This will be two reflections on two different bivies that I own, both made by Borah Gear. One will be a long term review of their Cuben bivy, which I (and at times friends that I loaned it out to) have been using pretty regularly for about three years now. Hard to give an estimate on how many nights. But I would say at least 40, maybe over 50 nights out of use, plus a handful of times friends have borrowed it to use. In the above picture, it is the one on top.
I have written/spoken about this bivy quite a bit in the past, and if you are interested in checking that out for more context/history, here is the first time I showed off the key central vent modification, and here is a video I did showing off the bivy paired with a poncho/tarp. Here's a picture of the Cuben bivy and tarp combo in question all set up:
The next review will be my first impressions on the new Dimma bivy, which is the one on the bottom in the picture at the top. The Dimma bivy is not listed on Borah's main website because it is a new kind of bivy that I designed and had it custom made. Due to several unique aspects of this new bivy, John over at Borah and I both felt that it should be given a name to make things easier. Dimma means "fog" and/or "mist" in Swedish, and I came up with it based on where I mostly spend my time backpacking, in humid, rainy, foggy, misty, beautiful Sweden.
So if you are interested in this new bivy after reading this review, just contact Borah and ask them to make you a Dimma bivy. I paid the normal price of an Argon top side zip bivy, which was (and is still at the moment) 95 bucks.
But before I get into the details of the long term review or the first impressions, let's first check out the specifications of each bivy:
Modified Cuben Bivy:
- Weight of Bivy alone - 135g / 4.8oz
- Weight of Bivy with guy line and stuff sack - 143g / 5oz
- Options: Side zipper, four side tie out loops (two at each end), and one hood tie out loop.
- Materials: M50 top, nano netting hood and central vent, and .75oz Cuben fiber bottom.
In the above picture the Cuben bivy is packed up on the right, and the Dimma is on the left. Good bottle of beer for scale. The Dimma bivy came with a Silnylon stuff sack, but I preferred another one that is a regular, thin, nylon sack so that it can wick any moisture that might be on the bivy. And it is slightly larger to allow for easier/faster packing.
Dimma Bivy:
- Weight of Bivy alone - 220g / 7.8oz
- Weight of Bivy with guy lines, mitten hooks, and stuff sack - 235g / 8.3oz
- Options: Side zipper, no side tie out loops, and two top tie out loops (one at each end).
- Materials: Argon top sides, eVent ends on hood and foot box, nano netting hood and central vent, and Membrane Silpoly PU4000 bottom.
I will elaborate more on the thought that went into the Dimma bivy, but first the long term review on the Cuben bivy.
Simply put, my modified Borah Cuben bivy has been one of my favorite pieces of gear over the years. I feel like I really cracked the elusive puzzle of using an UL bivy as part of a fully enclosed shelter system. The most common critique that I have read about bivies is hands down condensation. This is not a issue for everyone, for example those living in or hiking through arid terrain. But it is a valid concern and criticism of using a bivy if one lives or hikes through humid terrain, and I found this out the easy way (doing testing in my backyard rather than the hard way out in the field--it's a good idea test new gear before you go on trips!) shortly after I bought my Cuben bivy used but in great condition off a gear forum.
Yet to be fair, not all top fabric for bivies are the same. Some breathe better than others, and according to John at the time, the particular batch of M50 that Borah was using then was much less breathable than previous batches, but with the added benefit of being much more water resistant. Soon after Borah switched over to Argon as their lightest top fabric choice.
There are so many benefits to using a bivy, that in spite of this M50 being very poor at breathing, I was determined to make this bivy work. The weight was/is amazing, even by the most hardcore of SUL standards, for one. Pair this bivy with a good UL tarp of some sort, and you've got a fully enclosed shelter for half or even a third of the weight of many popular UL shelters. We're talking a total of around 300g / 10.6 oz for a fully enclosed shelter, with say a small .50oz Cuben tarp or poncho/tarp. But it's more than just weight, of course. A bivy is very easy to set up and pack up, is low on volume/bulk, and perhaps my favorite benefit is that with a tarp it is a modular system that allows for flexibility of use.
Trail shelter ahead? Great! Just throw down my ground cover and bivy, and in literally under a minute I'm done with shelter. Another minute more and I can fluff my sleeping bag and put it inside the bivy, then get started on blowing up my sleeping mat. From arriving at a trail shelter, to tucking into my sleeping bag for a good night's sleep, this can be done very quickly--around 10 minutes or less--which can be nice after a full day of hiking. Often in the summer I will stop and eat my dinner and then continue hiking, so when I finally get to camp it's just a matter of setting up, brushing teeth, hanging up food, changing clothing, and going to bed.
