There have been innumerable discussions about dual-skin tents, single skin tents, tarps and bivy bags on various websites, forums and blogs across the various media available to us today. It is a venerable theme but to make sense of it all, I am going to explore and probe the various options that seem to me to be some of the best ones. An extremely positive attribute of the blogs I follow is that they are independent and the reviews, and ensuing discussions, are profitable. Of course, they are limited in usefulness by the amount of actual hill-time available to their authors, but the exercise of some objectivity still mitigates that small detriment. I hope that, by drawing together the various alternatives as I see them, anyone reading my own journal will be assisted and can conduct their own research to make some sense of the bewildering array of fabrics, blueprints and theories.

The baseline for my analsis centres around two, dual skin, tents. The first, the Big Agnes Fly Creek UL1 which is, to my mind, one of the finest UL dual-skin tents around. With Vargo titanium tent pegs, this shelter is a genuine 3-season shelter and weighs in at 965g. The second is the Tarptents Scarp 1. This tent has begun to emerge as the true contender for the throne currently occupied by the Hilleberg Akto as possibly the best, lightweight 1 person all-year shelter. It weighs 1250g without the optional pole-set which, when added, strengthens the tent further for an additional 340g.

Therefore, when considering UL shelters of any description, the weight and efficacy of the shelter must compete with these two shelters. I agree that not all people will agree with my choice of baseline shelters and the Terra Nova Laser Photon, for example, could be considered a better 3-season choice but I am using shelters I know well.

So, to break down the options as I see them means an analysis of degrees of protection. Much of this, it appears to me, seems to be about perception. Clearly there is very little prospect of any wet ingress into a dual skin tent, with the exception of condensation. In other formats, tarp-shelters particularly, the chances of wet ingress into the area protected by the shelter is substantial and other methods of keeping dry are necessary - usually a bivy bag.

If the greatest level of protection could be said to be offered by a tent, and the least level of protection, ostensibly, by a tarp then is there a middle ground? Indeed there is - a ground that is occupied by shelters that are like tents in that they go all the way to the ground, but tarps in that they have no bathtub groundsheet that creates a fully-enclosed cocoon.

We can say, then, that there are 4 levels of shelter:

The advantages and disadvantages of dual skin tents are well documented. They are the best way to prevent wet ingress from below and above, as well as the sides. They protect best from wind and other inclement weather and conditions, they can protect all of your gear from those conditions and they are also more private. The disadvantages are a greater bulk requiring, potentially, a larger pack as well as, ostensibly, greater weight. Further, they are far more liable to condensation and excessive warmth in the summer months without adequate ventilation. A far more personal, potential, disadvantage is the feeling of being cut-off from the wilderness in which you are sleeping. I say potential as, for some, this may not be an issue at all; for others, it may actually be fatal to the enjoyment of the trek.

This is Henry Shire's photo (on Martin Rye's blog) of a Scarp 1 and what it is capable of:

The Stand-Alone Bivy
An example of this shelter is the Big Agnes 3-Wire Bivy and those made by Terra Nova and Rab. It is so much like a tent and offers so little in the way of a different type of protection it is beyond the scope of this article. They can be excellent shelters, but that is not what I am analysing here. They are usually completely waterproof and breathable, often being made of Gore-Tex of eVent.

The “To-Ground” Tarp Shelter
This area of the playing field occupied by the likes of the Mountain Laurel Designs Duomid and Solomid as well as the Gossamer Gear SpinnShelter and the Six Moon Designs Vamp Tarp. These are essentially tarps that are designed to be staked in such a way as to be in contact with the ground creating a secure environment with the exception of the ground itself. There may well be more, but these three provide a useful starting point.

The advantages of these types of shelters are primarily their light weight (ranging from c.250g to 450g) as they require only trekking poles to set up and have only a single outer layer, as well as their positional versatility (where they can be set up) and their pitching versatility (how they can be set up, to tailor ventilation to the conditions, for example). The disadvantages are the proximity to what may well be wet and cold ground as there is no groundsheet and, consequently, the ingress from that ground both of inclement conditions and insect life which may disturb sleep. To offset this disadvantage, particularly when using a down sleeping bag, most users of this type of shelter will use a bivy bag if rain is forecast, possibly even if not.

