planning on buying the superlight bivy with the optional cuben fiber floor in the spring and the optional all net hood.
Maz – just ask Ron Bell at MLD. He's co-developed some new silnylon floors, so I wouldn't assume anything about his materials. You can contact him using the [email protected] address at MLD. He usually responds very quickly. Also check out the fabric mojo link on his homepage.
Brian – that cuben floor is a new option. They're always innovating at MLD.
I have two. One same spec as that and the older version. Reading your review made me smile as I had thought of doing my own. I wrote on BPL recently after Ron had posted to say he has other new bivyt bags he had designed that the superlight is tops for me. I cant fault it in the most damp and variable conditions it works. I don't always want to use a bivy but it is so good it would be foolish not to have it on long trips like a Challenge walk.
My gear of the year is also an MLD bivy – the Bug Bivy. It made my favourite tarp, the Golite Cave 1, viable in Scottish, summer conditions. Midges never found the zip.
Have you seen a bug bivy like this that is wider, perhaps 36″-40″ towards the top end? My husband and I are searching for one that we can both fit in together, we’re both pretty small.
I agree, I have one of these and I love it. However, I had no idea how many different ways I could use it. Thanks for this post, it gets me thinking in new ways.
ABout 6 years ago I looked at bivy's with an eye to getting one for light weight camping. At the time, the best I could find was a simple sack and screen at about 10oz. Soo, I pretty much gave up and went back to my screen tent and bathtub floor for two (18oz.)Your writing has me much interested in renewing my search. Given the weights of the new materials for the tarps and bivy's, I will have to take a fresh look at these. They now hold the promise of dropping the combined weight for two to less than 16oz. I hate to make a change unless I can save significant weight.
It really is possible to drop to the next weight tier.
Yeah. 42oz is not that bad for two people, though. But the wife's knees are getting quite bad. She really can't get out unless we can canoe somewhere (meaning she can sit down for at least half the trip.) I am thinking solo but that means all new gear…probably more than I can do since I am retired. As soon as I finish the canoe, I will put together a list for what I need for a bivvy, tarp, and ground sheet. (I think I can make those too.) If I do it myself, I can use cuben for everything, 'cept the bivy top, the netting and the ground sheet. Cuben can be tough to work with, though. Not the same as sewing and sealing… I will compare that with a tarp tent set up (I have plans for those)and see how they compare, using silnylon for the floor.
I think the nice thing about cuben is that you can make a tarp or even a pyramid that is big enough for two and still use it for solo. For example, I have a Grace Duo flat tarp and a Duomid from MLD. Both provide a lot of space for one, and quite enough for two. For me, solo, the incremental weight is immaterial. I think you'd get an equivalent benefit with silnylon as well but to a lesser degrees. I doubt I will ever use either shelter for 2 people, but having all that extra space is really nice.
Looking to add this bivy to the gear I'm taking on my PCT thru-hike this next year. Have looked around, there's really nothing as light and as well made it seems.
Especially important to me is the fact I have a Jacks'R'Better Sierra Sniveller quilt, which is down filled. This next year looks like a La Nina year, which means wet and snowy all through the Sierras, and into Oregon, maybe beyond. The ability to keep my down bag as dry as possible is key, as is the extra warmth I'll need. Also, not just insulating warmth, but warmth lost to draft, as I'll be using a semi-open quilt.
This is good stuff. Thank you for the review!
Great review and great comments as well. I am really interested in this bivy. Would this bivy breethe enough during hot, humid, summer evenings in the Mid-Atlantic?
Yes, I used it all year in New England and it was plenty hot and humid. Just be sure to use a lighter sleeping bag/quilt.
I realize you're under a tarp, as I am as well!, but are there any concerns about moisture getting into the bivy thru the zipper? My current bivy works well, but that zipper would be a great convenience in terms of getting in and out. Thanks for the great site; it's a must read for me.
I don't think letting moisture IN is the problem under a tarp. Most bivys have trouble getting moisture out. Condensation from normal perspiration (and through a sleeping bag)is the more usual problem. It will usually condense on the first surface with a temperature differential consistent with the air humidity….usually the outer shell of a bivvy or tent. (Really glossing over a lot of stuff here…) It becomes important only at low temps, say ~40F and below, where it has low evaporation, hence, build up without good ventilation. Or, in very high humidity (super saturated air, I am thinking of, such as Earlylight encountered in Scotland.)If
anything, the zipper would also help with this, too.
Marco – I think Andrew is concerned about moisture seeping into the bivy from the surrounding snow under a bivy or in a snow trench/shelter. This is something I also considered. Under a tarp, I doubt there will be a problem simply because I will prepare the site by stomping down the snow on which the tarp is set up, and it will harden up. In a snow trench or cave, I doubt water will get in because the zipper will be located about halfway up the side of the bivy. I'll also be on a down filled air mattress and even if it does leak, the water should pool under my sleeping pad.