Then there is cowboy camping, which is just camping on a nice, flat spot in nature with just the stars above you. Not always the best option if rain clouds are on the horizon, but if all is clear, cowboy camping can be a real treat. There is nothing like looking up at the stars and moon while you drift away to sleep.
So damn it, I would make the bivy work. And I did. It worked great after I added this central vent modification. And I got such good use out of it that my first mesh fabric (which was a recycled mesh curtain) started to fall apart, so I sent it in to Borah to have them repair and replace the fabric with nano netting. And it continued to work great, though now it is a bit worn out. I've done a few small repairs with both needle and thread and a bit of duct tape, but it is still in serviceable condition. To the credit of either luck or Cuben (or both), none of these repairs were done to the bottom of the bivy--all the wear and tear is present in the M50 and netting.
But being the restless soul that I am, I saw some room for improvement in my Cuben bivy, and the day finally came when I decided to replace it. The goal was to improve it on all fronts. Enter the Dimma Bivy, which I received just a few days ago:
Right off the bat, I have to say that the bivy is well made and the craftsmanship is good. Shortly after I got the Dimma bivy I put it on the floor and got out a sleeping bag and sleeping pad to test it out. The zipper works great, and there is lots of space inside. Not much to bivies really, so the real test will be in the field, which will happen soon enough (I have a trip planned in just a few weeks). So for the record I have not tried it out in the field just yet. The seams and where the different fabrics meet are neat and mostly straight. This is a challenging project, after all, with four different fabrics to work with, and lots of odd intersections, so given all that, I think the end product came out great.
But why this odd configuration of fabrics, anyhow?
After giving a lot of thought on how to improve upon the design of my modded Cuben bivy, here are the conclusions I came to. But it is worth saying that this is admittedly knit-picking from an avid and active backpacker, and overall I would give my modded Cuben bivy say an 8 out of 10. I'd still use it, it works well, and I will keep it as a spare for friends or in case anything happens to my Dimma bivy.
One factor that clearly could be improved on was the netting. It could be a bit wider both in the middle and the hood for improved ventilation, and also vision in the hood area. In having the netting replaced, the seams were also compromised some by having to remove the older fabric, so starting with the central vent from scratch would eliminate this issue.
Next is the foot box. Sometimes there would be some minor condensation and/or dampness still present at times in the foot box in my Cuben bivy. So to solve this, an eVent foot box that I hope will be both more breathable and more waterproof than the old M50. And why not put some on the head end too? When I use a bivy and a tarp together, 9 times out of 10 I will pitch a good ol' A-frame with the tarp.
And kudos to Borah for having the foot box eVent be a bit longer than the head end. I had asked for each end to be in eVent, but this shows that they were thinking on their feet when they made the bivy, as the foot end should be a bit longer than the head end. This is because it is better to give your head/torso more coverage than your legs/feet while you are under a tarp, so it makes sense to have the foot box be made with more protection from rain spray and/or snow flurries because it is closer to the edge of the tarp. And further kudos for putting in a tie out loop on the foot box so that I can pitch it for both better ventilation and cover.
The bottom was the trickiest part for me to pick for my new bivy. I got the idea when I noticed that the new Membrane Silpoly comes standard with the Borah Snowyside bivy as the bottom fabric. The Cuben bottom has held up great, but if you are reading this you probably already know that one of Cuben's downsides is resistance to abrasion. With time I have read other UL backpackers report back on pinholes and wear with certain types of Cuben gear that naturally face more abuse, like stuff sacks, ground covers, tent floors, etc. The other downside of Cuben is cost, which also made my ultimate choice of Membrane Silpoly PU4000 all the more appealing.
So Silpoly is cheaper than Cuben, and on paper and/or in theory, it should be better than Cuben when it comes to abrasion--but worse when it comes to tearing, as it has no rip-stop grid. And for what it's worth, the Silpoly is very smooth, and feels like pretty much like Silnylon to me. Cuben feels more like worn out paper, so I would not exactly call it smooth. I figured that abrasion for the bottom of a bivy is more of an issue than tearing, and I always use a ground cover anyhow. A bivy, after all, is pretty much just for sleeping, and if you are careful with site selection, tearing shouldn't be as much of an issue with a bivy as abrasion would be.
And finally it is worth mentioning that this Silpoly is exceptionally waterproof. It is listed as having a hydrostatic head of around 4,000 at Ripstop by the Roll, and independent testing done by a dedicated UL backpacker at BPL named Richard Nisley demonstrated that this fabric had 3,514mm HH both new and after aged testing. For a fabric to be considered "waterproof" it needs a minimum of 1,500mm HH, so this is more than double that.
But choosing this fabric was a bit of a risk, because after all it is a very new fabric on the market. From what I can gather, it has only been around for less than a year, and not that many of even us UL gram geeks are out there testing it out. I am determined put this fabric to the test, and will do a follow up report on how things go after I have gotten good use out of the Dimma bivy. The other fabrics have been tried and tested, and have good reputations--to the point of there being somewhat of a consensus on Argon, eVent, and nano netting.