The Tarp
Examples of this type of shelter are manifold but I will stay with the companies I have quoted already - the Mountain Laurel Designs Grace series and the Gossamer Gear SpinnTwinn. They are also the easiest shelter to MYOG (Make Your Own Gear). The advantages, again, centre around the weight, but, in the case of some of these tarps, they are highly versatile - they can be pitched to the ground so they are only open at the ends and they can also be used as a poncho (if manufactured that way), thus obviating the need for a rain jacket. The disadvantages are the clear - they can be extremely open to the elements and inclement weather and conditions. They would, I would venture to suggest, require a bivy bag in most circumstances, unless used by Ray Mears.

For both these latter shelters, bug netting is available but this adds to the weight and brings it within the remit of a dual-skin tent.

First off, I should say that I would be uncomfortable suggesting using any type of shelter in winter that is not a proper, 4-season tent. That said, many SUL proponents in the lightweight community would be happy doing so. That is a matter of preference and experience as well as a balance of comfort and endurance. Do your own research and make your own decisions but, please, know your limits and experience.

However, for 3-season use, the margin of appreciation is significantly larger. So, the primary reason for considering the use of alternatives to tents is weight. It is not the only reason, but the major one.

Assume that a bivy bag and, probably, some sort of groundsheet, are both required - the latter to protect the base of the bivy bag as well as provide more waterproof protection generally. I will come on to bivy bags later. Given the lesser weights of ‘To-Ground’ tarp shelters and genuine tarps, they tend to provide more space which may be a serious consideration. The Duomid, for example, is a palace.

I should say that none of the weights include stuffsacks as well all pack differently.

The MLD Duomid weighs 454g and does not include stakes of which there would need to be 8 (8 x 5g Vargo titanium stakes = 40g, although you may need stronger stakes given the fact that the poleset is not as stable as a dual skin tent, which would be heavier). It uses one trekking pole in the middle. The Solomid weighs 368g and is similar but, clearly, smaller. The Duomid is designed for two people so is a palatial one person shelter.

The SMD Vamp weighs 454g and does not include stakes of which there would need to be 5 (25g). It uses two trekking poles. It is somewhat smaller than the Duomid.

The Gossamer Gear SpinnShelter weighs 292g with the lines required and the stakes weigh 50g (supplied by GG). It also uses two trekking poles. It is, however, significantly smaller than the Duomid but extremely versatile as it can be set up as a genuine tarp as well as a windbreak. Have a look at Gossamer Gear's website for comprehensive details on what the SpinnShelter can achieve.

Moving on to genuine tarps - space does not really appear to be a consideration, which is one of the joys of tarp camping:
The MLD Grace solo weighs 212g with line locks, grommets and lines. Stakes would also weigh 40g as there seem to be 8 stake-out points.

The Gossamer Gear SpinnTwinn weighs 259g with the lines required and stakes weigh 50g. It also uses two trekking poles but has enough coverage for two people. Space is not really an issue as it is an open shelter.

If you do not use trekking poles, there is a range of carbon-fibre and aluminium pole-sets which generally weigh around 50-90g for these shelters.

Bivy Bags
Much has been written about bivy bags and I suspect they occupy a mystical place in hillwalking legend as both adventurous but uncomfortable sleeping cocoons. Whether those labels are accurate or not, they have the potential to immerse us deeper in the wilderness we love than any other medium. One need only read Ronald Turnbull's "The Book of the Bivvy" to see that.

 There are a variety of bivy bags, some of which are almost like miniature tents - the Big Agnes 3-wire bivy, for example - but, as I have said, I am not going to consider those here.

The bivy bags I am considering are much more like weather resistant sleeping bag covers that are either waterproof, being made of eVent usually, or water-resistant being made of DWR coated materials to maintain essential breathability. They tend not to be completely closed like the Stand-Alone bivy but could be, if necessary (although this is, perhaps, not recommended as a general rule).

Two of the best are these:

Mountain Laurel Designs Soul Bivy weighs 210g. It can be staked out for stability and has space and loops to place a Thermarest NeoAir inside or a CCF mat outside. It has a Momentum (see below) upper and Silnylon base. It has a single zip across the head area and noseeum mesh in that area too to prevent insect ingress. The bottom can be upgraded to 70D ripstop nylon for greater durability which would add 42g. It also has an eVent footbox to prevent condensation and can be manufactured in full, 2-layer eVent which adds 50g. Momentum seems, if one looks at BPL, to be the best water resistant (as opposed to waterproof) material around. See below:

Bozeman Mountain Works Vapr Bivy has three levels balancing, inversely, weight vs functionality and durability. They are the Nano, the Lite and the Pro. The Nano, with mosquito mesh, is 155g, the Lite is 170g and the Pro is 210g. All have a Pertex Quantum upper and varying degrees of waterproof base becoming more durable as the weight increases. All can be staked out as the MLD Soul Bivy can be.

These are, from reviews I have read, likely to be the benchmark for bivy bags available at the moment. Both, at the most durable and functional levels (i.e. the Vapr Pro and the Soul) weigh 210g although the Soul can be even more durable and waterproof if necessary but that would add 92g placing it at just about 300g.

Bivy Materials

Ron Bell at Mountain Laurel Designs has this to say about Momentum, the material used in most of his bivy bags:

“Momentum (tm)
1.05oz /sq/yd A 20dx20d nylon taffetta with single side heat calendering and state of the art DWR treatment. The surface is a flat black for speed drying. Also, it's made in the US. Momentum's tight weave adds to the DWR ability by virtue of the tight weave Momentum on our quilts.

Real Life Testing

#1: We continue to get frequent field reports that bivys with Momentum tops repelled all splashed and blown rain and snow under even the smallest tarps and that internal condensation was non-existent or at least far lower than any other bivy used before. Note: In particularly adverse humidity conditions, all bivys will experience some internal condensation. The amount varies with the bivy design, weather specifics, user's moisture output (sweat and exhalation) and bivy venting.

#2 We lined a bivy with tissue paper and then poured water on the top to form multiple shallow pools ( think: splashed or blown rain) of approx. .1 to .3 ozs and left it overnight undisturbed. The tissue stayed fairly dry and by moving the bivy all water ran off the top. (All tests with more generic 1.1 DWR's had some soak though, some really horrible!) if a lot water is soaking through, the wind is too and your losing heat.

Momentum Compared to Pertex Quantum
The closest lightweight dwr fabric to Momentum's performance found in our testing was Pertex Quantum. Momentum has the same 20d X 20d weave and the same final weight of 1.05oz/sq/yd. We do not know of anyone else that has directly tested Momentum against various other SUL breathable DWR fabrics (over a dozen) including 2006/7 Pertex Quantum in bivy tops and SUL bag/quilt shells like we have. In bivy and sleeping bag applications, we found them equally breathable but the Momentum had better water resistance and snag resistance. We suspect that this is due to Momentum's highly symmetrical weave that creates more uniform moisture venting intricacies in the weave that are of a smaller size but more numerous than Quantum's.

We feel that Momentum is the Best of the Best for our applications. You get what you pay for, and with Momentum that's true too. It was the most expensive raw fabric of all the light DWR fabrics we tested.”

So - what are we left with, when considering weights? Remember, the baseline is the Fly Creek UL1 at 964g and I am using the Soul Bivy as an example, given the reviews of Momentum fabric. All weights are approximate as many tarps need seam-sealing and may weight slightly differently depending on the manufacturing process. They are all using trekking poles as a pole-set. They should, however, give you a sense of the sort of weights concerned.

Duomid or Vamp with a basic Soul Bivy: 696g
Duomid or Vamp with more durable base Soul Bivy: 738g
SpinnShelter with a basic Soul Bivy: 555g
SpinnShelter with more durable base Soul Bivy: 597g
SpinnTwinn with a basic Soul Bivy: 521g
SpinnTwinn with more durable base Soul Bivy: 565g
Grace Solo with a basic Soul Bivy: 456g
Grace Solo with more durable base Soul Bivy: 498g

Safety and Protection

It’s clear that, with less weight, comes less protection. That much is incontrovertible. The question is whether the protection in the combinations listed above is enough for the purposes of the individual concerned and my feeling is that, in most situations, it will actually be more than sufficient. All tarps can be put into "storm mode" which basically means lowering the pitch so that the two sides are touching the ground to create a better wind-bleed. The tarp will protect from the majority of direct rain as well as wind, and anything that sneaks under the tarp will be resisted by the bivy bag. That's the theory and the practice, I suspect, is not far off. And that's with a tarp, the least "protective" of the set-ups. With the "To-Ground" Tarp Shelters, the weather protection is even greater.

In terms of weight, even with a pretty full-featured bivy bag (that is to say a more durable base which should obviate the need for a polycro groundsheet although it wet conditions, one might be advisable, adding 50g) and a Duomid or Vamp, the weight saving in excess of 220g.

If you are content to sleep under a SpinnTwinn or Grace Solo, with a durable base Soul Bivy, you could go as low as 498g, saving exactly 466g. That’s a fairly huge weight saving!

Add the 50g for a full 2-layer eVent bivy, making it waterproof and extremely breathable and it’s still only 416g. The waterproofness depends, of course, on the opening for the head and whether the tarp, in bad wind, would protect from ingress of the odd spot of rain.

It seems to me that the "To-Ground" shelters are, for obvious aerodynamic reasons, going to protect from wind and rain more than genuine tarps. However, given that any shelter should be pitched sensitive to the conditions and, if possible, areas sheltered from the wind should be chosen, perhaps this is not much of an issue. The problem is, we do not always get to choose our pitches.

In the end, whatever kit we take is a balancing exercise and the more informed we are about how our kit performs in certain conditions and the conditions that are to come, the better the choice we can make as to what kit to take.

Further research:

Hendrik Morkel uses a GG SpinnTwinn and has commented on it and, because he is no technophobe, has done a video review for you and a fuller review here. See what he has to say generally at his excellent website which really is the fulcrum of European lightweight backpacking. His resources are uniformly superb.
Joe Newton and Martin Rye have both used the Duomid and have reviewed it here, here and here. They are well worth reading.
Dave Hanlon also discusses the relative merits of bivy bags, tarps and tents in his blog - have a look at it, especially here.
Also, you can see a very good report on 4-Season tents here.
BPL in the US has all sorts of reviews and forum discussions on bivy's and shelters and, since tarp camping is practiced far more readily in the US than in the UK, it's worth paying the money and taking at least a year's perusal of everything they have.


  1. An excellent overview. It also strengthens my belief that there is fairly little weight difference between the lightest tarp/bivy combos and the lightest double wall tents, like TN Laser Photon.
    A solution worth mentioning is Gossamer Gear The One, a single skin tarptent with floor and bug protection that needs no bivy and weighs 490 grams. In my opinion the lightest solution, which gives excellent ventilation, close-to-nature living and decent poor weather protection.

  2. The One pitches with trekking poles or it's own poleset weighing 176g. It also, because it is easy to achieve a taut pitch, as a VERY spacious inner. It's certainly worth looking at. I am always intrigued by the stability in strong wind of the set-up of a tent like The One, vs a dual skin tent with a poleet like the Fly Creek. Something to discuss!

  3. Interesting article. I've been intrigued by the super lightweight options and can see how appropriate they are for North American conditions. It is interesting to see them catching on in Scandanavia too.

    I'm of the opinion that a robust tent is the best (only?) option for Scottish conditions. My reasoning? We often have wind, rain or midges to contend with. In settled winter weather I'm happy to doss out in the open but in settled summer weather I want a tent to keep the insects at bay!

    I am currently considering a Hilleberg Akto but after reading this I will look up the alternatives that you suggest.

  4. Good article Maz.

    I've got the Grace Duo which I use with a Titanium Goat Ptarmigan bivy bag. Great gear.

    Another good contender, which I now have on order, is an MLD Trailstar, which Colin Ibbotson reviewed on/in Andy Howell's blog.

    I'll use the trailstar with either the Ptarmigan or the MLD Bug bivy.

    I'd be happy to use the Trailstar in adverse conditions in Scotland. It does seem to be pretty robust by all accounts.


  5. I've just seen a cracking review of the SpinnTwinn by Hendrik Morkel which I have linked now - I am very interested in the MLD Soul Bivy with a 70D base and a Momentum top, in conjuction with a SpinnTwinn. Joe Newton is going to test a SpinnTwinn in the Norwegian hills and I think I may do the same in Lakes in October/November depending on the arrival of our first little one. I am re-reading Ronald Turnbull's Book of the Bivvy and it's setting off all sorts of emotions...

  6. A great read and a neat introduction & overview - good work, Maz!

    I'd like to say that I think it is very much a personal journey and decision of what kind of shelter one sleeps under/ in. I think many just won't feel comfortable sleeping under "just a sheet of plastic" and looking at our society at large it is understandable.

    With that said, personally I haven't slept better outdoors than under a tarp. I have the SpinnTwinn (and the SpinnShelter) which I both use with a tyvek bivy, so the real trail weight is 652 g incl. everything (pegs, aluminum poles & also the bivy). I find that quite good. There are lighter options (Laufbursche Solo Tarp, BPL Nano Tarp) but those come at substantial higher prices.

    I think the common argument one reads of "A robust tent (bombproof) is the only option for Scottish conditions" is bollocks, sorry. Colin Ibbotson, Andy Howell and Gordon above are perfectly fine in Scottish conditions with a tarp, and I think everyone can "survive" if not even enjoy a trip with a tarp and bivy. I guess they just lack the will to try it. And yes, I reckon that Scottish conditions are very similar to the conditions we have in Lapland and Northern Europe =)

  7. Hendrik tarps are a option but in the strong winds and midge season not ideal in Scotland camping high. Q. you wrote recently about your sleeping bag being damp and drying it out over a fire. Hardly feasible for four days in the rain on a TGO Challenge. I don't recall Andy Howell proving tarps work in Scotland on multi day walks as he used tents and a DuoMid on his Challenge walks. Ibbo proved they can but his tarp used on his last Challenge is far from yours and built to take the wind. His cuban version got damaged in 08 in superb weather. Hence Gordon is after a Trailstar. The wind is the issue in Scotland. Another issue I have is the need not to have to get up and and re pitch a tarp when the rain blows in the open end during the night as the wind has changed direction. Andy Howell wants to avoid that and got a DuoMid.

    Midge time in a bivy in the heat under a tarp low in the glen - yuck. I will carry 500g -700g more and be able to pitch high in winds stronger than a breeze, have the option to not need to be cocooned in a bivy night after night, not have to re pitch it when the rain blows in the open front and wind gets up. A Scarp 1 has two doors for views and room. The inner protects me from condensation and damp. I can stretch out in its room. A lot better choice than a tarp in Scotland for me. I always challenge people to point me to a high level route with high level pitches done by some one on the TGO Challenge using a tarp on the web? So 500g more gives more options like pitching high instead of needing to drop down in the glen every time the wind blows unless you are going to follow the advice of Eddy Meechan who recommends pitching the tarp so low you need to slither under it to get in. Great time spent in bad weather compared to a good tent like a Akto or Stevenson 2C. So tarps can work in Scotland no doubt but comfort and being the best choice is debatable.

    Maz great write up. So saving 500g over the Fly Creek will give you what? More miles and summits bagged in the day. That open view you can still have opening the tent door?. More ventilation? In Scotland in my DuoMid I had the hood of my bivy in my DuoMid unzipped and a bit of the sleeping bag exposed. in the night the cold air seeped in and the bag section exposed got damp. It would have not happened with a inner tent. Condensation can happen in a bivy (MLD Super light is superb by the way) dampening the sleeping bag. Inner tents protect you from condensation. Not using a bivy under tarp when the wind is bashing the condensation over you again gets your kit wet. Saying condensation is not a issue with tarps is a myth and DuoMids with doors suffer from it as well. Yea tarps can work. Over a fortnight of walking I would rather have a tent. Killer that 500g more, real killer to carry. But if that is what you want then go for it. The bottom line is have shelters that give choices baed on the trip you are planning to do. Roger on Nielsen Brown is taking a 2C on his trip next time. He uses tarps.

  8. I've refrained from commenting as I have no experiences with tarps, just with tents.

    I was interested to read Chris Townsend's comments on Jorgen's blog, which confirmed to me the diffence between northern Europe and the US.

    If you are camping above the tree line and on open fells, in bad weather, you really want a tent. Soild or mesh inner is open to debate.

    Personally, I tend to plan for the worst in my gear choices. Hence, I tend to carry more clothes and take a tent. I'm not saying others are wrong. It's their choice.

    I will be pushing the envelope a bit with a Duomid (on order). I was hoping that Ron would have the solid inner option by now, but I've had to go with a net inner.

  9. I have had this tent the terra nova voyager for just under a year now mostly took out out in fair weather I decided to camp on top of Pen-y-fan 11/04/15 the wind condition's were moderate to strong at the time's but with this being rated a 4 season tent I was confident it would withstand the weather being thrown at it , but boy was I wrong the arch pole over the door kept being blown back onto the tent and me inside all night despite being pitched correctly the result in the morning was a broken pole and where the red pole sit's over the two blue horizontal poles it had rubbed holes in both pole sleeves and the stitching inside was tearing through the inner tent where the pole sleeves attach, now I cannot insert the poles through the sleeves without them coming through the holes . I contacted terra nova about this they were useless after many emails and pictures of the damage were sent I had to send it off to them, 2 weeks for them to look at it and after they make a dissension another 2-3 weeks for them to repair it at my expense when it is clearly a design fault as there is no reinforcement protection where the poles overlap on the front of the tent but there is protection on the rear. Truly disappointed in there poor customer service I expected more form a British company I have lost faith in there product's and will buy a Hilleberg for a better experience .