Thanks Marco. I understand condensation. I was thinking more of spray or direct rainfall with a smaller tarp just covering your head area.
Earlylite- OK. Yeah, snowshoes or skis help with that. More to it apparently.
Andrew – I sort'a thought that went the way of the dinosaur since it leads to a LOT more condensation. Back in the 50’s and 60’s, these were a popular myth. The typical sleeping bag also had an awning for rainstorms. You could take canvas, paint it (coating,) and it became fairly waterproof. Of course, you know how successful that was if you know about condensation. There are few holdovers from that time. A good thought though. Check some of the really fancy bivy’s out there. More along the lines of a small tent.
Most of the breathable fabrics (all that I know of, anyway, Epic, eVent, Pertex, etc) get "plugged" when wet, they stop breathing. As I understand it, the pores get coated with a film of water…sort’a like a plastic coating. Then they condense on the inside. With water on both sides, it will penetrate. One or two hours and your bag would be getting quite wet. Only if you are sure of no real rain(mountaineering for example) would I consider it for the weight savings. You might be better off with the bivy you have if it has worked for you this way. Unless you are sleeping in a deep puddle, I don’t think the zipper will be a real problem.
You can also siliconize the zipper, like I do with sil-nylon floors. While it will leak a little, a mixture of mineral spirits and silicon calk (not siliconIZED) can be made up…about 80/20 thinner/calk. Paint both sides of the zipper, inner and outer, with a fine foam brush. This should waterproof the zipper, ‘cept the teeth. This also works well for sil-nylon floors, as was mentioned. You actually need thicker to seam seal, though.
My thoughts only . . .
Marco, thanks again. I think we're having slightly different conversations together. My only concern was direct leakage (snow, rain, spray) thru the zipper itself. Neat idea with siliconizing the floor of the bivy. Is it any harder to stuff?
Philip – you've convinced me – I have the Hexamid Tarp with extended beak and was using an Oware Biv (286g). Just sold it and placing a order for the MLD Superlight with Cuben floor.
Do you think this combo will be good for the JMT this August?
Ditto Rob, I also have the Zpacks Hexamid (with optional door) and have just ordered the MLD Superlight with Cuben floor. I have been using an Alpkit Hunka bivy but am really attracted by the side zip and of course the lighter weight of the Superlight.
Having sleepless nights – MLD superlight with cuben or Sil floor? There is an 81 gram weight and $US55 ($NZ75) cost difference – decisions, decisions, decisions!!!
I used to be willing to pay $20 USD for every oz of gear weight reduction. Performance wise, I doubt the fabric will make much difference,
I calculated my cost would be just on your $US20 mark!
Re the Sil base – any problems with slipage of your sleep pad – I have a Kooka Bay 3/4 (nylon).
Also I note you use a Polycro ground sheet – is this necessary? Was this only in boggy Scottish conditions to aid waterproofness, or to add some protection to the base (stones, twigs etc)?
The base could so with a few lines of seam sealer to reduce sliding. It was an issue when I used a shorter pad.
In Scotland, I used the polycryo because of boggy conditions. I don't use it much anymore in the states except in shoulder season.
That cost metric is useful, huh?
Thanks! I wonder if one would get slipage on cuben?
Re – ground sheet – I am doing the JMT late August so guess I leave the ground sheet at home?
I hope you've been enjoying your spring hike. I just received a super lite bivvy from MLD. I ordered the regular , which was a mistake, it's too small(I'm 6' tall and use a regular neoair pad). How big is your extra long? I'm going to exchange this for a bigger one and I don't know if I'll get the large or something bigger.
Evan – I just got the large (I'm 6') – but use the Kooka Bay Air matt – 2" high – It works well – great biv – very well made and LIGHT!
Evan – I'd just call Ron at MLD and talk to him direct. I think mine is 6'6". It's longer than my regular Neo.
Would this bivy keep things dry if you weren't using any tent or shelter, and sleeping in snow or rainy weather?
No. Mine has a screen over the head for air circulation. If you want a general purpose bivy that provides all that, you really need to look at bivies that have have a lot more structure in them like the Big Agnes 3 wire bivy or some of the Outdoor research bivies that close up fully. The problem with these is that they're heavy and they don't have enough space for you to lie out a storm without going crazy. You're better off getting a small tarp with an optional bathtub floor and netting for the weight. They also have a small enough footprint that you can pitch them anywhere – like a bivy.
Hi, I wonder whether the MLD Endurance on top of the bivy is waterproof or just waterrepellent (big difference).
Thank you for your answer
Contact Ron Bell at MLD and ask him. My model, which is now 2 years old, uses Momentum not Endurance, whatever that is.
Great write up; I would love to find one like this that is about 36″ – 40″ wide towards the top. My husband and I are both small and live / travel on foot out of 2 smallish 30L packs, one good bivy would be awesome but so far I’m unable to find an oversized one!
It looks like I spoke too soon or I was reading the wrong product specs. MLD lists:
Med: 72″ shoulder 54″ foot
LG: 78″ shoulder 58″ foot
XL: 82″ shoulder 60″ foot
So these are 36″ – 41″ in width at top, just might work!
We tend to travel in warmer climates and no sleeping bags. Not digging the hammocks too much yet, too partial to sleeping together with shared stuff for less to carry! Have lucked out with rain so far, usually find some sort of weird shelter options, but the mosquitoes and fire ants have been something else to contend with!
How has the all net hood worked out for you in the winter? Does it get drafty or still perform fairly well? I’m on the east coast as well and leaning toward the all net hood to help combat condensation. Just wanted to see what your thoughts were on it and if you would go with the all net hood if you did it all over again.
I don’t use it in winter. See https://sectionhiker.com/integral-designs-event-micro-bivy-sack/
Hi, I purchased one of these earlier this year, and its been great, but as we get further into summer, I’m having a harder time sleeping: within a few minutes of getting in, it gets to be like a sauna, but if I open it up, i’m assaulted by mosquitos. Any advice?
Don’t sleep near water like a lake or stream and avoid sleeping directly on wet ground. Also sleep on top of your insulation, not under it. That’s all that comes to mind.
My Zpacks Hexnet weighs only 7ozs, full netting and cuben floor. So for the same weight as a bivy I can sit up, cook inside etc. Fits inside any mid or shelter
Agree John – I had the Tarp and MLD biv set-up for a couple of years (did JMT with it and never pitched the tarp!).
I’m a Hexamid man – been using it for a couple of years now, it’s the bomb. I got mine custom made in .75 cuben for NZ conditions
Tried out my new MLD Superlight bivy this week on an overnight on Glastenbury Mountain in Vermont. It wasn’t crazy wet weather, though we did have rain the next day. I woke about 0300 to find my bivy has condensation from head to toe – just enough to wet the quilt I was using, but not much more. I was able to go back to sleep but had to dry out the bivy the next morning. I wonder about 5 days on a trail like that.
Philip – over time have you had any condensation issues with your bivy? What can I do to help offset this? Dry camp, away from the creek, under a tarp with plenty of air floor, decent ground sheet (polycro).
I was disappointed by the amount of condensation but still I had the best sleep ever in tarp/bivy than I have ever had in the woods.
Edit to add: I did go with a large mesh (as you did for yours) and opted for the CF bottom.
Never much. Maybe a little dampness over the foot box of my bag/quilt. Condensation is very weather dependent and will be worse if you sleep near a water source like a lake or river.
I have this super light bivy and really like everything about it but I have one issue. If I’m on the slightest grade I find myself sliding down hill. I use an inflatable pad and sleeping bag with it. Any suggestions?
Prop up your feet with a jacket or your pack.
I ordered a MLD Superlight bivy, all net hood, and am wondering what tarps I can choose from that work well with that bivy. I think there have to be points, line or loops from which I can suspend the hood of the bivy – but then again I guess one could rig a line under most tarps, which would probably work as well? Lacking experience, I find it difficult to assess the options/set ups of a tarp. The MLD tarps are a bit too expensive for me (except for the Monk which is too small for my taste).
Some possibly suitable tarps: DD tarps, the Snugpak Stasha, the Alpkit Rig 3.5, Terra Nova tarps, Integral Designs tarps, Rab Siltarp. Any ideas on those? Other options are welcome as well!
try Boarah Gear
This bivy seems really nice and I’m about to pull the trigger but I’m wondering about the flat length of the superlight bivy (med or large)? It doesn’t seem to show on MLD website. Thanks.
They change the specs all the time. I suggest you send them an email and ask.
Great article and discussion! One of the things I do WHEN CONDENSATION WILL BE A PROBLEM is to use a vapor barrier liner between my body and quilt. That eliminates condensation except at the area immediately around my mouth. I ware heavy weight long underwear. Be prepared for a sudden chill when you get out, but know that it lasts only a few moments even if you are outside for several minutes. When you get back into your vapor barrier sack under your quilt or bag, you will warm up almost immediately. I use the Emergency Bivvy from SOL. REI has them for less than $20 last time I looked. I don’t think they are intended to be used for many days, it’s called an Emergency Bivvy, but if you are careful getting in and out you can get many nights of use. I’ve had mine for over two years now and no signs of wearing. It weighs about 3.5 oz., takes the space of a 12 oz. coffee cup and increases my temperature range by , at least, 10 degrees. Another idea for dealing with condensation is to use a light/thin synthetic quilt/blanket over your quilt/bag so that the dew point is in the synthetic and not in your down where it won’t dry on a winter trip.