I own gear with that uses those fabrics, and they are some of my most used and favorite pieces of gear, namely my Borah Gear down vest (which uses Argon for the shell), MLD gaiters (eVent), and several shelters with nano netting. This is the very first piece of gear I own that has Silpoly, and I hope that it's high HH is accurate and that it is durable enough to last me at least as long as my Cuben bivy (and hopefully longer).
Yes, it's slightly heavier than my old Cuben bivy. But I am hoping that this will be well worth the weight to fix up the issues in question, plus it also has the added bonus of having more space inside by being slightly bigger. The real trial by fire will be how the Dimma bivy can compete with my MLD Serenity solo net tent shelter. I love the Serenity and have gotten good use out of it for nearly the past year now, but all in with stuff sack and guy lines it comes in at 343g / 12.1oz. This is 108g / 3.8oz more than the Dimma, but obviously comes with the advantage of space, and the drawback of having to take a few extra minutes or so to set up. I also don't needs extra tent stakes to set up the Dimma, which I need for the Serenity.
There are nuances to when I think a net tent or a bivy are preferable for a given trip. I think for an extended trip in a humid/temperate terrain, like say a thru-hike in Scandinavia, it's pretty much a coin toss for me. It boils down to: one is lighter, is less work, and needs no stakes; the other has space to sit up and hang out in, but is more work and needs stakes. What I think the main factor that will get me to choose one over the other for shorter trips, like section hikes and weekend trips, is what season it is.
During the summer and the winter there are conditions that I think a net tent works better than a bivy in a modular shelter system, but the reasons for each season are different from each other. In the summer the main issue is that there are loads of bugs, so the additional space of a net tent is of value for changing clothing, eating, just relaxing and reading a book, etc. In the winter the main issue for me is that because of the cold I will most likely be using my SOL Escape Lite bivy along with my sleeping bag for additional warm plus a drier foot box of my sleeping bag. Fumbling around with a bivy inside of another bivy is not something I would want to do. Plus in the winter any snow that may blow under the tarp is kept further away from me than it would in a bivy, which could pile up on top of me.
It is in the spring and the fall that I would choose the Dimma bivy more often. This is because there are either no bugs or only some bugs, so it is easier to hang out and sit around outside, and the bivy is just for sleeping. Even if it's raining I can chill under the tarp on its own without having to seek cover from any nasty biting/stinging pests. There is also less of a chance for snowfall, and if there is snow, it is usually the wetter/heavier type of snow that is less likely to be blown under the tarp and onto the bivy. And the weight savings is nice to have as a bonus during these seasons. The extra weight of the Serenity net tent in the summer does not matter as much, as summer weights are generally lighter (less clothing, lighter sleeping bag, etc.).
That about wraps up another double review, this time of two unique Borah Gear bivies. I will end as I always do with the obligatory disclaimer: I bought both of these bivies on my own and am under no obligation to write a review for either bivies. I contacted Borah on my own about designing the Dimma and paid to have it made.
I will be doing a vlog sometime soon (see update below) where I show off both of these bivies and talk more about bivies in general and the discussions surrounding them in the backpacking community. When the video is ready I will update this review by adding it here. Hope this review was helpful, especially for anyone that also lives in foggy, misty, damp, soggy, wet, and otherwise humid climates and areas out there.
Updated 28/02/2016: Fixed up some typos, formatting, and added a few lines for clarity.
Update 06/03/2016:
I've had the chance to play around with the Dimma and my Zpacks tarp and have settled on the following combination. Here is a full breakdown of weights:
Base weight of shelter: Dimma bivy plus guy lines 225g, Zpacks 6x9 Cuben tarp plus guy lines 235g = 460g / 16.2oz
Additional extras: Dimma stuff sack (10D nylon) 10g, Zpacks stuff sack (Cuben dry bag) 20g, ridge lines and S clips 30g, 9 Ti shepherd's hook stakes 65g, SOL trimmed ground sheet 40g = 165g / 5.8oz
Total = 625g / 22oz
Next weekend I will have a chance to test it out for the first time, and this is when I plan on doing my follow up video on it as a companion to this first impressions review. I had planned on doing this video while on a dayhike this past weekend, but got the flu and of course had to stay inside and rest. So sorry to those of you that have been waiting for the video! It should be up in another week, I hope.
Update 13/03/2016:
Finally got around to going out on a great weekend trip and got to try my Dimma bivy out for the first time. While I was out there, I shot a short video of where I set the bivy up, and as luck would have it, there was plenty of fog around. When I got home I shot another video where I shot from the hip and talk more about the bivy. Check em out:
